Transmissions and Drivetrain Need help with your trans? Problems with your axle?

TH700R - service?

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Old 04-04-2019, 08:36 AM
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Car: 1989 IROC Convertible
Engine: 350 TPI L98
Transmission: WC T5
Axle/Gears: 3.42
TH700R - service?

Is there a service or refresh available for this trans short of a rebuild? Mine has 120,000 on it and is currently running on Mobil 1 ATF. It runs fine but has a few peculiarities like under WOT it won't go into third from second and when down shifting from top gear goes into second instead of third. I am looking at a manual conversion but in the meanwhile, is there a service/mod I can do that will freshen this thing up and sort it out?
Old 04-04-2019, 08:44 AM
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Re: TH700R - service?

Sometimes when you service one on its last leg it gives out shortly there after.
Old 04-04-2019, 09:00 AM
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Re: TH700R - service?

Sounds like 2-3, 3-2 solenoid on the valve body. IDK
Old 04-04-2019, 06:46 PM
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Re: TH700R - service?

Originally Posted by dmccain
Sometimes when you service one on its last leg it gives out shortly there after.
That is VERY true. You really don't want to mess with a high mileage trans.
Old 04-04-2019, 06:47 PM
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Re: TH700R - service?

Originally Posted by Bob88GTA
Sounds like 2-3, 3-2 solenoid on the valve body. IDK
Can I throw in a rebuilt valve body without rocking the boat too much? How can I tell it's not the governor?
Old 04-04-2019, 06:58 PM
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Re: TH700R - service?

Tootie, you don't need to remove the valve body to replace it. Just the pan. IDK about the governor. My TTA had that exact same issue in a a 200R4. Solved the problem.
Old 04-04-2019, 09:19 PM
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Re: TH700R - service?

I didn't find 2-3 solenoids. Is there a search term I need to use?

Last edited by Tootie Pang; 04-04-2019 at 09:33 PM.
Old 04-05-2019, 12:43 PM
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Car: 86 Imponte Ruiner 450GT, 91 Formula
Engine: 350 Vortec, FIRST TPI, 325 RWHP
Transmission: 700R4 3000 stall.
Axle/Gears: 9 Bolt Torsen 3.70
Re: TH700R - service?

It's 30 years old. The seals for all the pistons are dried out and sooner rather than later it's going to need gone through. Half measures will yield half results or worse.

A 700R4 rebuild is not very expensive in the scheme of automotive repairs. Yank it and rebuild it. Or just buy a ready to install replacement and drop it in.

GD
Old 04-06-2019, 11:42 AM
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Re: TH700R - service?

Transmissions were always mysterious to me. You got me looking to see exactly if it really is all that difficult. Some quick browsing around the web makes it seem very doable. Here a nice write up.

https://www.uscars.biz/uscars/extras...Procedures.pdf
Old 04-06-2019, 05:39 PM
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Re: TH700R - service?

Originally Posted by LiquidBlue
Transmissions were always mysterious to me. You got me looking to see exactly if it really is all that difficult. Some quick browsing around the web makes it seem very doable. Here a nice write up.

https://www.uscars.biz/uscars/extras...Procedures.pdf
That is so cool. Now I want to rebuild it!! Great book.
Old 04-06-2019, 07:45 PM
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Re: TH700R - service?

Oh sure, it's easy... Until you've got 3 million parts blown apart all over a 4x8ft work bench. There's more info available now than when I dipped my toes into the 700R4 many moons ago, but ultimately there are a LOT of small parts. Springs, check *****, seals. I can rebuild an engine, rebuild differentials and gears and have them come out quieter than factory. When it comes to the 700R4, I still get angry. I suppose if a person has a really great work space, excellent documentation, a few special tools like a holding fixture and the tools to compress the springs and remove snap rings, it's certainly doable. But I'd much rather pay someone who is qualified to do the job, assuming I could find anyone qualified to do the job that isn't a total squirrel about getting the job done. Left my car, and a transmission at 2 or 3 different shops for weeks and months at a time, only to have them tell me they didn't know when they could get to it, or that a broken fluid pump required completely rebuilding a trans that had only a few hundred miles since it was built... Yes sir, there's a reason I've got a T56 in the corner for a rainy day.
Old 04-07-2019, 01:35 AM
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Re: TH700R - service?

Call Dana at probuilt automatics.com I bought the holding jig and a few out special tools for under $200 and the kit from Dana to rebuild my trans to optimize it for running on a road course for about $450 and then a converter for a '96 Astro 4.3 trans worked better than new.
Old 04-07-2019, 04:43 AM
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Re: TH700R - service?

Dana is absolutely the way to go. I read a post a while back that he's selling rebuilt assemblies again, along with his parts kits and knowledge. Best to call him though. His website has never been a consistent means of communication for me. I know he's had web service provider issues years ago.
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