Link needed for th350 info

[fatbob]

My th350 was not shifting from 2nd to 3rd untill the rpms got pretty high. {no tach or speedo so I dont have more detailed info. }
Now it wont shift out of 1st gear so I gotta tear into it
I already checked kickdown cable for binding and the vacuum line to the modulator, no luck.
The chilton said to check the governor valve and screen but their pics suck. Since the upshifting got progressively worse, a clogged screen could be a likely cause. So if I have to drop the valve body, I would like a better diagram to reassemble it with, in case I drop any of those check balls.
Does anyone have any links to any good transmission articles?
Thanks
Bob

 

[diesel4me]

check the govenor gear first..

I'd pull the govenor out and inspect the nylon drive gear..it might be stripped or worn down in the center..its pretty easy to remove and check..

Its under a round cover on the drivers side rear of the tranny..Most TH350's have a spring steel bail to hold the cover on--like the one on a master cylinder..the cover is a tight fit so you might have to pry it off..it has an "O" ring in the hole to seal it..the govenor slides right out once the cover is off..the gear should be straight across when you look at the teeth,like the one on a distributor..not all stripped or if it looks like an apple you ate down to the core,its junk..

If the govenor doesn't turn due to stripped teeth or gear damage,it will not upshift out of first..or it might shift erratically...gears are cheap,and easy to change,just drive out the roll pin holding it in..or just put in another used govenor with a good gear from a boneyard tranny (TH350)..its quicker....

A modulator with a bad diaphram will cause late shifting,and will let ATF get sucked into the motor and burned(could make it low on fluid without any leaks!)--..if the detent cable isn't adjusted properly,(too tight)-it might hang in the lower gears too..I doubt if the screens are clogged--but if they are,they are under the valve body,and aren't exactly a job for a novice to remove and clean..

I limit my tranny work to replacing filters,modulators,fluid,and seals and govenor gears..never been brave enough to do a shift kit,or total rebuild of clutches,etc.-good luck,maybe it'll just be a modulator or govenor problem..if not,a local tranny shop can test the line pressures and give you an idea of whats wrong..

 

[fatbob]

Thanks, I'll check out that gear tomorrow. I really hope thats the problem because I also like to restrict my repairs to the outside of the transmission. But I have changed the filters , and after looking over the shiftkit article in the tech section, it does appear to be too bad if you dont lose any parts. That article covers a th400 though, so it wouldn't help much with the th350.
I do have a parts th400 out back. I wonder if the gears on the governor are interchangeable?

 

[diesel4me]

doubt it..

I don't think a TH400 govenor or its gear would be the same as a TH350..a TH250 might be interchangeable,thats about it AFAIK..

I do have a tranny book with good pictures of where the check balls go,but no way to copy them and post them..I think someone posted a picture here once in the past..maybe a search will help..try Google too,look under.."TH-350----check balls"...sounds sexual doesnt it??

 

[roadnotca]

Th350

Everything you need is in "Turbo Hydra-matic 350 Handbook" by Ron Sessions, ISBN 0-89586-051-1. There was no way I was ever going into an auto, and I wasn't looking to learn, but I came accross the book, studied it and figured, "Hill yea". I rebuilt it, it was interesting, didn't piss me off at all, that tranny is one of the best pieces of equipment I own. That's my answer to your current Q, beyond that I built-in all the beef-ups in the book, I used the TCI Master rebuild kit so I have full gear selection, and I converted to the HURST Promatic 2 floor stick. I drag raced the trans in my '77 Nova, which included slapping gears, swapped it from there into the Burb when the 700R4 pooped, works really well for the technical stuff off road what with select shifting and floor stick. Good luck.

 

[76zimmer]

If you get a
GM service manual (from Helm inc.) you can rebuild one on your own, they are that detailed. Although some special tools are needed.

 

[fatbob]

Tranny faries visited

When I left for work this morning it looked like those damn tranny faries visited last night and fixed the tranny. But I dont trust those guys, and sure enough it didnt want to shift again after it warmed up, unless I reved the piss out of it. A related issue is that I just installed a hydroboost brake setup, and I noticed quite a bit of heat coming from the front rotor. Now I'm thinking that if the front brakes are draging, it could be appling enough resistance to delay to the tranny shift point. So I opted to reroute the brake lines instead of checking the governor gear. I mean if the gear was striped it would be bad wouldnt run different when cold. And if the residual pressure valve for the rear drum brakes were routed to the front calipers, then I would have dragging brakes that may get worse when hot. I guess I'll find out tomorrow.


PS. Thanks for the book recommendations guys, but I'm cheap and hoping to find more online info. Like that shift kit article in out tech forum. I have seen other writeups but can't remember where I found them, and my searches seem to just find sites selling parts.
Thanks again
Bob

 

[roadnotca]

If you get a
GM service manual (from Helm inc.) you can rebuild one on your own, they are that detailed. Although some special tools are needed.

Don't mean to dump on your reply 76zimmer but the Sessions book is written for "build your own", which I did, and it's an "OffRoad" tranny (more robust than stock) and didn't require GM tools, just some simple stuff. The GM book will show you how to build a stock tranny. And FatBob, I suspect a GM book would sell for ?$40, the Sessions book maybe $15 at a book seller. Sessions also wrote the book on TH400. I haven't seen a 700R4 book from Sessions, I wish he would; I've got a 700R4 core.

 

[76zimmer]

A great reply.....Helm books are expensive, 60-100$...but have every detail in them. I just added upgrades from the manufacturer of whatever part I was installing at the time. I think I will look into the Sessions books though. Thanks

 

[roadnotca]

A great reply.....Helm books are expensive, 60-100$...but have every detail in them. I just added upgrades from the manufacturer of whatever part I was installing at the time. I think I will look into the Sessions books though. Thanks

You bet, and you'll stunned at the content of the book.
"The only thing between us and wealth is info."