# 98 GMC 2500 Slight shutter on take off



## Bob V (Nov 29, 2002)

I have had a slight shutter in the drive train, in 2 wheel drive, at standing starts or low speed (first gear) accelerations. It is only noticable once in a while and always disapears when I level off or get into second gear. It is a 98 2500 ext cab 4x4 auto 8' box with 46,000 miles and 285 x 16's. My warranty is up at 60,000 and I have put on about 20,000 trying to get it fixed.

Dealer can't find anything, but did replace all the u-joints and said that could have been it. Still does it. I think it could be a trany mount or carrier bushing, they say no. A buddy told me the limited slip does this and don't worry about it. I could see that maybe, if I was in stone or turning from a stop, but not on dry pavement going straight.

Went and had tires rebalanced, what for? I wanted to check for lug nut tightness and was curious.

Anyone else have this slight shutter like feeling?

Thanks, Bob V


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## John DiMartino (Jan 22, 2000)

Has your dealer checked the pinion angle,if the truck is lifted or the axle wasnt flanged correctly/or the truck has hit somthing pretty hard in the back,it may have changed,this is usually a problem on lifted trucks only,but at t his point they have checked almost everything else.Unlikely but also possible is the ring and pinion are worn out or a tooth is 1/2 chipped off the ring gear,not likely but when all else fails....The torque side(drivers) side motor mount should be looked at also,as should the exhaust system,to see if its hitting somewhere,when the engine torques,make sure they check by the spare tire.Good luck


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## Bob V (Nov 29, 2002)

John ,

Nope, truck has not been lifted, except to turn up the front when I bought the plow 3 years ago. Never hit anything hard that I know of.

This shutter makes no noise or growl, only can feel it, like tires slipping slightly, but I'm not hard on the pedal. Normal acceleration.

They will have the truck on Monday the 23rd to have the drive shaft balanced and I'll have them check the motor mounts and ask about the ring and pinion wear. But I would think if that was it then I would feel it all the time, don't you? Maybe.

Thanks, Bob V.


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## dozer (Dec 8, 2002)

If I read it right you have a manual tranny, had a old beater in high school, did same till I replaced throw out bearing and a heavier clutch assembly. Just another "what about....". Good Luck.


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## Bob V (Nov 29, 2002)

Dozer,

I have 454 with automatic. Thanks

Anyone have any thoughts on the limited slip rear?


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## John DiMartino (Jan 22, 2000)

Bob, the limited slip rear is not used by GM, I have both Dodge and Gm trucks,the Dodges use them,Gm uses the Locker style.The locker should not shudder when in free wheel mode,it takes a certain RPM difference between the 2 axles,AND the speed must be below about 10 mph or the locker will not kick in at all,You shouldnt need an additive for the gm locker either.Even when i dont add an additive to my Dodge,it will not shudder in a straight line,only when making turns,sharp turns.


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## Bob V (Nov 29, 2002)

Thanks John,

It was just a suggestion from a friend and I thought I would include it in my thoughts as to what might be the problem. 

I still believe it is in the mounts or carrier bearing. I have had several Dodge (72 & 76) Power Wagon and Sno Fighter that had carrier bearings go, but that was a few years back, and they seemed to have the same type of shutter. Also had tranny mount go on 1980 F250 and motor mount go on 1978 F250. The F250 motor mount you knew pretty much what was going on.

Probably have to trade up to get this problem out of my hair.


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## John DiMartino (Jan 22, 2000)

Bob,I'd replace the carrier bearing anyway,its cheap,and to to hard to do.Dodges that tow heavy eat them and they shudder the same.Some of the 2001 GM HD's shuddered so bad that GM made a 1 piece shaft made to repalce the 2 piece.


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## Bob V (Nov 29, 2002)

John DiMartino,

I pull quite a few hay wagons home durring summer months and usually 2 at a time with 7000lbs on each and each wagon wieghing in at 2000lbs for a total of 18,000lbs, that I'm pulling through rough fields and down the shoulder of the back roads. So what you say about "Dodges that tow heavy eat them" sounds like I'm back to what I origanally told the dealer it could be.

Even though they can't see anything wrong with the carrier bearing, I will insist that they replace it Monday when they take the shaft off to balance it.

Thanks, I'll let you know how I make out.


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## Bob V (Nov 29, 2002)

Got the shaft balanced and again they say the carrier is in good shape. Noticed on the way home the shaft is vibrating worse than ever. Now I wish I would have never tried to get the slight vibration fixed. Big mistake. I will have to take it back in, Again.

Maybe they installed the caps not fully seated. I will look when the sun comes up.


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## Bob V (Nov 29, 2002)

Update:

Went back to Dealer this AM and mechanic found slight play in splined shaft and also found the 2 shafts were not lined up to each other. He slid them apart and tried to line up the 2 shafts and couldn't seem to get the caps from front shaft and rear shaft to line up.

Says it must have been this way from factory. They ordered a new shaft assembly and will get it in next week.

Bob V


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## Joey D (Jan 6, 2002)

The locking rear could be what your feeling. It will chatter from time to time. Not to say it's not the driveshaft. Have you changed the rear fluid yet?


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## Bob V (Nov 29, 2002)

Havn't got to the rear-end yet. I'll wait till they get it up on the lift and put the new shaft on and then I'll make the comment about changing the fluid. I'll let them put all the new parts on that they want as long as it is covered under the warrenty.

Thanks for the suggestion.

Bob V


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## Joey D (Jan 6, 2002)

Bob, I would also let them replace all the parts they want to. Has the rear fluid be changed at all? At 46,000 it should have been changed at least twice. The most noticable time my truck will do this is when coming off the freeway where there is a light to stop at then making a turn it will chatter.


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## Bob V (Nov 29, 2002)

Joey D,

I have had the truck since 22,000 miles and I put the first plow on it. No I have never changed the rear-end fluid.....Yet! Will ask them do it when they are tightening the the shaft u-bolt nuts. 

What are your thoughts about the trany fluid and filter? Might as well work our way up to the front-end and see how much more I can get replaced before the warrenty runs out.

Just kidding....I really want the shutter/vibration to be taken care of. That would make me feel better.

Bob V


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## plowking35 (Dec 21, 1999)

Bob, I change my fluid and filter everey fall. If it hasnt been done, do it. I also have changed the rear diff fluid at 7500 miles and again at 50K, with the additive. My locker works with no sound at all.
Dino


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## Joey D (Jan 6, 2002)

I just did a trans flush with Mobil 1. Do the flush as just dropping the pan won't get all the fluid out.


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## plowking35 (Dec 21, 1999)

Still gotta drop the trans pan to change the filter.
Dino


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## paul soccodato (Nov 9, 2002)

if the rear has a locker in it, you shouldnt have to put an additive in it, if it has a limited slip, with friction plates in it, then put the additive. it prevents the plates from chattering while turning.


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## plowking35 (Dec 21, 1999)

If it has the G-80 locker from GM it does need the additive.
Dino


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## Joey D (Jan 6, 2002)

Dino, You are correct in dropping the pan for the filter but flushing it after is what I meant. The locking rear does not require a additive.


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## John DiMartino (Jan 22, 2000)

Ive never needed to run an additive in the G80,since the clutches do not slip,they are off (disneganged)when it is in open mode,or on when locked.A limited slip type,like in my dodge,has constant spring preload on the clutches,and they need the additive to prevent chattering.An additive will not hurt the G80 setup ,its just an added cost factor.


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## plowking35 (Dec 21, 1999)

It is right in my 98 CK 3500 owners manual that the locking rear differential REQUIRES the additive.
Dino


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## dsrour (Dec 29, 2002)

*rear*

Would a 98 sub 2500 have a locker rear or limited slip. I have a oblem w/ my rear seems to lock up arond trns. Dealer said change fluid and has helped, but not elimnated.


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## plowking35 (Dec 21, 1999)

look on the build sheet in the glove compartment, if you see code G-80 you have the rear locking differential. GM only installs this unit.
Dino


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## dsrour (Dec 29, 2002)

as you said its got the G80. So what would make it seem like it doesn't unlock properly. Noticed when going around turns . Thanks.


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## Joey D (Jan 6, 2002)

Dino, I have my 98 manual's in front of me and it says nothing about an additive. This is the Helms manual set like the dealer has, as well as my owners manual. The only axle GM requires a different type of fluid in is the 3500HD, the 15000 GVW 2wd and it states synthetic fluid only nothing of an additive.
Think about it there are no clutches in the locking rear that would requir any additives or friction modifier.


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## plowking35 (Dec 21, 1999)

Doesnt take a different fluid, but it does require the additive. I know cause I have the truck, and it is what is required.
Dino


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## golfmanres (Jan 3, 2002)

might be off subject but how do i tell what rear end i have in my turck it is a 1998 chevy k2500 ext cab


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## Joey D (Jan 6, 2002)

Golfman, Read 5 posts back.

Dino, What truck do you have? I also have a 98 and don't see where it says that. I had a 96 before this with the locker and the 1st few times I changed the fluid I used it then I was told not to by the dealer so I looked it up and it said none required. Is it your owners manual in the glove box that says it?


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## plowking35 (Dec 21, 1999)

Yes that is manual that states that the limited slip additive is required. I have a 98 K-3500 12K gvw.
Dino


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## Joey D (Jan 6, 2002)

Dino, I would like to have a copy of the sheet for warranty reasons if mine takes a dump and my book says I don't need it. I have the 10.5 rear axle in my truck so they are the same.


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## plowking35 (Dec 21, 1999)

PM me your fax number and I will get it to you
Dino


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## fastjohnny (Nov 14, 2002)

*golfmanres*

look on your rpo codes in glove box

3.42 would be a GU6
3.73.................... GT4
4.10.................... GT5


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## unclepaul (Dec 24, 2002)

Bob,both my plowtrucks have that shuttering in first gear. I can feel it more when pulling my trailers. One is a 89 4x4 with 5.7 and a 93 with 5.7 . It has drove me nuts for years ! I have put it on the lift and changed fluids and had everything looked at including changing diff bearings. We are leaning to the t converters, not a fun job we just replaced one motor and we could of swaped it then.  good luck !


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## SnowMatt13 (Jan 8, 2003)

*shudder*

I owned a 2000 K2500 reg cab long bed, and for the past 6 years have worked at a Chevy dealer, before I got rid of the truck they told me that that problem was called a "launch shudder" Meaning all of the components of your driveline are starting to move and "mesh" together. Therefore they called it normal and offered no fix. Odd enough, before I got rid of it I had new tires put on. After the tires got put on the truck wouldn't shudder. A few days later I noticed that the tires we "C" rated in the load range and it being a 3/4 ton needed "E" rated tires. The day they put "E" range tires back on the shudder came back. I told my dealer, and they said impossible


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## fastjohnny (Nov 14, 2002)

*same prob*

My 97 GMC K2500 Extra-Cab Long Bed with 454 does the exact same thing, slight shudder on acceleration from stop, in 2 wheel drive. Seems a little more noticeable when towing a trailer (light load, maybe 2000lbs gross trailer)

Don't seem to notice it with the plow on. I think there may be something to the tire theory. If my front is loaded with the plow, and I am not running with any counterweight or ballast, there would be a significant reduction in the downforce on the rear tires.

Anyone care to comment?

Other than this, no complaints, here's to GM trucks drinkup:

John


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## SnowMatt13 (Jan 8, 2003)

*shudder*

The best advice I can offer is if your truck shudders, and it's under any kind of warranty (factory or extended) take it in, and have the put in writing what we call at my Chevy dealership the 3 C's ....i.e. Complaint, Cause, Correction. It shows up on our bills, what the customer says is wrong, what we found and any correction made. If they don't find anything at least you have in writing that you think that there is a problem. That way if for instance let's say your drive shaft gets ruined because of excessive vibration at 50K, you can go to the dealer and say you first noticed a vibration and let's say 25K. They might relate that to your concern and cover it under warranty since you noticed it and had them look at it while the truck was under warranty. I've seen it happpen at our shop, Yes they can do that!!!!


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## Bob V (Nov 29, 2002)

*Shutter*

*UPDATE*

The new driveshaft is finally in, so Tuesday we will know if the new shaft assembly (carrier bearing included) will solve the shutter/vibration problem. I have my fingers crossed.

Alot of work the month of Jan. for the truck since we had measurable snow everyday since the first. Friday I finally gave the 454 a rest and washed it for the first time since Christmas. Washed off enough salt to salt the streets of Buffalo.

I will let everyone know Wed.

Bob V


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## tnt69tnt69 (Jan 12, 2003)

I feel like I got the same problem with my truck. The problem is that my truck is an '03 with 1500 miles on it.


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## Bob V (Nov 29, 2002)

tnt69tnt69

Is it a 2500 4x4 ext cab? Seems like quite a few have the same problem.


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## tnt69tnt69 (Jan 12, 2003)

Bob- Mine is a 1500 reg cab long bed 2003 with 1600 miles and it seems like i am noticing the shudder at straight line moderate to heavy acceleration.


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## Bob V (Nov 29, 2002)

UPDATE:

Well, after several weeks all the entire drive shaft from the tranny to the rear end finally came in and were installed. 

I have been driving it for 5 days and have not felt the shutter or vibration, yet. This is not to say the problem has been solved. I am optomistic. 

The old shaft were the 2 splined parts came together, were off. All the u-joints should be in the same position. One was off and sliding the splined shafts apart and repositioning them did not help.

Thats why they replaced the shaft.

I am hoping this is the cure.


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## ebaron (Dec 27, 2002)

*shudder*

Had this on my '00 GMC 2500 ext cab with limited slip. Not bad, but slight shudder on take off after driving 50-100 miles on highway. Also during towing. About 30K,replaced the rear end fluid, with the long life $$$ stuff (which was in it when new) and it went away.

Got an '03, 2500 HD ext cab with limited slip rear. Does it more often after 5-10 miles on the highway and then on take off. Shudder only occurring on take off in both cases. I have a feeling it is just the limited slip rear and normal.

Trust me if it gets worse, the dealer will hear about it. I remember putting in an aftermarket posi in my old blazer. That rear end would make all kinds of fun sounds when in slow tight turns, but damn, it worked!


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