I had a local old timer who does a lot of speed work install a set of FRRP 3.73 gears,I got Him the master install kit with bearings etc. He was only charging Me $175.00 for the install. When I went to pick up the car He said the gears were quiet on drive but had a slight whine on coast. He told Me to break them in & see what happens, He wouldn't even take any money, He said to stop back. The whine is only there from 60 mph down to 30 mph and is slight. Above & below that speed they are quiet on drive & coast. I saw the pattern when he installed & it looked good to Me. I' ve put about 220 miles on car gently, the other day I decided to get under the car & check things out & I can move the pinion flange & pinion gear a little in all directions. I guess he messed up on the bearing preload, I went back & asked him if he set the preload to recomended 16 to 26 in lbs. & he laughed & said he just does it by feel & never heard of such a thing. He said he couldn't look at it for a couple of weeks, I left a little mad. My buddy is a transmission builder & he said we could pull out carrier & replace pinion bearings & torque preload correct. My question is do you think thatcaused thenoise & do you think the gears are trashed (heard no bad noises other thar decel whine)? Do you think we could just replace the pinion nut & properly load the existing bearings since they were set to loose? Do you think I should pay him & how much?

 

Mine whine too. Ive had 3.73's in my car for about a year. They whine no more or no less than they did when they were first installed.

Im not expert, but I would guess that you and I got shetty installs. [:-]

 

I'm pulling apart Saturday & resetting pinion preload as it is loose, new crush collar & nut then I will check backlash & pattern when I reassemble. I think its so minor it may be related to the pinion moving due to little preload.

 

Through the years I've had 3:73 to 4:56 gears installed on different cars and only had a whine when something wasn'tset right. Backlash etc. If you haven't beat on the rear the gears should be OK. Pull it apart and do it again. Or have a better mechanic do it.

 

bad install, dont pay, take it to another shop, helical cut gears will NOT whine

 

Update, yeasterday I tore it apart and started over, I used a technique from the folowing article to determine pinion depth & it turned out the so called professional install had the pinion depth .009 shallower than what I finally calculated it to, the backlash was also only .075 (recomended .008 to .015. When I reassembled with my new calculated pinion depth to my suprise the original factory shims (I had the other installer label them) went back in & gave me a backlash of .012. the pattern looked good & I put it all back together. Took it out & no more whine sounds perfect, I couldn't be happier. Any one trying this without the pinion depth gauge should read this article, It made a lot of sense to me & worked like a charm. Thanks to James Adkins who wrote article.

http://www.superstallions.com/tech/d...ars/gears.html