Bad gear install :(

**yellowv** · 03-05-2007, 05:39 PM

Well I took my car into the shop for the rear to be totally rebuilt. New diff., Motive 3:42's, bearings, seals, new axle shafts and new TA cover. The guy was supposed to be the best around. Well now the rear howls like a banshee on accelleration above 50mph. Obviously the gears were not set up right but he says he set them the best he could. How much work is it for a competent guy to remedy the situation? From what I see here it is probably a pinion depth issue. I would have went with 4:10's if I wanted to deal with whine. Also will it hurt the gears to drive it like this for a few days. I drive about 100 miles a day. Thanks.

**volleybill** · 03-05-2007, 05:51 PM

You did the break-in thing, right? Allow them to go through a couple heat cycles before really getting into them?
You should drive them easily for at least 500 miles, a few heat-ups and cool offs and then at least change the fluid- that would be a good time to check the mesh- might be a bearing issue, too- take it back to the mechanic that did the install, and give him a chance to make it right- if he can't, then you know who to stay away from, and can help 'advertise' that fact-

**yellowv** · 03-05-2007, 05:58 PM

Yeah I'm not getting on it hard. Just rolling on the throttle upwards of 50mph is whine city. I brought it right back to him and he acted like he did a perfect job and couldn't possibly see how he could align the gears better. We'll see how bad it is on my hour drive at 70-80mph to work tommorrow morning. He knew he f'ed up because he gave me back half of my money real quick. I just might be getting the rest back after I see how bad it is tommorow.

**99RedRagtop** · 03-05-2007, 08:05 PM

what brand gears and what ratio? did the guy use a depth guage to set it up? theres a lot of variables to whats wrong. i've done several and found a few of the depth setting numbers to be inaccurate. its one of those trial and error things then, to get it right. unfortunately, most shops aren't gonna be willing to spend the time it takes to do it that way, and you're not gonna want to spend that kind of money, either. i'd say if it doesn't get better to find someone else to do it, and buy a different brand.

**yellowv** · 03-06-2007, 01:33 AM

The gears are Motive 3:42's. There should be no reason in the world for them to whine. IF they were 4:10's I wouldn't be complaining.

**jmhvenom** · 03-07-2007, 12:33 PM

Did you get the Motive performance or the regular ones? I have the regular ones, 3.73s and they are fairly quite. Now, the performance ones can whine bad.

also, I had a problem with my wheel bearings when my gears were installed. Might want to check that one out. Made a really bad whining sound.

**Midnight02** · 03-07-2007, 06:18 PM

I just had Motive Performance 3.90s installed in my 2002 M6 SS and they have a good bit of whine around 70 - 80 mph. The shop that installed them is very reputable, so I'm guessing it might be the gear!

**jmhvenom** · 03-08-2007, 04:35 AM

Yes, thats why my shop (daves total performance) told me to go with the regular Motive gears. Pretty much the same thing, but not whine.

**9t8z28** · 03-11-2007, 05:16 PM

Take it back. He gave you money back to shut you up and deal with it. He soesn't want to deal with it cause he is gonna lose time and money on it.
If he gave you half of the money back, I would be scared to drive it.

**OreoLt1** · 03-11-2007, 05:50 PM

I have been building rear ends for 5+ years now and I have yet to hear a Motive brand gear without some type of gear noise whether on accel. or deccel or slight load. You can get the pinion depth, backlash and gear tooth pattern correct all day long but that does not change the design/cut of the gear. Even if you go by the depth numbers scribed on the R&P set using a pinion depth geauge set.

I have also ran across just about every f-body has some type of gear noise whether it's off the showroom(when they were still being manufactured) floor or has 35K on it. This is due to even a slight gear noise being transfered through the alum. d/s. which enhances the sound.

And as long as everything was set up correctly the next biggest issue that many people abuse is the break in period. Directly after install the rear should be brought up to operating temp(approx 10-15 min. of very light driving) then completely cooled. After that is should be lightly drive for 500mi.(maybe 750 but definately 500) Then have the gear oil changed. The oil should have a light metallic color to it due to the gear breaking in. After that you should be good to go.

If you can verify that the technician set the gear up correctly and the break in process was perfromed you might try giving Motive a call and I have heard of them sending a replacement R&P set possibly due to a bad gear cut/manufacturing process. Good Luck

**yellowv** · 03-12-2007, 06:46 PM

Thanks for the advise. I have been taking it pretty easy on it and have around 500 miles on the gears already. When I get a chance I will change the gear oil and see if it quiets down some. It's really not too bad. Once I install the headers, ory and LM I probably wont even notice it anymore

**Midnight02** · 03-14-2007, 09:59 AM

Originally Posted by yellowv

Once I install the headers, ory and LM I probably wont even notice it anymore

My mechanic offered similar advise....my 3.90's have a slight whine and he said the only effective way to fix that would be to install an exhaust cut-out!! HAHA!

**StangBanger03GT** · 03-29-2007, 01:58 AM

Loud Exhaust fixes everything....lol....I get some whine from my FRPP 4.10's in the stang......does the whine build up or does it seem to just kick in at 50mph???

**Roastem** · 03-29-2007, 11:33 AM

Every gear I have installed, except in my 88 GMC, has howled a little. I put 3.73's in the 01 Cobra, gear howl. First set of 4.10's in the Z, howled. Second set, 400 dollar set, howled also.

Nature of the beast I guess.