Bronco Forum - Full Size Ford Bronco Forum banner

1 - 20 of 39 Posts

·
Registered
Joined
·
651 Posts
Discussion Starter #1
My right front (passenger side) tire is cupping pretty badly. What would cause this? Bad alignment? The ball joints are new.

-Curtis-
 

·
Registered
Joined
·
651 Posts
Discussion Starter #3
That's what I assumed. I'm going to try the airsoft bb balancing method. Have about 13 ounces of bb's per tire to put in. May try getting an alignment done too. We aligned it pretty decently ourselves then put it on a machine at Big 10. The passenger side was a hair farther forward than the driver's side.

And yep, mine shake pretty bad above 65 too.

-Curtis-
 

·
Registered
Joined
·
2,900 Posts
You have to rotate them very regularly so they wear evenly, and even sometimes half way through their life flip the tire around on the wheel so you can run them on the other side.
 

·
Registered
Joined
·
651 Posts
Discussion Starter #8
do me a favor lakemary. put a regular set of 33's on that truck drop the lift several inches and sell me the truck. i need an ex cab. you can have my regular cab short bed. what do you think.
The ole girl turns too many heads and is awesome to cruise the beach in. Haha everything is for sale for a price though.

-Curtis-
 

·
Registered
Joined
·
651 Posts
Discussion Starter #11
After looking it appears both are cupping. Guess I'll either run them backwards for a little or put the rears up front. I'll snap some pics tomorrow.

Is the air pressure the same as all the others?
No 18-20psi in the front and 15 in the rear.

-Curtis-
 

·
Former owner of Shadofax
Joined
·
17,038 Posts
You have to rotate them. The fronts will always wear the outsides more with turning. Cupping, have to see pics. if it's both sides I'll go check again by searching google, but I believe cupping is usually improper toe, good news for you since that is an easy fix. You really need to check that side to side axle placement as well and get it as close as possible. It's pretty easy to check your camber as well, there are discussions on here about that. But basically if you see any very slight outward lean at the top of the front tires, that is ok. If it looks pretty noticeable compared to the rear, you should check the spec on it.
 

·
Registered
Joined
·
527 Posts
Typically cupping across the entire tire is a sign of a bad shock. If the valving is poor or the shock is simply bad, the tire will not stay in contact with the ground, an the tire actually bounces like a ball down the road.
Verify that the shocks are dampening properly, and that you do not have a bad shock or your shocks are not valved too soft for these tires.
Boggers are bad for this, but not uncontrollable. Ive run 40's and 44's for several years, and have not had any problems, and I do not run BB's or other balance media.
Something about the balance media that tend to bounce around when I hit a pot hole or even an expansion joint that seems to upset the media.
I wheel the snot out of my rig, and have chunks of tire missing and over 25K miles on a set of 40's. They are true, and not scalloped or cupped. I might add that they have only been rotated twice over the life of the tire.

Just recently I loaned some shocks to a buddy that started to show signs of tire wear, and suggested to him that he run the shocks, and run the tires in the same direction for his 500+ mile trip.
Once he returned he was amazed at how well the same truck drove with better dampers, and noticed how the tires wore flat and true once he returned.

Boggers tend to bounce, and seem to get worse if you dont get the dampers under control.

Borrow a nice set of shocks if you can, and see for yourself.
 

·
Registered
Joined
·
651 Posts
Discussion Starter #14
I don't exactly have cheap shocks but not top of the line (Bilstein 5125 pretty sure 255/70 valving). The cupping i'm referring to is not the sides of the lugs but the front side of the lug is wearing more than the back side. If that makes sense.

-Curtis-
 

·
Registered
Joined
·
527 Posts
I don't exactly have cheap shocks but not top of the line (Bilstein 5125 pretty sure 255/70 valving). The cupping i'm referring to is not the sides of the lugs but the front side of the lug is wearing more than the back side. If that makes sense.

-Curtis-

I understand exactly what you are talking about. Leading edges start to wear and develop a ramp. This means the tire is always trying to go over a bump. You can really feel this when the tire gets worse. Drive slow, and you can feel each and every individual lug.
Let it go too far, and the smaller lugs will wear faster than the larger ones. Probably at that point now, if you inspect carefully.
Its worth a shot at inspecting the shocks, though I do believe that if you are running a single shock, the 255/70 valving is not enough, and this supports my theory.
2550 Newtons @ 0.52 m/s of rebound and 700 Newtons @ 0.52 m/s of compression does not sound like enough to me.
You may want to verify this with your shock manufacturer. Did theu assist you with this shock selection?

I do believe that this particular shock is only available in this valving and even less. To obtain greater dampening, you will have to consider a different shock, or consider duals.

Bilstein can recommend a dual shock set up with as much as (360/80) 3600 Newtons over 800 Newtons for IFS trucks.

I see many 275/78's out there, and I see some of the ones that you have, though I do believe that the tire you have selected is quite a bit more aggressive than the lighter duty shock is capable of controlling.

Just throwing that out there, but as I mentioned I have been running a slightly higher end shock with slightly larger Boggers and have had enough success to not wear them out (other than normal wear, no cupping) while never really having to rotate them.:thumbup
 

·
Registered
Joined
·
651 Posts
Discussion Starter #16
I understand exactly what you are talking about. Leading edges start to wear and develop a ramp. This means the tire is always trying to go over a bump. You can really feel this when the tire gets worse. Drive slow, and you can feel each and every individual lug.
Let it go too far, and the smaller lugs will wear faster than the larger ones. Probably at that point now, if you inspect carefully.
Its worth a shot at inspecting the shocks, though I do believe that if you are running a single shock, the 255/70 valving is not enough, and this supports my theory.
2550 Newtons @ 0.52 m/s of rebound and 700 Newtons @ 0.52 m/s of compression does not sound like enough to me.
You may want to verify this with your shock manufacturer. Did theu assist you with this shock selection?

I do believe that this particular shock is only available in this valving and even less. To obtain greater dampening, you will have to consider a different shock, or consider duals.

Bilstein can recommend a dual shock set up with as much as (360/80) 3600 Newtons over 800 Newtons for IFS trucks.

I see many 275/78's out there, and I see some of the ones that you have, though I do believe that the tire you have selected is quite a bit more aggressive than the lighter duty shock is capable of controlling.

Just throwing that out there, but as I mentioned I have been running a slightly higher end shock with slightly larger Boggers and have had enough success to not wear them out (other than normal wear, no cupping) while never really having to rotate them.:thumbup
You named the symptoms spot on! :rockon So what sort of valving would you suggest? They are just 14" travel eye-eye shocks. Do you think the oil is just breaking down to fast? Which valving or shocks would you recommend? I thought possibly some Triple Bypass shocks if I could find a set on race dezert.

-Curtis-
 

·
Registered
Joined
·
527 Posts
You named the symptoms spot on! :rockon So what sort of valving would you suggest? They are just 14" travel eye-eye shocks. Do you think the oil is just breaking down to fast? Which valving or shocks would you recommend? I thought possibly some Triple Bypass shocks if I could find a set on race dezert.

-Curtis-

Tell you what I can do. I'm by no means an expert at this, and perhaps I have either underestimated my understanding of shock valving, or have gotten rather lucky.
Maybe a combination of both.:thumbup
When I told you that I loaned out one set of shocks, it is actually two sets, and one set will be coming back for a re-build. Once I perform the re-build, I can verify the valving and forward the shock dyno results.

Share with me your suspension combo, as well as your rig. Full specs, including wheelbase, and spring info if you have it. I suggest wheelbase, because longer wheelbase vehicles seem to hit expansion joints in such a way that makes shock selection difficult.

If you contact Bilstein, and share the suspension combo you can make a comparison. Instead of just taking my word for it, you can compare the two and have a little extra information that can help you make a more informed decision.

More information never hurt, but I am leaning towards a dual shock set up with similar valving to what you have now, or a single shock with a value closer to 3000 Newtons over 780 Newtons, or even 3200 to 3500 over 800.
Something like that might be in the ballpark.

At this point I dont believe that your current shocks are getting hot or fading, so oil breakdown is not an issue. I just believe that your current shocks simply do not provide enough control.

Again, just a guess, but the guess does come with a little bit of education.:toothless
 

·
Registered
Joined
·
651 Posts
Discussion Starter #18
Ok, I took some halfassed pictures with my Blackberry. (I'll post them at lunch time.) I'll take some over the weekend with the DSLR. I have been busy as hell with work this week. I had it reversed. The back edge of the lug is wearing more than the front.

As far as suspension/truck info goes.
Roughly 12" of lift via 9" 79 Superlift coils with 3 inch bucket drop. Extended cab short bed truck. 38.5x15.50 Boggers on 15x12's. Bilstein 5100 Shocks with 255/70 Valving.

-Curtis-
 

·
Registered
Joined
·
651 Posts
Discussion Starter #19

 

·
Registered
Joined
·
1,263 Posts
Wow. I'm interested to see how this pans out. I know they're Boggers, and comparatively their street manners suck. But you haven't been running those for to long if I remember right and the lugs already look like that? Jeez. Not saying there's anything wrong, just curious to find out what makes that happen so fast.
 
1 - 20 of 39 Posts
Top