BossV8

I have had a transmission noise since about one year, after I had my clutch replaced for a LS7 and my rear diff replaced for a 3.90 rpm stage 2.

We have changed the rear diff three times. We have just changed it again yesterday and also replaced the clutch (complete incuding flywheel).

No transmission noise for the first 20 miles, and then more and more noise. The noise starts to show up in gear 5 and 6. And then 4. And then 3. It progressively gets louder and louder, until it is like this after 100 miles :


I am getting a little desesperate here. What I cannot understand it why we don't get the noise immediately after we have changed the rear diff. Why it is increasing progressively like that.

Please give me your ideas if you have encountered the exact same symptoms. My guy says I should try with a new gearbox, but it is money again!

Thanks.

TheBlueKnight

iTrader: (4)

If the clutch is acting normal, (engages, pedal height is normal ect...) and I knew the noise was coming from the tranny I'd take it to a transmission shop to get checked out or call Tick performance and see if you can send it out to them.

BossV8

I and the car are in France, unfortunately.

calhoon

iTrader: (6)

Is this just a drive noise? Seems that there is no noise in coast.
With the number of rear swaps you have had it seems there is a set-up problem ...who did the swap ( s)? What was the reason to do the swap? Was it wear?
Just because you detect the noise at the transmission does not mean the noise originates there. Transmissions are great amplifiers of rear gear noise.

BossV8

There is noise only when in gear. Not when the car is stopped, not then I push the clutch, not when I am in neutral.

The first diff change was to get a shorter ratio.

The three swaps were done by three different companies.

The thing which is the less understandable. Is that each time we hav done a swap, there was no noise in the beginning. It gradually became worst and worst over 100 miles. The noise appears in gear 5 and 6, then 4 and 3. And the gets more and more audible in the car until the noise you hear on my recording. I cannot understand how it is just possible.

calhoon

iTrader: (6)

I am still most supect of the rear set-up/ shimming. Is there , maybe a problem with the housing?

BossV8

Here is a new vid I just did today.

Raven02TA

iTrader: (11)

sounds like your backlash isnt set properly. heres a thread with the same issue


http://forums.corvetteforum.com/perf...rear-ends.html

BossV8

I am not sure about the translation of the word "backlash". It is the internal setting of the rear differential? This would mean i had 3 bad rear differentials delivered in a row from rpm?

calhoon

iTrader: (6)

New vid helps more. That is a serious bearing concern. Did the pilot bearing get changed with the clutch? This noise may be due to a bad pilot bearing and the front bearing in the trans and / or the internal bearing between the input & mainshaft (pocket bearing) is really stressed. I would not drive this much like that.

Raven02TA

iTrader: (11)

Back lash is how much play there is between your gears, the play becomes important when the loading and unloading goes on(acceleration).

its entirely possible that they are not setting it properly

BossV8

RPM transmissions send the whole differential with a preset backlash. I doubt they would have sent three differentials with a wrong backlash?

BossV8

I don't I just drive it to test it.

How can I make more tests to investigate more in the direction you just pointed?

The pilot bearing was not changed this time. It was changed with the preceding ls7 clutch kit with the tick master.

Raven02TA

iTrader: (11)

their process or measurements for their particular gear set could be wrong. every brand/set of gears comes with a backlash recommendation. they may be using a particular process of setting backlash for all of their sets....

either way. the fact of the matter is this. RPM is sending you a product where something is not set or clearanced properly.

Vexzer

iTrader: (1)

Sounds like it's in the rear differential gear. Have the gear pattern checked before it self destructs. If you pull the diff cover the ring and the pinion should each show even wear wiping the length of the gear surface. Do a little research and you can find how to put a paint on the gear that demonstrates the wiping pattern and what it should look like. When you pull the cover, you might save the fluid so you can put it back in to drive to a shop. Definitely replace it after the work is complete since it may be full of metal. Do not forget the limited-slip additive if it is positraction.

Jeremy@RPMTransmissions

iTrader: (12)

Like you have already said, having 3 noisy differentials is very unlikely. We build 2 differentials a day and have a very good success rate with them. What type of oil are you running in the differentials?

BossV8

Hi Jeremy,

As you see, I am still with my problem.

I am using what was on the label of the differential. I think 75W90. And added two bottles of GM special additive. My guy told me to try 75W140 motul. I doubt it will change anything.

Before buying a new gearbox, I want to make sure it would solve my problem.

I am very interested in any solutions you could propose (bearings, etc).

Thanks.

Cedric.

Jeremy@RPMTransmissions

iTrader: (12)

Verify 100% what type of oil you are using. Please send me a part number.

We are willing to do whatever it takes to help you get this issue solved. We just need more information to help you.

Jeremy@RPMTransmissions

iTrader: (12)

Also have you inspected the transmission fluid?

BossV8

You already have been incredibly professional in after sale service I have to say.

I cannot check now as I am away from the car. Our plan is too change the oil ASAP and we will take the opportunity to inspect the diffenrentials oil.

But in the two cases before, I am sure here correct oil was used.

In one case I couldn't inspect the oil after the noise.
In one case I could and it was black and burnt.