Wednesday, Jul 03, 2013 at 19:45
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
AnswerID:
514223
Follow Up By: olcoolone - Wednesday, Jul 03, 2013 at 21:22
Wednesday, Jul 03, 2013 at 21:22
X2...... my guess as
well.
It is better to have a drive line out of alignment physically then to have it in alignment..... but too much can makes it worse.
FollowupID:
793148
Follow Up By: Ross M - Wednesday, Jul 03, 2013 at 21:36
Wednesday, Jul 03, 2013 at 21:36
I Agree, All universal joints must operate with some amount of driveline angle. If a uni runs dead in line, then it lasts only until lunch time as the rollers do not move and they burrow into the hard surfaces of the cup and trunnions.
The centre bearing unit on a Dmax is made to be 12.5mm off centre so even if the load brings the unis inline, ie. looking horizontally, they are always slightly offline sideways (vertically) and therefore always made to have an angle in all three unis so they last.
FollowupID:
793150