I have 2007 Rubicon JK. I have 6 inch TeraFlex long arm and 37 in tires. My JK is automatic. I also have 538's for gearing.
My wife was driving the car on the freeway at 75mph. She said 4 wheel high was not on but somehow the transfer case blew up into 55 different pieces.
My question is this with gearing like this is it possible for the front driveshaft to be spinning at a rate that would destroy the transfer case? Does the front driveshaft move if the car is not in 4 wheel drive? I dont know alot just trying to figure out what happened?

 

It is possible if you have driveline vibrations. There was another user on here who had the same problem. There was soo much spin on the driveshaft with the gearing, and the added vibes, the transfer case shattered.

Do you have aftermarket driveshafts?

 

I have after market JE driveshafts I believe.

 

Ouch. Save your parts from that t-case. I know there was another forum member here that scattered his rubi case. Have you taken the JK to a dealer yet?

 

Unfortunately, the driveshaft does spin when not in 4wd. There is a Warn kit to disconnect the wheel from the axle shafts but it is muy expensive and requires you to change wheels (as the bolt pattern is 5 on 5.5 rather than 5 on 5).

Unfortunately the 2nd, when you moved to 5.38, your driveshaft is spinning 24% faster than with the original 4.10s which would exacerbate a vibration or t-case bearing problem.

Unfortunately the 3rd, a 6" lift puts a pretty steep angle on the driveshaft coming out of the t-case. I would know as I have a 4" SL which is pretty tall and I added a 3/4" lift and whenever I look at the front driveshaft coming out of the t-case, I cringe. Yours would be worse. I am considering removing those spacers.

 

Stock Rubi, 75mph, drive shaft rpm =3333.
Your Jeep, 75mph, drive shaft rpm = 3664.
Not a big difference.
It looks like it was the steep drive shaft angle that was the big factor.

 

Not quite...

The difference in the ratio would lead to 31.2% increase if the tire size was the same. 5.38/4.10 = 1.312195 rotations where there would have been one.

Then, you take into account the tire size. 32" tires travel 100.48" per rotation, but the stock tires are actually slightly smaller than 32. (2*pi*radius, or 2*3.14*16) His tires are 37's (which probably measure <37, but we will use that as a number) meaning that his tires travel 116.18 per rotation. The difference between the two is a decrease in driveshaft speed = 1 rotation where there would have been 1.15625 (or a reduction of 13.514% making the RPM's 86.486% of stock tires)

So... if you take his RPMS and multiply them by 1.312195 and then by 0.86486 you get a net difference of... 13% increase on driveshaft RPM's.

Bottom line... at 75 MPH, his driveshaft would have been spinning at the same speed as if he had stock gears and tires and was going 85. The driveshaft and everything on either side of it should be able to handle 85 MPH, so he probably had a poorly balanced driveshaft.

Damn... all this math makes my head hurt.

 

Yeah, but you clarified that oh so well... good job!

 

dealer said they will not warranty. Thanks for all the info. Looks like its time for the atlas.

 

This happens to another member of the forum, does anyone know if this problem occurs to other jeeper? It seems that a quite a bit of rigs has been lifted up to 4-6'' and run 37'' wheels.s