Rear Vibrations after a u joint change

M

Mark.Sibole

Well-known member
I want to share with everyone so you dont make the mistake I made.
I replaced a rear U joint on my RTV 900 and after I put it back together I had a horrible vibration in the rear.
I removed the rear 6 times and re aligned everything and still vibrated.
I took it to a dealer and he went over it all and told me I needed tires and it was the tires causing the problem.
I bought GRIM reapers and installed them and low and behold the vibration was still there.
Now im fuming and 600 bucks lighter for tires and u joints.
Today having a major attitude I tore it down by my self again and noticed something I didnt notice all the other times.
When you sunc the splines on the spline coming out of the trans there is a mark but not on the axle side.
I had the u joints lined up but not the right way to be in sync.
I was off 45 degrees on 1 end.
When you go to line up the splines you NEED to line up on the spline part and not just making sure they look straight
Im attaching a picture for referance so you dont waste time and money like I did.
Make sure you line up on the spline side of each shaft!!!!!!!!!
splinealignment.jpg


Hope this helps

Regards

Mark
 
At least you got some nice tires out of the ordeal..Thanks for the tip...something that can get easily overlooked.
 
Good Detective work Mark!!!!!!!!!!!!!!!! Thank you for posting this information- I'll tag it with "u joint repair" so it will pop up if someone searches. Thanks Again. bordercollie
 
I thought that there was one double wide spline or something like that to "Murphy-Proof" the installation of the joint on the spline. I just can't recall clearly at the present. I marked all the shafts and joint alignments with a paint pen before I took them apart just in case. My RTV is a 2005 so maybe the other years are different. Bummer at any rate...
 
On the spline from the trans there is but not on the axel mine is a 2002 i believe hopefully on the newer models there is but wither way I hope this post helps
Regards

Mark
 
I know I'm bringing this back from the dead, but what are we supposed to be lining up? I've got a loose rear axle shaft, so it looks like I'll be doing this job soon.

Additionally, where are you guys getting your parts?

Thanks,
 
Same as on an automotive drive shaft, you want the two crosses of the universal joints to be parallel to each other. That way both u-joints start to bend or fold at the same time while the shaft is rotating. It is easier to see than explain, in the picture up above look at the two u-joints on the drive shaft. One part of the joint is vertical at the same time on both u-joints.
Bryce
 
I read in an old thread where somebody used a center punch to make permanent marks on the two half's of the shaft before they disassembled it so all they had to do was align the marks when they reassembled.
 
Kanook said:
U-JOINT PHASEING
Click to expand...
That's the clearest diagram I've seen illustrating this.

I've read the reason phasing is so important is a u-joint style driveshaft accelerates and decelerates each revolution if the yokes beyond the crosses aren't straight in line with each other. (A CV joint doesn't do this but that's another topic).

If the u-joints are sync'ed as shown, then the speed of the opposite ends of the driveline cancel out so the motor and load turn the same speed. The driveshaft itself is so light that this constantly-changing speed is harmless.

But if the yokes are out of sync then the load beyond the end of the driveline has to absorb an acceleration then a slow down during each revolution. This obviously causes vibration, and also extreme inertia loads when the the load has enough inertia to resist this change in speed.
 
Kanook said:
U-JOINT PHASEING
Click to expand...

Good diagram.

And it's funny you posted a swuare drive shaft - I made one for my Toyota rock crawler years ago, and yes I made sure they were in phase.

So I got the phase part down. What I still don't understand is why people are marking the driveshafts - is it because one part is not visible when installed? And where are people making the marks?

And whoever said that the RTV workshop manual is lacking in this regard is exactly right on! Terrible instructions. :pat:

Thanks,
 
Quick question how much fluid will I lose when I pull the tranny side u-joints. Do I just need to drain the transmission?
I also have to wonder about the wide spline on tranny side female shaft and the lack of wide spline on the male shaft on the hub side. This is going make it interesting to get this back together correctly since my hub side shafts will go in the tranny half in any orientation
 
just drain the gear case only. you won't loose very much oil and after a service the oil should be changed anyway.
 
Look at the thread "rear ujoints needed again". The latest fix I did was improved over the first one , The first time I had a good bit of trouble with the aftermarket joints . That was on the 05. The 2011 was an improvement in so called "technique". I'm still an amateur fixer.
The marking is important because when replacing the tube "bumper" its hard to see up in there where the shafts come together. It can be done but was easier for me - one less thing to worry about. Put it back like it came off is my motto. ;) https://www.nettractortalk.com/forums/threads/new-rear-u-joints-needed-again.13788/page-14
 
You must log in or register to reply here.
Top