My ride has a th350C transmission. I’ve been running it without the lockout hooked up now I believe the torque converter is going bad as it bucks every time it tries to down shift . My question is can I swap the converter to a regular th350 converter? Or is this not the problem at all? Sent from my iPhone using The H.A.M.B. mobile app
Would the torque converter cause this bucking on the downshift Sent from my iPhone using The H.A.M.B. mobile app
I'm not sure that is exactly true. I have a 700R4 that has a non locking converter. Don't know why prior owner had it built that way, but it has 40k miles. Phil
It wouldn't be a 1980 model, would it? That was a stand alone, troublesome unit. Correct , not interchangeable. The non lock up , standard model, won't slide all the way in on the input shaft.
Can anyone tell me exactly what these came out of . In having trouble finding that out to get a new converter? Sent from my iPhone using The H.A.M.B. mobile app
Usually that is from the lockup solenoid stuck in the on(locked) position. If you drop the pan and remove the solenoid, check the linkage for the TC is not jammed on or that the solenoid has somehow gone into the 'ON' position causing the TCC to activate or drag. Th350C was offered in '80 before the TH700R4 was available('82). And was still offered well into the Th700R4s timeline. Th2004R is a single piece case and does not allow for useage with AWD/4WD applications. Fairly sure all the 'C' and 4R/R4 transmissions used the same four plug connector for lockup and overdrive activation in the ATs.
Mike is most likely correct here about the solenoid. Also troublesome. Maybe you should just drop the pan and if it looks fairly clean inside, do a solenoid and filter change, and try it like that. You could also just unplug the electric connector and road test it like that.
There is nothing electronic Hooke up on this car I’m just running it as a regular th350 Sent from my iPhone using The H.A.M.B. mobile app
There is no plug on the case then? If it's 81 to 84 then the lock up converter won't come on. If it's early 1979-80 then it could be one of the governor controlled early lockups. Like I said earlier that could be very troublesome. It had its own separate valve body section. One thing you could do is have a local rebuilder cut the converter open and take the lock up out of it. At least you wouldn't have to worry about it sticking on.
All the electric connections are on the transmission but I do NOT have anything hooked up to them and haven’t for the past 4 years I’ve driven it. I did adjust the vacuum modulator today and that helped a lot Sent from my iPhone using The H.A.M.B. mobile app
Mr Vroom, you are missing the point. The solenoid and plunger assembly are fairly light weight. If the linkage in the solenoid moves and is sticking it will cause the TCC to drag or lock which will cause for harsh downshifts when slowing down. This is a mechanical issue with the solenoid assembly. Doesn't need to be plugged in. A good jostle and some varnish build up may cause it to stick. The solenoid is about the size of your thumb and it actuates(at least on the Th200s) a plastic plunger that activates the TCC circuit. If that is the same setup as your 'C' then it may simply have jostled 'on'. Now if your downshifts are from passing then I would suggest you look at your down shift cable and vac mod for correct adjustment. If this is a new problem, I would look at the last thing you did to the car prior to this problem.
Thank you mad mike this is good information.im assuming the solenoid is inside the pan . I’m not a transmission expert .when I drop the pan to change the filter I’ll change that too. Sent from my iPhone using The H.A.M.B. mobile app
That solenoid can be costly, depending on where you get it. I would inspect the original, make sure there is no gunk on it or the plunger. And manually exercise the TCC linkage to make sure it is coming back to its at rest state. I can't recall if you can just pull out the solenoid and just leave it out. If you can(without causing an internal leak) I would just do that.
Not you can't just remove it. You need a special bushing in it's place. I doubt that it's activating itself with no power. It has to completely reverse the fluid flow in the converter. If it did that , then the pressure would push back the check ball in the valve and cancel it, with no magnetic field to hold it on.
I’ll take it back out today and see how it acts I have a new vacuum modulator ordered and will be here tomorrow Sent from my iPhone using The H.A.M.B. mobile app
May I ask a question or two about the TH-350C? Background.....a few years ago I found one of these at a salvage yard while I was looking for something else. What caught my eye was the ‘universal’ bell housing bolt pattern as is the standard for the TH-2004-R trans. Looking at the data tag, I noticed the ‘C’ model designation. I brought it home, but to date have not needed it. My question.......are the foregoing comments to be construed as a caution that these ‘C’ models are inherently problematic and not recommended for use? If so, it is solely because of the lockup solenoid or are there other common problems on the ‘C’ series? Ray
Ray, There shouldn't be any issues, except those related to the lock up portion. The rest of it is common 350 stuff. There are a few issues that could be addressed there.
The car drove ok today just a few times it had trouble downshifting Sent from my iPhone using The H.A.M.B. mobile app
Could be several different things. There are shift valves that have to return on the downshifts. Gum, sludge can be a problem. Drop the pan ..Dump it out, then post a picture before wiping it out. We won't be too hard on you here.
This transmission has always shifted to early I’ve adjusted the vacuum modulator all the way no in but still to early . Any suggestions? Sent from my iPhone using The H.A.M.B. mobile app
Readjust the tv cable. And no the TH350 lockup transmissions are no more problematic than a TH350 non lockup unit. Get a controller for the lockup converter from TCI and get better gas mileage too. Denny
There is no TV cable on a T350, C or otherwise. It shifts by governor and modulator. He doesn't need a TCI controller. Let's leave the Summit catalog on the shelf for now.
Oh, okay. I just assumed that because you had a new tech question. All this stuff might be readily apparent once you look inside
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