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Vibes at 70 MPH?

sjd78

sjd78

NAXJA Forum User
Location
Bakersfield, California
Well, since I swapped in my D44 in the rear I am now noticing some vibes at 70 mph. I didnt notice it before with my C8.25 but that could have been due to not having my speedo calibrated and maybe I wasnt ever driving at around 70mph? Dont really notice them below 65 mph but as you gain speed from there up to or over 70mph you can feel it. I am running RE 4.5" leaf packs with Terra Flex 1.5" shackles and 4* shims. What should my pinion angle be at? Right now it looks to be just below the drive line angle. Also, I have an SYE and cv driveshaft.
 
I get vibes around 70+, but it's all because of the front angle. I remove the driveshaft and it's nice, only tire noise!

Have you removed the front DS and tried it out? You may be surprised. Of course, it may not be the front.

Are you using the same driveshaft? Did you check the length and balance of it?

I don't remember the angle for the pinion off-hand, but I am sure it's in one of the posts on here somewhere....

Good luck!
 
I had the same problem with my D44, the way to really deal with it is with a magnetic angle finder. Check the angle on the driveshaft and the angle on the dif. housing and use the shims to match them up, they need to be parallel. Save the headache and do it right, I speak from experience. My .02
 
pierceME311 said:
I had the same problem with my D44, the way to really deal with it is with a magnetic angle finder. Check the angle on the driveshaft and the angle on the dif. housing and use the shims to match them up, they need to be parallel. Save the headache and do it right, I speak from experience. My .02
Click to expand...

If you saved all your $.02 then you buy yourself something nice! LOL JK.
 
WheelinJR said:
Your Jeep with 6" of lift vibrates at 70mph, NO WAY! heheheh

How large are your tires? I am on 32's and 65mph on my speedo comes up as 74mph on my GPS.
Click to expand...

35" tires with 4.88 gears and speedo recalibrated so when my speedo says 70 its actually going 70 lol.
 
rpraterxj said:
I get vibes around 70+, but it's all because of the front angle. I remove the driveshaft and it's nice, only tire noise!

Have you removed the front DS and tried it out? You may be surprised. Of course, it may not be the front.

Are you using the same driveshaft? Did you check the length and balance of it?

I don't remember the angle for the pinion off-hand, but I am sure it's in one of the posts on here somewhere....

Good luck!
Click to expand...

It feels like it is coming from the back, and since it didnt vibrate before when I had my 8.25 rear axle it leads me to believe it is coming from the back. I will try out removing the front driveshaft just for shits and giggles and see if it gets any better. The front is the factory drive shaft but the rear is an RE cv driveshaft and SYE. I am going to try and figure out my pinion angle in relation to my driveline angle and I will post back.
 
Ok, you threw me off with talking about not having it calibrated in the old setup.

If you were at 70mph on the old non-calibrated setup, it would've definitely been off.

Sounds like its time for you to play with driveline angle.
 
WheelinJR said:
Ok, you threw me off with talking about not having it calibrated in the old setup.

If you were at 70mph on the old non-calibrated setup, it would've definitely been off.

Sounds like its time for you to play with driveline angle.
Click to expand...

I am going to play with an angle finder and if need be I will take a couple pictures and post em up on here so you all can give me a better opinion.

Thanks!
 
pinion should point 2º bellow parrallel of the driveshaft. check your u-joints as well.
pull the rear shaft and drive in front wheel drive. if the angle of the dangle is ok and it drives vib free without the rear shaft then you might want to have the balance checked on that shaft.
 
Rawbrown said:
pinion should point 2º bellow parrallel of the driveshaft. check your u-joints as well.
pull the rear shaft and drive in front wheel drive. if the angle of the dangle is ok and it drives vib free without the rear shaft then you might want to have the balance checked on that shaft.
Click to expand...

I will check the angle today and post back. The U-joints are all new as they were already installed on my RE cv driveshaft. Can I drive 70 mph in front wheel drive?
 
There isn't one specific pinion angle to use in relation to the drive shaft as each vehicle is different. Two degrees may work well on one vehicle while 0º (inline) works great for another with the same set up. In theory, the pinion should be pointing inline with the DS for those with an SYE. Tom Wood (http://www.4xshaft.com/index.html) recommends setting the pinion about 1º below to account for axle movement during acceleration. If this doesn't work, then try different angles in 1º increments, either up or down, until it smooths out.
 
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