Driveshaft too short?
 

Hi, I've recently installed a 3" lift on my 2001 xj, and I've been getting this "thunking" sound on acceleration, like the slip yoke is sliding in and out. I have a Chrysler 8.25. Anyone know why? Maybe driveshaft is too short? I'm debating a TC drop kit, to see if this would give more length, but I've also heard of replacing the driveshaft with the longer one from a d35. Any input would be killer!

yes. could be that it's too short, pulling down on the slip yoke while driving.
putting in a tc drop should help it out tremendously.
also, now the u-joints are turning at a different angle than they were used too before, so that could be playing a part.

but do the tc drop. i wouldn't change the drive shafts. if the d35 shaft is even a bit too long, it could push through the t-case should your suspension "bottom out".

Pictures tell a thousand words if angles a issue a longer shaft will create more issues.

I snapped a few of my angles, I'm sorry if it's hard to see. I agree with what you're saying though, like I said earlier I'm leaning towards the tc drop

Thanks for the reply, I think I'll go in that direction to begin. Think I should replace the ujoints in addition? What about the fronts?

If you can afford it I'd highly suggest a slip yoke eliminator.

With a t-case drop you're putting strain on things that don't like it. You can use a front drive shaft from an XJ and be good to go.


Just noticed you're about 30 miles up the road from me.

Cant see the important part the slip part. A tc drop will help but a sye is the best bet cures angle issue and gets a yoke on the rear shaft.

No way, where in sc are you? And if you were going to recommend a sye, what would you go with? Hack and tap seems a bit half-assed IMO

Any reason why I couldn't run a tc drop for a few months, until I got the money together for sye?

No it will be fine with a drop until sye can be done.

Alright I think that'll be the plan then, thanks again. Have you used a sye? If so which did you go with?

The output shaft on the transfer case and the pinion at the axle must be parallel or you'll get "thunking" sounds and vibration issues as the u-joints bind. T-case drop may make it worse if you pinion is rotated upwards. With a SYE and double cardan shaft, the axle pinion must be about 1* below pointing directly at the output shaft (not parallel) using degree shims or cutting off spring perches and rewelding new perches on at desired angle. Hack and tap is hit or miss IMHO. I recommend JB Conversions' SYE kit. If you want to buy a new double cardan shaft, check out Tom Woods.

I removed the t- case drop from my 2000 when I changed my suspension and lift. It currently gathering rust, dirt and grease and taking up valuable space in my garage. Name your price and I will box it up. Jeep was a 4 liter auto trans for reference.

I'm in Abbeville. Straight down Hwy25/Augusta Rd from Greenville.

I have this SYE on my 99.

http://www.seriousoffroadproducts.co...c658b3fe1b82bb

Hey I appreciate the offer, but I've already got one ordered up from someone local. Thanks though!