Sax Suspension

Hi Shakeejob,

Which kit did you get, 3sds,the equqlizer lift kit, or hd leaf spring?

Has the rear axle pinion angle alingement in realation to the front uni-joint been changed? This may put a vibration through the tailshaft if changed too much.
Alpero

G'day Shakeejob

After a suspension upgrade/lift there is usually a vibration and/or shudder on take off.
Most after market springs do not allow for the lower pinion position and many also point the pinion downward toward the ground than the previously position.

Mazda BT50/Ranger (when standard) has the diff pinion around 2 to 3 degrees upwards from horizontal and both of the rearmost unis run about 3 degrees of driveline running angle. I have measured these.

After suspension mods the pinion position/angle relative to the centre bearing needs to be altered to correct any effects caused buy the lift.

Also the centre bearing needs to be lowered around 5 to 6mm so it also corrects the driveline angles and makes both the middle and rear unis run close to equal if not the same angles.

Nearly ALL suspension mobs do not address this issue and duck and weave to avoid doing it properly, they should have done it in the first place but they DO NOT.

Often the system is fitted by people who can undo bolts and stuff, but do not understand the dynamics they are altering or how to recognize it and don't seem to have the skills to understand it and correct it.

If yours vibrates on overrun ie. trailing throttle/backing off, I strongly suspect the pinion will be pointing downwards too far and only a corrective wedge in the spring seats will restore it, IF they get them fitted the correct way around that is. Don't laugh it was done recently by a very well known PROFESSIONAL Orstrayan aftermarket maker/supplier based east of Melbourne CBD.Brisbane Branch.

The significant vibration may be the tailshaft speed shudder which is caused by the centre bearing uni operating at too much angle and forcing the centre bearing to flutter in it's rubber mounting. If left to continue IT WILL DESTROY the centre bearing mounting rubber.

Universal joints accelerate and decelerate twice EVERY turn so any angle over the norm or not matching the other in the set will vibe and or cause short uni life.

Fitters seem to be blissfully unaware of the physics behind drivelines and also seem unable to detect vibrations IF road tested despite the owner noticing it immediately they drive it afterwards.
Who ever did the job is incompetent, and as mentioned previously in other posts, "the company should have sold you a solution and not a problem".

This happens so often, likely more times than you have had hot dinners.

If a qualified,trained, competent, warm and vertical mechanic fitted the system he wouldn't have let it go out without being correct.

Cheers and hope this helps.

Ross M

Hi Les,
The others are on to it by the sounds of it.
I had the same issue with my bt50 (2010 model) after fitting an old man emu suspension.
The centre bearing will need to be lowered in order to correct the angle. Unfortunately for me I had to do this by packing some washers in the mount with limited thread availability. The good news for you is that your 2012 bt gives you plenty of thread to play with. The even better news is that ARB make a spacer kit specifically designed for this issue.

By the way, the quick way to test this is to put a load in the back and test drive. The load will push your driveline angle closer to whee it would have been prior to the lift.

Hope this helps.

Ash