# vibration, feels like front end, like hitting rumble strip on highway?



## ontario026

I keep getting a vibration, almost feels like hitting a 'rumble strip' on the highway. But it only happens quite occasionally, like maybe once or twice in a 20 mile trip and only for a second or two each time...

any ideas?
Matthew

2000 silverado 2500 4x4 ext cab short box


----------



## mkwl

Maybe out of alignment- does it do it at all speeds? What kind of tires are you running? Have you checked the tire pressure?


----------



## redplow

You might have a broken belt in your tire.


----------



## ETMegabyte

redplow;858927 said:


> You might have a broken belt in your tire.


I was just going to suggest this. I've had a broken belt in a tire before, and though I've never had it as bad as like hitting a rumble strip (particularly the noise), I have had it shake the whole truck pretty badly at certain speeds...

Also, did this just start doing it one day, or did it start out quiet and get louder as time progresses?

Also, is it speed sensitive? Can you reproduce it at will, or is it semi-random? Normal human response when something like this happens is to let off the gas, slowing the truck down. If you don't slow down at all, does it continue? Think back on all the times you can remember it happening and see if you can find a common factor (speeding up each time, slowing down each time, braking, riding down the highway, windy outside, a/c was on, etc)... Figuring out WHEN it happens can help tremendously when trying to figure out what it is...


----------



## ontario026

Thanks for the input guys, I beleive it just started one day, I don't remember it increasing over time. I only remember it happening on my way to and from work where I normally travel 80-100 KPHish, some times it seems like it starts when encountering a slight uphill grade. But it can and will happen on flat streaches as well... it seems like it may go away if I let off the pedal as it starts to vibrate, but hard to tell since it normally only happens for such a short time, it might just be a coincidance that it stops when I pull my foot off the peda it was probably going to stop anywaysl... I've had lots of broken belts before, and this does not seem like one...

Matthew


----------



## ontario026

well for the heck of it I just dropped the truck off at the local chev dealer for a physical... They are going to look it over, brakes, front end, suspension, etc and look for the cause of the noise... Plus I figured I'd have them dump and change the front and rear diff oils, and transfer case while they were at it.... I just changed the oil in my extreme V this morning... Hopefully they find the cause of the 'rumble strip" noise and it's cheap! LOL

Matthew


----------



## ontario026

Well it's in the shop, looks like it needs a pittman arm, idler arm and a tie rod end, and they think it was the combination of the pittman and idler making the noise?? sound feasable?? Hopefully I guess we will know tomorrow...

Matthew


----------



## aeronutt

Sounds feasible to me. Expensive too since it's at the dealer... If this is the first front end work done in 9 years, you're way overdue for something anyway. The front wheel bearings would have been my first guess. They're not known to last forever. Be sure to post back with results. I'm curious.


----------



## Donny O.

ya know I think mine does the same thing ocasionaly. and like you said seems like when I am going up hill. does it in almost the same place....when it hit the highway by my house it goes uphill right away and it does it there quite often. I have no idea what is causing it but I highly doubt it has anything to do with tires, or alignment or anything like that. almost seems like it could be the ABS cycling. and I think that because it reminds me of the traction control on my wifes chrysler van that uses the brakes....but no traction control on my truck.


----------



## Snowzilla

Might possibly be a bad cv joint in your front end. I have had strange noises from front transaxle in an '89 K1500 when engaged in 4wd at highway speeds.


----------



## ontario026

well $960 bucks spent at the dealer, but I now have fresh fluids in my front and rear diffs, and transfer case, as well as new pitman arm and Idler arm.... So far so good, I went for a drive, and it feels nice to drive, I didn't really notice much steering slop before, but it is nice and tight now... plus so far my rumble strip vibration has not seemed to return, so maybe it was under certain situations almost a "speed wobble" induced by the play in the front end?? I guess only time (and a few more miles) will tell if it is gone....

Matthew


----------



## ETMegabyte

OUCH!

Considering what you had done, the price isn't too bad, but still... Quite a bit of money to spend as a surprise regardless... I hope it at least fixes your problem...


----------



## ontario026

So far so good, it's several days later, and still no rumble strip noise! looks like it must have been the combination of play in the pitman and idler arms, allowing some 'speed wobble'

Matthew


----------



## ontario026

I thought I'd update this post, well the problem came back, and kept getting worse over time... I changed all the tie rod ends, still the same, a while later I had it in the dealer again and they pulled both driveshafts to check u-joints... They were all good.... then they said they thought it was the torque converter lockup, so they cut the wire running to the lock up solenoid, so now my torque converter does not lock up, but the vibration is gone...

B+B or any other tranny experts, how bad is it for me to be driving around with the 4L80E and the torque converter lockup solenoid wire cut? Other than a firm shift due to I assume an 1870 code (no engine light though) there does not seem to be any odd performance problems, no noticable slipping when going through the gears etc.. Should I have the tranny yanked for a new converter and full rebuild, so do I stand a chance of making it though the plowing season as-is? I recently had a tranny flush and filter change at the dealer, and they never made any coments, so I assume that they did not find anything out of the ordinary... 

thanks
Matthew


----------



## B&B

Not a wise idea to run it with the TCC disabled unless you never drive over about 40 MPH. After the PCM detects slippage in the TCC when it knows it's been commanded to apply it then begins increasing line pressure to reduce/eliminate the slippage, which it can't because the wire was cut. That's why you're experiencing harsh shifts, because it has the line pressure commanded high. Running it with the pressure elevated constantly is tough on various internals, especially in a plowing application...

May not need the actual TC replaced. Most 1870's are caused by worn valves (AFL valve is the most common one), the TCC solenoid itself or simply poor grounds. And ll are repairable without removing the trans so don't let a shop simply talk you into a TC replacement or trans rebuild. Instead insist they do a proper test drive with a good thorough diagnosis first.

It's either fix it right, or disconnect the battery for a few minutes to clear the codes (there will be codes even though the MIL isn't illuminated) and all currently adapted shift strategy and designate it to a lot use truck only where it'll never command the TC to apply.


----------



## Donny O.

I thought I would update this old thread. my truck became worse and worse and paying close attention I am convinced it was the torque converter locking and unlocking real fast....could see the RPM raise slightly when it happened and always when the load went up a little. so ran into a friend that owns a tranny shop and told him I might need to come see him soon and told him what was happening. his reply was 'change your fluid and it should be fine...fluid gets old'. so that is what i did. dropped the pan and changed the fluid and filter and so far it has not happened once since.

he also said if that doesn't work change the plug wires. said he sells lots of wires to people coming in thinking they have tranny troubles and just have bad wires. on a side note he could have charged me and others for a lot of expensive tranny work that we didn't need...I appreciate that.


----------



## meborder

+1 to the fluid change.

Had the same thing with a ford, did a fluid exchange with full synthetic and the problem never returned.

I'd start there, hook the TCC wire back up and see what you have.

Transmission shops all told me that a fluid exchange wouldn't work, but it worked for me.


----------



## larboc

If it comes back, I'd have to question the tcc pwm solenoid and have it tuned so it won't ever modulate the TCC pressure. I did that to my '01 4l80e just to make the trans last longer and use less fuel. The only draw back is that you can kind of notice the tcc lockup, just like you used to be able to on older 4l80e's and 4l60e's that didn't have that stupid tcc pwm valve.

in 1996ish and up gm auto's they will reduce the pressure to the tcc by adding a pwm solenoid so that it locks up smoother and keeps engine speed up by slipping the tcc clutch, sometimes for a very long time (minutes). If you know what to watch for, you can notice when it's slipping it. Makes me cringe knowing whats going on in the tranny when it's modulating.


----------



## Donny O.

meborder;1376195 said:


> +1 to the fluid change.
> 
> Transmission shops all told me that a fluid exchange wouldn't work, but it worked for me.


they rather make more money on a rebuild or other repair maybe??


----------

