I though I'd post a happy ending to another noisy gear story.

Yesterday we swapped my annoyingly whiny Precision Gear 4.10's for a set of FRPP 4.10's. My installer ended up using the same exact shims and spacers and once again got a perfect pattern on the install. The result, however, was night and day.

The new FRPP's make almost no noise. I do get a little tiny bit of whine in the 50-60 mph range but it's a small fraction of what I got with the Precisions. Perfectly liveable, whereas before, I couldn't drive for long without getting really pi$$ed off and headachy. I had all but stopped driving it for fear of road rage against my own car!

The FRPP's backlash is from .0065 - .008.

The Precision's came up anywhere from .007 - .011, which = Sloppy!

Apparently the Precision's were anything but. Surprising since they have a rep a being a quailty gear. We'll be sending those back to the manufacturer hoping for a full refund. I won't hold my breath though...

I'm just happy to have her back!

 

Always nice to hear a happy ending. Welcome back to the world of sane people.

 

It's good to be back!

 

Glad to hear all is well now, Adam. I have had my FRPP 4.10s for over 2 months now and no complaints whatsoever.

 

My FRPP whine like crazy. I will be going back soon to see if they can be adjusted.

 

I feel for ya, man. I didn't like my car very much with all that noise coming from the gears. I do strongly believe that these '05 Stangs are very sensitive to noise and vibration coming from the differential and you will need a spot on install as well as some good old fashioned luck. I looked at the pattern from the noisy Precision's that we took out and the it looked just as good as the quiet FRPP's. Didn't make sense, but I'll take it. Good luck getting it resolved. There is hope.

 

I'm sure I'll get flamed, but why not just leave the original gears on. Do you plan on racing? If so, then I suppose I could understand.

 

Why??????

BECAUSE ITS FUN!!!!!!!!!!

 

Only every week (or as often as possible)!!

 

What is the difference in the original gears and the 4:10 gears? Does it help the car's performance significantly? Also what is the whine everybody is talking about? The reason I ask is b/c someone suggested this as a mod to me in a previous post.

 

Mustang + 4.30's = Tire burning mayhem.

Gear "whine" is a bit of a misnomer. It is actually the gear faces slapping together. Hypoid gears are supposed to be in constant contact to stop this noise from happening... if they are not properly manufactured or installed they will whine at certain RPM's. The mechanical effect is always present, but can only be heard when the frequency of the noise matches a resonant frequency of one or more components.

 

I want to get some 3.90's because I think 4.10's will be too much for me. I think only Motive makes 3.90's. How reputable are they? What do you think my chances of "gear whine" are? I'm probably going to get it done in 2 weeks, I hope I'm not making a mistake...

 

There's only a ~5% difference between 3.90s and 4.10s... FWIW


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What do you think my chances of "gear whine" are?
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Based on what I have read on these forums... about 50-50. Good luck!!

 

Now why did you have to go and tell me that...

Ok, so stock are 3.55. What's the percent difference between stock and 3.73's, 3.90's, and 4.10's?

 

Each step up is around 4.5% to 5%.

 

Sweet, thanks. 10% sounds perfect to me...

 

If you do a fair amount of driving above 70 mph, the 3.90's might be just about right for you. My car with the 4.10's is not driven daily, but if it were I would consider any more than 4.10's to be too much. I bought my car strictly for entertainment purposes and I think my gears are perfect for that. On an every day basis, I'd be giving it more thought.

The Motive gears are less expensive than some of the other brands, but based on what I've read, they aren't more problematic. You may also have a slightly better chance of a quiet install with the 3.90's.

 

I've been thinking of the 4.10s myself. I have read that the frpp gears are the best and quietest out there, but it sounds like the set up is the KEY. I'd give up the top end, for sure, for some stop light to stop light, back in your seat action!