NOT a death wobble thread.

[w squared]

So I put 35X12.5 Toyo MT's  on my JK last Thursday.

I've noticed the following things since I put them on:

#1. Slight pull to the right.

#2. It doesn't track as well as it did with 32's. By this, I mean that it requires more small steering inputs to stay where I want it within a lane. Nothing unmanageable, but more work than I think it should be.

#3. A little bit more bump steer than it previously had.

I'm running Currie adjustable front upper control arms, JKS track bars, and OME coils and shocks for +/- 3.5 inches of lift. After the lift, the handling was every bit as good as stock. Currently, caster is set to the same point as stock (a little over 4 degrees).

I'm bringing it in for an alignment on Wednesday, which should fix problem #1. I'm thinking that a degree more of caster will probably help with #2 - hopefully without pushing my pinion angle too far out of whack.

Will taking my caster up between 5 and 5.5 degrees make any real difference with regards to the bump steer, or is that simply a product of the extra weight of the Toyos? If so, I'd imagine that adding some dampening to my steering might help - perhaps an upgraded steering stabilizer? (or am I comitting a mortal sin by saying those words?)

Before anyone gets too carried away, I understand that 35's are going to change the way that my Jeep handles. I just think that a little bit of attention to detail on my part can help keep it's road manners reasonable. On the plus side, those Toyo 35's required less weight to balance properly than my BFG 32's. Maybe some of the Toyo lovers on the board have a point....

[FiEND]

the tracking is because the roads are dipped and narrow tires fit into the dips better.  wider tires will ride the edges of the dips and wander a lot more.  simple fix is drive with a light touch on the steering wheel.  let the jeep wander a little and it corrects itself mostly.  you might hate it, but you will get used to it.

bump steer is probably from your poor trackbar angle.  a damper might help a bit.. i dont know, i am not running one either.  less tire pressure is probably needed as well.

i guess i better go to Billy's and pick up my track bar bracket before he runs out again.

pulling to the right a little is OK, at least you hit the ditch when you fall asleep instead of oncoming semi

[Bnine]

Bumpsteer is STRICTLY due to a geometry relationship between the draglink and track bar.

A satabilizer upgrade is always a good idea, and no steering should really go without one. They just shouldnt ever be used a sole means to try and correct issues with severely compromised front ends. (the death wobble guys)

4 degrees of caster should be sufficient for your setup. The only funtion of caster is return to center, which inadvertantly will contribute to a reduction in wandering. No relation between caster and bumpsteer.


The wider tire will naturally exhibit more wandering issues. They just have a tendency to grab ruts a lot more then a thinner tire.

As far as aligment goes, the only thing to really worry about now that you have widened the tire even more is your toe. The wider the tire, the closer you should go to almost 0 toe. That will help slightly with the wandering and pulling.

Good luck

[w squared]

Thanks for the quick replies, gents.

I haven't changed my suspension geometry (I've been running the suspension modified for the past five months), so I'm not sure why I've seen the increase in bumpsteer. A quick visual inspection shows that my trackbar and draglink are fairly close to being parallel...but I don't have the experience to know how close I should be aiming for. Is this where something like the Clayton "high steer" kit would come in? It looks to be an axle-side track bar bracket (taller, and with a new steering stabilizer mount), and a new draglink.

I'll seewhat I can locate for an upgraded steering stabilizer as well. Northridge stocks a Teraflex stabilizer for the JK, but I'd like to look at some options....

[FiEND]

tires are much stiffer so they wont absorb very much road shock.  air down on the trail and i guarantee you wont have bump steer.  it will be noticeable on the roads.

yes that kits sounds like what am doing to mine... some year

[shayu]

1 Did you ajust your draglink to center the steer?
2 4°caster just not enough,ppl on the other forum recommand 6°--7°for a over 3'' lift?the only thing is the upper control arm probably can not be shorten enough.But im running 5°caster,it handles pretty good tho.
3 yes,i think a SS is a must,especially when you are on a bumpy trail with lots pot holes.

[Bnine]

Who ever told you that about caster, doesnt understand caster Shayu.

The larger the tire, the less caster angle required to porduce the same handling effects.

Anywhere between 3.5-5.5 is enough caster for a 35" inch tire, and proportionally identical to 7 degrees of caster on a 27-31 inch tire.

[w squared]

Yes, my steering has been re-centered (had to, otherwise the ESP would go nuts).

I'll check  my caster, and make sure that it is where I think it is. As long as it's currently between 4 degrees and 5 degrees, there shouldn't be any reason to monkey with it.  I know the forum that Shayu speaks of...some of the information on there is good, and some of it is....not good.

I will be looking at airing down a little on road too - I will start on a chalk test as soon as things dry up a little. Right now I"m at 37 psi - that's the indicated pressure for the stock tires. I know that it's high for 35's on a 4000 pound vehicle, but that's why I'm doing a chalk test   Once I settle on a pressure where the tires are happy on pavement, I'll pull out the pro-cal and re-flash the TPMS.

[Pookapotamus]

can some one explain this "chalk test? i have never heard of this?

[Pookapotamus]

thats what i was thinking it was. thanks

[FiEND]

37 lbs?  seriously? 

[Bnine]

37 lbs in a toyo is way overkill even for the C rated versions. I suspect yours are d or e. You are going to find that 22-25lbs will be a lot closer to where they should be after you chalk test.

[SwampSinger]

can some one explain this "chalk test? i have never heard of this?

You all line up and draw a line 10 feet a head... the first one that pees on Nathan's tires win.

[Rubi03 jef]

you SHOULDNT be running those at 37psi      drop down to 30psi and see how that helps   .

mine are down to 26psi and they are perfect . and wear is even better .  and mine arnt 10 ply so you might still have to go lower then 30psi


and tracking can be just the fact your up higher now 

and bump steer is    well BILLs specialty

[XJHERO]

 

You all line up and draw a line 10 feet a head... the first one that pees on Nathan's tires win.