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Old 11-08-2004, 02:31 PM
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TH350 Manual Valve Question

I just bought a cobbled together '82 Camaro that has a carbureted 350 engine and a TH350 of unknown lineage in it. Evrything on this car has been taken apart and put back together with something different, chrome plated or 'performance', and maladjusted without fail. I am getting things sorted out one by one, but now I came upon something I need some advice on.

The shift detents were in all the wrong places. I took the console out to discover that the shifter had been cobbled (I mean pieces welded in & such). I figured, OK, now I can sort this out. So I straightened everything the best I could. There is some adjustment available at the shift cable attach point at the transmission (now I wonder if they machined that in themselves, to try to fix what they screwed up). I set the thing up so that the neutral detent inside the trans lines up with the neutral lock in the shifter, it had been way out of adjustment.

To my surprise, the thing still wasn't proper. Several more adjustment attempts, and I arrived where I have it now, temporarily until I can fix it right. That is, I needed the neutral lock in the shifter to correspond with neutral in the trans, so as not to accidentally get reverse, and I need park to work. I got that to happen, but everything is approximately one detent removed from its proper function.

The problem is, that the detents inside the transmission (not at the shifter, I have verified this with the shifter disconnected), do not properly line up with the functions on the valve. In order to get normal operation in any of the forward gears, the thing has to be sitting up on top of a detent. The drive detent (which I believe is really supposed to be the neutral detent) puts it between second gear and drive, but not far enough to lock the band in second (doesn't upshift into third or lock into second). It has to be pushed forward some to get proper Drive behavior. Proper second gear sits on top of the next detent. And the next detent gets first gear. The parking pawl doesn't engage until the shifter is pushed well past the park detent.

Never having been inside one of these, and not wanting to disassemble it without knowing what I am doing, I hit the books. My thought was, obviously, that the linkage to the valve must be messed up somehow in the transmission. OK, so when I look at the pictures, there is the manual shaft, and an S-link that hooks it to the manual valve, and a rod going back to the parking pawl assembly. So far, I can understand. Attached to the manual shaft is a piece of sheet metal with cogs on it. When I saw this, I thought, well this must be it, these cogs must be what make up the detents in the manual shaft rotational travel, and someone screwed with it and got it messed up somehow. But, as I read further in the assembly manual, here they describe putting in a 'detent rod, spring, and ball', the picture shows it going into the valve body right in line with the manual valve. Well, I've been around enough pneumatic and hydraulic stuff in my work life to know that the easiest way to put a detent into a linear travel on a rod sliding in a bore, is to machine a land into the rod, and push a spring loaded ball in at a 90 degree angle to it, so that it snaps into place, precisely locating the rod while giving a positive feel to the location. So now I'm thinking, if that's how they get the detents in the manual valve spool, then what the heck is that cogged part on the actuating shaft for?

I need someone who has had one of these apart to explain it to me, I can't find a book anywhere yet that tells how that part works. If one of the previous owners got in there and mucked it up, I can probably fix it (they weren't smart enough to do too much real damage to everything else they 'fixed'). I just need to know whether that cogged part gives the detents, or whether a spring loaded ball clicking into relief areas on the spool gives the detents. If it is the latter, I suppose the valve body is screwed (could they do this by screwing up a shift kit installation?). I can probably scrape up another valve body and put it in there if I have to. The trans seems otherwise OK, as in no slipping and fluid smells OK, and of course I haven't burned it up yet, so if I can fix it to run until I get an overdrive transmission, that would be nice.

I've read at length how this manual valve operates. So I figure if there is a spring loaded ball sitting in a land to locate it, then that's all there is to it, it's located, and if the trans doesn't behave right, then something is screwed with either the spool or the passages in the valve body. I'm hoping to hear that the detents are derived from the cogged wheel, and either they bent the S link or mis-located the cogged wheel, because I figure I could fix that pretty easily. Maybe they bent it up internally by forcing it with the wrong shifter?

I have read a good deal of this forum and I respect you transmission gurus a lot. I hope you get the time to read this and lend me the benefit of your experience. Thanks!

PS. Yes, I will replace the shifter, but it does function for now.

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Old 11-08-2004, 06:32 PM
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Cool

there is an early detent spring and linkage setup for the t-350 tranny.


If the early dentent spring is used with the late rooster , this will cause a mis alignment
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Old 11-08-2004, 08:19 PM
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Yours will probably have the "S" link in the valve body.
From the rooster comb to the manual valve.
With the detent in D position the manual valve should be close to the back of the valve body.
If it's too far out squeeze it with a pair of pliers.
Too far in use snap ring pliers and spread it a bit.
There is a possibility of the nut that retains the rooster comb is loose.
This would allow excess movement.

Last edited by stu; 11-09-2004 at 08:53 PM.
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Old 11-08-2004, 10:51 PM
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Thanks Guys .....

I appreciate you taking the time to reply.

From what I read, the thing I was calling the cogged wheel is the 'rooster comb', I guess that's pretty obvious. And I guess it rides on something to give the detent positions. So if they haven't put the wrong one in, I should be able to just adjust that S link. Or should I just replace it? Is this something that usually needs adjusting, or is it supposed to be a standard dimension? If it is not unusual to have to adjust it, is there some way to tell when the valve is in the proper position while the pan is off? Can you feel it click into each position? Is there an easy way to tell whether they switched in an early or late part that doesn't belong?

Thanks again guys!

I feel a bath in trans fluid coming on ......
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Old 11-09-2004, 06:57 AM
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check the manual valve as stu points out.

I've never seen them so far out of adjustment that the tranny did not function well. unless soemthing is bent
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Old 02-17-2006, 12:59 PM
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th350 shift alignment

this may not be of any help to you, and the th350s I am working on are 75-79 units, but, since you said you have not been into the guts of this beast before it has been my experience that people who are willing to deform shifter patterns may be trying to compensate for equally inventive wrenchwork.
I haven't had the occasion to figure out an inappropriate retro-fitment of a rooster comb yet, but have run into a couple of other wierdnesses which could seem detent-related. Both are related to aftermarker parts which allow for adjustment of the governor and vacuum modulator. I'm not sure, but it seems that either alone, or in tandem, either part - if sufficiently tweaked - could throw off the base-line pressure referenced by the detente valve assembly.
Again, I'm not sure this has anything to do with what may be no more that an inadept set-up of the rooster comb, but there is more info available through google at th350 governor and th350 rooster, both of which have listings for shift problems, old and new.
hope this helps,
alex
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Old 02-19-2006, 01:48 PM
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Thank you for answering this very old thread.

The question in moot now anyway, since a few days after this conversation took place, the transmission totally self-destructed. Probably from being driven with the detents pushing the valve into the wrong position all the time. I got about 30 miles out of the thing.

It's sitting, and when I get to it, it will get a 4 speed auto or conversion to 5 speed manual.

Got all the parts, but no time with my job heating up big time. I might just junk the damn car.
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