Vibe-zilla after shimms (7 Viewers)

[Red Herring]

Hi All,

Preface... My 61 has a typical crappy JDM shackle lift, and the vague steering was driving me nuts! Solution... tighten the ol steering box... --->good... shim the front 4 degrees... --->good ... but now, at 80 km's on the highway... I start to get a violent front end shake, as if the tire was loose. There does not seem to be anything really loose at the hubs... the left was slightly loose, but not bad. So, did I over shim it? Will rotating the axle too far back give you that kind of reaction? I was thinking NOT. But don't know for sure. I know the front is not perfectly aligned, and the wheels are not prefectly balanced, but neither of those would cause the aggressive shaking would it?

The steering otherwise has improved a good deal at around town speed, enought to live with till i get my Belton in there.

The front axle is now apart for a complete rebuild... doing the tie rods at the same time. Next week tires and alignment.

Is there anything else you knowlegable gentlemen can think of that i might be overlooking?

Steve

 

[beanz2]

Search the POR and the Cruiser Tech section on "Death Wobble". I think you'll find some answers there.

Dave

 

[crushers]

Hi All,

Preface... My 61 has a typical crappy JDM shackle lift, and the vague steering was driving me nuts! Solution... tighten the ol steering box... --->good... shim the front 4 degrees... --->good ... but now, at 80 km's on the highway... I start to get a violent front end shake, as if the tire was loose. There does not seem to be anything really loose at the hubs... the left was slightly loose, but not bad. So, did I over shim it? Will rotating the axle too far back give you that kind of reaction? I was thinking NOT. But don't know for sure. I know the front is not perfectly aligned, and the wheels are not prefectly balanced, but neither of those would cause the aggressive shaking would it?

The steering otherwise has improved a good deal at around town speed, enought to live with till i get my Belton in there.

The front axle is now apart for a complete rebuild... doing the tie rods at the same time. Next week tires and alignment.

Is there anything else you knowlegable gentlemen can think of that i might be overlooking?

Steve

as Dave mentioned this is the tpical "death wobble" scares the crap out of yah, eh?

the belton kit comes with a new stabilizer and that "should" cure the problem instaed of masking it...
cheers

 

[Red Herring]

Death Wobble..... brrrrrrrrrr ....

Yup... tonnes of info there... just gotta know what to search for!! Death wobble... damn I love these machines! Thanks fellas

 

[Stone]

I was driving behind Greg's 60 coming back from Sinrise Lake/Hale Creek and witnessed him get a Death Wobble after crossing some train tracks. Yikes! If it feels scary from the inside, I tell ya...it looks just as scary watching those front tires do that!

 

[Greg_B]

Hi Steve.

From your search I would imagine you have gotten lots of ideas.

From mine I have gathered it can be a bunch of little things all together, or one or two major things.

Steering box slop, TRE play, wheel bearing play, knuckle bearings toast, negative caster, wheels out of balance, toast spring bushings, incorrect toe-in, etc. It's a matter of checking and eliminating.

When you added the shims, this brought the pinion down, correct? Did you adjust the toe-in? No more then 1/8" is what I have gathered talking to a few people.

Is this what your research is showing you?

From what I have been able to gather the larger the tire the more positive caster you want. Does your steering wheel return to center now?

I am going to add another 1 deg positive caster to my 60, adjust the toe-in, then take it in to an alignment shop to get the numbers. Steering box is on the agenda too, then everything is new or tight...and it will have come down to caster/toe-in.

hth's

gb

 

[Red Herring]

Positive/negative castor... hate to admin it, but im not sure which is which. I am guessing that positive is a forward rotation of the axle... ie. top forward, whereas negative is top back??? So, I installed the thick end of the 4 degree shim towards the front (bringing the pinion down, right?) making it a negative adjustment I think(??). I did NOT follow up with an alignment, but the beast tracks straight. Before this I did get some loose steering when cornering at speed. Kinda like ya steered into the corner, then one wheel would pull into the turn suddenly... like loose ball joints.

Im going through the whole front end this week... Like you said Greg, could be a number of small things, could be one big thing... Hope to eliminate everything within the next few days. I did not have the wobble untill i installed the shims. I think I will pull them back out before getting a final alignment after the re-build and tires. The guys at Victoria Spring should be able to set me straight, and suggest whether i need the shims or not. They might say not, as someone posted on another forum, that front axel shims are illegal...oops.

Steve

 

[crushers]

on most of the trucks i have dealt with it was the steering satb that was the cuplrit... even brand new stab can be faulty...
i have also found the factory to be the best bet, costly but effective...
i have also found worn king pin bearings, loose wheel bearings and unbalanced wheels to cause this fearsome wobble...
cheers

 

[Red Herring]

Steve says...need that Belton!!! Wife says... Need thet Belton!!!! Dog says... need that Belton!!! Baby son says.... hahahahehehe wheeehooo... thinks its fun!

 

[Greg_B]

Hi Wayne.

All the reading I have done indicates that using a steering stabilizer to get rid of the issue will mask the problem, not solve it. The trick seems to be to eliminate the problem at teh cause, without relying on the damper. Do a search: There is some excellent reading here and on POR about this issue.

gb

 

[Greg_B]

Positive/negative castor... hate to admin it, but im not sure which is which. I am guessing that positive is a forward rotation of the axle... ie. top forward, whereas negative is top back??? So, I installed the thick end of the 4 degree shim towards the front (bringing the pinion down, right?) making it a negative adjustment I think(??). I did NOT follow up with an alignment, but the beast tracks straight. Before this I did get some loose steering when cornering at speed. Kinda like ya steered into the corner, then one wheel would pull into the turn suddenly... like loose ball joints.

Im going through the whole front end this week... Like you said Greg, could be a number of small things, could be one big thing... Hope to eliminate everything within the next few days. I did not have the wobble untill i installed the shims. I think I will pull them back out before getting a final alignment after the re-build and tires. The guys at Victoria Spring should be able to set me straight, and suggest whether i need the shims or not. They might say not, as someone posted on another forum, that front axel shims are illegal...oops.

Steve

If I read your post correctly Steve, it is the other way around. Putting long shackles on the front rotates the top of the axle forward (brings the pinion up) and give negative caster from stock settings. This is why the truck will wander and track ruts. For this reason people put shims in to rotate the top of the axle back (rotate the pinion back down) to either get back to stock caster settings, or go past stock to the + 4deg area if running 35's or larger. Another way to picture this is look at your steering arms on the knuckles. If the front of the arm is rotated down, you go into negative caster, and if the front is rotated up you go into positive caster.

HIJACK=Of course this effects pinion angle/driveline issues...hence many peoples feelings that 2" to 2.5" is the max safely to lift and not introduce a ton of issues. There are 4" SUA lifts on the market, and I really do not understand how they are done without some fairly major compromises.=END HIJACK

My entire front end is new as well. I think mine is caster/toe-in related, however will tighten the steering box too, to eliminate it.

gb

 

[crushers]

Hi Wayne.

All the reading I have done indicates that using a steering stabilizer to get rid of the issue will mask the problem, not solve it. The trick seems to be to eliminate the problem at teh cause, without relying on the damper. Do a search: There is some excellent reading here and on POR about this issue.

gb

actually Greg, if you have to double up on the stabilizers then that is masking the problem. a worn single stab will cause this problem. think about it, why would Toyota put one on and what is the reason for the stab in the first place...
BTW, i am not trying to be condensending in this sentence.
there is a difference between masking and replacing...

test, take the stab off a perfectly good truck and go for a boot over a couple train tracks or a potted road and find out what happens...
cheers

 

[brownbear]

not having a stabilizer is the same as not having shocks in my opinion. if you are on a pot holed road the steering wheel will bounce all over. the stabilizer is there to slow down the back and forth. not prevent it. with a worn out stabilizer you will feel all the minor surface ruts etc. a constant wobble is a different thing., that should not try to be masked up.

 

[crushers]

not having a stabilizer is the same as not having shocks in my opinion. if you are on a pot holed road the steering wheel will bounce all over. the stabilizer is there to slow down the back and forth. not prevent it. with a worn out stabilizer you will feel all the minor surface ruts etc. a constant wobble is a different thing., that should not try to be masked up.

but if replacing the stab with a new one eliminates the problem is that really masking the problem?
as you say the stab is there to slow down the back and forth movement, if it is worn then what is to stop the back forth movement from going violent?
cheers

 

[brownbear]

but if replacing the stab with a new one eliminates the problem is that really masking the problem?
as you say the stab is there to slow down the back and forth movement, if it is worn then what is to stop the back forth movement from going violent?
cheers

exactly, if the stabilizer isn't there to eliminate the small movements, it could escalade into much larger movement. as it is going from over correction back and forth. bigger tire size may make this even more prevalent.

I also don't think it is masking it. and if you had something worn out like a end rod, wouldn't you have wander and pulling to one direction? how would a fresh stab mask that?

your safer to have a stabilizer on there and in good shape, before it gets jerking all over the place. I don't understand the benifit of removing it.

 

[crushers]

oh, now i understand, "why am i suggesting remove it" to show that by having a worn stab the death wobble will result...
cheers

 

[Greg_B]

not having a stabilizer is the same as not having shocks in my opinion. if you are on a pot holed road the steering wheel will bounce all over. the stabilizer is there to slow down the back and forth. not prevent it. with a worn out stabilizer you will feel all the minor surface ruts etc. a constant wobble is a different thing., that should not try to be masked up.

I am not saying do not use a stabilizer: Yes, it's job is on the pot holed road.

The death wobble is something entirely different. I do not get it all the time...or even when it is at a certain speed all the time. The correct situation has to present itself. Others experience is different. Some experience the death wobble with a mondo steering damper, in the right situation. Others have built their trucks, gotten all the right angles, have never run a damper and have never had the death wobble with large tires.

Again: YES...run a steering damper.

Technically, anally, obsessively...you "should" be able to run your truck down the road and not experience any type of death wobble with no damper. That is what I am saying. If you experience the death wobble, and putting on a damper solves it for you...great. That is not good enough for me. My Opinion...

The death wobble should not be covered up, you are right.

Gb

 

[beanz2]

Technically, anally, obsessively...you "should" be able to run your truck down the road and not experience any type of death wobble with no damper. That is what I am saying. If you experience the death wobble, and putting on a damper solves it for you...great. That is not good enough for me. My Opinion...

I agree with Greg. My 75 does not have a steering damper since I bought it. No wobble, nada.

Dave
75 FJ40

 

[crushers]

I am not saying do not use a stabilizer: Yes, it's job is on the pot holed road.

The death wobble is something entirely different. I do not get it all the time...or even when it is at a certain speed all the time. The correct situation has to present itself. Others experience is different. Some experience the death wobble with a mondo steering damper, in the right situation. Others have built their trucks, gotten all the right angles, have never run a damper and have never had the death wobble with large tires.

Again: YES...run a steering damper.

Technically, anally, obsessively...you "should" be able to run your truck down the road and not experience any type of death wobble with no damper. That is what I am saying. If you experience the death wobble, and putting on a damper solves it for you...great. That is not good enough for me. My Opinion...

The death wobble should not be covered up, you are right.

Gb

how is the alighment?
agreed to an extent...
cheers

 

[Greg_B]

how is the alighment?
agreed to an extent...
cheers

Dunno yet. I know I am positive caster, and I have a tad too much toe-in. I am thinking of adding another 1 deg positive, adjust toe-in to 1/8th" and adjust all slop out of the steering box...then take it in and see what the shop says. Everything else is new, checked and adjusted. Maybe I will take it in the way it is now and get a datum anyway...

It will be interesting to see what results Red Herring gets from going through his entire front end.

gb