Just got home from picking up my GT3 which had been regeared as follows:
19x32 3rd
22x30 4th
23x26 5th

Because of the heat and traffic at 2:00 pm on IS 10 I didn't really push the new package. However, I did notice a substantial whine in 3rd gear only. The noise has me concerned since an indy shop did the change. Anyone experience this before...generally speaking will the noise go away as the gears "mesh". No clunking going into any gear, no other noises apparent. I have only 25 miles on this new gear set. New synthetic Havoline gear oil.
Comments will be appreciated.

 

Generally speaking, gear whine does not go away.

A couple of more clues:

Is the whine present on accel, decel, steady load?

More of a whine or a rattle?

 

What gear did they use for third? Was it a Porsche factory part or an aftermarket part?
In my experience some gear whine will diminish as it wears in. I had some Powerhaus gears in my 993 and they were very loud compared to the Porsche gears in the same transmission.

 

My gears make some noise, it's the cut of the gears, it was expected and normal.

is it realy bad or is it just a slight whine?

 

I think most will agree that can be very normal when you regear a trans. Changing gears, using steel syncros, and solid motor mounts will create a lot of noise. Welcome to a race car! Also it would have been a good idea to braze steel syncros to gears.

 

The noise is not loud (at this point in time) and it makes the noise under acceleration and also while holding steady. I put the tech on notice and will drive the car for a couple of hundred miles, and if still present I'lll try different gear lube. The noise doesn't annoy me but my concern is what the future may hold. I also have the CUP LWF and its a little louder than the whine. Just something else to worry about.

 

I'm probably a little less accepting than most and I don't agree with the "that's just the way a race box is" school. I've got a race prepared G50 and it's quiet.

My concern on a whine is that you have a mis-match on one side of the gear set that could lead to premature wear. The key word being could and it could take a while to show up. If it was me I would notify the shop so you have some recourse if it gets worse. Then I would drive it and change the fluid often and really watch the plug for shavings. If it's pretty clean I wouldn't be that concerned.

I've been through the input pinon gear issue that was on some of the G64 boxes in 993TT's so perhaps I'm a touch paranoid.

 

From what Brian told me is the Guard gears he uses will make some noise.

 

What shop did the install? Was the ring and pinion messed with? Can you verify if this whine is speed dependant or whatever speed your using third gear for?

 

Chris,
I initially took the car to Precision Motors in Riverside, Cal. They shipped the trans to an unknown company in El Cajon, then back to Precision for the re-install. I drove the car last night (hard) and this morning the gears are much more quiet. The faster you go in third the noise diminishes and disappears around 6000 rpm (I never noticed the speed @ 6000 rpms). They did not mess with the ring and pinion, although I discovered my LSD isn't working. The LSD should be a warranty item as the car has never been abused or heavily modified.
BTW: The car is a real torque monster. Going down an onramp the tires broke loose in third gear agout 5500 rpm.


Thanks guys for your imput.

 

larry,

let me know when you're ready to sell it. lowering gears in a 3 is the best thing one can do to improve fun-ability

 

Copans always finds worn out LSD when he opens a street GT3 transmission. It's kind of funny how many people is driving a GT3 thinking the LSD is fine. A rear engine masks the lack of the LSD pretty good. Ask the 997S track drivers.

 

At the time Brian did my car my LSD was good.