flyboy1294

Hey guys,

A few months ago I bought a set of aftermarket gears for my Mustang. I went with FRP 3.73's seeing as I drive on the interstate occasionally and wasn't really interested in drag racing.

Anyway, the gears made a small amount of noise upon deceleration as soon as they were installed. Like, if I had my music down and rolled down a window it was somewhat noticeable. I was told this noise would gradually decrease as the gears wore together. I drove the car 2,000 miles and the noise began to get a little bit louder. My installer said that this was normal and they may just need a bit of adjustment, so I took it back in.

This turned into a several day fiasco with the car in the shop. My mechanic put the gears in and shimmed them too tightly I believe. (They made a loud whining/grinding sound.) So I took it back after not driving more than a couple miles, and told him to re-do it. He checked with Ford Racing and they informed him that he needed to purchase their shims to shim the gears because they were a different size or something along those lines. So we did as Ford Racing suggested.

Anyway, on the third try, my mechanic said it was the way it was suppose to be. The whining was less noticeable, but still louder than stock. I can now hear it with the windows up on deceleration. Especially when the car goes from a higher gear to a lower one (it's an auto).

So here is my question, is this extra noise to be expected with aftermarket gears? Or should I take my car to a larger, more reputable shop, such as the dealership. These gears were pretty pricey so I'd rather not risk damaging them if there is a risk. And I figured since they are Ford Racing gears, the dealership would be willing to work on them.

As always, thank you for the input!

BraMas

A properly set up gear will not whine. What probably happened is that they where set up wrong the first time and now no adjustment is going to get the gear whine to go away now because of how the gear meshed when it was set up wrong the first time.
And a stealership is the last place on earth I would take a car to. Stealership techs are so closed minded about modified cars

flyboy1294

Ah shoot, so do I need to go ahead and replace the gear assembly altogether?

BraMas

my honest opinion is yes! gears are pretty cheap. and your going to be paying the same amount of labor if you have new gears as you would paying another shop reset up the gears hoping they will get the gear whine to go away. I could be wrong about the gears being ruined because of the bad gear mesh.
What you need to do is find a different shop tell them what happened and see if they agree with what I said

cliffyk

That the gears whined and got worse pretty much indicates they are fubar--you might get lucky however I'd have a new set waiting just-in-case when I opened up the rear-end...

madjimmax

My first question is what ratio was in there previously? Generally you can jump from say 3:27 to a 3:73 or even a 4:10 and all the shims that was in the stock rear should work, also any shim kit will work if he's telling you FRP require a special shim kit he is blowing smoke up you a$$. IMO you need to get your money back and go to someone that knows rears. I agree that you should never let the dealership EVER work on your car. The majority of dealership techs and notice I did not call them mechanics are only a parts swapper. As long as they can plug your car in and figure out what is wrong and replace a part to fix it thats all that they are good for. I just recently had the pinion bearing go out of my 2000 F350 that I use for work, so I went and talked to a relative that is a head tech at Bob Bell Ford here in Glen Burnie and his opinion was go buy a rear at the junk yard because a rebuild would be to much of a pain in the a$$ because of the crush sleeve. Well needless to say I didn't listen to him, I went through Summit and bought everything for the rebuild for $448.00 and did the rebuild myself, when the junk yard wanted $1400.00 for a used rear that they couldn't tell me the mileage on. So now I have a pretty much brand new rear instead of some junkyard trash.

cliffyk

I have often thought that there must be a series of books out there called Lame Excuses and Just Plain BS You Can Tell Your Customers.

One for auto dealer service managers and mechanics, one for motorcycle dealers, one for building contractors, etc...

NewEdgeStang00

Would you be able to post up a video of this sound? I had my ford dealer install a FRPP 4.10 with a full rear end rebuild kit and tlok kit I purchased from American Muscle and have had no problems with it. But then again the mechanic who worked on my car had previously worked in a race shop in California, so I had some faith in him. I don't hear any particular whining noise, only if I'm in first gear and accelerating about 2.5k revs but I've always figured it was coz of how tall the gears are. To hear a whine noise on deceleration really is troubling though, so I would like to hear it in case I just got used to the sound and ignored it

Also did you have your car properly tuned to take the taller gears?

flyboy1294

BraMas, I was afraid someone would say that. I will start setting aside paychecks for the new gear install just to be safe. I do still have the stock gears, which are in flawless shape, but installing them would be a serious downgrade so I'd prefer to avoid it.

Madjimmax,
the stock gears in my GT were 3.27s. And I assume when he first installed the new gears he used the stock shims. What I realize now is that it was WAY quieter from the beginning when I "thought" it might need adjustment. For instance, before, only when the car was idling and rolling at a good speed could I hear the gears, and I had to have my windows down most of the time to notice it. Now, unless I have my radio cranked way up, the noise is VERY apparent. I will try to avoid the stealerships in the future though. I haven't had any experiences as bad as yours, but they do not have a history of being honest in my area. If push comes to shove, I can take it an hour south to Nashville to get worked on. There are a few good race shops down there.

Cliffyk, I know this guy personally that is working on the car, and I honestly believe he is a good guy. However his primary area of experience is exhaust. I thought that he would be capable of installing gears, but at this point I would agree with you. He is in over his head and making excuses. It's been made clear that I need to take my business elsewhere I guess.

NewEdge,
I can make a video of the noise no problem. I did not drive it to school this week because I was concerned that it would not be able to make the 100 mile trip with the rear end acting so funny. However, this weekend I will see if I can get a video as a point of reference.

Thanks again for the great info!

uberstang1

Victim of a bad gear install.