SWB GQ Vibrations at Highway Speeds...

[Toyo Truck]

Hi Guys,

I previously wrote this topic here:-
http://www.outerlimits4x4.com/PHP_Modul ... highlight=
But it is no longer available (Has been this way for last 2 weeks at least)
So here I go again,

I have a mate who is having vibration problems on his GQ Shorty between
80 kmph and 110kmph. He says it vibrates then starts to drone as he goes faster.
He reckons with a horse float attached its not as bad but still vibes a bit.

His Rig Stats:-
1991 - Nissan GQ SWB Patrol
Automatic - With gearbox packing kit to angle gbox down toward pinion.
3" OME Suspension Lift (Coils and Shockies)
31"/10.5" A/Ts

What does he need to do to fix this problem??
I know I have had this question answered previously ages ago, but it seems all my searches come back with the same response -
"The Requested URL could not be retrieved".

Cheers,
Bart

[matsmad]

Try replacing the uni's (might be a bit worn) otherwise go the Double Cardan shaft. Off road industries in Silverwater Built mine for $500. I have 5" coils and it fixed it Immediately.Also try Adjustable control arms to flatten out the bottom pinion angle.

[KIWI]

How long has the vibration been there? ie, only since the lift?
If not, try uni's as suggested, or you could try adjustable top arms for the rear diff to get uni angles sitting better, which may allow you to take out the gearbox packer kit, or at least reduce it.

The reason it leasons when towing may be because the rear of the truck is sagging due to the weight of the trailer, allowing the uni angle to lesson.
I found my noise/vibration went away sinply by greasing the rear drveshaft.

Dave

[Screwy]

mine does this, its the lift.

when the float is on the rear end comes down lower correcting the shaft angle.

i will be putting gearbox spacers in mine first, and if that fails ill be replacing the unis

[Suspension Stuff]

When he gets adjustable upper trailing arms he has to get the angle of the front uni parallel to the angle of the rear uni (In Phase). If not then as the unis' rotate they are moving at different speeds causing the vibe (Out of phase). If it doesn't vibe then you just can't feel it but it is wearing the uni's faster. So the uni's are probably stuffed. LWB is more forgiving because of the longer tailshaft.

[Suspension Stuff]

There is a current thread in General Tech called Pinion angles. It has a diagram and everything.

[turps]

If he's going to replace any of the rear trailing arms. I would replace the lowers. Cheezy (others have backed the comment up) has said that by making the lowers approx 16mm longer gets rid of most of the vibes in a swb GQ.
Also I have never heard of the uppers breaking with out major carnage of something else as well. Where as I have broken 1 lower and bent another. Before I replaced mine with HD lowers.
So if hes going to get aftermarket arms replace the lower ones with either HD adjustable or HD 16mm longer arms.

[viperguy]

that droning noise he is talking about wont be in uni's... it will be the spline in the shaft.. when u lift the shorty it pulls the shaft longer and as a result the spline has a smaller contact patch between the sleeve and the main shaft. this causes another place where vibrations occur..and it only comes at the kind of speeds u are talking about.. the noise unladed will come when u back off, and then momentarily when u get back on the gas..loaded with the horse float, he would be on the gas more often, there would be less time for the vibes to come as the shaft will decrease speed quicker as the trailer will slow the vehicle down quicker. also as others have said loaded the rear end will squat and the shaft may just shorten in length enough to help quiten vibe too..

couple options.. 1) lengthen shaft the same amount that the slip joint opens up after lift
2) use a spacer between flanges of shaft and either diff or tranfer output and rotate diff or lower transfer so angles remain at optimum angles ( details in other threads) as spacing will effectively shorten the shaft
3) do what i have done and use a top quality high temp grease in the shaft that will take up the slack and help reduce the vibes. this is what i have done. i use the nulon red grease.. dunno exact name but very bloody good.. need to regrease regularly but is the cheapest and easiest option.

good luck with it all..

[hottiemonster]

Carl,

where the best place to buy unis for a GQ and what price are they as you said you were looking into replacing yours.

[ozy1]

i replaced mine in my SWB GQ and Hardy Spicer unis were $60 but if you want, you can get other brands for $30, but was told not to expect a very long life outa the $30 ones,

i got mine from my local autoparts place

[hottiemonster]

is that $60 ea or for a pair?

[Screwy]

is that $60 ea or for a pair?

will be, each

[ozy1]

each indeed, sorry for the misunderstanding

[hottiemonster]

ouch, might get mine checked rather than just replace. also need to put some packers in as my vibes have got real bad recently, but only after the clutch was fitted any ideas?

[turps]

Carl,

where the best place to buy unis for a GQ and what price are they as you said you were looking into replacing yours.

I got my front ones replaced.
I took the front shaft out and gave it to the mechanic who charged $90 to fit new unis and alot of grease. Then I just refitted the shaft to the car.
Think the unis worked out to be $30 each. Will find out what brand and part number they are (think the old ones are still in the back of the car).

[Scone]

Hi mate. Dont know if this has been mentioned yet, but if all of the above fails (transmission spacers, new uni's etc) you may have to add the double cardan joint and have the tail shaft balanced.

I am about to do a small lift in mine, and I have been told that it may have to be done (worst case scenario) if it developes a vibration after replacing the uni's and doing the spacers. Apparently it is a problem that affects about 20% of the shorties with lifts. No one seems to know why.

Hope it doesnt get to that, because it is apparently not cheap to have done.

Good luck to us both (I will find out about mine next week).

[giantracing]

as some people said. i do 6 inch lifts on shortys all the time . you must do lower and upper arms. cut the spring plates off the diff so you can rotate the diff with out bowing the springs. get a tail sharft made with cardenal joint fitted.you also need to make sure the diff is central(panards) to do the job 100% you must spend about 1500 to 2000. or you can live wih it.......................................................................

[Toyo Truck]

My mate wants to know,
He is thinking of getting this done ASAP to stop the vibes.

The SWB Shorty is located at Ourimbah,
Who are the best Nissan repairs, and who is the closest professional 4b modification company to where he lives?

There are a heap of 4wds up that way, where do you guys get your
repairs/mods done??

Cheers,
Bart

[ozy1]

okay, i have 6" coils in my SWB, i am running a standard tail shaft (with new unis) and i have just installed 3rd's upper adjustable rear arms and 3rd's lowers,

i have set my pinion up, so its near parallel to the ground, and i have very minimal vibes, enough to be more than happy with, i will take it for a longer drive tom orrow and report back,

the trailing arms you can fit yourself, the uppers are adjustabel on car, a bit of mucking around to set up, but no real dramas at all,

[muzza_fattire]

My mate wants to know,
He is thinking of getting this done ASAP to stop the vibes.

The SWB Shorty is located at Ourimbah,
Who are the best Nissan repairs, and who is the closest professional 4b modification company to where he lives?

There are a heap of 4wds up that way, where do you guys get your
repairs/mods done??

Cheers,
Bart

Try Mannell Motors in Thornleigh. Only a couple of km's past the end of the freeway in Sydney.
Nick deals with SWB Patrols a lot.