Author Topic: "TH" gearbox rebuild, has anyone done it themselves?  (Read 1698 times)

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Offline Sir english firebird

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"TH" gearbox rebuild, has anyone done it themselves?
« on: November 15, 2009, 11:50:32 AM »
Ok i had a looky through the forum and couldnt find what i was looking for so its time to post.

I want to rebuild my poor ol tired TH slushbox, im pretty sure its a 350 but to be honest i cant be sure as the previous owners where less than kind to my poor ol Bird.

Its needed a new box ever since ive had it, but time and funds just never seem to be together , but the old box plodded on and put up with the grief.

Now its really had enough, ive had a looky at rebuild kits and was wondering if anyone had built their own or has any usefull advice.

Yes i could buy a recon box here (UK ), but the prices are just sky high and as for a new one, well the only way to go would be to get one there ( US ) and have it shipped and then im talking again.

Thanks guys, i took the poor old girl out for a spin today and it made me realise just how bad it is.......  :'(
Power is nothing without Control.

Steve, :-)
1979 Trans am.

( no point in adding what else i keep changing them ! )

Offline RENOVATIONS

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #1 on: November 17, 2009, 08:22:30 AM »
I'm no help on that but you might check with ih8z28s (Joe)...I recalll he rebuilt his own trans in the past ;)
Jeff

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1970 Camaro
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Offline kjkjkcjkcj

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #2 on: November 17, 2009, 08:39:22 AM »
If you do I siggest taking lltons of photos. I could only imagine
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
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Offline SoonerTA

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #3 on: November 17, 2009, 11:19:32 AM »
I have seen step by step videos online.  I will try and find them again.  I think it would help a lot. 

Offline Sir english firebird

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #4 on: November 17, 2009, 12:34:18 PM »
Cheers guys, i have bought a " rebuild and uprate " book off Ebay, i was lucky as its the only one ive seen over here.

When i do get my finger out ill shoot pics etc, but it wont be for a while yet, i havent even pulled the transmission yet!
Power is nothing without Control.

Steve, :-)
1979 Trans am.

( no point in adding what else i keep changing them ! )

Offline deadfish

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #5 on: November 17, 2009, 02:27:43 PM »
Did mine years ago using a "B&M Transkit" and a manual I found through a parts supplier. You will need a few special tools to compress springs but I made them as I needed them...not too difficult if you're a bit inventive. It is also VERY important to keep everything extremely clean as there are small screen filters here and there that will clog easily...even lint free shop rags. To get it all back together in the proper order, as each part was removed and cleaned, I'ld put it in a wax paper sandwhich bag marked with a label and strung them along a wire with clothespins, then when it came time to reassemble, I simply started from the far end of the wire and replaced the parts in reverse order. The case was sent to a tranny shop to be hot tanked. I also bought the low/reverse clutches and steels and a "case saver" from the shop. Those parts were not included in the "Transkit". Anyway it can be done more easily than you might think..heck...mine still works!
Good luck and keep us posted!

Rick C.

Offline turbota400

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #6 on: November 17, 2009, 05:17:39 PM »
I also rebuilt mine.  I agree, keep the parts on order as you take them apart and keep them CLEAN.  Any little bit of debris could plug things up or scar the clutch plates.
Shawn
1972 Chevy C-10
1980 Trans Am Pace Car - 428 ci Poncho in the works
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1997 Chevy X-cab 4x4 - Vortec 350

Offline Sir english firebird

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #7 on: November 17, 2009, 06:16:09 PM »
Rick and Shawn thankyou, i appreciate what youre saying, as for tools, well im pretty inventive but well see, its a little way off yet, i need to source the " kit " to do the job.

Thanks, i dont know if im looking forward to it or not but im most certainly going to have a go..... whats the worst that could happen? 3 reverse gears perhaps? LOL
Power is nothing without Control.

Steve, :-)
1979 Trans am.

( no point in adding what else i keep changing them ! )

Offline deadfish

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #8 on: November 18, 2009, 06:33:20 AM »
Rick and Shawn thankyou, i appreciate what youre saying, as for tools, well im pretty inventive but well see, its a little way off yet, i need to source the " kit " to do the job.

Thanks, i dont know if im looking forward to it or not but im most certainly going to have a go..... whats the worst that could happen? 3 reverse gears perhaps? LOL

Your welcome...LOL three reverse gears? no problem!...just move the steering wheel to the back seat!

I got my kit from "Jegs". Summit also used to carry them. (Jegs was less money at the time...1991?)
Seriously...it really is easier than you might think...hardest part is taking it out and putting it back in!

Rick c.

Offline Sir english firebird

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #9 on: November 18, 2009, 10:27:21 AM »
I think the 3 reverse gears will probably be the least of my worries! PMSL

Ill check into Jegs etc, thankyou again for the heads up!

Much appreciated from over here!
Power is nothing without Control.

Steve, :-)
1979 Trans am.

( no point in adding what else i keep changing them ! )

Offline SoonerTA

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #10 on: November 18, 2009, 05:10:10 PM »
Rick and Shawn thankyou, i appreciate what youre saying, as for tools, well im pretty inventive but well see, its a little way off yet, i need to source the " kit " to do the job.

Thanks, i dont know if im looking forward to it or not but im most certainly going to have a go..... whats the worst that could happen? 3 reverse gears perhaps? LOL

Your welcome...LOL three reverse gears? no problem!...just move the steering wheel to the back seat!

I got my kit from "Jegs". Summit also used to carry them. (Jegs was less money at the time...1991?)
Seriously...it really is easier than you might think...hardest part is taking it out and putting it back in!

Rick c.


What kit did you get?  Did you also install a shift kit?

Offline deadfish

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #11 on: November 18, 2009, 07:14:30 PM »
I believe it was called "Transkit" or "Transpak" put out by B & M. One is just the shift kit (reroutes fluid in the valvebody) The other is the whole thing and includes the shift kit) (minus the low/reverse clutches and steels for some reason) At the time, they were the only two available from them...(can't remember exactly which was which or if I got the names perfect...I did this in like 1991)

Rick C.

ps.. Oh yeah..I did install the shift kit...utilizes the whole low/reverse piston (stepped piston) in either shift position. Normally only one step section received fluid in each position...makes for a better launch!
« Last Edit: November 18, 2009, 07:19:45 PM by deadfish »

Offline Chobby68455

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #12 on: November 21, 2009, 02:29:52 AM »
Hey i did a TH350 and TH400 in auto trans class(college) what i did was take pictures of how the parts looked inside the transmission. Also be vary careful on the valve body. The little check balls are gonna want to fall out and u dont want to spend ur time looking for them when for some reason they seem to dissapear when they land on the floor. And make good note or take a picture on where they go. O and keep your snap rings in order because i noticed there are two(if i remember correctly) snap rings that are almost identical but actually a little different from each other. Thats if i remember correctly. Im not a master transmission mechanic hence im still learning and in college but, these are some things that might help. Have fun!
Pontiac livin, n ridin.
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Offline Sir english firebird

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #13 on: November 21, 2009, 10:16:25 AM »
Unfortunatley my college was too long ago and we only messed with Europeans!

I think this is going to be a labour of love, i appreciate the comments and theres alot of good advice........ i could always fly it over as "hand baggage" PMSL
Power is nothing without Control.

Steve, :-)
1979 Trans am.

( no point in adding what else i keep changing them ! )

Offline Chobby68455

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Re: "TH" gearbox rebuild, has anyone done it themselves?
« Reply #14 on: November 21, 2009, 01:37:48 PM »
hahaha well thats what happens if u live in england. Actually i also own a jetta and man can i tell u the parts are expensive. if i could have only kept that money used in german parts and used it for american parts for my bird.....it be running mid 12s by now hahaha
Pontiac livin, n ridin.
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