1971 TH400 Transmission Replacement
Thread Starter
7th Gear
Joined: Oct 2009
Posts: 7
Likes: 0
From: Virginia Beach Virginia
1971 TH400 Transmission Replacement
I've all but given up on the TH400 in my 71 Vette... Pan, front & rear seals leak. She likes to get stuck in 1st gear after she's warmed up along with the 4.11 rear tach'ing at 3G at 60MPH doesn't thrill me. So I'm looking for opinions as to my best options for replacing the trans. and possibly the Rear End. The engine is the base 350CI/270HP engine. VIN is for the auto TH400.
If I were to drop in a replacment auto trans would one with 4spd overdrive fit (TH700R4, 4L80E, etc.)? If so, what are the best candidates and reputable sellers of new/rebuilt trans.? And then, would it make sense to drop the RE from 4.11 to something lower? Of course that could be the 2nd of two steps... do the trans first then see how the 4.11 RE is while driving and decide later.
I'm also toying around with putting a 5spd manual in there but that seems like it would be more work having to repace the brake pedal, adding the clutch petal and linkages. But if there are favorable opinions here, then the same questions above... what would be a good trans & reputable sellers? It would just be more fun driving a stick.
If I were to drop in a replacment auto trans would one with 4spd overdrive fit (TH700R4, 4L80E, etc.)? If so, what are the best candidates and reputable sellers of new/rebuilt trans.? And then, would it make sense to drop the RE from 4.11 to something lower? Of course that could be the 2nd of two steps... do the trans first then see how the 4.11 RE is while driving and decide later.
I'm also toying around with putting a 5spd manual in there but that seems like it would be more work having to repace the brake pedal, adding the clutch petal and linkages. But if there are favorable opinions here, then the same questions above... what would be a good trans & reputable sellers? It would just be more fun driving a stick.
Instructor
Joined: Apr 2009
Posts: 148
Likes: 3
From: Desert Hills Arizona
I looked at your profile and that looks like a real nice car you got there. I think you could be real happy spending the money that you were considering on other transmissions, on your original (if it is original) transmission. Since you're a new member, I'll might assume you might not be familiar with the upside of keeping most of the original parts on the car. or at least in storage for when/if you sell it. A rebuild shouldn't put you back too much considering the other options you mentioned. Some of the other members may be able to tell you if there's a good overdrive unit available that would let you keep the 4.11's. Good Luck with whatever you decide to do. Let us know how it turns out.
Last edited by BigBlock 72; Oct 7, 2009 at 01:50 PM.
Safety Car
Joined: Sep 1999
Posts: 4,930
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From: AnyTown NJ
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thread Starter
7th Gear
Joined: Oct 2009
Posts: 7
Likes: 0
From: Virginia Beach Virginia
I am aware of the keeping (close to) original equipment and am considering the TH400 rebuild and rear swap. And sure tach'ing <2200 at 60 with the 3.08 RE is a viable solution for me. It's just for weekend driving and certainly not fo racing. I did just (yesterday) join the Beachcombers Corvette Club here in Virginia Beach and am beginning conversations with the group to cosider all options. I'm going to try to identify serial #s to see what's matching and what isn't. I don't think its drivetrain is original and certainly wasn't sold to me as anything original. Know that I do want to take the best care of her that I can!
Know also that I took ownership of her on 9/12/09 just 3+ weeks ago!
Know also that I took ownership of her on 9/12/09 just 3+ weeks ago!
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Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
Keep the 4.11 and put in a 200-4R, it has over drive and its a direct fit to your application, you just need to replace the output yuke, this way you'll get the best of both worlds, acceleration and highway cruise.
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Burning Brakes
Joined: Nov 2002
Posts: 1,245
Likes: 21
From: Abingdon MD
William,
Your 71 looks terrific. Obviously, you are looking at spending some serious $$ on either a rebuild or other options.
I have the TH400 in my 72 LS5 Coupe. It is bullet-proof, and the lack of shifting allows me to watch for cops and wave to the chicks. In your case, however, I would be tempted to look at the new offering from Keisler (www.keislerauto.com, 888-609-0053) as listed in Nov. 09 Corvette Fever Mag.
Keisler's new offering is the T45-RS, a 5 speed manual in the $2,200 range. (In your case, it will cost more, since you are going from AT to manual.)
It is worth a phone call to discuss your options, which include OD At's as well. Just about everyone who converts to an OD trans in their C3, AT or manual, raves about the increased "driveability" of their cars. Don't expect, though, to recover your investment in gasoline $ savings.
One more thing: keep the TH400 in case you ever sell and your buyer cares about originality. Let us know how it goes. Rickman
Your 71 looks terrific. Obviously, you are looking at spending some serious $$ on either a rebuild or other options.
I have the TH400 in my 72 LS5 Coupe. It is bullet-proof, and the lack of shifting allows me to watch for cops and wave to the chicks. In your case, however, I would be tempted to look at the new offering from Keisler (www.keislerauto.com, 888-609-0053) as listed in Nov. 09 Corvette Fever Mag.
Keisler's new offering is the T45-RS, a 5 speed manual in the $2,200 range. (In your case, it will cost more, since you are going from AT to manual.)
It is worth a phone call to discuss your options, which include OD At's as well. Just about everyone who converts to an OD trans in their C3, AT or manual, raves about the increased "driveability" of their cars. Don't expect, though, to recover your investment in gasoline $ savings.
One more thing: keep the TH400 in case you ever sell and your buyer cares about originality. Let us know how it goes. Rickman
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I think it obviously depends on your driving situation, city, combo or mostly freeway.....my '72 336 rear muncie vette had almost no where to go over 60 mph in the Wash DC region, for very long or very far, so the cruise at 80 was minimal.....upon driving here to Florida house looking, I found hour after hour a 4000 rpm 80 indicated speed was a tad much...most folks here cruise 75+ mph on the freeways, hours on end....
keep in mind, most speedometers are junk, I believe Garmin and no one else on that speed stuff.....even the stock tachs in these cars are suspect, especially that mechanical crap pre '75.....and the later shark electronic tachs leave something to be desired 5% error factor is HUGE IMO....
keep in mind, most speedometers are junk, I believe Garmin and no one else on that speed stuff.....even the stock tachs in these cars are suspect, especially that mechanical crap pre '75.....and the later shark electronic tachs leave something to be desired 5% error factor is HUGE IMO....
