i gots the mega-shakes! mad steering wobble - sorted!?

[shorty_f0rty]

well.. i threw on the jt2's today.. previously on the 40 steering the were all good.. didnt wonder too bad and when you went over a bit of a rough patch it was all good..

well i have since done the 60 steering conv and i hit a rough patch tonight (outside lane at intersection of kelvin grove rd + samford road outbound.. just outside the alderly hotel)..

it practically ripped the steering wheel outta my hands (i was probably going about 50kph) and was unable to bring it to a stop, i had to just about stop for the vibes to stop..

i pulled over a little bit after and checked everything out... steering rods are straight, arms are secure, box is fine, intermediates still attached and fine.. rag joint is ok... but one thing i did notice is that the steering dampener was a bit out of wak.. its never really been very good its pretty thin and i dont think it offers much dampening..

do you guys reckon that it could just be the steering dampener is not up to the job or is shot? would you get this kinda thing with no steering dampener?

any suggestions are welcome.

[dogbreath_48]

I had a problem that sounds EXACTLY the same on my HJ75 when i put 37's on. I upgraded from the std dampener to an old man emu one and the problem's gone!

[shorty_f0rty]

good stuff.. the current dampener is about as thick as the tie rod.. so im not suprised.. i'll get one orderd during the week

[DIRTY ROCK STAR]

let us know if this fixes it?

[dogbreath_48]

Problem is the dampener is probably just masking an underlying issue (my steering box/rod ends/rods/alignment etc probably aren't the best). I.e. why did the wobble start in the first place?

...but works fine for me!

[shorty_f0rty]

well my steering box is leaking something chronic so i'm hoping thats the culprit or maybe i fcked up and mounted the box wrong causing it..

you can see how skinnny the dampener here:

[shorty_f0rty]

replaced the dampener last night and a test drive over some rough stuff not reproduced the mad wobbles ive had before.

I hear what you guys are saying that the dampener masks the real issue so I'll spend some time trying to find it.. I hope the geometry of the steering links isn't the issue as that would be a bit harder to fix.. all angles on the tie rods, etc are not extreme at all so.. we'll have to see..

if you think of the steering wheel as a clock.. the wheel only moves an hr's distance before it resists and some movement is noticed on the pitman arm..

would you guys reckon this is excessive?

also going to get that $10 seal for the box to try and fix the leak.

[bj on roids]

replaced the dampener last night and a test drive over some rough stuff not reproduced the mad wobbles ive had before.

I hear what you guys are saying that the dampener masks the real issue so I'll spend some time trying to find it.. I hope the geometry of the steering links isn't the issue as that would be a bit harder to fix.. all angles on the tie rods, etc are not extreme at all so.. we'll have to see..

if you think of the steering wheel as a clock.. the wheel only moves an hr's distance before it resists and some movement is noticed on the pitman arm..

would you guys reckon this is excessive?

also going to get that $10 seal for the box to try and fix the leak.

you runnin much lift? might need a balance on the tyres too, check the TREs

[shorty_f0rty]

replaced the dampener last night and a test drive over some rough stuff not reproduced the mad wobbles ive had before.

I hear what you guys are saying that the dampener masks the real issue so I'll spend some time trying to find it.. I hope the geometry of the steering links isn't the issue as that would be a bit harder to fix.. all angles on the tie rods, etc are not extreme at all so.. we'll have to see..

if you think of the steering wheel as a clock.. the wheel only moves an hr's distance before it resists and some movement is noticed on the pitman arm..

would you guys reckon this is excessive?

also going to get that $10 seal for the box to try and fix the leak.

you runnin much lift? might need a balance on the tyres too, check the TREs

TRE's are brand new (with the 60 steering conv)
JT2's were rebalanced prior to removal last time i had them on ( was experiencing similar wobbles, after balance confirmed issue was gone. no wheeling done since then so i dont think i lost any weights)
and caster plates are on to suit the lift (no wandering steering etc).

All steering uni's have NO play (replaced a uni prior which had a bit of play in it)

Only things I can think that are left are:
- play in the input shaft of the steering box itself
- too much play from the rubber rag joint from the 80 series.

[me3@neuralfibre.com]

Steering damper is there to stop harmonic wobble w/ positive feedback inherent in steered solid axle designs. Sounds like it's nto doing what is supposed to.

RTC dampers mask issues.
Steering damper is designed to stop oscillations. I think you are prob on the money.

Collyn Rivers has a few articles on it somewhere.

Paul

[RAY185]

Steering damper is there to stop harmonic wobble w/ positive feedback inherent in steered solid axle designs. Sounds like it's nto doing what is supposed to.

RTC dampers mask issues.
Steering damper is designed to stop oscillations. I think you are prob on the money.

Collyn Rivers has a few articles on it somewhere.

Paul

I understand what you are saying and agree but:

it practically ripped the steering wheel outta my hands (i was probably going about 50kph) and was unable to bring it to a stop, i had to just about stop for the vibes to stop..

this sounds a little more violent than a harmonic wobble. Hey if it fixes the problem then its all good, but I am surprised (not necessarily disputing) a dodgy stabiliser would cause this.

[shorty_f0rty]

Steering damper is there to stop harmonic wobble w/ positive feedback inherent in steered solid axle designs. Sounds like it's nto doing what is supposed to.

I think this is pretty much what happened.. go over a rough spot which starts the wobble. the speed kinda kept that wobble going and increased its velocity and violence due to the inability of the steering dampener to do its job.

[RAY185]

ahh, ok Andy. Seems more plausible now. From your first post I understood it as a sudden wobble violent enough to rip the steering wheel out of your hands rather than a gradual wobble leading to it.

[shorty_f0rty]

ahh, ok Andy. Seems more plausible now. From your first post I understood it as a sudden wobble violent enough to rip the steering wheel out of your hands rather than a gradual wobble leading to it.

yeh sorry about that but at that speed it took like 3-5seconds from first contact with the rough spot to mega wobble.. so i reckon a distance of about 15-20mtrs..

in my books thats pretty quick.. not a slow gradual increase over 100mtrs or so .... but with the JT2's maybe it accentuated the wobble quicker with more weight behind the tyres.

[bad_religion_au]

alloy or steel castor plates? my alloy ones crumbled to nothing in the span of 6 months,

[shorty_f0rty]

alloy or steel castor plates? my alloy ones crumbled to nothing in the span of 6 months,

onto my 2nd set of alloy castor plates...

[Dyna Beast]

Have recently had much the same problem.Had replaced the 45 series front springs with 60 series springs.This would have moved the axle forward about 50mm so I redrilled the locating holes in the axles perches and bottom plate to split the difference.This still altered the caster angle abit so fitted caster wedges and then made sure the wobles I had were gone.Then replaced the ever so slightly stuffed steering damper with a new one.Got a new Gaberial damper with a decent size bore for $20 of Ebay.Got to be happy with that.
Cheers

[shorty_f0rty]

I had an opportunity to look at Ray's steering setup this morning and there is virtually NO PLAY in his intermediate shaft->steering box input where as I have considerably more play..

So I think this might be the culprit after all.. At the moment its managable and I haven't had a repeat of the issues.. so I'll run with it until I can find an affordable steering box to swap it in.

thanks for everyones suggestions so far I hope this info helps someone else in the future.

[dow50r]

Looseness in this joint will cause this problem, so will loose wheel bearings...so will out of balance tyres forget the weights, have the tyre doods measure, mark and strip tyre before sticking balance patches inside each of them...then you have half a chance to get them balanced with less than 30 grams hanging off the rim.
Is it also possible to put an 80 pitman arm on and loose the rag joint??

[shorty_f0rty]

a bit of an update on this..

since the last post I have:
- replaced steering box with one that doesnt leak and has no play
- replaced uni that goes to steering box with one with no play
- upgraded steering dampener to a bigger bore dampener
- spread the spring retainers a bit to get more flex from the leaves
- closed the spring retainers to stop leaves spreading.
- taken the 40 to the mechanic for a service
- tightened wheel bearings
- driven to The Springs 4x4 park and back on JT2's (on the way there one front was 20psi and the other was about 34psi, limited top speed but that was about all, on the way back both same pressures and could do 100kph easy), total distance of about 300kms or so..

so after getting back from camping last weekend... the cheese cutters went back on for daily driving. they are 31" AT's on 5.5 rims, I am not sure how well they are balanced though. (each time they go on they get rotated to a different corner).

On Sunday we were driving down the freeway at about 80kph and the wobbles hit again.. no bumps to introduce the wobbles they just came on..
pulled off the freeway and checked shackle bolts were tight, ubolts were tight (got a few turns out of the ubolts) and steering was all good on the front end ..

again when I got on the freeway everything was ok until about 80kph when the wobble came back again.. it wasn't started by a bump it just started and worked its way up to a violent wobble requiring a reduction in speed and nursing off the freeway.

When the girlfriend was turning the steering wheel when I was checking over stuff.. I noticed that the leaf packs would kind of lean when turning.. i'm sure this has something to do with the wobbles but apart from clamping the spring packs more (tightening the spring retainers) I can't think of much else I can do to fix it..

apart from being a hazard to other road users the fact I can't seem to fix this is really starting to give me the shits.. that and the fact it only seems to happen when the girlfriend is with me..

The only other thing I can think of is gaffa taping a video camera under there and recording whats happening at speed to try and find the problem..

Any other suggestions are welcome..

[RAY185]

Simple, don't let the girlfriend in the 40.

The "lean" on the springs when turning the wheel is interesting. I'd assume that has alot to do with your problem Andy.

Is the lean only at the shackle end of the spring or at the diff perch?

If its at the diff, somehow the springs are not being adequately retained to the diff via the U bolts. Possibly stretched threads on the U bolts? How old are they? Also, is the head on the centre pin for the front springs long enough to go through your castor wedges and properly engage the hole on your spring perch?

If its at the shackle end, you have standard length shackles (don't you?) so its unlikely that the shackle is flexing (are they tight). Check for cracks around the hanger causing the hanger itself to flex away from the chassis.

Thats all I've got at the moment...

[shorty_f0rty]

Simple, don't let the girlfriend in the 40.

if only it was that easy.. it is a 40 afterall and we all know.. chix dig 40's!

The "lean" on the springs when turning the wheel is interesting. I'd assume that has alot to do with your problem Andy.

Is the lean only at the shackle end of the spring or at the diff perch?

I'll have to get some vid and post it up.. its almost like when steering the box is pushing the diff to one side instead of turning the wheels.. but again. you've got to see it to understand what I mean.. this is where the vid will help.

If its at the diff, somehow the springs are not being adequately retained to the diff via the U bolts. Possibly stretched threads on the U bolts? How old are they? Also, is the head on the centre pin for the front springs long enough to go through your castor wedges and properly engage the hole on your spring perch?

The center pins have about 20mm long heads and they are ok, locating properly. Ubolts aren't that old and I tightened them on the weekend after the first batch of wobbles.. I have spares but not enough for all front ubolts.

If its at the shackle end, you have standard length shackles (don't you?) so its unlikely that the shackle is flexing (are they tight). Check for cracks around the hanger causing the hanger itself to flex away from the chassis.

thought it could be the front shackle mounts being cracked but they appear ok at a glance.. shackles are no std length and i'm thinking of swapping in the std lenght shackles to see if that helps at all..

Thats all I've got at the moment...

That'll do.. it all helps.. cheers Ray.

[jessie928]

if you castor os way out, you will get the shakes.
large tyres mask the castor problem, when you put smaller tyres on, you will get the shakes more often.
Jes

[shorty_f0rty]

if you castor os way out, you will get the shakes.
large tyres mask the castor problem, when you put smaller tyres on, you will get the shakes more often.
Jes

but ive got 3deg castor plates in at the moment.. i reckon the castor is ok.... same size ive had since i did the lift.. its not squirrely road manners.. its ok at lower speeds.. it just has a tendancy to do the mega wobbles at a certain speed..

maybe i need to change all my bushes up front?

[jessie928]

if you castor os way out, you will get the shakes.
large tyres mask the castor problem, when you put smaller tyres on, you will get the shakes more often.
Jes

but ive got 3deg castor plates in at the moment.. i reckon the castor is ok.... same size ive had since i did the lift.. its not squirrely road manners.. its ok at lower speeds.. it just has a tendancy to do the mega wobbles at a certain speed..

maybe i need to change all my bushes up front?

this does not mean your caster is correct, have you had it wheel aligned?
you may have bent something when you went wheeling also.
my 6" lifted patrol was all good on the way to our thrash spot on the weekend, it was exellent all the way to the first servo where i aied up from 20psi to 38. as soon as i hit the road after that it woudl get megashakes at 70km/h. reason being is i have heaps of toe in on the drivers side now due to a bent relay rod.

JEs

[shorty_f0rty]

if you castor os way out, you will get the shakes.
large tyres mask the castor problem, when you put smaller tyres on, you will get the shakes more often.
Jes

but ive got 3deg castor plates in at the moment.. i reckon the castor is ok.... same size ive had since i did the lift.. its not squirrely road manners.. its ok at lower speeds.. it just has a tendancy to do the mega wobbles at a certain speed..

maybe i need to change all my bushes up front?

this does not mean your caster is correct, have you had it wheel aligned?
you may have bent something when you went wheeling also.
my 6" lifted patrol was all good on the way to our thrash spot on the weekend, it was exellent all the way to the first servo where i aied up from 20psi to 38. as soon as i hit the road after that it woudl get megashakes at 70km/h. reason being is i have heaps of toe in on the drivers side now due to a bent relay rod.

JEs

this is a good point... i have not had it wheel aligned yet.. I have booked it for this on Wednesday morning.

[lil red zuke]

Have you checked the king pins/bearings? This is a common thing in the zukes.

[bad_religion_au]

what's your toe in/out settings?

[shorty_f0rty]

what's your toe in/out settings?

NFI! wtf does that mean?! Wheeling alignment dude might be able to tell me this tho wont he?

Kingpins/bearings are relatively recent (18months old or so?)

[shlacks]

so wheel align and wheel balance is being done... check wheel bearing play nip up if loose... you already have replaced steering box with known good one... checked panard rod bolts/bushes for whole diff sideways movement???