4inch lift, rolling rear diff up to stop uni vibration

[351ciofgrunt]

I've put in a 4inch lift and I'm getting a vibration from the rear driveshaft at around 100km/hr.

So I'm going to roll the rear diff up slightly to fix this but I wont be buying adjustable top and bottom control arms, I'm going to sleeve the originals.

Just wondering if anyone took note of how much longer they made the top control arms and shortened the bottom control arms. I was thinking of trying 10mm.

[HeathGQ]

well, most of the manufactured arms are either standard, 10mm, or 16mm longer.

[fatsogq]

I've put in a 4inch lift and I'm getting a vibration from the rear driveshaft at around 100km/hr.

So I'm going to roll the rear diff up slightly to fix this but I wont be buying adjustable top and bottom control arms, I'm going to sleeve the originals.

Just wondering if anyone took note of how much longer they made the top control arms and shortened the bottom control arms. I was thinking of trying 10mm.

i've got a 94 rx 4.2d and i get a vibration at low speed (just after take off) its got a 4" lift and 33s witrh adjustable panhards, put a new tailshaft in and its better maybe adjustable upper and lower arms might help? any reply gratefully recieved

[351ciofgrunt]

well, most of the manufactured arms are either standard, 10mm, or 16mm longer.

Thanks, I think I will go 10mm then

[steveothedevo]

The angle of the universals need to be equal to prevent any vibration!!

So the angle of the shaft out of the gearbox to the tail shaft needs to be the same as the angle of the drive shaft into the pinion shaft on the rear diff.

I can email you an autocad pic if you like. Email me and i can send to you.

steven.coleman@hazelwoodpower.com

[turps]

Its rear to see a top arm break. But now that your lower arms are now exposed. I would replace/sleeve them instead.
For shorty's to get rid of the vibration, they make them 16mm longer. This should bring the unis back into the correct phase.

[351ciofgrunt]

The angle of the universals need to be equal to prevent any vibration!!

So the angle of the shaft out of the gearbox to the tail shaft needs to be the same as the angle of the drive shaft into the pinion shaft on the rear diff.

I can email you an autocad pic if you like. Email me and i can send to you.

steven.coleman@hazelwoodpower.com

Thanks but I do understand the theory, what i was asking if anyone had already done it for a 4inch lift, and measured how much they had to lengthen top arms and shorten bottom arms.

[SuperiorEngineering]

Why would you want to lengthen the uppers and shorten the lowers this is going to make it even worse for vibration.
The pinion needs to be lowered not raised.

[steveothedevo]

Im with superior... Well if you want to estimate it then up to you. Not all 4" lifys are the same. Your call mate

[N2O]

I think you should lower the pinion.

[HeathGQ]

oh yeah... didn't fully read your question. Longer lowers....

[351ciofgrunt]

Yeah sorry guys I meant make the lower arms longer, top ones shorter.

I ended up doing it last night, but only made the bottom ones 15mm longer, left the top ones alone, looking forward to a test drive today.

[j nissan mavrik]

how did it go?????

[bj on roids]

Why would you want to lengthen the uppers and shorten the lowers this is going to make it even worse for vibration.
The pinion needs to be lowered not raised.

If you went REALLY far with it you could run the uni's 'broken-back' and they would cancel each other out perfectly.

[SuperiorEngineering]

Why would you want to lengthen the uppers and shorten the lowers this is going to make it even worse for vibration.
The pinion needs to be lowered not raised.

If you went REALLY far with it you could run the uni's 'broken-back' and they would cancel each other out perfectly.

I understand the theory you are talking about but i wonder in the real world if it would work okay.
The reason is if you set it up "broken Back" for driving on the road when you get articulation or drop in the suspension the pinion angle will go upwards and as we know the cardin joints have less travel than unis so i would guess that you will bind up the pinion before maximum travel causing it to fail.
This may work on a long link comp truck or leaf spring but i would doubt it will work on a nissan?
I could be wrong .
It would be good to hear from someone that has done it on a street driving nissan.

[300WinMag]

I agree with Superior Engineering, I put adjustable upper control arms in my SWB and shortened there length to tilt the pinion down, I used a magnetic angle gauge from bunnings $30, on the drive flanges to get equal angles thus the pinion angles will be equal aswell. No more vibration. I will also be getting ajustable low control arms for strnegth and more ajustability. If you get snake racing arms they are ajustable on the vehical.

[Nelso]

Why would you want to lengthen the uppers and shorten the lowers this is going to make it even worse for vibration.
The pinion needs to be lowered not raised.

If you went REALLY far with it you could run the uni's 'broken-back' and they would cancel each other out perfectly.

I understand the theory you are talking about but i wonder in the real world if it would work okay.
The reason is if you set it up "broken Back" for driving on the road when you get articulation or drop in the suspension the pinion angle will go upwards and as we know the cardin joints have less travel than unis so i would guess that you will bind up the pinion before maximum travel causing it to fail.
This may work on a long link comp truck or leaf spring but i would doubt it will work on a nissan?
I could be wrong .
It would be good to hear from someone that has done it on a street driving nissan.

You also have to rotate your spring perches which is a much bigger job than just running them parallel.