NDT Tire Wear, alignment good, next step suggestions?

[Valence]

I realize that there are a lot of threads on this.

I have stock 9.00x20 NDTs, and my deuce does have the extra weight up front of a winch. I check tire pressure regularly and run them per TM specifications of 50 PSI. Due to outside wear, or cupping, of the Passenger Front tire I thought I had a front alignment toe-in issue. I jacked up both passenger and driver's front tires, and spun the tire while holding steady a piece of white chalk to tire's center.

Basically followed:
TM 9-2320-361-20
Page 674
View attachment TM9-2320-361-20_Unit_Maintenance_pages_674&675.pdf
(except instead of moving the whole truck, I moved just the tires)

I measured from inside to inside chalk lines between passenger and driver's side tires at as the TM specifies at about 18.3" from the ground, both front and rear of the tires. I even spun the tires to measure from the SAME spot both front and rear. Each time I came up with about 67 3/16" (+/- 1/16").

To me, this says that my truck has excellent alignment. So I don't know how to account for the severe wear, cupping, on the outer tread of the Passenger Front. (yes, I've read around here, see below)


The Driver's front shows a little cupping on the outer tread too:


I've read varying opinions/suggestions on SteelSoldiers; one fellow reported that he never got more than 5,000 miles out of his NDTs when using his truck as a daily driver (I'm not sure if he meant ALL his tires, or just his fronts). AceHigh suggested "I think it is the drive train pushing the truck thataway while you are turning thisaway."
http://www.steelsoldiers.com/showthread.php?68910-M35A2-Alignment

This thread started by maddawg308 in 2009 seems to mostly suggest wear due to scrubbing, and said wear can be reduced by locking out the inner (center) axle, decreasing speed of left turns, increasing front tire pressure, and possibly switching to radials:
http://www.steelsoldiers.com/showthread.php?41220-front-tire-wear-on-the-deuce/

There also seem to be conflicting reports on the helpfulness of replacing the front shocks. (I haven't taken my shocks off my truck to test if they're still good or not. However, they're not leaking but, I'm sure, they are old).

I also haven't done any tire rotating - I've only put about 1500 miles on my deuce in 5 years. Here's a couple of shots of the rear axles (passenger side):



If I had to guess, it would seem like the most effective resolution is "most of the above", as cranetruck put it:
http://www.steelsoldiers.com/showth...r-on-the-deuce&p=455996&viewfull=1#post455996

Since Cabell mentioned the article, it's "Front end alignment" , Issue #105, October 2004.
I have little wear on my front tires, about 1/32 for every 1,000 miles and attribute it to the following:
1) Check alignment and replace the shocks to dampen high frequency vibes. Check the leaf springs for sag.
2) Free up the rear bogie, the two rear axles are coupled w/o a differential and will force the truck to go straight on hard pavement, causing front tire scrub in every turn.
3) Single out your truck to lessen the tendency to force the truck to go straight.
4) Keep higher psi for the highway than specified in the TM. I use 70 psi for the hwy.

----------
Has anyone's opinions changed in the matter regarding resolving/reducing front tire cupping?


If I'm not keen to lose a rear drive axle (via performing the inner axle lockout) should I be changing to singles sooner, rather than later? My plan was to still keep duals on the rear but go singles on the front - Will excessive tire wear still be an issue in this setup? My plan was just like this fellow's rig:

(Michelin 11.00R20 duals in the rear and 14.5R20 singles on the front)


Thanks!

 

[Flyingvan911]

Have you changed the front shocks? It made a big difference on my truck though it didn't completely eliminate the tire wear. I think it's just part of having Bias tires on the front of a big, heavy truck. They are going to wear in strange ways. The best thing to do is upgrade to radial tires. Then you won't have wear issues.

 

[phil2968]

Maybe with weight on the front tires you have a toe in issue. Jacking it up made it go away. Try checking toe in on the ground. I had cupping issues and found excessive toe in. I set my to 0 toe in. Cupping ceased.

 

[Valence]

Have you changed the front shocks? It made a big difference on my truck though it didn't completely eliminate the tire wear. I think it's just part of having Bias tires on the front of a big, heavy truck. They are going to wear in strange ways. The best thing to do is upgrade to radial tires. Then you won't have wear issues.

I have not changed the shocks. What was suggested in multiple threads was "Monroe 66903" shocks. Does anyone know if this is still the case?

Maybe with weight on the front tires you have a toe in issue. Jacking it up made it go away. Try checking toe in on the ground. I had cupping issues and found excessive toe in. I set my to 0 toe in. Cupping ceased.

That's a very good point. It crossed my mind in the writing of the post, but I dismissed it. I should remeasure just to be sure. Thank you.

 

[jbayer]

I realize that there are a lot of threads on this.

I have stock 9.00x20 NDTs, and my deuce does have the extra weight up front of a winch. I check tire pressure regularly and run them per TM specifications of 50 PSI. Due to outside wear, or cupping, of the Passenger Front tire I thought I had a front alignment toe-in issue. I jacked up both passenger and driver's front tires, and spun the tire while holding steady a piece of white chalk to tire's center.

Basically followed:
TM 9-2320-361-20
Page 674
View attachment 540897
(except instead of moving the whole truck, I moved just the tires)

I measured from inside to inside chalk lines between passenger and driver's side tires at as the TM specifies at about 18.3" from the ground, both front and rear of the tires. I even spun the tires to measure from the SAME spot both front and rear. Each time I came up with about 67 3/16" (+/- 1/16").

To me, this says that my truck has excellent alignment. So I don't know how to account for the severe wear, cupping, on the outer tread of the Passenger Front. (yes, I've read around here, see below)


Thanks!

From the TM:
6. Rotate tires (3) by moving vehicle forward until ''Points of Measurement" are 18.3 in.
(46.5 cm) above the ground at rear side of tires (3).

It needs to be done this way to simulate the truck driving down the road.

Even though there not be any wear that you can visually see, or feel, there may some.
If you move a vehicle in reverse and measure toe, you will generally get a different reading than moving it forward and measuring toe.
(My dad told and proved this to me when I was younger and new everything)

Doing it as you did might not give you a correct measurement, especially when you're trying to diagnose tire wear problems.

 

[Valence]

From the TM:
6. Rotate tires (3) by moving vehicle forward until ''Points of Measurement" are 18.3 in.
(46.5 cm) above the ground at rear side of tires (3).

It needs to be done this way to simulate the truck driving down the road.

Even though there not be any wear that you can visually see, or feel, there may some.
If you move a vehicle in reverse and measure toe, you will generally get a different reading than moving it forward and measuring toe.
(My dad told and proved this to me when I was younger and new everything)

Doing it as you did might not give you a correct measurement, especially when you're trying to diagnose tire wear problems.

Ah, understood. I will amend my poor testing methods!

 

[peashooter]

I have not changed the shocks. What was suggested in multiple threads was "Monroe 66903" shocks. Does anyone know if this is still the case?

M35a2/M109a3- Monroe 66605 (Exact Match), 66903 (Very Close Match, less
expensive)

M35a3/M109a4- Monroe 34787

 

[Valence]

Thank you very much peashooter!
For the record, I found RockAuto.com + shipping was cheaper for me over Amazon with free shipping (and anywhere else I searched locally or on the web).
http://www.rockauto.com/catalog/moreinfo.php?pk=118670

And the Monroe 66605 was only a few dollars more than 66903

I also love RockAuto (their website is designed a bit weird, but it works).

Finally ordered some 383 Green Substitute from Rapco too. Hey look, I'm broke!

 

[Flyingvan911]

I used the NAPA 76787 shocks and they work well.

 

[cranetruck]

No change of opinion here, the main reason for the severe tire "scrub" or rubbing the pavement on every turn is the rear duals forcing the truck to go straight (as quoted in your original post). Try making a turn in snow or slippery mud, the truck may not even turn...

 

[Valence]

No change of opinion here, the main reason for the severe tire "scrub" or rubbing the pavement on every turn is the rear duals forcing the truck to go straight (as quoted in your original post). Try making a turn in snow or slippery mud, the truck may not even turn...

Since going to super singles was a suggested mitigating factor, do you know how, or why, super singles help prevent said tire scrub? Would my desire of going radials all around but still having duals in the rear with super singles in the front (without locking out the inner axle) still be met with excessive frontal tire wear?

Thanks!

 

[welldigger]

How's your kingpin bushings?

 

[Jeepsinker]

I was wearing tires really bad on the front too. I set my toe to 0 as well and saw no improvement. I was getting 2-3000 miles out of a front tire at a time. Changed the front shocks to the Monroe shocks and the wear stopped. Note: the new bushings that come with the Monroe shocks will not fit unless you grind them down some. They are too thick.

 

[Valence]

How's your kingpin bushings?

Unknown. I will look up what that is, check it and report back! Thank you.

 

[Valence]

I was wearing tires really bad on the front too. I set my toe to 0 as well and saw no improvement. I was getting 2-3000 miles out of a front tire at a time. Changed the front shocks to the Monroe shocks and the wear stopped. Note: the new bushings that come with the Monroe shocks will not fit unless you grind them down some. They are too thick.

Thank you Jeepsinker for the grinding tip - that'll save me from panicing later. Also, as mentioned earlier, I had read conflicting reports on the success of replacing the shocks. Seems now that far more than I had believed are reporting replacement as helpful.

Did you check if your shocks were worn out first or just replace regardless (figure age & etc)?

 

[welldigger]

Unknown. I will look up what that is, check it and report back! Thank you.

They are the bushings on the top and bottom of the steering knuckle.

 

[rustystud]

How's your kingpin bushings?

That is another wear problem most people never realize. The wheel starts to bounce up and down due to the Kingpin wear. My problem was just the shocks though. I went with the 1/2" rod Monroe's.

 

[Valence]

I pulled the deuce out of its "winter storage" and did a proper alignment check on it (as the TM specifies, all tires on the ground, driving forward...)

I used paper staples pushed vertically into the center of the tire, and measured. I then drove straight forward until the staples were the same ~18 5/16" off the ground on the back side.

The toe-in is about 0.156" (~5/32"). Spec says 0.13" +/- 0.06". So I believe it's within spec (granted a little on the upper end).

Question: However, did I FUBAR the test because in driving forward I over shot just a bit and had to back up a few inches. Just inches though.

I then checked the shocks... Oh my, they should have been replaced years ago. (See pics)

The shocks just stayed in at any length you moved them to. So I fully extended one and compressed the other to help give perspective. The shocks were shot!


One had a seized bolt, and the shock would spin with it. As much as I have the physique of Superman, unfortunately I'm not He. I couldn't squeeze the shock tight enough to move just the nut. So I used my laser vision, I mean cutting wheel, to remove the offender.


The replacement shocks are still drying (they were bright yellow - can't have that on the deuce!) Monroe 66605. I'm wondering about repainting them black instead.

When I refinished the troop seats in the bed of the deuce, I painted all the nuts and bolts black. The black against the green looked sharp.


Next I need to check the kingpin bushings. (I'm still ignorant in that area, so I'll start with some needed reading and research).

 

[gringeltaube]

......................The shocks just stayed in at any length you moved them to.........

Stock shocks all do that; they are not gas-filled.



G.

 

[Valence]

Stock shocks all do that; they are not gas-filled.



G.

Oh. Well, here's to looking like a fool.