How much wobble and wallow...?

[leighh]

I'd just like to know from anyone who's running a similar set-up to me (2" BL, 2" Sus, 285/75 Cooper STT Muds on a 3rd gen) what kind of handling you experience? I'm finding that I've got a bit of a steering wobble above 50mph or so and it feels very wallowy. To the point that changing lanes on dual carriageway at 60 is a little bit unsettling.

I'd previously put it down to either balancing or wear in the steering rack bush, which Tony pointed out when he fitted the lift. But I had a garage re-check the balancing, along with all the other obvious stuff today, which is apparently all fine. They did say as Tony did that I had play in the steering rack, but not enough to contribute to the steering wobble.

To be honest, with the lift and the heavy MTs, I expect it to handle badly and if that's normal then that's fine, I'll just slow down! I'd just like to rule out anything being amiss. I know roughtrax stock replacement poly bushes that claim to reduce wander and such, does anyone have any opinions on them? Worthwhile, or a good way to throw away money?

Thanks

[Albannach]

Change lanes slower and get the steering rack fixed.

[BUSHWHACKER]

Tyre pressures OK?
Could also be the tyres themselves i.e. the tread pattern and thickness of the blocks that give a wallowy feel to the steering/handling.

Whats the 'rag joint' on the steering shaft like, has it just been spaced or replaced with a solid block?

[leighh]

Tyre pressures OK?
Could also be the tyres themselves i.e. the tread pattern and thickness of the blocks that give a wallowy feel to the steering/handling.

Whats the 'rag joint' on the steering shaft like, has it just been spaced or replaced with a solid block?

Yeah, I figured it might just be the tread pattern, didn't have a problem before the tyres went on. I didn't think to check the tyre pressures, I'll do that. Tony made a spacer for the rag joint, HDPE possibly? Cheers for the suggestions.

[Wolfracer]

What width wheels are you running and what pressures are in the tyres?

[JD_975]

I get a similar sensation on my 33" M/T`s, fine upto about 55, fine after about 65 but anything inbetween is an unnerving sensation. I was advised by the guy I bought my tyre`s off to run high tyre pressures on the road as it reduces the wobble and also helps prevent the uneven tread block wear M/T`s suffer from road use.

I wasnt keen on running too high a pressure at first but to be honest it did make a massive difference, I now run them at about 35-37 PSI on road and although the wobble/vague feeling is still there it`s no where near as bad as it was.

[Predictable Bob]

I'd be more concerned about the affect of the high pressure on braking performance than a bit of wobble/wallow BUT if it seems speed related there's a possibility that there's another issue somewhere ...

[leighh]

What width wheels are you running and what pressures are in the tyres?

Checked pressures today - they're at 33psi, which is what I ran on the 265/70s. Wheels are 8" wide, but I did find a cooper chart recommending 7.5"-9.5" for 285/75s as apparently they aren't actually as quite as big as 33s.

[JD_975]

I'd be more concerned about the affect of the high pressure on braking performance than a bit of wobble/wallow BUT if it seems speed related there's a possibility that there's another issue somewhere ...

You can be as concerned as you like but the chances of locking the brakes up on a surf running 33`s with a 12.5 inch footprint on each corner is negligible to non existent

I think 285/75`s are about as near as dammit to 33`s, it may be worth trying a few extra PSi to see if it helps, you may just find though that there are certain speeds your truck just does not like anymore, thats what I have resigned myself too, wobble comes on at 55, goes off at 65, I avoid those speeds except to accelerate through

[TonyN]

I leave the 'rag joint' on, and the spacer sits on top between it and the rest of the steering shaft.

It wasn't noticably soft or baggy, I don't think it's the/a problem.

Solid joints on 2nd Gens are ok, but there isn't a lower UJ on 3rd Gen columns, and the rubber joint flexes noticably as steering rotates so not sure I fancy a solid coupling TBH.

Personaly I don't like to run M/T's to hard, as you end up with very little tread on the road actually doing any work, but blow them up to 40 or so and give it a try, if it feels better then you know its just sidewall flex in the tyres and live with it, if it dosn't get any better then you can carry on looking to improve stuff.

Nearly every 3rd Gen I've lifted has needed new TRE's, and they always make it feel better after. I'd do that first and also the rack bushes, there was noticable side to side movement of the rack when you rock the steering like I said at the time, then see how it goes.

Yeah, I figured it might just be the tread pattern, didn't have a problem before the tyres went on. I didn't think to check the tyre pressures, I'll do that. Tony made a spacer for the rag joint, HDPE possibly? Cheers for the suggestions.

[leighh]

I leave the 'rag joint' on, and the spacer sits on top between it and the rest of the steering shaft.

It wasn't noticably soft or baggy, I don't think it's the/a problem.

Solid joints on 2nd Gens are ok, but there isn't a lower UJ on 3rd Gen columns, and the rubber joint flexes noticably as steering rotates so not sure I fancy a solid coupling TBH.

Personaly I don't like to run M/T's to hard, as you end up with very little tread on the road actually doing any work, but blow them up to 40 or so and give it a try, if it feels better then you know its just sidewall flex in the tyres and live with it, if it dosn't get any better then you can carry on looking to improve stuff.

Nearly every 3rd Gen I've lifted has needed new TRE's, and they always make it feel better after. I'd do that first and also the rack bushes, there was noticable side to side movement of the rack when you rock the steering like I said at the time, then see how it goes.

Okay, thanks Tony. I'll try upping the pressure to see what happens, and if not I'll sort track rod ends. Think I'm going to get those rack bushes done anyway.

[Wolfracer]

Slightly off topic, I did 150 miles of motorway driving with Mud 33's on. and it was fine, no wallow, it turned in and responded well. I pulled in at some services half way and they weren't even warm to the touch.

I used 3/4 tank of fuel in the process, but i can honestly say it was as steady as a rock ( bar the slight A Team style "play" in the system)

Mine was wallowy using 33 muds on 7" rims at 35 PSI. but with the 10x15's it's great!

[Predictable Bob]

OK, it appears that I have some misconceptions that need addressing by the adults on here.

Am I correct in thinking that:

1. In general, MT performance on road is nowhere near as good as AT/road tyres with regard to braking and road holding - obviously I'd expect the differences to be less significant with high end MT's

2. In general, tyres with a larger footprint give less ground pressure per square inch and are thus more likely to spin

3. In general, tyres with a larger footprint give less ground pressure per square inch and have less grip in corners


and now a question ...

Would a tyre with a larger footprint be more inclined to lockup under braking than a smaller footprint ?

[Wolfracer]

My 2p FWIW

Yes
No
No
No

In general, the more rubber touches the road the better the grip, be it cornering or braking. Else why would performance cars have wider tyres than standard models?

[Predictable Bob]

I was always led to believe that the more rubber, more grip argument only applies to performance tyres - soft rubber is stickier, hard rubber slides ...

I've no idea what sort of rubber MT's are made from but I'd be amazed if they made them out of the same stuff they use for slicks