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Just did SYE, how are my pinion angles?

S

Sleeper

NAXJA Forum User
Location
Pittsburgh
I just did my SYE install finally and i am wondering what my angles look like to you, i had good vibes before. Right now i sit at close to 6'' in rear and 4.5'' in front with my kit ready to go on this week for the front leveling out.

I still have a lil bit of vibes but i think it might be from the front angle, i replaced the DS today. Tell me what you think, mayne ADJ Uppers will work?




front

 
rear looks good. Depending on the year- the front shaft shouldnt move at all in 2wd, thus no vibes. but the rear shaft is a "front" shaft and looks fully extended
 
If you have an angle finder measure the angles. I use one like this: http://www.sears.com/shc/s/p_10153_12605_00939830000P

I think the difference between the drive shaft angle/slope and the pinion angle is supposed to be less than 3 degrees. FWIW on my rear shaft the difference is 1 1/2 degrees.
 
O sorry it is a 2001, and i am pretty sure the front shaft does move front what i have seen before.

Do i do the angle finder/socket thing to measure then? Do you think upper adj will work for the angle then since the front will be 5.5''-6'' when i am done.
 
Yes. The pinion needs to point straight up the driveshaft, or optimally one degree low to account for the pinion moving up under torque. I can plainly see in the picture that's not the case.. bring it up at least 3 more degrees.
 
JJacobs said:
Yes. The pinion needs to point straight up the driveshaft, or optimally one degree low to account for the pinion moving up under torque. I can plainly see in the picture that's not the case.. bring it up at least 3 more degrees.
Click to expand...
Thanks, i do not have an angle finder yet but am i right that i use a socket and the finder? And what degree am i shooting for?/ shim size.

Adj uppers will fix the front correct?

Thanks
 
Hard to say on what degree shim. Some lift leaf packs have angle built into the midsection. Shackle length plays a big role too. If you've already got a chunky shim in there, might consider burning new spring perches on at the right angle.

The front's a low pinion- not a whole lot you can do. Adjustable arms will bring the angle up but at the expense of caster. Less caster can contribute to wander. The front DS is a 3-ujoint, just like the rear is now, so the same theories apply to getting it vibration free. Since it doesn't carry torque all the time, though, it's a lot less touchy than the rear.

I'd get the rear dialed in- see how it is- remove the front and compare.
 
JJacobs said:
Hard to say on what degree shim. Some lift leaf packs have angle built into the midsection. Shackle length plays a big role too. If you've already got a chunky shim in there, might consider burning new spring perches on at the right angle.

The front's a low pinion- not a whole lot you can do. Adjustable arms will bring the angle up but at the expense of caster. Less caster can contribute to wander. The front DS is a 3-ujoint, just like the rear is now, so the same theories apply to getting it vibration free. Since it doesn't carry torque all the time, though, it's a lot less touchy than the rear.

I'd get the rear dialed in- see how it is- remove the front and compare.
Click to expand...
Cool, the rears are RE 3.5''s with a one inch rc adj shackle and no shims. As far as the front goes well it wonders pretty good now and i do not know what to do about it and it drives me crazy!
 
JJacobs said:
I can plainly see in the picture that's not the case...
Click to expand...

From this pic?
syeinstall011.jpg


Your eyes must be a helluva lot better than mine, I don't see it.

Probably a good idea to get an actual angle finder, to be sure...

Robert
 
ya i cna see that but thought a few degrees would help? Im going to go get an angle finder today and post what they actually are, thanks
 
It appears you are using a front shaft on the rear. There really isn't any too much engagement on the slip yoke. Personally it looks like the shaft is too short. That can cause the slip yoke to flex due to too little engagement and cause vibes at speeds above 50mph.
 
Yes your front DS spins all the time. If you get vibes from the rear with that little angle off, just think what you get from the front. I Know the front has no load. I was where you are till I put in a HP 30. No easy answer, vibes from front DS or wander and possible DW from no caster. Hindsight tells me that it would have been a good idea to have a D44 built up with hubs.
 
Pics can be deceiving, but to my super calibrated wavefront lasik'd eyes, the rear angle looks good. I estimate pinion is 1-1.5 degrees lower which is fine.

The front looks not so great, but you in the same boat as the rest of us unless you're willing to rotate the "C"s. The front DS angle is more forgiving since it's usually not under load, so you may be okay. If you have the time and resources, you can play around with the pinion angle with respect to caster using adj uppers, but try running without the front DS to see if it's indeed producing vibes.
 
Thanks guys, i got it on a decent road with about 50mph kinda steady and it does not feel too bad, seems like the rear is smoother. I can feel a slight vibe form front but as HIGHWAY said it is a LP 30. I am looking in getting upper adj arms and have to play with the caster and also looking for a hp30. I will have to deal with it for now. But i do have ball joint playan d pass outer tie rod end to fix as well and the xj is squirrly on the road.

Seems the exhaust since the muffler is bad and has holes makes the xj vibe as well.
 
CaliGold said:
Pics can be deceiving, but to my super calibrated wavefront lasik'd eyes, the rear angle looks good. I estimate pinion is 1-1.5 degrees lower which is fine.

The front looks not so great, but you in the same boat as the rest of us unless you're willing to rotate the "C"s. The front DS angle is more forgiving since it's usually not under load, so you may be okay. If you have the time and resources, you can play around with the pinion angle with respect to caster using adj uppers, but try running without the front DS to see if it's indeed producing vibes.
Click to expand...
Rotate "c"s?
 
Hey Lasik-eyes, how's it look now? :)

syeinstall011mod.jpg


If it was set correctly at one degree low, the two angles would be almost identical. You can see it's off quite a bit.
 
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