'93 Intrepid - shudder at 35~40mph

Hello,

Whenever I reach between 35 and 40mph, I hear a shuddering sound toward the front of the car. It only does this during accelerating up to/through this speed range. It does not happen when decelerating by coasting/braking. It also does not happen if the shifter is not in the Drive position. ("3" for example.) During the shudder, I can see the speedometer slowly moving up and down over about a 2~4mph range. Once the shuddering stops, the speedometer is rock solid again. I don't feel the shudder in the steering wheel when it happens. This seems odd to me, but then again, this is my first front wheel drive car, and maybe front end problems aren't as easily communicated to the steering wheel as they are with rear wheel drive?

I had the tranny rebuilt back in 9-03. It was starting to make very loud thunks when downshifting, finally reaching a point that a strong thunk when coming to a stop would leave the tranny in limp mode. (I would have to turn the car off/on again at the light to continue on normally.) Ever since then it will occasionally make a thunking sound that can be felt/heard when slowing down to stop. It varies in severity from barely noticeable to quite loud, but nowhere near as bad as before the rebuild.. The people at the transmission shop insist that "all Chryslers do this when downshifting". I've owned the car since it had 14K miles on it to the present ~70K, and in the seven years before the problem that led to the rebuild it never acted this way. I'm on the last month of the warranty, so any information and/or links that supports my side of the situation would be greatly appreciated!

Thanks for any help, DSF

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Some things to check: CVJ's (outer axle joints) and DOJ's (inner axle joints), also steering parts, especially loose inner tie rod bushings (where the tie rods attach to the steering gear). Almost a dead giveaway on the axle joints would be a split boot, but good boots don't necessarilly mean good joints. Most likely if tires were the problem (out of round, out of balance, broken belt), it wouldn't be that much dependent on acceleration vs. coasting, but don't ignore the possibility. Also brakes: rotors, loose calipers (slides).

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

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Bill Putney

That could very well be that the torque converter clutch (TCC) is chattering because lockup is coming at a too slow a speed. I had never experienced this problem until just recently when I had the tranny rebuilt on my '94 LHS. Instead of occurring at 40+ MPH, the converter would lockup at ~35 MPH, which was causing the shuddering that your describing. A new Transmission Control Module (TCM), with the latest firmware, fixed the problem. I'm guessing that the rebuild resulted in different pressures in the tranny which didn't work well with the original (day 1) firmware in the TCM.

I would have the shop that rebuilt your tranny drive the car with a scan tool connected to the data port. They'll be able to verify that the TCC is (or isn't) the problem.

Reply to
Steve Raft

{My stuff snipped}

I forgot to mention in my previous post that I had both front axles (CV joints and all) replaced a few months ago. I will have the rest checked out.

BTW, I also neglected to mention that the problem doesn't occur when the car is cold. I had to drive it several miles today before I could get it to shudder. (I live in Florida, so 'cold' means avg temp of about 80F today.)

DSF

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Sure sounds like torque-convertor lockup clutch shudder to me. TC lockup is altered when you select "3" so you don't get the shudder. TC lockup is inhibited until the engine reaches a certain temperature, so you don't get it when "cold."

I bet whoever rebuilt it didn't put ATF+3 in it- typical of a shop that would say "all Chryslers do that." They probably put in Dexron and a tube of some magic monkey whizz that they claim "makes it work like ATF+3." Drain the fluid, change the filter, and fill it up with +3 and see if that fixes it. Also, if you haven't had the transmission controller flash memory upgraded to the latest software, get that done at the dealer as well.

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Steve

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