Hi Guys, After doing a recent engine build, I finally bit the bullet and got a new torque converter for my TH350. It's a B&M Tork Master 2400. Definitely improved the situation of my engine wanting to die when stopping in gear. Problem is, now it goes back and forth between running better than ever and then not wanting to shift out of first gear. I have a B&M Quicksilver ratcheting shifter. When this happens, it doesn't matter if I try to shift it manually or just leave it in drive. It just wants to rev up. So, my guess is the converter is bad. But when they go bad, will they work intermittently like that? Runs beautifully about 70% of the time. Also, tried changing vacuum modulator and vac hose. All good there. This started within the first mile I drive after the TC swap. Thanks for any help guys.
Out of curiousity....did you get the convertor to go into the pump all the way...2 notches? A little hard to explain that typing....
I'd call B & M's Tech line. Yes, converters can be bad, we had a TCI go bad in one of our cars but it simply stopped moving altogether. One of two possiblilities, either the converter is bad or coincidentally something in the trans is screwed up, making you think it is the converter. The thing that makes me think it is not the converter is it not wanting to shift out of first. The converter has nothing to do with how the trans is held in gears it is simply the "clutch". Don
This is actually the only service job i've farmed out. Had a friend do it since he has a lift and trans jack. He is an experienced mechanic, so can only assume he put it in right.
I would check the Kickdown cable cable, make sure it's moving freely and then check the governor, pull it out and move the butterflies in and out, make sure the valve in the center is moving. If I remember correctly you held it with the gear up it's been a while.
The converter won't make the trans shift funny. I would bet the kickdown linkage (TV cable) is binding up somewhere. The governor can do it too, but I am assuming your guy just pulled the trans and reinstalled it, and didn't open it up.
How long had trans sat before convertor install....don't usually pull pan when I put in a convertor...lol
I have revved it up like this a couple times while the shifter is locked in 2nd. Never hear it upshift into 2nd, but does seem to downshift if I lock it back down in first. Either way still lots of revving, without much moving.
Now that you describe it as a slipping problem, that makes me think it might be the TC. Call B & M. Don
From a dead stop and light throttle, how high does the rpm go before the car moves? If you power brake, how high does the converter stall up before moving the car? It may be shifting and you just can't feel it, you did say it will down shift which means it shifted with out you knowing. Sounds like the converter is really loose. Joe
Here is something else we learned recently about TC (the hard way ) They need to be shimmed to the flexplate sometimes or they will not engage the tangs on the front pump deep enough. Every TC is dimensionally just a tad different than the others so what fit for one may not work for another. We had the same 2400 B & M in my Kid's rpu and it took 3 grade 8 washers on each of the TC to flexplate bolts to seat it correctly. Yet when we went with a B & M 3000 Holeshot in the same setup it only took one washer to make it work. If the TC is not deep enough into the front pump it will not drive that pump. The right way to seat the TC is to put the trans on a downward angle (tailshaft lower than the front) and put the TC on the shaft. Start turning it by hand CLOCKWISE until you feel it go down a click, then keep turning it until it goes a second click, and then turn it more until it seats down a 3rd click. It will physically drop down a notch each time. When it is fully into the front pump put a 3/8 inch combination wrench on the frontmost lower pan bolt and use it as a "stop" to keep the TC from sliding forward while you are mating the trans to the engine. That step is hard to explain, but all you are doing is inserting a 1/4 x20 bolt through the round part of a 3/8 combination wrench to make it act as a lever, then you swing the wrench back against the front of the TC until it touches, then tighten up the 1/4 x 20 bolt so that the wrench can not move. The wrench will keep the TC from sliding out of the front pump until you are done bolting the trans and engine together, then you can remove the wrench. After you have the engine and trans totally mated, remove the wrench and see how much of a gap you have between the TC and flexplate. This gap can vary, sometimes it is just a 1/16 or so and sometimes it will go as high as 3/8 to 1/2 inch. You do not want to pull the TC further than about a 1/6 or maybe an 1/8 inch, so if it is more than that you need to insert as many grade 8 - 3/8 washers stacked in between each mounting spot to take up the distance. If you pull the TC too far forward it will not be inside the front pump and can break off the tangs on the pump. The first time I learned this was from Mondello and I questioned how strong it would be with those washers in there, and they said they use that same setup on their 1200 hp drag car and that is the way it is done. The transmission shop that replaced the front pump we broke confirmed that is the way to do it. I suspect that there was a dimensional difference between your first TC and the new B & M unit and the guy who installed it pulled the TC too far forward, pulling it partially out of the tangs. It might be making contact sometimes and not other times because the flex plate may be "walking" back and forth a bit under torque. Like I mentioned , we had the very same 2400 in the car originally and it was somewhat shorter than the 3000 we replaced it with, so you might have the same problem going on. But without seeing it firsthand it is impossible to say for sure. Don
If that's the case, start it up bring up the rpms and snap the kickdown cable a few times....my 700r4 acted stupid, shift wise, after sitting a couple years.
He hasn't said what trans it is, but I am assuming a th350 since he said he is using the 2400 B & M. If that is the case, the kickdown can be disconnected and still function ok, unlike an AOD or overdrive trans where the TV cable has to be right on the money. Don
Your first sentence is right, but the second one isn't since TH350's don't have a TV cable. Sounds like that could be the case. If it downshifts, it HAD to Have Upshifted - no way around that!
I agree with Don, tc depth issue. Is the trans making a whining sound now that might indicate front pump damage.
I was thinking about this thread tonight ( I have a lonely life ) and something stupid came to mind. How is the fluid level in the trans? I have had th350's that would act like you describe even if they were a quart low on fluid. One day I was driving up an incline in my 23 and it suddenly started to act like it was in neutral, then it would catch. When I got home I checked the fluid and added a quart and the problem never came back. I'm sure you have checked it, but just in case................... Don
It's not the converter... They don't "slip" It's not the kickdown cable...No effect on the 1-2 shift Not the converter hub pulled out of the pump tangs ..Either it works or it doesn't.. An "experienced mechanic " would know if the pull up to the flexplate was too much anyway. It's probably a T350 conv. core , so nothing was changed with the overall length. If you never dropped the pan or touched the governor, it would have to be ,either the fluid level , or a modulator problem. Oh yeah, I suppose it could be the Ratchet ass shifter acting up.
Didn't really sit up recently. Turns out it was the governor gear. About a third of its gear surface was broken off. Surprisingly, none of the parts stores carry those or even have them in their computer systems to order. Was able to find a good used one from a mechanic who works out of his home garage nearby me. Luck was on my side. Thought I'd have to wait for one in the mail. The truck is running better than ever.
Just seems it was a strange coincidence that the governor gear suddenly broke at the exact same time as the TC install. Seems everything I fix on this truck just leads to the next repair. Sure everyone here knows that story all too well.
One thing to watch for if you do the shim thing on the converter, if you shim it out to far you will pull the snout out of the crank and have a worse problem, in 30+ years of doing transmissions i have never had to shim one more than a single washer.
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