# Limited Slip Differential



## Kennedy (Jan 18, 2000)

I am wondering what people think about using limited slip diffs (or lockers) in plow vehicles. My particular case is a shorter wheel base, full-size truck, a K-5 Blazer. I like the idea of more traction, but I wonder if you get that unpredictable "kick-out" to the side. What do we think guys?

Dave Kennedy


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## Doug406 (Jan 24, 2000)

I have a Detroit locker in my 86 chevy and I love it. Regarding the kick out thing, in four wheel drive it is not a problem what so ever, although in in 2wd it is a blast. Do not put a locker in the front though, as you will loose all control of steering when accelerating


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## plowking35 (Dec 21, 1999)

What do I think?
Well if you read my post about me being stupid during the last storm. Long story short, I had no 4wd during Fri night into sat morn, and my limited slip got me through.
it will be standard on all my new plow trucks.
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## GeoffD (Dec 21, 1999)

Limited Slip is a great thing to have. Some of my trucks have it and some don't, i think only one has it. My trucks stay in 4wd most of the time, only it's nice to be able to used 2wd and have limited slip on those little snow and ice falls.

Geoff


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## gene gls (Dec 24, 1999)

I am all for a locker in a work truck. I had to get a Lock-Right for my Chevy 2500 because of the rearend size.It works great but is very noisey and it has kick-out.


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## Kennedy (Jan 18, 2000)

So the Detroit isn't to harsh? I hear reports that Detroit lockers add an inherent 
"clunk" to the drivetrain. I'm happy to hear such strong support for them. Thanks guys


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## thelawnguy (May 20, 2001)

I ordered my 95 Dodge new with a LSD its great in the rain but its a pain in the snow, I have a couple crunched running boards from sliding into walls. I wouldnt get one again. An open diff is much more predictable in the snow, and if you need the extra traction just ratchet down the e-brake a click or so, works just like the two brake pedals on a tractor.

Bill

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"...half my brain tied behind my back, just to make it fair." R.L.


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## Doug406 (Jan 24, 2000)

Yes the detroit has an occasional clunk, but that just lets you know it is back there. It is not something that will interupt you listening to the radio or something. As for the previous post about &quot;kicking out&quot; , I'm telling you, if it is in four wheel drive this can not logically happen, because the front wheel will turn at the same rpm a s the rear, keeping you in line with the rear. In fact, when I have salt in the back, I plow 60% of the time in 2wd and nave no traction or kick out problems. I like 2wd because then you do not have the binding problems with the front axle while turning on drier pavement. GO WITH THE LOCKER!


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## plowking35 (Dec 21, 1999)

IU agree 500% with Doug. The factory limited slips work fine for me, and having posi, especially in reverse is a huge +. The front binding drives me nuts, so I like plowing in 2wd. Having 4wd at the move a lever is a nice feeling tho.
Also would you consider changing your signiture, it seems kinda over the top.
I think most of us here are pretty smart people, and that seems kinda degrading to me.
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## chad (Feb 27, 2000)

you can get the best of both worlds with an airlocker which is activated with an under the hood aircompressor when not activated your diff is open when activated its locked, they work great ARB LOCKERS are probably the best out there


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## nsmilligan (Dec 21, 1999)

I always custom order my trucks. I been there done that, and don't buy diesels for plowing. The return isn't there. Diesels are great if you're putting on a couple hundred thousand a year, but my trucks don't back up that far! I go with Big block gas, same torque, which is what counts in plowing. I've found that fuel economy is abut the same plowing. With the big gas engine option trans and engine coolers are included. I always add the trailer towing pkg. because it will add these options anyway, plus the hitch (usually less then the cost of a hitch)
ALWAYS add positrack or limited slip to a plow truck, You'll pay for it the frist time you don't have to pulled out. As for the side slip, stop back up and take a smaller bit, you're already pushing more snow then you could without it. 
PS With a little weight e.g. salt spreader you can plow in 2 wheel drive for the lite stuff.

Bill


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## John DiMartino (Jan 22, 2000)

Bill,I disagree with your don't buy a diesel theory.You are right in that it probably wont pay off-but the resale more than makes up for that,and the torque of my Cummins isnt attainable by any gas engine operating at RPM's we see when plowing.A powerstoke is just also very strong-the V10 6.8 is a sorry motor,all rpm's no torque 'til 3000+.GM's are both about the same,but 6.5 is still stronger at low rr's when pushing.As for fuel economy,you must be kidding.I burn about 1/3 the fuel in the Dodge as my 350.My cousin has 454 vortec,and he fills 4 to 1 with me.I have 35 gal tank,he has 34.That 454 cant touch my diesel when it comes to pushing,diesels put power down smoother and steadier allowing them to push without wasting any through the tires or tailpipe.As for locking diffs,I like the Dodge's tight posi better until you really get one tires on ice and other on blacktop.Gm used lockers that are open diffs until a speed difference is apparent and a load on it.Some times I've got stuck and had to bring the locker alive by dragging the brakes,by then its too late.You would've made it through with a posi rear or detriot.Either is way better than none and I like the soft detriot locker best.I had an older one,it banged but it worked.

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John D


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## Kennedy (Jan 18, 2000)

Well I went ahead and did it. I just ordered a Detroit Locker for my Blazer. I am converting the truck to 3/4 ton axles this summer (with the 10.5" ring gear 14-bolt, that you guys with GM 1-tons have).

I decided based on the fact that I have a locker now- I'd hate to learn what it's like to be without one while plowing.

This forum has also made me realize that if and when the transfercase, front axle, front driveshaft, etc fails... I will be in much better shape with the locker in the rear. I'll let you know when I get it in.

Thanks again,

David


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## nsmilligan (Dec 21, 1999)

John, I haven't plowed with a Dodge, Just can't accept their 1950's suspension. I have a 6.5 Turbo, and a Vortec 454, at the end of the day the extra cost of diesel( up here about 12% ) the cost for fuel is about the same. I did have the dealer recalibrate the 454 to GM's towing specs, they both deliver about the same fuel mileage around town, the Diesel only shines on highway mileage. I can't really detect a difference in the way the power comes on when plowing, both are smooth. Maybe I have an exceptional 454, because a buddy of mine has one that seems to eat gas, he replaced the air fiter with a K&N and reprogrammed the computer with a kit, and is a lot happier with the truck. I am going to look at the new duramax, but again the initial cost may outweight the benefits. The resale value is higher with the diesels, but I find they're also more costly to maintain, more expensive filters, more oil, etc. Anyways happy plowing, and watch out for raised manhole covers.
Bill


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## John DiMartino (Jan 22, 2000)

Bill,I didn't know you had a 6.5.They aren't as good on fuel as a Cummins or Pwrstroke.My dad has one and I agree,it isn't worth the money unless you get a discount for buying it.The indirect injection is to blame,I get 17-19 average w 4x4,6875lbs 2500 dodge,my dads 1500 2wd 4685lb 6.5 gets 15.I can get 23-25 mpg at 65 mph,he gets 17.They do tow well in a 1500 truck though.Bill,my trucks never shut down in a storm,unless they break down.This is where the diesel burns hardly any fuel,so little in fact that laws of thermal efficiency wont let them warm up unless you work them,or rev them up, so as to burn enough fuel to generate some heat in the motor.I notice the 6.5 warms up way faster than my cummins,proof that they burn more fuel.In your case Bill,i would have went gas too.But Dodge's V8's are more thirsty than the Vortecs and put out less power,(exV10).The reverse is true for diesels so that is why I have one.What do you think is 1950's on a Dodge.Mine rides as good as my 1500 Z71 did,and the posi rear is better than GM's failure prone locker.You have no ground clearance with a GM,I know I have 2 of them and they get stuck and the Dodge has to pull them out.GM has no overloads for heavy loads,no rear anti-sway bar and a weak idler arm,pitman arm.I still love mine,but these are facts.It is one area where my Dodge is so much beefier.Yeah,my track bar went,and so did a U-joint,but the Dana 60 front and 80 rear in my 2500,are also used in F450's.So who's will last longer.

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John D


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## GeoffD (Dec 21, 1999)

I don't think Ford uses the same rear end in a F 450 or 1 1/2 ton truck as Dodge would use in there 2500 or 3/4 ton truck. I could be wrong but i think the 550 and 450 use the same rear ends. I don't think you would find the 3/4 ton rear in a 1 1/2 ton rear. I could be wrong

Geoff


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## Lazer (Jan 1, 2000)

The 550 rear end is larger than the 450 by quite a bit.


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## GeoffD (Dec 21, 1999)

From what i can find in the Ford Commercial Truck book. The F 450 and F 550 have two rear end choices depending on if you have the 6.8 v-10 gas or 7.3 power stroke. You can get a 4.88 or a 5.38, i don't think you will find those in your Dodge 2500. You may find a 3.73 or 4.10 ( again this depends on model and motor choice ie 5.4 v8 6.8 v-10 or 7.3 power stoke) found on the F 250 SD and F 350, in your Dodge.

So the 450 and 550 do use the same rearends.

Geoff


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## plowking35 (Dec 21, 1999)

Well I will throw this into the fray. I know guys with 6.5's getting into the low 20's for fuel mileage. I know guys with cummins getting in the mid teens for mileage, and vise versa. 
I get 13 mpg with a 6.5 in a k-3500 that weighs 9500 all the time. I am at 15000# with the plow sander and sand in during a storm. While plowing I dont check mileage just hours. I can go 30 hrs on 35 gals of fuel. My last truck was a 86 k-30 with 4.56 gears and the same weight ratios. It would burn 32 gals in 15 hrs plowing. So I get 2x the plowing with the same amount of fuel.
Now we all could argue Ford vs Chevy vs Didge all day. they all have pros and cons. I agree with the pitman arm, took my dealer 4 visits before they changed it, an I had to tell them what was wrong. It started to go at 24k and they fianlly changed it at 34k.
But I know just as many dodges with diesels that have junk front ends. Cant keep tires or alignments on them.
BTW I test drove a 2000 F-350 mason dump auto with a PS, and all I can say is WOW
What a POS. Loud ,obnoxious and no power till at least 2200rpm. Then it takes off and you can feel the power. But the noise is so overwealming at from 500-2200 that it sounds like the engine is going to blow.I cant imagine driving one all day, I would kill myself. WHile the 6.5 doesnt have as much power, it is alot more driver friendly, and quieter.
I have also driven a cummins as of late and of the 3 the cummins is really the class of the field, to bad its wrapped around a dodge body. Just my personal feeling as a loyal chevy man. Dont know why I am one, glutton for punishment I guess.
All of the diesels mentioned tho do much better with a standard behind them. Diesels really are made for a stick, to bad sticks and plowing are such a bad combo for ruined knees.
If and when I buy new again, I dont know If I will get another diesel. The break even point is so far down the road I dont know if it is worth it. When I bought mine, the 6.5 was only a 1200$ option, so I broke even at about 25K. If I payed the 4k+ for the dodge or ford diesle option I would need at least 100K before I reach that point. Of course you get alot of little things with the diesel option package that you pay extra for with a gas, so one has to consider that also.
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## GeoffD (Dec 21, 1999)

That Ford 7.3 may be load in a truck. Only when we pull a 12,000 exevator on a 4,000 pound trailer with an F 350 it makes all the difference. Only back in the day i used to pull that same set up with an F 250 HD and a 5.8 gas engine, so go figure.

BTW we all drive work trucks, so sometimes ya have to let a few conforts go ie the loudness of the truck. Just remember what was around in the early 80s, remember the inside? Oh yea the other reason i buy Ford is i am 6'4" with a size 16 foot. Just can't seam to fit in a chevy, and didn't like the seats in a dodge.

Now with the 550 and 650 towing isn't an problem, and anything bigger we just use the L8000.

Geoff


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## Kennedy (Jan 18, 2000)

Now that we are talking about axles,one of my favorite things I'd like to set the record straight.

Dodge 3/4 tons with either the Cummins or the V10 use a "Dana 80" rear axle.
All the 1-tons(even the 360 V8's) use it as well. This is an 11" ring gear axle.
3/4 tons (HD) use a Dana 60 front axle, and 1-tons use the Dana 60 in the front as well.

Ford likes to be a little bit more confusing. The Super Duty F-250, and F-350 both use Dana 50 front axles, and their own Corp. 10.25" diameter ring gear (Steerling) rear axle. F-350 Duallies use Dana 60 front axles and either the Steerling 10.25" axle, or the Dana 80 (like the Dodge 3/4 tons (Diesel or V10).
The F-450 uses the Dana 60 front axle (9.75" ring gear front axle- again just like the Dodge 3/4 tons). And in the rear they use the Dana 80, but on the F-450, they add an aluminum differential cover.

And the F-550 still keeps the same Dana 60 front axle (Same as the Dodge) but steps up to a Dana "135" in the rear. This is a 13.5" diameter ring gear axle that looks much like the Rockwell or ZF axles that medium duty trucks use.

I'll add the loop hole that there may be a few F-350's and Dodge 3500 daullies running around out there with Dana 70 rear axles (10.54" ring gears)

All of the above axles are of the full-floating variety.

GM uses their own Corp. 14-bolt 10.5" ring gear, as well as some Dana 70's on 3500 DRW. 
And their 3500HD's use the Dana 80.

With the new Duramax engines come a new rear axle, the corp 11.5" ring gear, but that is one I have yet to see in person

Kennedy


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## plowking35 (Dec 21, 1999)

Ok Kennedy
My ? is. Why do some people have problems with the front axels/tires on the cummins powered dodges, and not with the PS fords. They both have the same axels, and about the same front axel weights.
Also in 98 dodge said no plows on any diesel 4x4's except cab chassis, while it was no prob on the ford trucks. ?????
BTW Ford does own dana corp and cummins engine co. so every dodge you buy makes ford that much stronger
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## Lazer (Jan 1, 2000)

Dino,
Dodges turn the axles tighter.


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## Kennedy (Jan 18, 2000)

When it comes to the Dana 60, there are a few changes that each customer (ie. Dodge, Ford, or GM) will make to the product. While it is true that they all use the Dana 60, they all use it in different ways. Dodge uses the front end design that some credit as being old Rambler engineering. We recognise this set up from the Cherokee. While the Ford uses a redesign of its old leaf spring suspension. Both ride very well given their weight capacity, but the leaf springs of the ford seem easier on the ball joints, tires, trac bar etc. In 1995 both Dodge and Ford use the same part numer for ball joints. Let me go on record now as saying that I think the in the HD 3/4 & 1 ton market-none of the big three make a bad product. Each have their pros and cons, but each seem to be a good option. Really for me it would come down to price and service.

Kennedy

p.s.

As far as the plow package no being offered on certain trucks. I know that GM use to play the same game, not recomending a plow on the extended cab trucks. I think it comes down to a question of frame strength and crash testing requlations. But these are thigs I am not certian of.


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## DaveO (Dec 21, 1999)

Dino,

The reason Dodge had no plow pkg available was the FAWR. Seems that with the Cummins installed (970lbs) the weight rating of the axle would be exceeded with a plow. I believe that was 4800lbs. This year (2K) you can order a plow pkg with the Cummins, FAWR is 5200lbs.

Kennedy, I think the Dana 80's were only used in the 2500's with the 5.9 diesel/V10 WITH the 5 speed. The auto's used the Dana 70's. John will know this I'm sure....Is this true John???

Dave


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## Kennedy (Jan 18, 2000)

Nope, I have driven Dodge 3/4 tons with autos and the Dana 80. I have also driven a Dodge 3500 DRW with a five speed/ Dana 80. I bet the five speed/360 package is true to what you say. I have not seen any 360 powered autos (Not Diesel here- remeber they're both 5.9 liters) 1 tons up close, maybe they use Dana 70's.


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## DaveO (Dec 21, 1999)

Kennedy,

If this is accurate...

Ram Axle Specs 
Gears, Axles, Payload, Torque, Etc.

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Ram Axle Chart 
Model Rear Axle GAWR 
Ramcharger/W150/250 to 1993 Corporate 9.25" SF ? 
250HD/diesel 1989-1993 Dana 70 10.5" FF 6500 
350 1989-1993 Dana 70 10.5" FF 6900 
BR1500 Chrysler 9.25" SF 3900 
BR2500 1994-1995 (LD) Chrysler 9.25" SF 3900 
BR2500HD V8 Dana 60 9.75" FF 6200 
BR2500HD auto trans Dana 70 10.5" FF 6500 
BR2500HD man trans Dana 80 11" Hybrid FF 6500* 
BR3500 Dana 80 DRW 11" FF 7500** 
* 6800 with Quad Cab
** 8000 with 3500 chassis cab

Ram Front Axle Chart 
Model 4X4 Front Axle GAWR 4X2 GAWR 
Ramcharger/W150/250 to 1993 Dana 44 8.5" ? ? 
250HD/diesel 1989-1993 Dana 60 9.75" 4500 4000 
350 1989-1993 Dana 60 9.75" 4500 4000 
BR1500 Dana 44 8.5" 3850 3650 
BR2500 1994-1995 (LD) Dana 44 8.5" 3850 3650 
BR2500HD V8 Dana 60 9.75" 4850 4500 
BR2500HD 1994-1999 Dana 60 9.75" 4850 4500 
BR3500 1994-1999 Dana 60 9.75" 4850 4500** 
BR2500HD 2000+ Dana 60 9.75" 5200 4500 
BR3500 2000+ Dana 60 9.75" 5200 4500** 
** 4850 with 3500 chassis cab


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## John DiMartino (Jan 22, 2000)

You guys are great,I sure stirred up some mud with this post.Thank you,Kennedy for setting thr record straight.I have crawled under and personally worked on F450 SD,that is how I know they have the same rear as my Dodge,The 550 has a much beefier rear axle,and I think most people buy 450 thinking just springs are different.The only 3500 dodges that have 70's are the 89-93 old body styles.Dave,you are right,the book says auto's have 70's,but mine and many others I seen have 80's so I dont know.It sure is overkill for a 3/4 ton,I love it.Dino,I was a GM man,but the low end muscle and love of a real I6,turbo screaming at 30PSI boost and the roomy ext cab(So much bigger than my94 z71 ex cab) that is great for my 3 kids in car seats,and a screaming deal from a Nissan dealer that didn't know what they had taken on trade and wanted to sell quick.There 7000 lb lifts just grunted when they tried to lift it to inspect it.It doesn't hurt that it turns tighter than my SWB z71,and it's a long bed.I love the truck,but it has nickeled and dimed me to death with things that shouldn't be happening at low mileage and age.I wish it were as trouble free as my 89 GMC w/140K on it.I also drove the PSD and as soon as it started I killed the motor,told the salesman that it sounded like someone left a spoon in a blender.I cant believe how loud and thrashy it sounds,it is not a good sound either,I also noticed no power until 2200+.No boost either,just a dog and then a rush.Kinda peaky for a truck motor.The Cummins has more pull at 1500 than PSD did at 2200.I think it was faster stock than my Dodge stock,but you had to wind it to 3300.That is to high for a 7+liter diesel.Now with power kit,PSD's are a snack and from 40 up V10's and 454 vortecs are too.If GM had the Cummins or a Cat they would dominate the market,I wont buy the upcoming Duramax no matter what,It has aluminum heads,no good.I do head gaskets on so many cars/trucks with them that I could never own one,and besides it's an Isuzu.Nuff said

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John D


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## GeoffD (Dec 21, 1999)

I still don't think Dodge uses a 4.88 or 5.38 gear ratio on the rear end of a 3/4 ton pick up. I might believe it on a 1 ton, but the end result is you can get a 550 4.88 rear end and you can also get a 450 with the 5.38. I just can't see a pick up with these gear ratios in their rear ends. I just would think that if Dodge offered a 5.38 or 4.88 rear end in their 3/4 tons than Ford would too.

Geoff


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## John DiMartino (Jan 22, 2000)

Geoff,dodge only offers 3.55 or 4.10.They do not need any more gear,I wish mine had 3.07 ratio.It's torquey motor can pull a taller gear than a PSD all things being equal,It also signs off sooner at 2500 on my 12v,3000 on a 24V.I never need more than 2000 rpms to pull any hills around here with 8000 lbs trailer,Ive ridden in PS and it needs to be kept at higher rpms to do the same work.I need around 20lbs of boost and I can get that at 1700,this leaves 10 lbs in reserve for any PSD'sthat come along-LOL.The 450-550 also have a much higher towing capacity due to the fact that they are just bigger and can stop better with those massive 4wdisc brakes,so htey need steep gears to pull big trailers.Dodges shouldn,t be pulling more than 15500 max,I know those 550's can do double that with no trouble.

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John D


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## GeoffD (Dec 21, 1999)

So if the gear ratios are different in the Ford F 450 and 550 how is the rearend the same? Thats the part that confuse me, but thanks for the info i am always learning.

Geoff


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## plowking35 (Dec 21, 1999)

Geoff you can install different gears in the same type of rear end. 
For the record, the duramax is a GM ENGINE. It was desinged and built here in the US. GM did have Isuzu engineers on the project, and they have used aluminum in their diesels for years. As a matter of fact Isuzu is the world leader in diesel engines. This engine debued in early 98 and will by time of production have under gone 2.5 yrs of testing and over 500000 miles per unit of mileage. Many of those miles being in the southwest where the aluminum heads would have shown their weakness. So far they have done fine. John I would say test drive one before you decide that it is junk, and wait till at least 2003 model year for all the kinks to be worked out before you buy.
I have driven all three diesels now, and say that the cummins is the class of the field, but with the 5 speed. The auto i have driven in a 97 was pretty doggy. The 93 I drove with the cummins was alot more driver friendly.
Like John said the 2000 PS was awefull. My 6.5 would walk it till 50 mph then I think the PS might catch up. But way to much noise and to little power unless you crank the snot out of it.
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## Lazer (Jan 1, 2000)

Geoff,
Am I missing something? The 450/550 has to have the low ratios: They have 19" wheels.


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## plowking35 (Dec 21, 1999)

Duramax 6600 FAQ
--------------------------------------------------------------------------------
By Jim Bigley
www.62-65dieselpage.com
Here is some FAQ on the duramax
--------------------------------------------------------------------------------

Q: When will the Duramax equipped trucks be available for sale to the public?

A: A pre-production run will begin in June of this year to get the line tuned up, but full production won't begin until August. This could mean the Duramax trucks won't be available at your dealer till September-November. A lot can happen between now and this fall, so stay tuned to TheDieselPage.com for all the latest news on availability.

Q: What are the GVW ratings for the new 2001 HD trucks?

A: The GVW for the HD2500 will be 9,200 lbs, and the HD3500 will be 11,400 lbs. The GVW for the 4x4 chassis cabs is 12,000 lbs, and 11,400 lbs for 2WD chassis cabs.

Q: What are the trailer weight (towing) ratings for the new 2001 HD trucks?

A: Trailer weight rating is 12,000 lbs with a suitable weight distributing hitch. Fifth-wheel tow rating has not been finalized. I've been told it should be close to 16,000 lbs. This provides for a "Best in Class" Gross Combination Vehicle Weight Rating (GCWR) of up to 22,000 lbs.

Q: What are the projected pricing schedules for the new HD Silverado and Sierra trucks?

A: Prices are yet to be determined, but they will be competitive with Ford/Dodge when equipped with the ZF 6-speed manual transmission. The new Allison 1000 series 5-speed automatic will probably be a more expensive option than either Ford or Dodge's automatic.

Q: What configuration will these trucks be available in?

A: The new Silverado HD and Sierra HD models will be available in: regular cab, 4-door extended cab, Crew Cab and chassis cab models. The 3500 series will only be available with DRW (dual rear wheels). Engines options include the standard Vortec 6000 with 325 hp and 370 lb-ft of torque, the big-block Vortec 8100 V8 at 340 hp and 455 lb-ft of torque, and finally the Duramax 6600 rated at 300 hp and 520 lb-ft of torque. The ZF-S6-650 6-speed manual transmission will be standard, while the new Allison 5-speed automatic will be optional for the Vortec 8100 & Duramax equipped trucks.

Q: Will there be any Duramax diesel Suburbans?

A: The 2002 model year Suburbans are scheduled to receive a Duramax option. However, the engine will be de-rated to 250 horsepower, and mated to an updated GM 4L80-E automatic transmission. Seems the new Allison auto won't fit the new Suburban sheetmetal.

Q: What kind of fuel economy is being projected for the Duramax?

A: GM rates the Duramax fuel economy at 15-20% better than that of the current 6.5L turbo diesel. This means the fuel economy should be at or above 20 mpg when comparing otherwise identical GM trucks (same gearing, model, weight, etc.). We didn't have the Duramax trucks here in Montana long enough to perform any fuel economy tests.

Q: Will the aluminum cylinder heads provide typical diesel durability?

A: General Motors has run extensive extreme durability tests on the Duramax/Allison powertrain. Many of these tests occurred in the Southwest region of the US and in Death Valley California this past summer. The Death Valley testing was performed at a 120° F ambient temperature, full rated GCVW and maximum power. From the reports I've seen, I can safely assume there will be no durability problems with any engine or transmission system, including the cylinder heads. The trucks performed beautifully, with no overheating and no durability problems.

The Duramax trucks were shown no mercy during the Performance Diesel Pull-Off here in Montana last October, and we ran them harder than just about any owner might. The engine temperature gauge never wiggled during the several maximum power mile-long loaded hill-climbs with a 10,000 lb trailer. I really can't see any engine temperature (or durability) problems occurring while towing or at any other time.

Q: Why didn't the Pull-Off articles in TheDieselPage.com and in Four Wheeler magazine compare an automatic transmission equipped Ford Super Duty Powerstroke (instead of a 6-speed) to the Duramax/Allison? Wasn't it unfair to compare an auto Duramax to a manual Powerstroke?

A: GM wanted to showcase the Allison auto as well as the new Duramax, so that's what they brought to Montana. We looked for a couple months trying to locate an identically equipped Ford Super Duty with an automatic, but we couldn't find anyone (including the local Ford and Dodge dealers, or individuals) willing to give us the keys to their truck, knowing we would be flogging the daylights out of it for two days. So, the local GM dealership bought a low mileage 1999 Ford Super Duty (and borrowed a Dodge from a local wholesaler) just for our testing.

All three trucks were ¾-ton 4x4 extended (quad) cabs. All three trucks were weight matched using sand bags. And finally, all three trucks were driven by the same unbiased driver (1997 Dodge 360 V-8 owner) who has been performing magazine truck tests for more than 30 years.

Only those who have put together a performance comparison test like this could appreciate how difficult it is to find three trucks with an identical configuration. Even with the lack of support from Ford & Dodge, we came very close to having just that. However, it's my opinion that a 6-speed manual has the advantage over an automatic on a loaded hill-climb. The time it takes to manually power-shift three times is insignificant compared to the total time it takes to run the hill. A six-speed also produces narrower gear splits, which helps keep the engine in the power band.

Starting the Ford in 2nd gear gave them a 3.31 ratio vs. the Allison's 3.10 first gear. Ford's 3rd gear (2.10) is also better than Allison's 2nd gear (1.81.) Ford's 4th gear and Allison's 3rd gear are only slightly different (1.31 for Ford/1.41 for Allison.) So, all the way through the first two gears, Ford had a numerical advantage in gearing. Both Ford and Chevy (as it turns out) were equipped with the same 3.73 differential gearing. Only the Dodge had 4.10 gears.

The Ford people should be glad we didn't have a ZF 6-speed Duramax truck to run against the 6-speed Ford. The Allison auto's computer limited the new GM truck to 3rd gear during the loaded mile-long hill-climb. Even at that, it produced 55 mph, and ended the run a full 30 seconds ahead of Ford. A 6-speed Duramax would have produced 60-65 mph in 5th gear, along with a corresponding reduction in elapsed time. All this from a standing start on a 6% grade with a 10,000 lb trailer, and ran wide-open for exactly one mile. And, don't forget the extra 500 lbs of sand bags the Duramax Chevy carried during all of the performance runs. The Ford made all the runs with an empty bed. Without exaggeration, the Duramax takes diesel performance to an entirely new level. No amount of rationalizing or fault finding will erase that fact.

Jim Bigley

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## thelawnguy (May 20, 2001)

I know this isnt what you want to hear, but the D80 in the Dodge isnt the sanme as the one in the Ford. The Dodge uses a "hybrid" dana 80, which means its a dana 80 center section mated to a dana 70 housing and shafts.

For more info go to http://dodgeram.com/ and spend a day or two poking around. Dave Fritz has done a stand-up job when it comes to info on post-94 Rams.

Bill


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## GeoffD (Dec 21, 1999)

Dino the new chevy sounds like a good truck for you chevy guys, lots of improvements.

My question is when they say duals are standard does that mean no more 1 ton pick ups single rears? I think that i am only going to buy F 35os from now on, but i don't want dual rear wheels on my pickups. That might not be a good move by chevy, only time will tell.

Geoff


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## John DiMartino (Jan 22, 2000)

Dino,in order to get the most out of auto/cummins you have to spend 600 big ones for an aftermarket TC and shift kit.Bill,I knew the 80 was a hybrid,and its center is still an 80,rest is 70.The class leading 22000gcwr that Gm will have whenever it comes out,is matched by the 2000-2001 ETH Cummins/6speed with either 3.55 or 4.10,which you can buy off the lot today if you can find one.Dino,I'm not saying the DDiesel is junk,its just 49%Jap with aluminum heads that arent tolerant to abuse.BTW, the power it makes is so easy to exceed with the Cummins.But it's lacking the auto to handle it.I cant wait to run one with mine when they come out.I almost bought a 2000 silverado2500 6.0V8,but they couldn't have 4th dr by plow season,so I passed.My dads 6.5turbo was a 4000 dollar option in 94,std was a 4.3.How did you get it for 1200,Dino?I think it should've been 2825 or close to that.If you paid 1200 you stole it.

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John D


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## plowking35 (Dec 21, 1999)

Well dodge has done that since like 93. I can see their point. The GVW on a 1 tom with SRW is 9200 and a HD 3/4 ton is 8600. Now very much difference. When you go to the DRW on a 1 ton you get near or above 10000.
The best is a cab chassis which puts you at 11K with the dodge and 12k with the ford and chevy.
By getting above the 10k gvw range you also can skip alot of emission standards. That also means more power in the cab chassis engines.I know that my 6.5 in a cab chassis has 20 more hp than the ones in the pick ups. Also no egr and mapp sensors. WHich may be partially why the cab chassis fuel delivery system is more reliable than the p/u systems.
Dino

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Professional Ice and Snow Management 
Products:Services:Equipment www.sima.org


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## tru cut (Jan 11, 2000)

I was reading an article today about the new gm and it said only duell weels on the 3500.i'm looking to buy a 1ton diesel this summer or fall when the lease is up on my SD.my question is could you take the outside weel off a duelly in the winter to help w/traction!Iknow you would lose some GVW.just a thought.the way things look now i need to start looking for a 350SD w/cummings motor,and a allison 5 sp auto?? any one know were i can get one??

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Todd


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## GeoffD (Dec 21, 1999)

Todd whats wrong with the superduty?

Also you might want to consider keeping your ford F 250 SD, and adding a second truck.

That way you can have a dump body with your sander and a second plow, and the pick up with the pull plow.

I don't think you want to buy the first model year produced by GM. Also if you have had good luck with your Ford, why not just get another and go with it.

If you use a truck for work, i think a dump body is the only way to go. Just my feeling on work truck, i mean yea i have pick ups, but those haul tools and stuff, the bodys hall dirt, rock, sand, gravel, polls, wire, pipe, ect.

Geoff


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## tru cut (Jan 11, 2000)

Geoff,
nothen wrong with the SD i love it .I like you am 6'7" and have a 15 shoe and fit in the sd better the the 96dodge or 91 gm all xcabs the lease runs out this summer and to buy the truck for 19000+ i don't know. the more i get into this bus. and landscaping i think i need a deisel.also the reason i have a xcab is becouse it was my fam. prymary vehicle.I really need the 8ft box and not so muth the xcab any more so i think i will turn this one in and get a 350pssd? i would love to have 2 trucks but right now i can't afford that so i 'll just make due maybe get older truck w/vbox and plow and just use it to sand and bach up plow.

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Todd


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## GeoffD (Dec 21, 1999)

Ok here is what i will tell you about the ford diesel.

It uses a lot of diesel if you have the 5.4 v8 is your 250, you might be getting better gas millage than the diesel. Only the power stroke has a ton of power. Also if your going to lease another truck which might not be a bad idea when starting out, just get the gas. The reason is you will not save enough over two year to make the diesel worth while, ya need to log 100K to see a high savings return on them. Ya the diesel will last longer, give you move power, better millage.

The only other thing about a diesel if ya can't let them sit for long over the long haul. My diesels get 50 to 100 miles per day, which is what they need.

Just a few ideas,

Geoff


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## tru cut (Jan 11, 2000)

the reason i wouldnt lease again is because you cant do any to the truck ie.add perament mount lights i will have to buy a new hitch becouse i weilded the brackets for the pull plow to it cant drill the dash for switches or bumper for lights ect.or you pay for damage when you turn it in .were if you buy it its yours you can customize it any way you want to put some dings init and not be raped whenyou trade it in.

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Todd


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