Outer Limits 4x4 Board

Hi all, I have just lifted my bundera some more so it now has about 4" suspension lift.

Firstly I would just like to say thet because I have lifted it so high the lateral control rod, on the rear axel has pulled the axelhousing/diff to one side (in other words the rear wheels are sticking out to the right about an inch and are not in line with the front wheels).

Apart from the car not tracking briliantly there is a small vibration that occurs at certain revs. Please note there is no vibration at high speeds 70-100kmph. It mainly occus when the engine has a bit of load on it.

Is this vibration being caused becuase the diff being off center or beause the tailshaft is at a too greater angle.

I am going to fab up an adjustable control rod tomorrow to bring the rear wheels back in line with the front so the car tracks properly.

Any ideas as to what is causing the vibration. I am just surprised it doesnt do it constantly nor at high speeds just as certain revs.

Regards,
Nick

Do the adjustable Panard Rod like you are going to do and then let us know if it still does it!

i will but do u think it will make any difference and if it doesn't then what should I do??

Nick

Your panhard rod will not be the problem. It is probably more the upper trailing arm link that will cause the vibe.

first things first:
The panhard rod will locate th diff sideways (left to right)
The trailing arms (upper and lower) locate the diff forwards and backwards (very basically). The Bundera has cast trailing arms, correct?

Tailshaft vibration is usually caused by the uni's running out of phase - ie transfer case drive flange and pinion drive flange not parallel. Each uni compensates for the other's rotation. The panhard rod will not affect the flanges running out of phase (in your case) because the diff moves to one side (flanges remain parallel even though diff is offset). The problem is when the pinion angle changes (after a suspension lift) while the transfer case flange angle remains the same, hence the imbalance in uni angles. On GQs and 80s etc you can put in adjustable upper rods to correct the pinion angle. With yours though you may be able to use some offset bushes similar to castor correction bushes, these replace the bushes where the cast arm attaches to the diff.

It would still be a good idea to go to an adjustable panhard rod (gives you more options for future lifts) to square up the diff.

does this help you?

Troy the Bunderas run radius arms front and rear there are no uper trailing arms.

Area54 wrote:Your panhard rod will not be the problem. It is probably more the upper trailing arm link that will cause the vibe.

Touche. I was still sleepy when I posted.

ok have made an adjustable panhard rod to bring the rear diff back in line.. Wheel tracking is spot on.

Some of the vibration has gone but there is still some vibration at certain rev ranges.

So the vibration that remains has definatly been caused by the new 5 or so inch lift...

What should I so now?

Cheers,
Nick

can you put a spacer between the G/B cross member and the chassis like on a GQ shorty?

i dont know bunderas real well so i am not sure if it would work

If you can get an angle finder - even a small spirit level and a plastic protractor will do. Park the vehicle on level flat ground, measure the angle of the flat face of the pinion flange in relation to the ground. Then do the same on the flat face of the drive flange out the rear of the trans case. these angles should be the same - ie the flange faces should be parallel. sorta like this |
| not like |
/
I would check these angles out to help diagnose your vibe prob. Also check uni for slop/play.Check with a suspension place, you might be able to put in offset bushes (front castor correction bushes) in the rear cast arms. I'm not sure if the rear bushes are the same diameter as the front, if they are you can go this option to rotate the diff pinion down.

BUNDERA wrote:So the vibration that remains has definatly been caused by the new 5 or so inch lift...

What should I so now?

Cheers,
Nick

Lower it by 3 inches!!!!!

damn, in tha last post all the spaces were removed from these /|

shoulda looked like this: | | <- parallel | / - not parallel.

the gearbox packers would also help as long as you have enough space between the radiator fan and the shroud /radiator.

i am pretty sure that it is not parrallel. I will check 2morro but as I am pretty sure it isn't...

What would I do to fix it?

Have a good one,
Nick

Took a good look at the drive line today and noticed something that I think could be contributing to the problem.

Firstly are the u-joints at either end ment to be exactly opposite (i always thought so) ? (as in the u-joint at one end will let it move up and down while the one at the opposite end lets it move from side to side)

At the moment one of the ends seems to be out by a few degrees. Can I seperate the drive shaft and realign it so that both ends are exactly opposite. Are there splines inside the driveshaft that may not have been realigned on a disassembly?

The angles of the tail shaft are not exactly parrallel ( | at transfer case end and slightly pointing up at the rear diff end....)


I am not sure if this helps.
Thanks for you help, it is most appreciated.

Nick

Good spotting on the u joint misalignment. Yes you can separate the shaft as there are splines inside. This is pretty easy to do, just undo the four bolts at the diff drive flange, separate the shaft (don't worry, nothing will fall out) and realign. You could also take the shaft (may be hard in a daily driver) to a driveshaft shop and have them balance it at the same time. They can inspect the uni's, inspect the slip shaft (splined section) for wear and fully balance for prob about $50 - $60 (qld prices)

The rear diff pinion flange angle is prob where the problem lies though. From memory most uni's will tolerate about 1-2 degrees misalignment (depending on the size of the joint), but the short length of the shaft will exacerbate the angle. You could put in a double cardan joint (have a look at the front shaft of an '84 onwards hilux), this would help but it will cost money to have the double cardan joint grafted on to your driveshaft.

Realign the driveshaft, then I would do some research to improve the rear flange angle, via some offset bushes if available (these bushes fit in the cast arms, where the arms bolt to the diff)

Hope this is of help. Any probs, keep posting.

does this make sense reguarding the misalignment?
The + symbol represents the u joint

+ at the diff end and # at the transfer case end
+---------#

... shouldn't it be
+---------+

?

So I take it if I rip ot out I can seperate the two parts and realign it?

Cheers,

Nick

I have been told the same thing hundreds of times about the uni angles needing to be the same, the theory all says yes . buat after 80,000kms in my SPOA zuk with lift springs etc I simply have not had any problems with vibration unless its from the uni joint being worn out.. and only on the lower joint, upper joint last 30,000kms or so, with the lower normally being destroyed by mud and crud before its actually "worn out".

Hmmm here goes my attempt at a techonogical drawing

both eyes on the main section of the d/shaft are in line.

I took the drive shaft off this arvo and I adjusted it by 2 or 3 splines. A little less vibration but it still hasn't gone so as we suspected it must be the angle of the flange on the diff (which is at a slignt angle).

I will see if I can get some correction bushes to correct it.

Thanks for all your continued advice,

regards,
Nick

We put a 6 inch lift in a Bundera a month or so ago and the tailshafts did not vibrate at all.

What you may find is it is simply old uni's. We have had problems with tailshafts vibrating after a lift and tailshaft angles are all ok, fit some new uni's and the vibration is fixed.