New springs, gears
 

Well I took my car to have 3.73's installed along with the eibach pro kit on Friday. I used frpp gears along with the new bearing kit. The springs have the car looking much better than the stock height and I am very happy with them. The steering wheel shakes a bit at highway speeds but probably due to not getting an alignment yet. I can tell a difference with the gears installed even though I have been taking it easy in the car for break in of the gears. However the gears do whine on de cel above 20mph. They are silent when accelerating. I called the shop and let them know and they said some gear noise when coasting will be normal with the 3.73 ratio over stock. They said to go through the break in period easy and to keep in touch about the gears and noise. I have read a lot about gears. Some people say gears should make zero noise when installed properly while others say even with everything adjusted properly some noise is not abnormal. My abs sensor also broke when they installed the gears. They said that the differential and underside of the car was pretty rusty. You guys think I should take it back to let them hear the gears ASAP or continue with the break in and if it continues bring it back. The shop was a reputable mustang only shop. Also getting a little bit of what sounds like quiet hissing from around the shifter.

Mine is a 7.5 v6, but I had the FRPP 3.73 gears and t-lok installed -they were quiet from day one. No noises what so ever. I have yet to hear anyone on this forum say their FRPP gears made any noise. That's a tough call, but if it continues to do that bring it back in. Obviously this is just my own experience but I'm sure other members will chime in.

Edit: Are you 100% sure it's the gears making the noise? Probably, but just thought I would ask.

I am fairly certain it is the gears, upon coasting in 3rd gear you can hear the whine. Give it just a hair of gas and it goes away with the pedal. Let off and it comes back. Usually only in 3rd-5th gears. Definetly coming from the back of the car.

Ok. Hopefully it will cure itself or someone else can confirm what you are hearing is normal or not. I was nervous when I had mine done since it's a daily driver, but it all worked out great.

+1 my 4.10 gears have never made any noise since day one and I never let mine break in I drove hard just like i always do with 0 problems

take it back and let them fix it the whole they make that nosie is bs.

yeah mine never made any noise, i would probably take it back and have them look at it

Im having the same issue with mine. Last weekend I had them put in and brought it hme, making some serious whining. I could hear it when i let off the accelerator at 75mph. Even worse when downshifting into lower gears. Took it back this weekend and had him redo it and its still noisy. Not as bad. but still noisy. I am at a loss, this guy is 45 minutes away from me, so its burned alot of fuel goin back and forth! Good luck, at least you have a mustang shop, not so lucky here in bohunk /nebraska.

Steve u had frpp gears also? I have read on some forums that certain frpp gears were noisy, particularly the ones where the part number ended with the letter N. supposedly the ones that are marked with the letter A or no letter at the end are a better gear according to what reading I have done. I feel you in the gas though. The shop I go to is 25 miles. Not ad bad as your 45 but I know what you mean. So what did they adjust when you took the car back in? Did the mech ride with you and agree it was not normal?

I didnt look at the part #, ill have to check that out.They are the FRPP gears. Motive bearing kit, new axle seals and bearings with cobra carbon fiber clutch packs for the LSD.

Yeah, the tech came over and I took him for a ride aftert he first time, he agreed it wasnt right. So I took it back to his place on friday night, he worked on it saturday, said he adjusted the pinion, and it is better...its just still not right. Its nothing I could record because my exhaust would drown it though...lol. But when I let off the acceleraor it has a kind of almost whistle, and it get louder in lower gears. With the accelerator applied, no noise. Im thinking of taking it somewhere and getting another opinion on it. I dont think it will hurt anything, but I know its not right...

I hope i dont have this problem when i do my 4.10