The rear axle in the S197 is EXACTLY the same as far as gear setup goes. An 8.8 center section is an 8.8 center section. There may be differences in tube and axle lengths and axle assembly mounting points, but the center section is set up in EXACTLY the same way.
Here's the source of the problem. When using FRPP gears, in almost all cases, you can simply install the gears using the exact same shims in the exact same locations as the original setup and you will get a proper pattern and backlash. THIS DOES NOT HAPPEN EVERY TIME! SOooo... what happens is some guys get too confident with the FRPP gears and simply slam them in place without checking the pattern and backlash. In most cases they get by with it, but every once in a while they get bit. In your case, you got bit because the tech and the shop allowed you to get bit.
ANY TIME a carrier is removed for ANY reason, the pattern and backlash should be checked and set up if necessary upon reassembly.
BTW, checking pinion depth is not an operation in and of itself. Pinion depth is checked by checking the pattern. If the pattern and backlash are correct, then the pinion depth is correct.
SOOooo.... for me, the fact that the shop used FRPP gears and ended up with a noisy rear axle tells me that they did NOT check pattern and backlash, while assuming that it would be okay. If it were me I would be asking some questions including; who was the tech that did the work, is it normal shop practice to not properly check their work, etc.
sounds like a pinion depth issue i beleive that they need to add a 0.030" shim when installing frpp gears
For what it's worth department: My installer told me to buy FRPP's without the "M" at the end of the part number (#M4209G410-"M") which is the Motive-built ring & pinion sold by FRPP.
He said that they have had no post-install problems with the FRPP part #M4209G410-"A" after dozens of installs. After a few post-install noise problems with the M version he won't install them anymore.
Looking at the Mustang parts supplier websites, the M version 4.10s can be had for $150-190 and the A version 4.10s are priced higher, about $210-$260 - so there's obvioulsy a difference in the reseller's cost. Many resellers don't even specify which version they are selling.
Jeff
The rear axle in the S197 is EXACTLY the same as far as gear setup goes. An 8.8 center section is an 8.8 center section. There may be differences in tube and axle lengths and axle assembly mounting points, but the center section is set up in EXACTLY the same way.
Here's the source of the problem. When using FRPP gears, in almost all cases, you can simply install the gears using the exact same shims in the exact same locations as the original setup and you will get a proper pattern and backlash. THIS DOES NOT HAPPEN EVERY TIME! SOooo... what happens is some guys get too confident with the FRPP gears and simply slam them in place without checking the pattern and backlash. In most cases they get by with it, but every once in a while they get bit. In your case, you got bit because the tech and the shop allowed you to get bit.
ANY TIME a carrier is removed for ANY reason, the pattern and backlash should be checked and set up if necessary upon reassembly.
BTW, checking pinion depth is not an operation in and of itself. Pinion depth is checked by checking the pattern. If the pattern and backlash are correct, then the pinion depth is correct.
SOOooo.... for me, the fact that the shop used FRPP gears and ended up with a noisy rear axle tells me that they did NOT check pattern and backlash, while assuming that it would be okay. If it were me I would be asking some questions including; who was the tech that did the work, is it normal shop practice to not properly check their work, etc.
Just got back from having 4.10s put in my Stang. They use the FRPP gears. They guy who did them said he has done atleast 30 of the S197 rears so far with very few complaints. He uses the Friction Modifier( before he started, I asked him if they use it, he just laughed and said they order that stuff by the case...you HAVE to use that stuff). He was saying how the backlash IS the key to doing it right. First he tries the factory shim as it came out, if that doesn't work he flips them over. After that he will use different shims(his cart must have had at least 100 or more shims on it). With the factory shims flipped over the backlash was at 12.5(he said it was to much for him). Used a diffrent shim and got it to 9. He likes to have them between12 and 7 to 7.5. I asked him about break in period. His answer was just take it kinda easy for the first 50 miles and NO burnouts!!!!! Well, it was a 42 mile ride home and there was absolutely NO unusual noises coming from the back of the car.
Just over 500 miles in just under a weeks time after the FRPP 4.10 install and not a single odd noise or whine from the rear end what so ever. So i'd have to say, if done and checked correctly along with some of the Friction Modifier, you should have no issues unless it is some manufacturing defect.
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