thearborbarber

From all your speeds it shows you have a 4.56 rear axle.

If your TC is slipping that much it should have rousted by now.

Rodney_Gold

Seems a little higher than stock , but nowhere near 2800 - feels like a 1800-2k TC

87 vette 81 big girl

What do you mean by you could not road test it ?

Get your Vette off the jackstands & get the rear wheels back on.

Go find a deserted 2- lane black top country road.

Launch your Vette from a dead stop.

Keep your foot planted firmly on the gas & do not lift.

Aim your Vette straight.

Let the trans up shift on its own in Overdrive gear selector position.

If your Vette has the original valvebody...........

It will upshift to from 3rd to 4th gear at 110 to 118 mph.

Mine upshifts 3-4 @ 114 mph.

I have a hard time thinking its the torque converter.
You have no upshifting issues from 1-2, 2-3, you are missing 3-4 I think.

Race your vette flat out top end.

Feel & listen to the engine rpm's during the automatic gear change upshifts.

Brian

mattwalker87

forgot one key thing. go do this by yourself. IF something were to go wrong, you dont want to be responsible for somebodys death.

Pete K

If the converter was slipping enough to lose 30 or more miles per hour in high gear, I would think that it would have killed the trans due to the excess heat generated.
I would suspect a slipping band first.

Bronze85

To some, it's just a video game. Do whatever without consequence,until something goes wrong. Hopefully no one on public streets would have to pay the price.

alx

I meen that I don't have such road nearbuy. When I tested it before I told you ,that it is shifting from 3 to 4 on 97 m/h.

alx

Nothing is slipping inside ,because the tranny is working in this way all 3 years. No difference between 1 day & today time.
When I checked it on the jack, the result was the same. I think , without load must be the difference between speeds , but there was no difference...
Oil is o'kay . I don't know what is it. I decided to install dana 36 with stock 2.79 & then check the speed.

87 vette 81 big girl

It is not the torque converter from Pete K.


One day you will discover that the original valvebody that your C4 left the factory with is long gone.

I have been telling you that over & over.

It may take you 10 more years to realize that I think.

Brian

alx

I bought this car absolutely stock with 25Kmiles from my friend ,who bought it new. When it was stock , I drove it 250 km/h with 4000 rpm.
Than I used procharger on the engine. The trany brake down. I asked somebody to help me to rebuild tranny to held about 600 hp . Pete Kane asked me , what i want to do with the car. At that time drag racing was
trendy in our place. I told him - drag ! He send me all parts to rebuild tranny & new custom made TC. Everebody told me to change Dana36 to Dana 44 , because 36 will brake down ....I bought Dana 44 with 3.55. Thats all. Then drage racing finished in our town. Now my car is street car without compressor , only 383 with 440 hp engine & street tires. With esp on it rides normaly only on the 3d & 4 th gears. On the 1st & second it try to spin ,but esp stops it. Now I need another rear end to realize good start & speed with street 315 tires.

alx

Today I checked the rear end. It is really 3.55 . Again tested car on the road. The tranny is working perfectly. All gears shifts , nothing slips....
It is torque converter make such big slip, because of it small size & drag mission. I have read many articles today. It's written there ,that drag ,smaller size TC with high stall speed are good for sharp start ,but lose the car speed on high rpm.....

My final decision....I ll install stock 2.79 Dana 36. I think it is the only way out of this situation .....

bjankuski

What is the problem you are trying to fix? The car will only go 125 MPH at 5500 rpm at WOT or???

What some people are pointing out is that at WOT the transmission will downshift from 4th or overdrive to 3rd gear and it will not shift back to overdrive or 4th gear until you take your foot off the gas. Only corvettes and some 350 GTA's and Camero's had the correct factory valve body to allow WOT 4th gear operation. All other 700 R4 will downshift into 3rd gear at WOT even when the shifter was placed in overdrive or 4th gear. You need to get a Corvette valve body to allow WOT 4th gear operation. Since your car appears to only go 125 MPH at WOT and is running 5500 RPM it appears your valve body parts or entire valve body have been switched to one that will not operate in 4th gear at WOT.

Changing the gears or torque convertor is not the correct answer, fixing the forced 3rd gear downshift is the answer.

383vett

If you're sure your tranny is hitting 4th gear and the converter is slipping, get a different converter with less slippage and a lockup. You will have the advantage of your lower rear gear to get out of the hole and good top speed. I always lock up my converter so going through the traps in 3rd, there is no slippage.

Rodney_Gold

I would never go back to my 2.6 rear from my 3.55 , get a normal TQ, its the cheapest and easiest option

alx

Please, read carefully previous letter. All parts , including valve body are CORVETTE original. It is 4L60. And I am not stupid, I told everybody ,that at WOT it shifts from 3-d to 4th at 97 m/h. What are you talking about ?

87 vette 81 big girl

OK.

You need to settle this issue with Pete K. then.

I don't think Pete K. would stick his neck out time & time again here on C4 tech.
I don't think he sells junk.

Pete K. & me don't always see EYE to Eye on opinions with Corvette Auto transmission or engines...............but he has been doing this for a long time too.

I do respect Pete K. & think he is a very good transmission & engine mechanic.

Pete K mentioned earlier that the 2-4 band may be slipping in overdrive 4th gear range on you.
That is possible too.

I think the factory original 1992 Corvette valvebody is missing & long gone.

Either way in time you will find the problem & correct it.

Brian

1963SS

It sure sounds like you're in 3rd gear. If you use the Top Speed Calculator above and and tell it 1.0 for the ratio (4L60E 3rd gear) and 25" tires it says 115 MPH. That's real close to what you're telling us. The other posts are correct. If the converter were slipping you would have some serious transmission fluid overheating issues. If the clutches were slipping they would have destroyed themselves by now. Surely in Russia you can find a good straight road. The road that runs just east of Sennoy looks straight. Go for a little drive and count the gears and see where it's shifting.

pologreen1

Yeah if it was slipping and you ran it like that more than likely more than once it would be shot.

If you have not owned the car from new, I'd say it's not a genuine vette trans or parts at least.

I think it's obvious you are in third gear. The RPMS say that and so does the speed. With stock 17 inch wheels you don't need a calculator, it's simple 3.55's on an auto in a c4 are not that low. 3.75's will get you more speed than 120mph with an lt1.

Something is slipping but more than likely it is in 3rd gear.

My stock 2.59's with stock 17" wheels did go up to 90mph in 2nd winding it out in and holding it in 2nd.

87 vette 81 big girl

If you used a TRANSGO replacement separator plate for a GM 700R4 like I did.............

There is 1 missing hole for the 3-4 WOT upshift function.

MTV hole.

It must be added.

Square hole.

Need a factory FSM to identify location correctly.

I had to replace my original 87 Vert separator plate.
They steel checkball seat holes were worn out.

I made the missing MTV hole discovery on my own.

I used TORLON Imidized checkballs in my 87 Vert rebuild & blueprint.
Eliminate steel separator plate wear.

Ford Auto trans checkballs.

Makes for lightning fast upshifts too along with dozens of other internal blueprinting & mods I made.

3/16" drill bit.

Add your own MTV hole.

Brian

87 vette 81 big girl

I never played video games as a kid.

At 14 I was wrenching on SBC & BBC Chevelles, Novas, Camaro's, & Trans Ams.

At 15 through 18 we were street racing my buddies & me.

And winning $$$ & Bragging rights.

1980's were great.

Too bad you were still a young kid playing video games at home.

I wasn't.