9” Rear end...

biminiLX

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Very nice! Yes all these mods take small adjustments but it’s worth it in the end.
Any idea the Backspace/offset of the Forgestars?
Good luck
-J
 

csvt98

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Just thought I'd update you guys...
I installed the Moser 9" and DSS driveshaft about two weeks ago. Had a few hiccups here and there, but overall wasn't too terribly bad. The little "C" shims that go in between the axle bearing and the caliper mounting plate didn't fit right so I had to take them down to a machine shop and have them milled down a few thousandths. The driveshaft seemed to be about an eight of an inch too long so I had to adjust the rear end back that much to accommodate for it. Which of course, made my rear springs just slightly off so they aren't perfectly straight up and down.

Side note: I'm getting a pretty good amount of "clanking noise" from the driveshaft when going from forward to reverse.

I changed the upper control arm last night to the one BMR makes for use on the S197 with a 9" conversion, that helped tremendously and is no longer making contact with the center section. All of this was a lot of work, especially trying to do it after hours and in my little bit of free time that I have. But I'd say it was definitely worth it. The 35 spline axles seem HUGE when compared to the factory 31 spline's, and the 3.89 gears made a world of difference. When I finally get traction, it pulls like a freight train!
I ordered some 17x10.5 Forgestar F14's and some 305/45/17 M/T ET Street R's, they seemed to hit the inner fender when I test fitted but haven't had time to really mess with them yet. Hoping a small spacer will fix it.

When you swapped rearends, why not swap brackets and rotors to run 15's?
 

Garrin

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When you swapped rearends, why not swap brackets and rotors to run 15's?
Mainly money. I wasn’t planning on doing all this near this soon. Especially with less than 30k miles. I just wasn’t prepared but had to do something pretty quick when the stock one started giving out. It’s my daily driver.
 

biminiLX

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Unless going to the strip regularly, newer 17-20” DRs will hook 4-digit power and bigger rear stock brakes are better.
Unless you need a tall sidewall wrinkle wall bias ply slick, forget 15s.
I’m running 17s on the street and 15s o the strip, both MTs and Welds, but lots of good options.
-J
 

csvt98

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Mainly money. I wasn’t planning on doing all this near this soon. Especially with less than 30k miles. I just wasn’t prepared but had to do something pretty quick when the stock one started giving out. It’s my daily driver.
Definitely understandable. For a DD I would not bother.
 

Garrin

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Hate to bring up an old thread, but I need some help. I only ran the truetrac for a couple of months before it started making all kinds of noises. I talked to Moser and they swapped it out for the Wavetrac and I have had that in there since July. I was still getting a good amount of gear noise, but everyone I've talked to said that was to be expected. A couple of weeks ago I went out and did a few pretty hard launches, and now I'm getting a "growling" noise but with the car in the air and tires spinning in 3rd gear, it sounds like it's coming from the driveshaft. Is that even possible? What could be causing this?
 

Garrin

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It's just weird that it's coming from the driveshaft. I didn't even know they could make such a noise.
No, not stock axles.
35 spline Moser axles, Moser 9" rear with Wavetrac and 3.89 gears. Adjustable panhard bar, adjustable upper and lower control arms, Eibach springs, and a DSS aluminum driveshaft.
 

Garrin

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DSS says that it is for sure not the driveshaft. Makes sense as I don't know what could be in there making that noise. So that points back to the rear end.......again.....
I'm gonna put it back on the lift Saturday and check pinion angle and re-torque all bolts (for about the 10th time)
I guess if all that checks out, I need to find a shop that can maybe check pinion depth or backlash or something. The 9 inch was set up by Moser (twice now) and it still makes all kinds of racket. I'm ok with a little gear whine here and there, but this doesn't sound healthy at all.
 

biminiLX

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My Strange 9” has been money. No more issues like the 8.8.
I went with a 4.0 gear and it’s been a good fit with the street 315/50/17 ETRs but I may try a 29” bias ply this year depending on how far the 28x12.5x15 ETR Bias let me trap at 7500rpm.
-J
 

Beercules

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No, all 9" 3rd members are not the same size. Do the measurement before ordering your shaft.

It's not the diff unless your extra long shaft is pushing the pinion in too far and screwing up the crush sleeve or something.

If everything is still set up the same, you need to start with shortening the DS to the correct length (just take it to a local shop). Otherwise your suspension geometry will be off and could play havoc with traction.

The bearings in the shaft u joints could be making noises, especially if you might not have allowed enough room for the shaft to compress enough when going over bumps etc. Also, make sure you've greased them if they have a zerk.

The guys over at yellow bullet seem to prefer the s-trac differential for strength, that's what I went with.

Don't forget Mark Williams for 9" axles, they make up to 11" if needed, super high strength.

Sorry for the way this sounds, and hope everything turned out well for you.


DSS says that it is for sure not the driveshaft. Makes sense as I don't know what could be in there making that noise. So that points back to the rear end.......again.....
I'm gonna put it back on the lift Saturday and check pinion angle and re-torque all bolts (for about the 10th time)
I guess if all that checks out, I need to find a shop that can maybe check pinion depth or backlash or something. The 9 inch was set up by Moser (twice now) and it still makes all kinds of racket. I'm ok with a little gear whine here and there, but this doesn't sound healthy at all.
 

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