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NEED TRANNY ADVICE - which one is best?

C3Vette Lady

Active member
Joined
Jan 23, 2001
Messages
43
Location
San Jose, California
Corvette
1981 Red Coupe, 1973 Big BlockStingray
I have an automatic '81 which was parked 10 years. The tranny works fine presently, but leaks. The leakage keeps me from autocrossing, so I want to repair/replace it. Please share what all you '81 owners have done with your trannys and how your tranny is better now. Half my "advisors" are saying to get a 700R4 and the other half are saying to just get my turbo 350 rebuilt with a shift kit. It is a daily driver, with hopes of autocrossing! Thanks for your time!
 
S

ssvett

Guest
No 350.........

I would go with the 700R4, because of it's higher gas milage and lower RPMs. And it's lower 1st gear(This will help with Autocrossing, I would think. If I was not going to go with the 350, I would go with a 400, this is a very strong transmission and has been used for years, mostly in Vettes and trucks from 1/2 ton to 1 ton. However, don't expect to pass many gas stations with the 400. BTW, the 350 trans in your 81, should be a 350C, The C indicates a lock up torgue converter, this gives you about 200 rpm's extra at highway speeds.Hope this helps ya........Steve
 
Joined
Nov 4, 2000
Messages
947
Location
Scottsville, Kentucky
Corvette
08 Jetstream Blue Z51 coupe
C3vette Lady,
If your only problem is an external leak or two I think that I would rather replace a seal or two than change/rebuild a transmission. I guessing that your rear shaft seal leaks from sitting. The seal and the tailshaft bushing are under $10 at NAPA. Will likely take you a couple of hours to drop the driveshaft and remove the tailpiece. While your there service the tranny with a new filter and pan gasket, another $7 at NAPA, 6 quarts of Dextron III and your done. Hope this helps with your decision.
 
S

ssvett

Guest
C-3, Dale is right, (and to answer your e-mail) the 350C in your car will be alot more inexpensive Then the a swap, and if in good shape, other than the leaks, should last a very long time with proper maintenance. I was mainly posting as if you were going to change out your current tranny. Now, If your trans has more problems then the leaks............I would look into the 700R-4, but be sure that this, too will be more expensive, in the short run, then repairing the 350C that you have now.......Steve
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Leaks!

Trans leaks are common when a car has been sitting. Mostly, the converter drains back to the pan and fills the trans pan area above the "normal" level and starts seeping out the front seal, around the T/V cable and rear seal.

However, when they have been sitting long enough, the seals eventually just go bad. A terrible catch 22. Sometimes driving a car on a regular basis can do more good than letting it sit.

Note above from DDL-81 about the NAPA seals. Just FYI. I shoe horned a fuel injected V8 in one of my last S-10 trucks (you see, I can't leave anything along). Just as I was putting the motor in I thought it would be a good time to put new seals on the trans (it had no leaks at the time). I got in a hurry and bought seals from the local high volume auto parts store. The seal was made in China or something.

Long story short, IT LEAKED! You don't want to know how hard it is to drop a 700R trans from a V8 S-10 with headers and all the exhaust welded back in.

Like a dummy I put another cheap seal back in thinking it was insallation error. IT LEAKED! Finally, I bought a set of seals from NAPA. Yanked the trans again, and slapped the NAPA seals in.

Dry as a bone after that. There is something to be said about certain parts and being picky about what you use.

I would get the original sealed back up and be done with it unless----you are in the process of a complete re-engineering project on the whole car. In that case, get the 700R 4 and work your way out with other complimenting mods.
 

Yoda

Well-known member
Administrator
Joined
Oct 12, 2000
Messages
4,885
Location
Amarillo, TX
Corvette
1981 UL5
Also.. one more thought

C3Vette Lady,

If auto crossing is what you are going for, then you may find that by going to another transmission (Other than STOCK) you will be in a higher class. If you are just beginning auto crossing I would suggest to stay as "stock" as possible.

As your skill level increases, and it will, you may find a niche, "High Speed" or maybe "Low Speed" auto crossing, then you can either set up the 81 or build one that will suite your needs better.

I agree with the previous posts,, I would fix the leaks drive the 81 as much as possible and auto cross every chance I got.. :D

JMHO ;)

BudD
:w
 
R

robert kirk

Guest
if you have to buy a trans why not go with a 6 spd. not a very hard swap and you will love it. just my opi robert
 

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