[suzi-fan-22]

ok here's the deal, my dad drove my car to the exhaust shop today. ( first time it has been driven since i have swapped all my parts onto a lwb chassis, and the car has major death wobbles when you reach around 30km's).

i have searched and it said to check ''every thing in the front end'' and ''my castor might be out'' but it never happened before i swapped the chassis over and when i did i replaced my spring bushes and got a w/t conversion could this be the problem?

also i moved my front diff forward around 17mm.

it is a leafy

so what could be the problem?

[Fatzook]

Do you have any more lift than you had before the swaps?

[suzi-fan-22]

no, same springs.

[zooky08]

Same wheels? Tyre pressures?

[suzi-fan-22]

yes, and yes.

[dunnjab]

Might sound stuipd but cheak your u-bolts are tight

[suzi-fan-22]

ok. ill check when i pick the car up.

also i might add they are the same diffs just re-perched to n/t.

[Fatzook]

Got a steering dampener?

[suzi-fan-22]

yer, the stock one.

[royce]

try loosening all your spring bushes, shake shit out of the car and do em up again

[Fatzook]

royce wrote:

try loosening all your spring bushes, shake shit out of the car and do em up again

This would be a good time to lube them with snake oil too.

[Fatzook]

Just because you didn't get the wobble before doesn't mean that they aren't worn parts causing it now. You have moved the front axle forward 17mm. Thats not much at all, but it has changed the weight balance over the front axle........

I can't see this being the cause of your current problem, but it may have been the final straw, compounding other wear issues that already existed.

Best approach would be to do as Royce suggested, and loosen everthing off, then re-tighten.

[suzi-fan-22]

i have worked out the problem it is the castor angle, i put some super long shackles to pull the diff to a better angle and i now can reach around 75ks before it gets the wobble but it still needs more correcting

[Hybrid]

You've got enough positive caster to cause death wobbles? That's insane. So I'm guessing the spring perches were done wrong? How long are the shackles you've used to counteract the issue. You'd be safer to buy caster wedges and run them back to front to reduce your caster if you are sure that's what the problem is.

[suzi-fan-22]

it was just a test to see what the problem was not a permant fix and the shackles are 3" longer than stock but it did make a big differace and now we know the cause and im getting castor wedges when i get some money

[wolf_rt]

That doesn't seem right....
what do you mean by "got a w/t conversion"?? did you replace the diffs?? or change the perches on your diffs to suit a WT chassis?

I would have expected that decreasing caster angle (longer shackles) would have 'shown up' any tendency for wobbles, rather than reduced it. But either way, I don't see how caster would 'cause' wobbles unless it was near 0deg, and even then wouldn't actually be the cause.

Checked you toe angle? changing caster will change the toe angle...

[suzi-fan-22]

i had a wt and i got the diffs reperched to nt to fit my chassis

[just_cruizin]

Tick some basics off first:

tyre Condition
Wheel mounting flush to WMS
Wheel nuts tight
Tyre pressure are correct (yes you said they are but did you check)
Bushes are tight - not worn
Springs in serviceable condition - not wrapped etc
Steering rods straight
Steering joints firm - not worn
Steering box condition - Free play etc
Kingpin condition.
Wheel Bearings.
Wheels straight - not buckled
Spring perches correctly aligned, same width as the chassis and the correct caster.
Bent chassis

How did you move the diff forward? Did you reposition the spring hangers, redrill the perches, what?

Get a wheel alignment. Front and back.

Steering dampener will only mask issues so don't pay too much consideration to this.

Jack the front up and rotate the wheels by hand, do they run true, this will tick off a number of the above.
while rotating the wheels does it feel smooth, doesn't rule out bearing but may indicate if they are the issue
rock the wheels top to bottom, could indicate kingpin issues
rock the wheels left to right, could indicate steering joint or box issues

A good 1/2 hour spent should help problem solve if any of the above are the issue.

[Jazzor]

Didn't he say it was long front shackles?, awesome list anyway!!

Turns out when I put springs in with rubber bushes i didn't put the metal sleeve in too, so mine wobbled for months until i bought new springs and found that :/.

I want to see a pic of these nice long shackles with ruf and no chassis extension or moving the rear dif mount back

[Fatzook]

Hybrid wrote:

You've got enough positive caster to cause death wobbles? That's insane. So I'm guessing the spring perches were done wrong?

Perches were welded in my Jig. I've done atleast a dozen NT/WT conversions in it now, and this is the first time someone has suggested that they have castor related wobbles.

As outlined by JC, there are ALOT of things that can contribute to death wobbles.

[just_cruizin]

there you go you can tick off the perches as a problem too.

Pete's jig would be right.

He said long shakles fixed the problem, where normally they would cause an issue.

[suzi-fan-22]

i put the longer shackles in and it helped but didnt fix the problem so i thought that it might have been the castor and i just needed more angle than shackles would give me

and whats this metal sleeve i never had one of those?

[Jazzor]

I can't quite picture if longer shackes on RUF would make a pinion difference or not... longer shackles would mean the dif pinion end points up more towards the transfer case.. but that could fix it or make it worse depending where it started.




Arg metal sleeves are for the leaf spring bolts if you have rubber bushes, well all the rubber bushes i have had, some might not. The hard poly ones i have had don't have them.

Googling up an example so i don't confuse anyone, these rubber bushes have a metal sleeve inside them. Lol i have no idea how i forgot to put them back in....

[Hybrid]

Fatzook wrote:

Hybrid wrote:

You've got enough positive caster to cause death wobbles? That's insane. So I'm guessing the spring perches were done wrong?

Perches were welded in my Jig. I've done atleast a dozen NT/WT conversions in it now, and this is the first time someone has suggested that they have castor related wobbles.

As outlined by JC, there are ALOT of things that can contribute to death wobbles.

I don't doubt you Fatzook. I didn't realise you did the work. I thought it was a home job. I couldn't see how else someone could have too much positive caster from a sierra. I've always found them to have not enough in stock trim. I had my doubts all along that positive caster could cause the wobbles. I would have thought if anything positive caster would work to counter death wobbles as it naturally returns the wheels to center and aids in tracking straight.

What about toe? I bent the tie rod on mine once effectively giving it too much toe in. This caused some nasty head shakes as the tyres fought each other. Maybe decreasing the caster reduced the wobble because the wheels are no longer fighting as hard to return to center. With too much toe in/out and 0 caster you'd be getting higher than normal tyre wear but as the wheels aren't trying to recentre there wouldn't be noticable wobbles. Just throwing some ideas out there. I'm no geometry guru.

[Fatzook]

The fact that longer shackles didn't fix the problem......they just moved it somewhere else in the speed range, makes me think that its something else.

[suzi-fan-22]

i havnt done a RUF i used ther tsor perches they have adjustment holes and they moved the diff forward around 17mm

[Jazzor]

Cool I'm getting more an idea of whats been done, have you checked everything on just_cruizin's list?

That would be the first thing while we just rattle on