So, I did have 3.73s installed and they were obnoxiously loud. I was going to go the 9" route but after pricing that out with a watts link and torque arm, it was insanely expensive. Not just a simple bolt in part for me, although I could have put the stock style BMR parts I have back in and not messed with the watts link and torque arm. Ultimately the final deciding factor was I found the 8.8 guru in the Wichita area and he charged me $350 for the install, it normally is $250 but he had to remove the entire housing because of my torque arm and that added to the cost. Also, I had a new set of FMS 4.10s, pinion bearing, and install kit sitting in my closet. Happy to report the 4.10s are nearly dead quiet. On a scale from 1 to 10, where 10 is my whiney 3.73s, the 4.10s are a 2 at the most. It is very pleasant to drive the car now plus I really like the 4.10s. It really is a blast to drive.
My 3.37s whined from day one. I had him check out the 3.73 install to see if there was anything that jumped out as the cause of all the whining. The gear pattern was ok according to him, but the pinion gear was loose. Loose meaning it turned easily with the carrier removed and the pinion nut still installed. I should have asked him to put a torque wrench on it and measure the drag. I know it was within spec before this install with a solid spacer. The carrier literally fell out which tells me there was absolutely no preload on the carrier bearings. I also noticed while driving the car and going through a right sweeping turn fast enough to apply a lateral load on the axel the whining would virtually disappear. This makes me think the lack of preload on the carrier bearings was at least in part the cause of the whining.
I spent quite a bit of time talking with the installer who is a mechanical engineer and does this in his spare time. Just listening to him, it sounds like he has built 100s of 8.8s and 9" rear ends. One thing he did tell me was that the S197 is tricky to get setup right. For whatever reason harmonics from the ring and pinion resonate with the S197's body. An example of this is a buddy of his had a loud set of gears in his S197, while getting it ready to sell, he installed the stock lower control arms and the whining disappeared. If my 4.10s start to whine, I'm going to take it back to find out what changed. I will keep you posted as time goes by.
If you live in the Wichita, KS area and need gears installed, msg me and I will give you his name and how to contact him. He does a good job.
Cheers
My 3.37s whined from day one. I had him check out the 3.73 install to see if there was anything that jumped out as the cause of all the whining. The gear pattern was ok according to him, but the pinion gear was loose. Loose meaning it turned easily with the carrier removed and the pinion nut still installed. I should have asked him to put a torque wrench on it and measure the drag. I know it was within spec before this install with a solid spacer. The carrier literally fell out which tells me there was absolutely no preload on the carrier bearings. I also noticed while driving the car and going through a right sweeping turn fast enough to apply a lateral load on the axel the whining would virtually disappear. This makes me think the lack of preload on the carrier bearings was at least in part the cause of the whining.
I spent quite a bit of time talking with the installer who is a mechanical engineer and does this in his spare time. Just listening to him, it sounds like he has built 100s of 8.8s and 9" rear ends. One thing he did tell me was that the S197 is tricky to get setup right. For whatever reason harmonics from the ring and pinion resonate with the S197's body. An example of this is a buddy of his had a loud set of gears in his S197, while getting it ready to sell, he installed the stock lower control arms and the whining disappeared. If my 4.10s start to whine, I'm going to take it back to find out what changed. I will keep you posted as time goes by.
If you live in the Wichita, KS area and need gears installed, msg me and I will give you his name and how to contact him. He does a good job.
Cheers
