: Car violently shaking and turning off at stops.

01-11-07, 10:08 PM
*Note: Rewrote it so you can get better info.

THM 200-4R transmission, 307 Oldsmobile Vin Y engine, 88 cadillac brougham RWD.

Symptoms: When the car is warm and has been driven a good 5 miles, when shifting 2-1 while slowing down the car abnormally delays the downshift. If you brake quickly even at 20mph, the car violently shakes 2-3 times and the engine recieves so much backpressure it shuts off. When this happens, the oil pressure light flickers on just before it turns off. It shifts fine from 2-3, and 3-OD. What I believe is happening is it's not shifting from 2-1 in time, and the lower gear ratio combined with the transmission moving slower is causing the car to sputter off.

*When accelerating or decelerating slowly, the car shakes when it shifts gears. During high acceleration or when you floor it, you can barely feel the transmission shift. I am unsure if this is normal operation.

*Car sometimes shifts hard from park into drive. I believe this is due to the car being on a slope. Additionally, before I started fixing the problems with the engine, shifting from park into drive would cause the car to turn off. When the car was warm and in 1 or R, it would turn off but this was found to be an issue with the ILC which has since been fixed.

*This car has, 4 times before, violently shaken while in 2nd and 3rd gears during points of high acceleration or high load. This is within 2000 miles of driving over 6 months and it has NEVER shut off due to this.

Stuff I know or suspect is bad:

*The shift linkage is loose; that means the pointer can be over N or D on the dash and the car may not be in nuetral or drive. However it still shifts and doesn't accidentally shift into other gears (or at least until now?).

*I haven't checked the TV cable yet.

Backround Info/work:

*This car sat in a garage for 5 years. It has since had about 2000 miles and $2000 of parts into it.

*Engine and trans have been replaced. The engine was replaced 45,000 miles ago with a rebuilt one; the car has 164-000-174,000 miles as the odometer was reset when the engine was replaced. The default trans was a THM-400 variant (inproved version) on this vehicle which was replaced with a 200-4R at some point. I know because the bolt pattern on the trans indicates it's a 200-4R, and because the dash has no O surrounding the D symbol indicated it has overdrive. Additionally, you can shift it into 1st, 2nd and 3rd but no 4th is present.

*Engine is running flawlessly, no codes have been set, there are no oil leaks as far as I can tell. Oil was changed last night; we thought it was an oil issue since I had 6 quarts in there. Drained, put new in, good to go, still did it. No swarf or filings in it. I was driving it to emissions when it started up :(.

*The transmission fluid and filter was changed about 800 miles ago. The fluid that came out had that old smell but wasn't burnt. Swarf was minimal, no large metal filings or shavings. Fluid level is good and doesn't smell burnt or contain excessive swarf or metal shavings.

*Rear differential fluid has been checked and replaced; no swarf, no filings; it's in good order.

*Brake pads, cylanders, and fluid were replaced recently.

After 4 hours of researching transmissions, my suspicions are that it's an issue with either the planetary gear linkage or the torque converter. Now that I'v been researching, I'm coming closer and closer to believing it's an issue with the shift linkage and TV cable, but I'm curious if anyone else here knows about it being anything else (like, say, a clutch or governer?).

01-11-07, 11:19 PM
Torque convertor solenoid comes to mind, but once you start talking about difficulty shifting gears, there may be a much more extensive problem. First thing I would check (easy) would be the shift linkage under the car. Once you verify the shift linkage is alright, then you'll know you have a problem in the tranny.

01-12-07, 07:53 AM
Try disconnecting the lock up converter on the trans

01-13-07, 02:55 PM
Found the problem:

Throttle Valve-Cable came unhooked from the carb somehow.

Without that hooked up, the trans didn't know when to downshift so it started getting freaky. Apparently the transmission, engine, and ECM are all designed to shut off in the event that happens with causing minimal damage to the car by turning off the engine which, if it kept runnign would blow something. But I'm going to baby it until I'm 100% positive that fixed the problem and nothing else got broken. Probably going to drain a little fluid since I think it's a tad too high.

The car seems to be working and not dieing now that it's hooked back up. I rerouted the vacuum lines around it so they'll never get in the way again. I haven't put it under a super-high brake test to see if it'll shut off, as in lockup, but last night an 8 mile trip from my buddies house to home resulted in the car not doing this once and I put her under enough load to cause it.

Thanks :)

01-13-07, 03:52 PM
Good work! The TV cable would certainly cause the symptoms you described. Glad you found the problem.

01-13-07, 04:53 PM
Damm Good Find Man,

Glad It Wasnt Something Serious


01-14-07, 02:38 AM
Took her out for a good 10 mile run tongiht through various roadways. Checked the fluid several times. The fluid is staying likewarm as it should, but it is light brown in color and the scent is pungent. No swarf; I couldn't really feel any.

From what I know from thermodynamics, when a fluid rapidly increases pressure, it also rapidly increases heat. The fluid definatly changed texture; it's lighter and milkier now than it was before and I'v been checking it every now and again for problems. So I think it needs a transmission fluid change. Anyone got an idea if using the cooler lines for the trans is a bad idea or a good idea? Haven't tried it before but I'm sure it'll do a very thorough change and I'v got the hose and 5 gallon buckets to do it with.

She's also shifting rough; not much more than before but the undercarrage of the car is making some strange clanking noises when it shifts from 2-3 that it didn't before. I think I either need to clean out my trunk and check the suspension and driveshaft for problems.

She upshifts normally, it's just downshifting that seems abnormally rough.

I also did 2 brake lockups at 20mph near the end; plenty to cause her to die and she didn't seem to mind them.

01-14-07, 08:25 AM
Yeah, definately change your fluid if it looks and smells like that, that very well may firm up your shifts, both down and up.

01-15-07, 07:20 PM
K, she's still doing the jerkyness she was doing before, but now she does it on both upshifts and downshifts. I'm going to take it to a mechanic I know and him look at it and see what he can do.

01-15-07, 09:08 PM
Try and move the cable yourself. Grab it with your fingers and slowly pull all the way in and out. Spray a little shot of WD-40 or Tri-flow on the cable and work it a few times. Then test-drive it again. Might solve your problems!

01-17-07, 02:43 AM
Talked to a mechanic today, he's quoting me $1200 for a complete rebuild if the bellhousing isn't shot. Mechanic says if the TV cable/kickback cable went out it can toast the transmission before I even have a chance to fix it. Says I shattered a gear and blew the pump. I'm heading over tomarrow to take a look at it. I'v been suspecting this trans was bad for awhile now, I guess it was time for it to blow.

I'm not sure I trust this guy 100%, but he has yet to screw me and has been able to get me quality parts at factory prices in the past so I think he wants to keep me as a customer. I'v also seen his work which is short of damn good. Nothing like looking under the hood of a thunderbird with a turbo the size of a 4 cylander. :X

*starts thinking outloud*

Looking at the situation, I'v sunk $2500 into the car thus far. Engine was rebuilt 45k ago and is running flawlessly, so it'll be due for a rebuild in 60k or so. Frame is in excellent shape, all she needs is mabye $1000 more parts plus some work on my end to get her into *perfect* condition. Looking at other used cars and new cars, and their tag, maintainance and fuel costs, even with the trans rebuild and all the other parts costs it'll be compairable in price to a new car. 24-26 cents per mile compaired to 22-24 cents per mile for a brand new 2007 honda accord. My sisters used corolla has setting her back about 20 cents a mile. Sure, it's over the sell price but hey, it'll get me to and fro for cheap and after this I don't see it dieing anytime soon. So the real difference is about 6 cents per mile to own this car, and to switch to a new car now I lose that much just to switch over so there's really no benefit. Plus it's a luxury car :X.

01-17-07, 08:06 AM
$1200 for a rebuild is not bad at all! I paid $2250 for mine. Along with it I had them use a bigger input drum, better 3-4 clutchpack, and new cooler lines. Go for it!

01-17-07, 09:37 AM

1200 better include r+r from the car too.

01-18-07, 06:56 PM

1200 better include r+r from the car too.

Tell me about it!

Talked to the mechanic. He says the bearings are worn, the clutches are shot and sticking, the plates are warped and the pump is leaking and it's giving off metal shards. I asked him how he knows; he dropped the pan and did a pressure test and checked the fluid. Looking at how my trans works and what it is doing, his story is plausable and probably correct. Although it's strange how months before I can drop the pan and find little swarf and now, when I take it in, he's finding metal shards.

At least I know once this is done and she passes emmissions, change the tires and fix the seat I can FINALLY drive the car without worrying about it blowing up on me and I can enjoy myself :). I'v only been able to get a taste of driving her around, and it's addictive!

01-18-07, 11:04 PM
Well, finding metal in the fluid comes from different standards, yours, and his, so what you might consider not much metal to care about, he might. Also to mention the fact that once one material is gone, another material may quickly wear through. I suppose it's kind of like brakes. Once you get through the pad, you get into the metal. They wear differently.

01-19-07, 05:49 AM
Yeah, and if by wears differently you mean "has the potential to destoy the car entirely and cause an accident" then sure, by all means, wears differently is fine. :/

I'm much more worried about the jerking around like a lowrider and potentially killing the engine. :X

02-02-07, 07:58 AM
Rebuild done!

Man, I can't even FEEL this car shift. Still is a bit sluggish due to the cold and the mechanic used a half tank of gas and moved the car about 100 miles. Mechanic says I need to change the fluid after 1000 miles.

$1250 out the door. 1 year warranty. And I got a box of parts they took out of trans. Basic rebuild.

Had Dave's Automotive and Radiator Repair do the job. It's on Saint Charles road in Carol Stream, Illinois.

Engine is tripping codes intermittently again but that's probably due to the weather and I need to check the electrical connections again.

02-03-07, 03:25 PM
I have a similar problem with my 87 Fleetwood. Only in my case the trans works fine. When i drive it for a while and the car gets warmed up the following happens:

When i slow down maybe from 60 to 30 and then step on the gas again the car will shudder. Sometimes the problem stays for a while and sometimes it completely disappears after maybe one full stop. I was thinking it could be the converter lockup wich might get stuck. Since the car has no tach it is hard to tell but i thought i might disable the lockup to see if the problem disappears. Since i am not too concerned about mpg i even might leave it without the lockup because i think the engine will feel much better without the sluggishness of the wimpy 307 in overdrive. Is there a simple way to do this like pulling out one cable or so? If so where is that cable located? I am no mechanic so a picture would be nice....

02-06-07, 02:00 AM
The torque converter lockup engauges and disengauges based on pressure flowing through the turbines. In short, there is no easy way to get rid of it.

The converter itself engauges at 40MPH. If it was sticking you'd feel the car jump right around that speed; if it never enguages, you'd never go over 40mph. Most trans issues happen around specific speeds and do wierd shit at those speeds, or the car has issues with the gears slipping and then you have a whole different set of problems.

Your issue sounds like a problem with either the carb or the emissions system.

02-06-07, 08:13 AM
Gwokable: Thank you for the input. I thought the lockup was engaged via a solenoid?

What kind of carb or emissionproblem could it be? Could you give me some hints for my mechanic? Where should they look and how could they test and locate these problems? The biggest problem is always to diagnose the problem correctly. Unfortunately most mchanics just take a wild guess and start replacing parts until the problem is solved - or not....

Any tips are welcome!

02-06-07, 01:02 PM
One more observation: I think that the problem only occurs after hard cornering manouvers like driving off a highway ramp etc.

DopeStar 156
04-27-07, 11:11 AM
This seems awfully familiar, tell me where the TV Cable is, I wanna check mine....