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Discussion Starter #1
I had my jeep at the driveline shop near home. I explained a clutch chattering noise to him in first gear and he told me it is actually my front DS bottoming out when the front pinion moves during 1st gear pull out. I have 4 inches of suspension lift and a TT. He said one way to fix the rubbing was to grind some of the thick metal around the area where the CV is. Can this lead to other problems if not fixed?? Would a new ( non stock) drive shaft fix the problem??

thanks
 

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Re: Front DS bottoming out???

Grinding the CV is to allow more angularity of the joint - usually only necessary on vehicles while the front suspension is drooping and the front driveshaft can almost handle the angle. I would think most driveline shops would discourage grinding the CV (and weakening it). As far as I know, this is not a common issues with near-stock TJs (but is used with other brands like chevy K5s). Bottoming out would refer to the slip spline bottoming on the driveshaft, which would indicate a driveshaft which is too long (would most likely occur when the front suspension is bottoming).

I would think any experienced driver can feel clutch chatter versus a driveshaft condition that should feel like a noise in the chassis.

One other thing to consider - with a coil spring, link-type suspension, there should be next to no movement of the axle, other than what is engineered to move. The exception to this would be movement through sloppy suspension and/or trackibar joints. This means minimal driveshaft slip (i.e. at the pinion).

I would find another shop and ask a second opinion.
 

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Jeepless in PA
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Re: Front DS bottoming out???

If your drive shaft is binding in the normal running position, you will have many more problems when you disco the front axle. iirc, grinding the shaft around the flange will only net 5 degrees of downward movement.


My first question is, does your driveshaft look like this? (how the angles are setup)




Before I would throw any money into the rig, I would lower the tcase skid by a 1/2" and see if the problem goes away.
 

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Re: Front DS bottoming out???

If the front axle moving is causing the problem is should only happen in 4wd, when in 2wd there is no torque transfered to the front axle so it should move only slightly. If the clutch is chattering you should be able to feel it taking off in a higher gear, you might try taking off in second and see if you feel it.
 

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Discussion Starter #6
Re: Front DS bottoming out???

1982cj7 said:
If the front axle moving is causing the problem is should only happen in 4wd, when in 2wd there is no torque transfered to the front axle so it should move only slightly. If the clutch is chattering you should be able to feel it taking off in a higher gear, you might try taking off in second and see if you feel it.
Tried starting in 2nd gear, noise gone. Going to disconnect it next. Thank you. I didnt think he was right, good chance i mis understood him, im a mechanical idiot :D
 

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Discussion Starter #7
So I spoke to my driveline guy and he said what is happening is that when the front of the Jeep rises during 1st gear acceleration, that is creating the noise that im hearing when the front two yokes on the driveshaft actually rub together. How should i fix this?? Should i lower the transfer case a little?
The specs on my jeep are as follows:

OME ZJ/LJ combo
3/4" spacer in front
1.75" spacer in rear
Clayton long arm
Tummy tuck
 

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Jeepless in PA
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What are your driveline angles? do you have any pictures?
 

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Discussion Starter #9
I am getting cell phone pics now. the driveline guy said you can actually see where the metal is binding together at the CV
 

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Discussion Starter #11
So i guess now im a little scared, I just put new 35's on the jeep and 4:88 gears to go with it and now I have a problem that im not really sure how to fix. Spoke to Jess at HAD and he advised limiting straps. I really do not want to go that route. I also have a BL and MML. Can I just lower the TC? Or does this create more angle problems? I could take the spacer out of the front and rear springs but than i have a tire clearance issue.. Very frustrating, never thought of this when i put the 35's on and the spacers in the springs. For reference the front has a 3/4" spacer and the rear is a 1.75"
 

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Jeepless in PA
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Lowering the rig's height will decrease the chances of the CV bottoming out. If possible, I would pull the MML.
 

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Discussion Starter #13
Greg, If i pull the MML ( which i can do) will that " maybe" solve my problem or definately solve it? I have a 1.25 BL, how will that be affected? I can pull the MML and drop the T case one inch. Hopefully that does the trick

Thank you,
Mike
 

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Jeepless in PA
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mikem04rubi said:
Greg, If i pull the MML ( which i can do) will that " maybe" solve my problem or definately solve it? I have a 1.25 BL, how will that be affected?

Thank you,
Mike
Removing the MML will solve your problem since you are lowering the output angle off the front of the tcase. The only issues that I can think of is your fan shroud will have to be lowered and your output CV on the rear driveshaft will now be at a greater angle so your rear pinion will have to be adjusted.


Either that, get a new driveshaft or you can lower your jeep's height to decrease the angle on the driveshaft.
 

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Discussion Starter #15
gregert12 said:
mikem04rubi said:
Greg, If i pull the MML ( which i can do) will that " maybe" solve my problem or definately solve it? I have a 1.25 BL, how will that be affected?

Thank you,
Mike
Removing the MML will solve your problem since you are lowering the output angle off the front of the tcase. The only issues that I can think of is your fan shroud will have to be lowered and your output CV on the rear driveshaft will now be at a greater angle so your rear pinion will have to be adjusted.


Either that, get a new driveshaft or you can lower your jeep's height to decrease the angle on the driveshaft.

Greg,

I already have a CV rear DS, so that will be no prob. Should i still lower the T case or just remove the MML?? thank you
 

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Jeepless in PA
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mikem04rubi said:
Greg,

I already have a CV rear DS, so that will be no prob. Should i still lower the T case or just remove the MML?? thank you

I thought about this some more and actually drew a picture :laugh: so if you lower the TT, your front output of the tcase would be a greater angle than it currently is so the best way would be to remove the MML if you still have the stock equipment. It is a cheap fix and there is no harm in trying. :)
 

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I would call Tom Woods or another driveline shop and ask about high angle cv's, they can handle more angle and would solve your problem without removing the lifts you have installed.
 

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Discussion Starter #18
1982cj7 said:
I would call Tom Woods or another driveline shop and ask about high angle cv's, they can handle more angle and would solve your problem without removing the lifts you have installed.
I called Jess at High angle driveline and he advised me that there is really nothing he can do to solve this issue on a front driveshaft. I would love to just buy a new front DS and call it a day. Not sure what to do. Guess i will start with removing the MML spacers.
 

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This is a little weird here. You're not running any abnormal lift height or anything, even with the TT, other than being a short wheel base-you do have too much for the TJ. I don't think pulling the MML will solve your problems. It MIGHT help with front shaft issues, but will immediately result in rear shaft issues due to your angles. I'd definitely drop some height, but would do it in the lift itself, not the MML. A 4" or greater lift with a TT adding another 2" is at or more than 6" of lift at your t-case as far as your angles are concerned. 6" of lift on a TJ is tough with such short shafts. You rob peter to pay paul here with simple bolt-on mods. Did you ever push your front axle further forward after the big lift to get things more in line there? If not, you're axle is pulled backward now, further inboard, shortening your wheelbase even more so and putting steeper angles yet on your shafts. Start by ditching the 1.75" rear spacers, drop that down to a respectable level and go from there. This will be trial an error for sure but I'm not positive removal of the MML will solve your issues-I think they'll just transfer them elsewhere. Not sure the exact answer for this, but definitely drop some height and go from there. Along with, reset from axle to where it should be then see how you do.

Best of Luck,

Mike
 
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