drive shaft vibrations

Post by **V8Patrol** » Mon Oct 20, 2003 11:11 pm

did a SOA on a diesel MQ and have problems with the rear drive shaft vibrating at speed. Balance of the shaft isnt the issue its the angle of the unis.
I can eliminate the vibration by loading the suspension (150kilos in the back! ), this decreases the uni angle off of the transfer and the vibration decreases to almost nill.
would a cardinal joint help?
In the pic, which angle would suit the best?

I'm also about to have the same problem now that the 5spd is inmy Patrol, see http://www.outerlimits4x4.com/PHP_Modul ... php?t=7890
The transfer and 5spd combination pushes the rear drive flange off of the transfer back about 135mm, which is about the same as the position a diesel with a 4 spd, transfer sits.

Pic borrowed from ...
http://www.outerlimits4x4.com/PHP_Modul ... highlight=

Post by **Slunnie** » Mon Oct 20, 2003 11:16 pm

Double cardins should help as they tolerate more angle. There are a few factors that may influance the vibration, like equal angles at the t/f and pinion ends. Also check that the tailshaft Unis have gone back into the truck in phase.

Post by **V8Patrol** » Mon Oct 20, 2003 11:28 pm

phase checked and double checked....

Post by **Wendle** » Tue Oct 21, 2003 7:19 am

sent you a monster PM regarding this, I'll try and find a photo to back it up!

Post by **Wendle** » Tue Oct 21, 2003 7:25 am

Wendle wrote: I'll try and find a photo to back it up!

nah, i've got nothing at work, I'll try and get a good one tonight with something there to reference the angles against or something.
meanwhile here is a photo of a cat.

Post by **Area54** » Tue Oct 21, 2003 9:35 am

Put in some caster wedges, and fit a track bar. I made some caster wedges out of some 60x12 alum flat , with my 6" saw, a triple cut blade and an electric plane. Just measure it accurately.

I concur with the other advice, make the flanges parallel. The soa conversion will provide more leverage to the rotational forces under torque, rotating the pinion up under load. A track bar will eliminate this rotational problem. The MQ/MK patrols don't have a super strong pack design as it is with long leaves and open clamps, so axle wrap is a certainty with soa.

I'm hoping the pic attached will also be of help.

Post by **bj on roids** » Tue Oct 21, 2003 6:32 pm

your second picture is a common solution, it is how my rear shaft is done, the setup is called "broken back" the unis will still cancel each other out just instead of the acute angles being on opposite sides they are now on the same side, just so long as your acute and obtuse angles are the same all other standard principles still apply. This is how i beleive the front of land rover discovery was done??

I first thought it was done on sams car to stop tailshaft damage, but that is just a really nice benefit (added clearance)

no cat pictures but here is something

Post by **bj on roids** » Tue Oct 21, 2003 6:34 pm

above picture shows how steep my pinion angle is, those cooling veins on my diff are normally horizontal :twisted:

Sam did explain this to me, and that is how i understand it and why i copied it.

Post by **V8Patrol** » Tue Oct 21, 2003 8:34 pm

Ok so now I have a fix....broken back setup .... next question ...
broken back with or without cardinal joint ???

Post by **beebee** » Tue Oct 21, 2003 8:53 pm

Wendle wrote:sent you a monster PM regarding this, I'll try and find a photo to back it up!

If this post contains tech on the driveshaft setups - is there any chance it could be forwarded on to me?

Post by **V8Patrol** » Tue Oct 21, 2003 9:09 pm

ya got MAIL !!!!! :finger:

Post by **2car** » Tue Oct 21, 2003 10:38 pm

V8Patrol wrote:Ok so now I have a fix....broken back setup .... next question ...
broken back with or without cardinal joint ???

If you are still getting vibration - go the double CARDAN joint on the transfer end.

Check out the funky Java applet near the bottom of this page http://www.ebroadcast.com.au/ecars/A.hints/Universal.html. It calculates the angular deflection for various ummmmm... angles! You'll see what I mean

Post by **Wendle** » Wed Oct 22, 2003 9:33 am

broken back won't work with a cardin joint, same as opposing angles won't work with a cardin joint. they would both work with a cardin joint at each end, but then you will probably have no shaft left between the joints. again I have no photo's as it was raining, and someone bought me a case of stubbies, and you can't just crawl around under your truck with one of them in your hand like you can safely do with a tinnie. here is another photo of the first cat, and an old photo of a cardin set-up.

Post by **bj on roids** » Wed Oct 22, 2003 10:39 am

Wendle wrote:broken back won't work with a cardin joint, same as opposing angles won't work with a cardin joint. they would both work with a cardin joint at each end, but then you will probably have no shaft left between the joints. again I have no photo's as it was raining, and someone bought me a case of stubbies, and you can't just crawl around under your truck with one of them in your hand like you can safely do with a tinnie. here is another photo of the first cat, and an old photo of a cardin set-up.

Excellent, the setup i described was for two single unis.

Post by **Wendle** » Wed Oct 22, 2003 11:49 am

bj on roids wrote:
Wendle wrote:broken back won't work with a cardin joint, same as opposing angles won't work with a cardin joint. they would both work with a cardin joint at each end, but then you will probably have no shaft left between the joints. again I have no photo's as it was raining, and someone bought me a case of stubbies, and you can't just crawl around under your truck with one of them in your hand like you can safely do with a tinnie. here is another photo of the first cat, and an old photo of a cardin set-up.

Excellent, the setup i described was for two single unis.

ya i know, I was refering back to this little ditty..

v8patrol wrote:broken back with or without cardinal joint ??

Post by **Area54** » Wed Oct 22, 2003 2:11 pm

beebee wrote:
Wendle wrote:sent you a monster PM regarding this, I'll try and find a photo to back it up!

If this post contains tech on the driveshaft setups - is there any chance it could be forwarded on to me?

Can I also have one of them fancy cityfolkwhatchamacallits mailly things please?

You're never too smart enough to learn...

Post by **Wendle** » Wed Oct 22, 2003 2:24 pm

I just cleaned out all my PM junk, someone else will have to forard it on.. It was about wildebeest and zaphod beeblebrox, I don't know why everyone is so keen to read it??

Post by **bj on roids** » Wed Oct 22, 2003 3:06 pm

rightio guys if we dont ge any porn in here soon this is going STRAIGHT to chit chat :finger:

Post by **V8Patrol** » Thu Oct 23, 2003 7:55 am

Area54 wrote:
beebee wrote:
Wendle wrote:sent you a monster PM regarding this, I'll try and find a photo to back it up!

If this post contains tech on the driveshaft setups - is there any chance it could be forwarded on to me?

Can I also have one of them fancy cityfolkwhatchamacallits mailly things please?

You're never too smart enough to learn...

ya got one of them fancy cityfolkwhatchamacallits mailly things

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