Frederic3

Hello and HAppy new year

I will try to take time to tinker with my vette!

Apart from all detected leaks (radiator, engine, gearbox, deck) ...

The subject that concerns me the most is the shift from speed to acceleration 1> 2 or 2> 3.

I feel a grip in the transmission to the rear wheels and the wheels lock slightly. The wheels squeal

What do you think ?

A problem of oil level in the box? I do not think so. I fill up regularly for leaks

A problem in the box? Garlic! do you know a box that can repair a box?

A problem of differential? brace ??

thank you

Alan 71

Hi F3,
Welcome!!!

Looking at your profile it appears you're in France, are you?
Is this car new to you?
Is the problem/noise new?

Might the 'squeal' noise be caused by the brake calipers dragging on the brake rotors?
Have you had any repairs done to the brake system recently?

Regards,
Alan

Frederic3

Hello, Thank you Alan

Yes I am Froggy French in France
and I like or love C3 and other american stuff (ZZ top...

I bought one C3 4 years ago
The squeaze is new and Yes I worked on brake system but rear wheels seems to have a short stop only when the gear shift up from 1 to 2 and from 2 to 3
can it be the brakes ???

I wonder wich part to look at first and if I really need to disassemble the gear box to retrofit it or I have to look at other parts before
Thank you

bradleyb66

I don't have any suggestions, but some extra information might help:

- is the 'squeal' coming from the tires, as if the wheel is skidding on the road?

- does this happen only after you let out the clutch, or is it while the clutch is pressed to the floor, and you're shifting to the next gear (but have not released the clutch yet)?

- I assume that if you press in the clutch and don't change gears (just coast), that the car moves down the road as you would expect?

Frederic3

is the 'squeal' coming from the tires, as if the wheel is skidding on the road?
YES

- does this happen only after you let out the clutch, or is it while the clutch is pressed to the floor, and you're shifting to the next gear (but have not released the clutch yet)?

Its an automatic Gear box, If I accelerate constantly it squeal when the gear goes up.

If I stop accelerate at the right rpm, the gear goes up, wheels do not squeal but its difficult to find the right rpm and of course I lost speed

bradleyb66

OK, automatic transmission..... I've never heard of an automatic transmission 'locking up' like that when changing gears (but I know very little about the transmission internals), so if I were to guess, I'd say something is going on in the differential? Is there any difference between accelerating very fast, or only doing a mild acceleration?

Also, do you know if the transmission is still stock, or has it been modified for harder shifts?

Frederic3

Is there any difference between accelerating very fast, or only doing a mild acceleration?
Yes there a difference
As far as I remember No troubles when I accelerate slowly

I don't know if the transmission is still stock, or has it been modified for harder shifts
I dont think so

C6_Racer_X

Check the vacuum line leading to the modulator valve on the transmission. It may have holes in it, or it might be disconnected. If that vacuum line isn't connected or if it leaks, it causes very harsh shifting.

Also, are you certain the transmission fluid is the correct (Dexron III/Mercon 4) transmission fluid? Some folks put the old "Type F" (Ford spec) fluid in older transmissions. It grips harder and causes harder shifts (even though the folks who do this claim it makes the transmission last longer). If you're not sure about the fluid, changing the fluid and the filter (drop the pan) is probably not a bad idea.

speedreed8

Sounds as if your transmission has a shift kit installed for harder shifts.

ignatz

Forgive me Frederic, but I am moved by your post to offer this koan*

I feel a grip
The wheels squeal
At the passage of speed
A problem of oil?
A problem in the box?
I do not think so!
________________
*Koan - a paradoxical anecdote or riddle, used in Zen Buddhism to demonstrate the inadequacy of logical reasoning and to provoke enlightenment.

calwldlife

am i to believe the whole thing is about wheel chirp?
interesting

bradleyb66

Possibly? Although his description of 'I feel a grip in the transmission to the rear wheels and the wheels lock slightly.' Made me think he is feeling something slowing the car down? Frederick - can you clarify further?

theandies

Just trying to get a better grip on your problem.
So when your driving and and accelerating hard and your transmission shifts from first to second or from second to third your getting tire chirp? It does sound like there is a shift kit installed to me if that's the case.

Duane4238

Has it done this ever since you bought it 4 years ago, or did it just start doing this? Is there any way you can contact the previous owner to see if he had a shift kit installed in the tranny?
Duane

Frederic3

Hi thank you all
sorry for my poor english
sometimes I don't use the right vocabulary

It's a quite new troubles . I didn't have this kind of troubles 2 years ago !

How can I know if a shift kit is installed ?

I m gonna check the vacuum line leading to the modulator valve on the transmission

bradleyb66

If it just started happening, then it's probably not a shift kit (unless people in France break into garages at night and perform upgrades to other peoples cars!)

Does it feel like the car is slowing down when the tires chirp? If not, I'd guess that you are just experiencing an extremely hard/fast shift.

lvmyvt76

could it be the emergency brakes are stuck on??? causing the car to pull down when shifting to a different gear? not really sure what the OP is saying, but a plane ticket to France might help me cure this(going in March anyway). Good luck with problem, see you in Paris!