Shim size for 3.75 lift

[bgcntry72]

I am between 3.5 and 4 inches of lift on my 99. I have the 8.25 and AW4 and will be installing the RE SYE this weekend. Any ideas what size shims I should get before starting this job? I have a 4*, but I have a feeling I may need a 6*. Any help would save me hours of experimentation(which I am sure I will have to do anyway, because its a Jeep), and an extra set of shims. TIA

[stoneattic]

It all depends on the how the lift was made, AAL, new leafs, shackles, etc.

The best way is to go the hardware store and buy an angle indicator for about $10.

If you have a standard driveshaft with a slip yoke then you want the same angle on the pinion yoke as you have on the t-case output shaft. Of course you don't want exteme angles between the t-case output and d-shaft, pinion and d-shaft. If you do then an SYE is you only solution.

[bgcntry72]

It is an OME leaf pack with RR 1" blocks using stock shackles.

[jimbar]

I had the same lift as you and used a 6* shim with a Chrys 8.25 axle. I also have the Tom Woods/AA HD SYE kit installed. I always wanted to try a 7 or 8* shim because 6* isn't quite enough for normal freeway 70mph + driving (Yes I could still feel some vibes).

[bgcntry72]

Good to know. I have no drop in now and no shims and I only cavitate on decel from 40-33. The low roar sets in at 70+, which I travel often. I was going to start with the 4* and move to the 6* if necessary, but now I will start with the 6*. Thanks for the info jimbar. Anyone else?

[Ivan]

With my 3.5" lift, 5sp, 8.25 axle, RE SYE; I was using 4* shims and was 2* under at the pinion. With my current 6" lift, 5spd, 8.25 axle, I'm using 6* shims now and still 2* under at the pinion...

I did have some minor rumblings on decel above the 50 mph threshold after my regearing, but it turned out to be a loosened pinion nut. Liberal amounts of lock tite cured that....

Ivan

[LawlessXJ]

FWIW - I've got an RE 5.5" lift (more like 7") and am installing the RE SYE on my '97. Guys at Rubicon said I would need a 6* shim with that combo. I can't comment on whether that is enough as it's not been put back together and driven yet.

[bgcntry72]

Thanks for the help. I will install the shaft and see what I get. Then the 4* shim, and if need be, the 6*, which I doubt. It is surprisingly well mannered now, no shaking, just a harmonic imbalance 60-70 mph. Appreciate all who took the time to explain their experiences, you guys made this a lot easier.