Need Help With Grinding Sound After Suspension Lift

[dasnoboarder]

Help!

I've finished putting in my suspension lift;
Lovells HR-15 lifted leaf springs, greaseable shackles, reindexed and raised torsion bars, ball joint flip.
This combo has been known to work for our trucks in the past.

Measurements from bottom of wheel rim to wheel arch:
Before lift: FL 729mm, FR 723mm, RL 700mm, RR 695mm (about 30mm of sag in the old springs?)
After lift: FL 780mm, FR 780mm, RL 790mm, RR 790mm (About 90mm lift over old springs, should be about 60mm over standard)
Springs have only been in a few days, so might not have settled.


It's developed some new noises!

The little tabs of metal in the leaf spring hangers were rubbing on the springs, I've bent them out a little so that's fixed...

But theres still this loud grinding noise that happens at high speed, I'll try to explain...

Going 60+ km/h, everything is fine at cruising, but when I lift off the accelerator and start slowing down, a loud grinding noise happens, and vibrates through the car.
It's not the brakes at none of them are seized, and the handbrake is disconnected at the moment.

Local garage thinks it could be the where the rear driveshaft joins the box.
Their idea was to lower the crossmember and see if the noise goes away.

Has anyone encountered this or have any ideas?

Stupid truck!

[dasnoboarder]

Just done a search on the old forum, seems quite a common problem.

Rear is lifted too high and so is causing tailshaft vibrations.

Has anyone found a solution to this?

I'm using the standard HR-15 springs, and shackles that are 5mm shorter than the standard ones.
I wouldn't have thought that this amount of lift would cause these issues, as people have used lifted springs and extended shackles together.

[Demonic]

Is the noise defintily coming from the rear of the vehicle? or centeral or front?

[Pissy]

Yeah I have it too and do a few more of us, no one yet has sorted it out. Definitely something to do with tail shaft.
I only get it when there is neither acceleration or deceleration, (slack/relaxed/neutral drive shaft). I can just barely hear it when doing 60km but its loud at 100km. I have just learnt to cope with it and try not to have the accerator pedel at the point where it causes a "neutral shaft"

Someone did try adding a spacer but that didn't work,....I think its the angle of the uni joints either into the rear or transfer case?

I have never thought to LOAD UP the car and see if the weight is enough to drop it down to eliminate the issue,...will have to do it sometime ?

[dasnoboarder]

How long have you had it for? Nothing has broken?

I don't want to leave it too long, as it doesn't sound healthy at all...

I think I'm going to try lowering the rear of the box... Anyone have a suggestion for how much? 10-20mm?

[Demonic]

If you took the tail shaft off it may be that it was not replaced in the correct position making it out of balance. But i agree with pigs, it is probly the angle of the driveshaft (cant be good for seals).

Without lookin at the gearbox maybe just a couple of bits (2x10mm etc) of plate between the mounts or something. But I think you have the right idea.

[holden]

Jeep Wranglers lower the gear box about 30mm to fix the shaft angle. But the dive shafts about 400mm long.

kane

[dasnoboarder]

Thanks guys,

We haven't taken out the tailshaft for the past 5 years, and there was no vibration before, so I think it's in the right way.

Just had another look under the truck, am I right in thinking that the spacers just go between the crossmember (that has the transfer case bolted to it) and chassis?

Probably start with 20mm spacer, may need some longer bolts...

[sprey]

Whoa after i lifted my vehicross i had a simular noise, say over 80kmh let off the gas get the sound like a chaddering noise.

I greased up the 3 points on the driveshaft it went away for a bit then redeveloped so yea maybe worn u joints? or just the angle like said above But hmm mine is also weird because if it is in Tod aka 4Hi i get it but in 2wd i dont think i get it as much i guess ill have to do some testing runs.

[geeves]

Check yout U joints. They may be siezed or worn. You could also remove the rear driveshaft and put the wagon in 4wd and give it a quick drive in front wheel drive to see if its gone. A catch with this though is that the rear of the transfer case is open and will spew out some oil. Block or cover as best you can.
Check the obvious things first.
A common trick on raised Nissan patrols is caster corection bushes and wedges under the spring hanger. For the nissan these can be bought off the shelf but nothing available for us

with the jeep without that mod they smash U joints

[sprey]

Hmm with mine could be dodgy taking off the rear driveshaft then driving in Tod as front is electronicaly controled but the rear is always on so it might trick it somehow. Plus knowing me id stuff something up and cant afford to muck anythng up, but yea ill talk to my mechanic at a later date at the moment it hardly does the noise so im not too bothered.

Wish we had off the shelf parts. even worse me tho lol

[pig75]

Just done a search on the old forum, seems quite a common problem.

Rear is lifted too high and so is causing tailshaft vibrations.

Has anyone found a solution to this?

I'm using the standard HR-15 springs, and shackles that are 5mm shorter than the standard ones.
I wouldn't have thought that this amount of lift would cause these issues, as people have used lifted springs and extended shackles together.

You could try some Caster wedges
http://72.34.32.141/~snakerac/product_i ... ba4103c53f

[slightlydodgy]

My front did the same after a gearbox and engine lift after a suspension lift. Put up with it for ages turned out both unis were had it and the sliding spline was stuffed. Good now 120 in 4x4 with no noise

[jezza]

What about a modifying a toyota cv joint to fit? you wouldn't have any problems then

[dasnoboarder]

Interesting, whats the procedure for checking out the U-joints? If everything moves free I guess they arn't seized, how do you tell if they're worn?

[geeves]

If you can grab the shaft and pull side to side and rotate. Any movement at all is a fail.
Could pay to do this them move the car a short way then do again. I had a sudden severe vibration after a sand dune track Checked everything on the drivetrain and all seemed fine. Upon moving vibration was still there along with strange noises Checked again 10 meters later Very loose rear u joint. It must of been bound up the first check. There bearing cups were completely gone and the yoke was bent. Driving above 10kph was impossible with this driveshaft as the wheels were bouncing off the road

[Fly3r]

manual or Auto? I had those same springs, brand and everything, in my truck with calmini shackles from a 3in kit, had the slightest of noises in the rear uni, but went away after 2 weeks. mine was a manual, auto have a longergear box, so the angle is a litll worse with the autos.
like everybody suggested gear box spacers, or spring wedges, (I'm pretty sure MUvit had the snake racing wedges between the springs and diff option with his lift before the SAS, he had extended snake racing shackle in too).

-Muvits is auto-

[wbski007]

too much angle on drive shaft, when you let off on fuel rear tilts even farther down, causing noise, your going to have to change angle of rear. Wayne

[geeves]

There is a catch to that though. The flanges at each end of each section of driveshaft should be parallel. If in the case of the early gearbox which has a splined shaft instead of a gearbox the effective flange is perpendicular to the shaft. If this is wrong vibration can be the result.
I have the same rear springs but the only issue is a slight judder on take off.

[daisy]

Yip do the spring wedges im running those rear leafs too and thats how i fixed it not sure what degree the wedges are they were just the ones i had at the time. ive got a mate that owns a SHOCK SHOP ill go see him tomorrow and find out the degree of the wedges i think i need a bit more than what ive got cause i still get a bit vibration over 100km