About ready to give up- Front DS vibes, 01 xj- Advice appreciated

[lazyxj]

Do you still have a LP30 up front?
I'd go through the effort of switching to a HP30 if it's that bad.

In retrospect, I should have found a HP D30 but I'm not sure if even that will fix it. Smithcell has a 1/2" lower lift and a HP D30 and he sufferers from the same problem. It's also a 2001, if that matters.
Right now, my biggest fear is damaging the transfer case's front output shaft's bearings.

Researching this, I was surprised to see many TJs owners having the same problem but it makes sense, we share the same axle, transfer case and drive shaft. Their problems always seem to occur when going to 4.56s or lower.

 

[XJEEPER]

Too bad this setup is sold as "off-road use only"..........wonder why not for a daily driver?

 

[lazyxj]

Too bad this setup is sold as "off-road use only"..........wonder why not for a daily driver?

What type of front CV joint is that?
Have a link?

 

[techno1154]

I had mine balanced to 3200 rpm. Their standard is 2800.

AW4 or manual shift, if the transmision is in over drive, the out put shaft and the drive shaft is spinning faster than the engine speed, ie: if the RPM is 3,000, then the drive shaft speed is 4,000 +/- RPM. 3,200 RPM for a drive shaft that will be used at highway speed is low.

 

[Boostwerks.com]

Too bad this setup is sold as "off-road use only"..........wonder why not for a daily driver?

http://image.4wheeloffroad.com/f/31...driveshaft_solution+land_rover_driveshaft.jpg

You would think that would be the other way around. Seems like a great solution.

 

[kastein]

It's sold as off-road only for liability reasons I'm sure.

I see absolutely no reason it wouldn't do fine on the highway if it's go-fast rated. Just keep grease in it.

 

[srmitchell]

There's like 100 different products listed as "off road use only" that we use on DD's. Link?

I've thought also- Didnt jeep put harmonic disk/balancer assemblies on some tj's? Maybe the OEM had this issue.

 

[Boostwerks.com]

There's like 100 different products listed as "off road use only" that we use on DD's. Link?

I've thought also- Didnt jeep put harmonic disk/balancer assemblies on some tj's? Maybe the OEM had this issue.

http://www.4wheeloffroad.com/techarticles/drivetrain/131_1101_the_cv_driveshaft_solution/

I didn't see anything listed under JE reels website, so it looks like you'd have to contact them to get more info.

I'm honestly interested in one as well. :thumbup: I love my 4.56s and 33s but the vibes have always sucked at 60+.

 

[Jonesy51]

I finished replacing the front differential. I broke the ring gear, but upon futher inspection I found the pinion gear was bad and the carrier bearing was shot. I beleave the vibration was coming from the bad carrier bearing. I have only driven a few miles down the freeway but there is no vibes so far.

 

[XJEEPER]

It's an RCV joint that JReel welded to the driveshaft. I don't see any reason why this wouldn't work for a DD......I'd like to hear some logic and reason behind the "off-road use only" designation. A double cardan joint can fail at speed if not maintained, as can any u-joint or cv joint, so the liability is on the owner to perform maintenance.

The bigger question for me is, will installing an RCV joint on a driveshaft reduce/eliminate vibration, when compared to the equivelent double cardan jointed driveshaft?

http://www.rcvperformance.com/index.aspx

 

[mako my day]

I have decided to unbolt my driveshaft at the diff pinion for traveling to our destination. Oh well. Just another due process.

 

[XJEEPER]

UPDATE: I bounced these questions off of Tom Wood, who's a friend of mine. Here is his response:

"The RCV unit delivers a true constant velocity through the drive shaft while a conventional double cardan delivers a near constant velocity. The RCV unit should create no torsional vibrations while the double cardan will create some. The amount it would create will be totally dependent on the net operating angle at the transfer case end.

I will add a couple of other things. I do not think the RCV unit will deliver a very long life as this type of CV is not really suitable for running at high speeds through a large angle. There is just too much sliding motion between the balls in the CV assembly and their pathways in the housing. This generates a lot of heat.

In the mid 1980’s Ford used a similar design in the Bronco II. It was notorious for premature failures. It may help to think of this as the same type of assembly used on front wheel drive cars on the half-shafts. On this application, it is almost always the outer joint that fails first. This is because this joint runds through greater angles, while steering through a turn. Keep in mind too; on a front wheel drive car, the half-shaft turns at a much lower speed and through much lower angles of operation."

Best Regards,

Tom Wood
Tom Wood's Custom Drive Shafts Inc.

 

[XJEEPER]

AW4 or manual shift, if the transmision is in over drive, the out put shaft and the drive shaft is spinning faster than the engine speed, ie: if the RPM is 3,000, then the drive shaft speed is 4,000 +/- RPM. 3,200 RPM for a drive shaft that will be used at highway speed is low.

If I did the math correctly, if my engine rpms are 2800 at 75mph, (4:88 gears/285/75/16 tires) and OD ratio on my AW4 is .75, then my driveshaft speed will be 3,733.33 rpms at 75 mph.

 

[Talyn]

FWIW; Some ZJs use a CV(not double cardan) joint in the axle end of the front shaft. Some WJs uses a CV joint at both ends of the front shaft. IIRC the JK may use the CV joint at both ends of the shaft, front and rear. Mind you, this is at stock height and the CV joints are a bit smaller than stock. Also, on the front wheel drive car analogy I have seen more CV joints failed because of a torn booth rather than the joint just plain out failing. Same for the ZJ & WJ with front CV half shafts.

 

[barillms]

Don't go any faster than 58mph.

 

[Boostwerks.com]

If I did the math correctly, if my engine rpms are 2800 at 75mph, (4:88 gears/285/75/16 tires) and OD ratio on my AW4 is .75, then my driveshaft speed will be 3,733.33 rpms at 75 mph.

Driveshaft RPM is directly determined by the active transmission and/or TC gear ratio. If the motor is turning 2800rpm and the driveshaft is spinning 25% faster than the engine; or 3500rpm.

2800*1.25 = 3500

 

[Boostwerks.com]

FWIW; Some ZJs use a CV(not double cardan) joint in the axle end of the front shaft. Some WJs uses a CV joint at both ends of the front shaft. IIRC the JK may use the CV joint at both ends of the shaft, front and rear. Mind you, this is at stock height and the CV joints are a bit smaller than stock. Also, on the front wheel drive car analogy I have seen more CV joints failed because of a torn booth rather than the joint just plain out failing. Same for the ZJ & WJ with front CV half shafts.

In stock applications that's fine though considering the static shaft angle is very low. Either way I think the only way to really test the durability of the shaft would be to actually try it out and monitor regularly for wear. For all we know it could last forever at an angle of 12degrees but need replacing every thousand miles at 14.

JE reel has the disclaimer for a reason though... if the joint failed at speed the end result would not be pretty. I'd be more than willing to try it out though as long as I had some form of safety hoop at the TC end.

 

[1990JEEPXJ]

Driveshaft RPM is directly determined by the active transmission and/or TC gear ratio. If the motor is turning 2800rpm and the driveshaft is spinning 25% faster than the engine; or 3500rpm.

2800*1.25 = 3500

He seems right with his math. 2800/.75= 3733.333

 

[Boostwerks.com]

He seems right with his math. 2800/.75= 3733.333

Yep, you guy's are correct. :worship:

Per Dana:

To calculate the maximum possible driveshaft RPM in vehicles having an overdrive transmission, divide the maximum possible
engine RPM by the overdrive ratio. (See examples below.)
.
Example 1:
Max. engine RPM: 2100
Overdrive ratio: .79

2100/.79 = 2658 maximum possible driveshaft RPM

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[blondejoncherokee]

i hit over 3000 RPMS with my 4.88s and 36s quite a lot. minimal to no vibes. the shafts spinning at 4000 rpms is pretty nuts.