LocostUSA.com

This question is not about a Locost but about a Corvette. To make it seem like a Locost post here is a picture of my Locost that sits in the garage next to the Corvette.
The photo is from the Downtown Mount Airy Facebook page. My wife and I were cruising Main Street back in February. We moved here from Maine so it seemed like a nice day. It was above freezing.

Back to the Corvette. The 48 year old innerds of the trans are giving up and the local shop has been putting me off for months. I live in Mayberry so if Goober won't do it I guess I'll have to get a replacement. I asked for help on the Corvette forum and so far have gotten very little. I thought I'd come back here where the helpful people are.

So the question is, does anyone have recommendations for rebuilt transmissions? I've checked out Monster and they have over 1,100 complaints on BBB. Jasper gets bad reviews too. The big catalog places like Jegs and Summit list high performance rebuilds not stock. The car is my wife's and she would not appreciate firmer shifting.

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My car viewtopic.php?f=37&t=16434
1930s Style Sports Car viewtopic.php?f=36&t=16888

I suggest you have your original rebuilt locally when they can do it with the RV shift calibration.
You could find a good, used thm400 (4 inch long tail housing and chevy bell pattern) to install.

That is a very durable, common trans used in everything back then but most had longer output shafts and matching tail housings. A lot of good transmissions are swapped for overdrive. They are not hard to find. Look for someone parting a 70-80s RV or grandma car or wagon. If the converter is larger in OD than your old one, buy a reman or new to keep the correct "K" factor. You may be able to have your old converter rebuilt.

If the short shaft is not necessary for clearance, a swap to a long shaft thm400 would require a new or shortened driveshaft.

Your trans may not need to be pulled and rebuilt unless it is slipping. A good cleaning with a valve body drop and clean with a new accumulator and "shift kit" maybe all it needs. Good kits usually address problems that have nothing to do with racing.

Continuing to drive it with problems can damage hard to find and expensive hard parts.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I'd love to get it rebuilt locally. The only transmission shop in town has been putting me off since January. There are two other shops but trans service are a sideline. I called the only shop in the next town over and he said it would be two months before he could even look at it.

I haven't been driving it mainly because I don't trust it. It leaks fluid and randomly slips. I fixed the leaking speedometer drive but can't find the other leaks. It seems to leak from a number of spots but it could just be fluid running around.

I haven't heard anything good or bad about Aamco or Cottman but I haven't checked BBB yet. I would have to pull the trans myself and drive an hour away to do it

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My car viewtopic.php?f=37&t=16434
1930s Style Sports Car viewtopic.php?f=36&t=16888

It's nice to check back in after six years. I read some of my stuff and it is like a trip back in time. I can't believe my interior thread got almost 16 thousand views. I'm sad JD is gone. He was very fun to read. I copied his front coilovers mod and it turned out very nicely.

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My car viewtopic.php?f=37&t=16434
1930s Style Sports Car viewtopic.php?f=36&t=16888

You can do a lot without removing the trans and the most specialized tool being a torque wrench and snap ring pliers. I would flush the old fluid, immediately drop the pan to install this $20 bulletin kit and change the filter, replace the modulator and any rubber on the end of the tube, then see how it goes. You can just install the parts that you have access to through the pan opening. Aerosol brake cleaner can be used (wear safety glasses to keep from getting splash back in your eyes).

https://res.cloudinary.com/transgo/wbiss/sk/SK400.pdf

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I'll give it a try.

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My car viewtopic.php?f=37&t=16434
1930s Style Sports Car viewtopic.php?f=36&t=16888

I said replace the accumulator above (edited to correct terminology). I meant modulator. It is on the outside with a vacuum port to the engine through a long tube. For the torque specs and other useful data, pickup the ATSG thm400 manual. Vaseline is useful to hold check balls in place.

Plenty of good hi-res videos on teardown before you get into it like this one: https://www.youtube.com/watch?v=_TMFibSiwVw

I'd clean the pan well inside and out before putting it back under to place the valve body into. Lint free towels (blue mech towels are adequate). Clean, clean, clean.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

There are at least two books on how to rebuild the Turbo 400 at home, and the ATSG manual reprints aren't expensive. You don't need much in the way of tools - snap ring pliers, some C-clamps, bushing drivers, and some homemade doodads.

It's a basic 3-speed transmission; it comes apart in subassemblies, which can then be further disassembled, cleaned, and inspected. There's no machine work involved, just parts replacement.

The fantastically complex hydraulic schematics are misleading; all those bits are in the valve body. Keep track of where the bits go, and put it back that way, or how the shift kit tells you.

It's not rocket surgery. I was leery of working on an automatic transmission for a long time, but the T350 and T400 are among the simplest to service.

A card table, old door or half a sheet of plywood across sawhorses, or other sizeable area to put the removed parts on in order is useful. Use sandwich bags for all the minor pieces; label the bags. Take lots of pictures with your phone.

It's really hard to reassemble one so it won't work. Take your time, keep it clean, and you'll do fine.