Newly installed TH700R4
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
Likes: 4
From: Northern Virginia
Newly installed TH700R4
I just had my trans mechanic design & install a 1987 TH700R4 transmission with extra HD bands (esp. 2nd gear), and a 2200RPM stall speed converter in my 1976 Corvette C3. I have around 200 miles on it and 3rd & 4th gear have failed. Has anyone else had a similar experience with this transmission?
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
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From: Southlake, TX
These are usually pretty bullet proof transmissions. Since if failed (almost) immediately upon installation, my thought is that your mechanic rebuilt it wrong or some of the "design" items conflicted with the factory tolerances.
Take it back to your mechanic and call for a "do over!"
Drifting
Joined: Aug 2009
Posts: 1,346
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From: new iberia la
or your T.V. cable linkage was not properly configured, and cable adjusted by pressure ..and the clutches burned due to lack of fluid pressure ... doesn t take long to fry one.. The 700r4 can be built to withstand big Horsepower , mine does......ask him for a DO-OVER like Bill said... BTW, when its installed properly, you will love it 
Last edited by fishslayer143; Sep 7, 2016 at 04:32 PM.
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
Likes: 4
From: Northern Virginia
Taking it back
What do you mean by "design?"
These are usually pretty bullet proof transmissions. Since if failed (almost) immediately upon installation, my thought is that your mechanic rebuilt it wrong or some of the "design" items conflicted with the factory tolerances.
Take it back to your mechanic and call for a "do over!"
These are usually pretty bullet proof transmissions. Since if failed (almost) immediately upon installation, my thought is that your mechanic rebuilt it wrong or some of the "design" items conflicted with the factory tolerances.
Take it back to your mechanic and call for a "do over!"
Last edited by jobber26; Sep 7, 2016 at 04:34 PM.
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
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From: Northern Virginia
Mechanic with experience
or your T.V. cable linkage was not properly configured, and cable adjusted by pressure ..and the clutches burned due to lack of fluid pressure ... doesn t take long to fry one.. The 700r4 can be built to withstand big Horsepower , mine does......ask him for a DO-OVER like Bill said... BTW, when its installed properly, you will love it
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
Likes: 4
From: Northern Virginia
Same mechanic for my TH350
or your T.V. cable linkage was not properly configured, and cable adjusted by pressure ..and the clutches burned due to lack of fluid pressure ... doesn t take long to fry one.. The 700r4 can be built to withstand big Horsepower , mine does......ask him for a DO-OVER like Bill said... BTW, when its installed properly, you will love it
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
He might know how to build the transmission internals to support that level of horsepower. But, does he know how to set up the linkage with the correct geometry and adjust the T.V. cable to have it work correctly?
BTW, if that cable is NOT set correctly, you will lose 3rd and 4th gears. Sounds to me like he wants you to think he knows what he's doing.
'nuff said...
BTW, if that cable is NOT set correctly, you will lose 3rd and 4th gears. Sounds to me like he wants you to think he knows what he's doing.
'nuff said...
Last edited by 7T1vette; Sep 7, 2016 at 04:44 PM.
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
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Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
For a high HP motor you need more stall and an efficient TC. i always recommend Precision industries vigilante 9.5 inch with mid 3000 stall.
I've run as high as 3800 stall behind my 434 small block and 3500 when i had 383 and 396 ci strokers
Look up setting a TV cable with a pressure gauge
I've run as high as 3800 stall behind my 434 small block and 3500 when i had 383 and 396 ci strokers
Look up setting a TV cable with a pressure gauge
Racer
Joined: Jul 2013
Posts: 294
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From: Palmer Alaska
Agree on the TV cable. Sounds like you had him do the conversion. What carb? Holley? The the adapter that corrects geometry was hopefully used.
What is the condition of the fluid? Burnt?
I agree with the other posts. If this was a turn key project, he should send a truck to come pick the car up. All you did was drive the car.......
What is the condition of the fluid? Burnt?
I agree with the other posts. If this was a turn key project, he should send a truck to come pick the car up. All you did was drive the car.......
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
Likes: 4
From: Northern Virginia
TH700R4 repaired
I just got the Corvette back and it looks like the "O" ring on the input shaft was torn in assembly, so this was replaced and so were 3rd and 4th gear clutch assemblies at no charge... Can't wait to get in and drive this weekend!!!
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
or your T.V. cable linkage was not properly configured, and cable adjusted by pressure ..and the clutches burned due to lack of fluid pressure ... doesn t take long to fry one.. The 700r4 can be built to withstand big Horsepower , mine does......ask him for a DO-OVER like Bill said... BTW, when its installed properly, you will love it
Somebody screwed up wasnt you upgrading
Edit:putting a GOOD quality good sized trans coolers on one of these is key in helping it live. Heat is their worst enemy esp the earlier ones that easily push the front seal out. Happened to me
Last edited by cv67; Sep 28, 2016 at 06:37 PM.
Thread Starter
Instructor
Joined: Jul 2013
Posts: 110
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From: Northern Virginia
Trans cooler on my list
I hope to get a trans cooler added to this TH700 before the winter sets in. The installer went through the whole trans and replaced the broken seal, 3rd & 4th clutches, coast clutches and a few other items to make sure it was back to new and a little better than before (more HD). BTW, this trans is from an 1988 Corvette before it was rebuilt and then set up for hi-perf; it's got the widest 2nd gear band he said he could install...
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
I hope to get a trans cooler added to this TH700 before the winter sets in. The installer went through the whole trans and replaced the broken seal, 3rd & 4th clutches, coast clutches and a few other items to make sure it was back to new and a little better than before (more HD). BTW, this trans is from an 1988 Corvette before it was rebuilt and then set up for hi-perf; it's got the widest 2nd gear band he said he could install...