Installed Radials, now truck wanders

[sandcobra164]

I just installed new Firestone T831's 11X20's on my truck and now the truck wants to wander around on the road. I've checked the steering box bolts (65 ft lb.), adjusted the steering box as outlined in the tm, ensured the drag link is tight and lubed, inpected my tie rod ends and increased front tire pressure to 70 lbs. The sum of those changes helps and I'm not sure which one's are helping and which one's did nothing. I'm considering raising the pressure to 90 lbs and see if that has any effect. I don't think the front bearings are bad as they felt fine while I was changing over the tires and had the front end jacked up. I have considered that it's just nature of the beast with the wider tires. I never noticed this with the NDT 9X20's. Maybe my new tires just need to wear in some?

 

[DUG]

I think you need to bring the front tire pressure down. Try 50 and work your way from there.

 

[sandcobra164]

I started at 50 but the sidewalls were sagging and it wandered worse set up like that. The rears are all at 50 though.

 

[pctrans]

Nature of the beast for radials with big lugs. Check your toe-in. 70 psi works well.

 

[bratpackdad]

OD_Coyote had a similar issue last year ask him how he resolved it.

 

[Oldfart]

It is usually a toe in issue when switching to radials from bias. Actually caster and camber are involved as well, but those are difficult adjustments to make on 4X4 steer axles. This is the reason I stick to bias swamper's on my M37 rather than use radials. The military should have some toe in specs that are different for radial tires on deuces as compared to the old NDT bias tires. M37's too long out of service for that kind of data.

 

[sandcobra164]

I've done a little research and probably should have searched as I just did. Apparently, the trucks run alot of positive caster to help with ease of steering. Radials steer much easier than Bias Ply's and that is where my issue is at the moment. I've done some research and it seems that I can pull the caster plates from under the spring pack and grind them down some to reduce the caster angle and should be a happy camper. Some guys with power steering replace the caster plate backwards to help with return to center issues and since they have the power steering, it's still easy enough to turn the wheel.

 

[Heavysteven]

Sounds like a lot of work. What about making sure your king pins are tight?

 

[Oldfart]

It really is the alignment. I did not know that Deuces used a castor plate, but so much the better. If you can't modify the existing plates then you ought to be able to make some. A large truck alignment shop ought to have ajustment plates you could buy. The M37 does not use plates, but locates the caster and camber with kingpin placement. Adustments are achieved by slight bends and twists to the axle housing. ~ I wonder if I added a caster plate to my M37 I could get radials to work? Since my bias are brand new I have time to think about this.

 

[jesusgatos]

I've done a little research and probably should have searched as I just did. Apparently, the trucks run alot of positive caster to help with ease of steering. Radials steer much easier than Bias Ply's and that is where my issue is at the moment. I've done some research and it seems that I can pull the caster plates from under the spring pack and grind them down some to reduce the caster angle and should be a happy camper. Some guys with power steering replace the caster plate backwards to help with return to center issues and since they have the power steering, it's still easy enough to turn the wheel.

This is pretty much what I was going to post. I'm running the same tires, and am planning on flipping the caster plates around.

 

[sandcobra164]

jesusgatos, I'm glad we're having similar issues so that I'm not the only one!!! I'll get to work on this soon and post the results but it seems this problem has come up before when switching to radials. Also, lowering tire pressure will make the sidewalls sag more, create more drag and reflect the steering qualities of bias ply's and would likely cure my current problem. When I say bias ply's drag more, consider that my truck would struggle to get to 55 mph on Bias ply's but easily does it on taller radials. I'm not a tire engineer but I'm convinced that the Radials roll much easier and that decreased rolling resistance has got the front end wandering. I think I'll flip the caster plates and post the results rather than let all the air out of my front tires and possibly ruin them in the process.

 

[jesusgatos]

Well, I haven't really put any miles on Mah Deuce since I mounted those tires. It's just on my list of things to do, while I'm installing a new cab, engine, steering and brakes.

I would flip those plates if I was you too. Even with stock (manual) steering, I think it might be an improvement.

 

[deathrowdave]

Flip the caster plates front to rear on the front axle and you will be happy !!!!
Have a great and safe day,Dave

 

[Bob H]

WOW?!?!?

When I put the 1100R20 Michelin XL's on my M36A2 I was amazed at how much better it went down the road as compared to fighting it with the stock 900-20's.
It tracks down the 2 lane blacktop with ease.

 

[nk14zp]

My bobbed deuce has 1100r20 xl's and handles great at 50psi front and back.

 

[sandcobra164]

xl Michelin's closely match what I took off, the Firestone's are much wider and leave a different footprint. Not much to compare if you ask me. The XL's peak at the top and I believe would act alot like an NDT 9X20. We're comparing apples and oranges with this logic. The guy's that switch to 395's have some of the same problems I've read since I searched. The wider tire tends to follow grooves in the pavement and would benefit from a caster change. Also, my kingpin's are fine, I just checked them by lifting the wheels and looking for play in the front end. Maybe it's the SHOCKS!!!!!!

 

[gimpyrobb]

What about taking the plates out rather than reversing them? I only ask cause I don't know.

 

[Jimma]

I have the michellin 11x20's on mine and it drives nice. So different than my other truck with the 9x20's.

 

[timntrucks]

i did a swap to 1100x16s mich on my 52 m37.. man did that thing drive like a caddy then.. no shakes or wobbles at all.. best thing i did.. i will soon be swapping in some goodyear radials on the 818 and i hope that makes for a super nice ride

 

[deathrowdave]

a2s have 0 caster with the shim the correct way, flip it and you end up with about 6 degs. positive caster . The best way to describe would be to remember riding your bicycle with the fork turned backwards , very hard to control, turn it the other way to get positive caster and handles great !!! Have a great day ,Dave