ClassicCar

Lars

Hello!!

I recently got the complete overhaul kit including a converter for my C6 auto-transmission from Summit and installed it in my car with a mechanic friend. Neither of us have any experience with auto trannies but all went smoothly just the same.

Now, the problem is that I am not at all satisfied with the way the car behaves now: the upshifts are ok and not jerky, however, the transmission seems to waste a lot of time (well, milliseconds...) slipping or at least not doing much work. For instance, when starting from a full stop the cars does not move the instant I start pressing (gradually) the gas...in fact there are several moments or some travel of the pedal before any action takes place.

Also when coming to a halt after driving at some speed, the tranny seems to take too long in coming back to low again.

A new fault that just commenced is that in reverse the car will not move smoothly now but will suddenly zoom back in a jerky way (chirping tires and all).

My "BIG" question is what can be wrong? Some tell me that I should replace the modulator, but we did already, so what else could it be?

I should add that there is no local shop that will take care of my beast, they are all seemingly busy making money on modern auto-boxes....so I need help!!

Any clues, possible steps to take, possibly troubleshooting tips, etc???

Thanks for any help!
Lars

Lee ODell

Hi Lars

It sounds like you got a high stall torque converter from Summit instead of a stock torque converter. With a high stall torque converter the engine RPM has to be higher before the car begins to move. You will probably notice a decrease in gas mileage because the engine RPM will be a little higher now, than it was before with the stock coverter, at the same speed.

Lee O'Dell

Lars

Hi lee:

thanks for your comments. I must say it makes sense, I'll check exactly what convertor I got and see if that could be the problem.

All the best,
Lars

Lee ODell

Hi Lars

I just wanted to add that the high speed torque converter would not be causing the other issues you mentioned.

If you can find a older, automatic transmission rebuilder mechanic from the 1960's-80's, he could probably give you some answers. If not, get a repair manual with trouble shooting guide lines to help you isolate and solve the problem or problems.

Experience is worth the money. With your explanation of exactly what all you did and his experience he might find out something that you may or may not have done to the trans to operate correctly. It may only need a throttle linkage adjustment or band adjustment. Or something more serious.

As a former mechanic and shop owner I can tell you, sometimes it can be more time consuming and expensive to find and fix a problem after someone else has worked on the car than if I had worked on it in the first place. And sometimes it can be an easy fix. Automatic transmissions is one area I left to the transmission shops.

Hopefully yours will be a minor problem to correct.

I wish you success.

Lee O'Dell

Lars

Hi Lee:

I really appreciate your help, it is obvious you have been thinking about my problem and decided to add your further comments now. Many thanks!

My problem is that I have actually not found a single oldtime auto-tranny mechanic in my area, so I will have to resort to a troubleshooting guide, as you say. (The one I have does not mention my C6, however!)
Although not a mechanic as you are, I have always tinkered with cars but automatic transmissions are a mystery!

I have been thinking what I can do to the box before pulling it out to check it all over again. Maybe rechecking the linkages would help.

At least now semi-retired, I have the time to deal with this!!

As I said, your comments are much appreciated.

Lars

Lee ODell

Hi Lars

I admire your determination. You might look on ebay or amazon.com for the C6 manual you need. I wasn't sure which trans was in your car. I checked through my manuals and do not have a C6 manual I could send to you.

I hope it will be a easy fix.

Lee O'Dell

Just saw a manual on eBay. Item # 200526666789

Automatic Transmission Diagnosis
C3-C4-C6-FMX
$17.99

I hope this helps. Lee

Lars

Hi Lee:

yes, it may sound a bit far fetched but I am actually quite determined when it comes to autos.
(If you knew how scarce or nonexistent that resources, knowledge, parts, etc are in my location for old car repairs and restoration, you would understand me much better, I'm sure.)

Well, back to the main subject: it is a C6 and the closest I have in my book is a C4, so I am still searching for more information.
But the truth is in comparison, I feel like farmer trying to be an astronaut!

Thanks!
Lars

Lee ODell

Hi Lars

Maybe the manual on ebay will help with the C4 and C6 comparison. Remember farmer succeded. So can you.

Lee O'Dell

ClassicCar

Howdy, Stranger!

Categories

In this Discussion

We'd love to hear from you! info@classiccar.com