Truck feels like it is going over rumble strips, only over 40MPH

chevrolet
1500

#1

Hi, My truck just recently started to vibrate like it is going over rumble strips. It only happens over 40MPH and sporadically. It seems to happen when I’m just giving enough gas to maintain speed. Once it starts if I let off the gas or give it more gas it goes away. It reoccurs anywhere from 20 seconds up to a few minutes. I’m afraid my tire is going to fly off or my drive shaft is going to drop. There is no unusual noises or thuds if I go on and off the gas and the universal joints seem tight, and there is no vibrations from on steering wheel. Please help before I end up in a ditch or worse.


#2

I’ll have to assume its an automatic transmission since you didn’t say so. You just gave a classic, textbook description of what torque converter clutch (TCC) shudder is like.

You need a transmission shop.


#3

Yes it is an automatic. Oh no not Transmission. Money is tight any idea if this could wait about a month? I put on about 8 miles a day 5 days a week. Thanks for your help


#4

It could actually go a month - or years. If you have a switch for turning off the overdrive (something like an O/D Off button) then turn it off. This will likely shut down the TCC altogether. If you do any long drives, esp highway-type driving don’t leave it off, but for normal everyday around home driving it will be fine. Do some general internet searches and read up on your transmission - its probably a 4L60E. Figure out what a TCC is, and how yours works. Drive in a way that avoids the symptoms.

If you’re long overdue for transmission service and are somewhat handy, I’d drop the pan & change the filter. Its not all that likely to help but it would make me feel better.

Is your check engine light on? What year is the truck & how many miles?


#5

99% of my driving is under 40 so I will leave it in drive. I just started searching the internet and if I just used the word shudder instead of rumble I would have found dozens of hits. Thanks again for help and letting me know the right terminology. I will do the filter change too.


#6

Me again. I never answered you last questions. The check engine light is not on but it has come on now and again for the past few months but usually goes out the next time I start the truck. It is a 1994 Chevy 1500 2wd with 185000 miles on it. I have another question I have research the TCC and I’m still a little confused. It looks like the TCC is actually part of the torque converter. Is this correct? If so if I change the TC do you think this will solve the problem. If not what about putting in a new(rebuilt) transmission. These are both with in my skill set. I also found this on a truck site "A possible cause for the shudder is a bad torque converter clutch (TCC) solenoid or a bad torque converter clutch pulse width modulated solenoid (PWM).

Thanks again.


#7

The TCC is in the torque converter but its control mechanisms are not and I would not bet on the converter being the central issue. These transmissions are actually well known for having the valve body bore for the PWM/TCC solenoid wear. Once it wears, it can’t handle the pressure so it can’t fully apply the TCC pressure properly. Those solenoids also do burn up.

The problem is that your issue could be in any of these things. The converter is actually a possibility. So is the bore. So is the solenoid. Or maybe all 3. A really good transmission shop with right scanning equipment may be able to tell you.

There are a couple of companies that make kits for correcting the bore problem (Sonnax is the one I’m remembering). Some people have DIY’s those but its not really a DIY kind of thing depending on which kit you’d use. (One has you reaming out the bore to install a new sleeve in it - not for the DIY’r).

As a '94 your truck is OBD 1. The next time that engine light comes on use these instructions to read the error codes: http://www.troublecodes.net/GM/

Honestly, if it were me, given that you’re broke and with your daily driving needs - I’d just figure out how to drive without aggravating it. This should prevent further damage while you figure out what to do next. (I would still drop the pan & change the filter). When you have some $$ ask your best local transmission shop to have a look.

If you can R&R a transmission, its pretty easy to find rebuilt units & make sure it goes in with a new torque converter.


#8

Yeah I was reading a lot about the solenoids. Thanks for the great link I will be sure to use it. Ok I found a transmission shop that does free evaluations. I’ll have them take a look and see what they think. Thanks for all the help.


#9

How many miles are on the truck? You can cross your fingers, but 9/10 shops, especially if they do free evaluations won’t spend a lot of time. Their logic will be “yep, that’s a problem. Don’t know why. Not going to spend all day trying to find out. You need a new transmission…” Just be prepared for that.


#10

There are 185k miles on the truck. I was looking around for rebuilts and found some for under 600. I thought that would be the best bet, that is with me installing it. That would take care of the TC the bore and the solenoids, it would probably be cheaper then having a transmission shop, even if they just have to replace a part. From what I read to replace the solenoid it a major undertaking, replacing the whole transmission would probably be easier.


#11

I would worry about a $600 rebuild. Do note that “rebuilding” a transmission could mean a whole lot of different things. For example, one might call it a rebuild if they tore it down, replaced all of the “soft” parts and then slapped it all back together (a soft rebuild). In fact, I’d say anything that inexpensive has to be something like a sift rebuild only. If I were you and were going to do through the trouble to do this I’d do a bunch of research on the suppliers and make sure I got something from a top notch place with a good & established reputation - even if I had to spend twice as much.