Re: c3 transmission question

Boy Scouts of America,

I seems pretty obvious that you need to change the transmission fluid. It's probably evaporated some and gumming up and something is sticking.

Ed

That is typical of some of the older trannys. Same thing happened on my 79. Seals start to harden and there is some wear and leakage so it takes a minute or so to warm things up to provide a better seal. Had to start mine and put it in reverse to back out of garage but hold brake while I put on seat belt, etc. In a short bit of time I would feel it start to pull and away we would go.

There are some additives that you can add that are specifically for that problem that contain chemicals that will swell the seals. Only problem is that they also soften them enough that they wear more, faster. That means a rebuild is near.

Good Luck PDDeen

Good first step that's worked for me.

Use the correct fluid (important in an older transmission to get the correct amount of abrasive additive).

Change the filter.

-- pj

Do you think it would benefit from adding something into it as someone else suggested BEFORE I change the fluid and filter - maybe run it for a few hundred klicks or so first?

Today it is about 45 F or so and sunny and there is no problem with it at all.

Do you think it would benefit from adding something into it as someone else suggested BEFORE I change the fluid and filter - maybe run it for a few hundred klicks or so first?

I agree with PDDeen. Those fix-its in a can can also do damage. Have the fluid changed by a good transmisson shop and make sure they drain the torque converter.

Spud

OK - How does one ensure they drain the torque converter? Is this the sort of thing one can do at home? I may have mentioned I have a lot of t hings I have to do to the beast anyway - like brake caliper rebuilds, new composite rear spring, shocks, etc, and I think maybe a new rad support.

#OK - How does one ensure they drain the torque converter? Is this the #sort of thing one can do at home? I may have mentioned I have a lot of #things I have to do to the beast anyway - like brake caliper #rebuilds, new composite rear spring, shocks, etc, and I think maybe a #new rad support.

Three ways to drain a converter, take it out and pour out the fluid or drill a hole in it and then plug it before you refill. Most of the time you can unhook the return line while running and let it pump new fluid through the system until you get no more old fluid. Not an easy task but it works, but in most cases not necessary.

I am ordering the bits and pieces I require, but how do I determine if I have a THM 350 or THM 400 to make sure I get the right parts? A 1976 automatic with L-48 engine.

Thx & regards.

I am ordering the bits and pieces I require, but how do I determine if I have a THM 350 or THM 400 to make sure I get the right parts? A 1976 automatic with L-48 engine.

Thx & regards.

Pan shape, 350 has one angle cut to keep it from having 90 degree corners, the 400 has 3 of the corners not square and is bigger.

Do you think it would benefit from adding something into it as someone else suggested BEFORE I change the fluid and filter - maybe run it for a few hundred klicks or so first?

Today it is about 45 F or so and sunny and there is no problem with it at all.

________________

The Vette is laregely a "fair weather motorcar" ................... but I agree will all of the above.

-W '68 roadster

Yes - thanks I checked and mine appears to be a TH350 from what I see of the pan shape. As an aside I called the dealership and they wanted $240 + tax to change the transmission fluid. I asked them what they did for that (I thought maybe some special machine flush) but that was just to drain the fluid and replace filter and gasket. They told me $80 for the filter. I checked with corvette central and a filter and gasket is $12.95 I think. Am I misunderstanding something? I can see it is a bit of a messy job, but ......

Dealership? Hadn't you heard, cars aren't moving of the lot at the moment, gotta pay the bills somehow!