06 TJ sye and rpm issues.

[riotsnclowns]

Hey guys!

A few quick questions.

I bought an 06 TJ with a four inch lift. The kid did cross between a budget booster and coil lift. I put in a T-Case drop and have noticed a whining noise from the rear end, when driving, which one could only assume to be my rear diff. Will an SYE correct this noise? Also once I get the SYE and put it in what else should I do at the same time? Any recommendations.

My other issue is that this is a 6 speed manual. When driving, down hill 5th gear 3500 rpm, and shift into 6th gear my rpms fall and so does my speed. What could cause this? Has any one come across a similar issue?

Thanks for the help and input in advance!

 

[TerryMason]

Welcome to Jeepz!
post a photo from the side of your Jeep of the rear driveshaft, including the axle / pinion and the transfer case. If you need a transfer case drop, or a SYE really depends on the angles your driveshaft is at.

To install a SYE, you'll need to get a new driveshaft (I used the front driveshaft from a Jeep Cherokee that was professionally shortened). You'll probably need new rear control arms (possibly just the upper ones) that are adjustable. You'll need the adjustable control arms in order to make the upper ones longer, and to point the pinion up some. Also, you won't want to run both the transfer case drop and the SYE.

Overall, the SYE is an expensive (but good) upgrade. I would make sure the angles are the problem before you go down that path.

 

[riotsnclowns]

Hey terry I'm on the road today driving home. So as soon as I get home tomorrow night I'll grab a few snap shots and post them on here.

 

[TerryMason]

As to the 6th gear problem, what size tires do you have? Do you happen to know if you've got stock gears?

The normal answer to this is that you have big tires, and the larger tires have changed your overall ratio, so that the engine isn't turning fast enough to be in the power band. Kind of the same thing as trying to take off from a stop light in 4th gear. To fix this you can regear both axles to a lower (numerically higher) gear. This is a pretty expensive option. I think most people just don't use 6th gear.

 

[JPNinPA]

That's true you need to be above 2200 rpm to not be lugging the engine. I have an 05 manual wih 3:73 and 33 in tires. I could still accelerate in 6tg on the highway but that's at ~70 mph