Tired hit inner fender on bumps! HELP!!!

[someotherguy]

Wow.. don't take this the wrong way but all that cutting should not be necessary with the tire size and drop OP has.

Had to go back and double-check the tire size I was running at the time. 4/6 drop, confirmed 255/45/20 on 20x8.5 5.4" backspace, only the fender lip is rolled. Zero cutting. No rubbing. That's a little bit less than .5" taller / .5" wider than a 245/45/20

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Same truck with 5" front drop, same front tires, some version of 295's out back can't remember for sure (maybe 295/40/20), this setup did rub in front on hard dips so I put the previous springs back in as my wife was going to use the truck for a while.

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His tire size and drop kit part #'s vs. model specs really shouldn't be causing an issue, the one set of details we don't have are specifics on the wheels. Also when you're getting at the ragged edge of clearance, tire design can come into play. If the tires are soft regular old P-rated tires for cars then they can bulge too easily at the sidewalls and will be in danger of rubbing or getting cut. I'd suggest XL load rated tires, plenty of them available, and ones with a fairly square profile shape help. The tires in those pics are Toyo Proxes S/T's which are obsolete now, I've got S/T III's on my current truck and they are similarly shaped.

Richard

 

[618 Syndicate]

My guess is that 1/2" diameter is the difference between rubbing and not. That's why I suggested that he measure before and after making changes.

 

[someotherguy]

My guess is that 1/2" diameter is the difference between rubbing and not. That's why I suggested that he measure before and after making changes.

Maybe I could have worded it better? The tires I was running are taller and wider, by just under .5" both ways. He's got 245/45/20, I had 255/45/20

Richard

 

[618 Syndicate]

Maybe I could have worded it better? The tires I was running are taller and wider, by just under .5" both ways. He's got 245/45/20, I had 255/45/20

Richard

I understood. Taller is the diameter, and given where it's rubbing that's the dimension causing the issue. That 1/2 inch could be the difference.

 

[someotherguy]

I understood. Taller is the diameter, and given where it's rubbing that's the dimension causing the issue. That 1/2 inch could be the difference.

I guess I'm dense. Had a really, really rough night at work, the end of my week. So I'm not following.. my tires were taller and wider, and did not rub.. but I relent. It must be time to sleep.

Richard

 

[618 Syndicate]

I guess I'm dense. Had a really, really rough night at work, the end of my week. So I'm not following.. my tires were taller and wider, and did not rub.. but I relent. It must be time to sleep.

Richard

No, it's my mistake, I didn't in fact understand.
On another note I'm pulling rollback duty tomorrow covering for my old boss. Fun times....

 

[gearheadE30]

Man...hearing "spring stiffeners" in the original post scares me.

Start with ZQ8 bump stops. These can help compensate for a too-soft spring as they are designed to be a part of the suspension rather than just a hard stop buffer, similar to how the GMT800s are set up. They are fairly tall and will be touching the frame most of the time. It's not ideal, but it's the cheapest option.

Every lowering spring I've seen for these trucks, including many of the coilovers, are too soft. I have no idea why this is. Stock springs are around 850 lb/in depending on your engine, options, etc. Diesel trucks were around 1400 lb/in. I have 950 lb/in in my Tahoe Limited and it's barely stiff enough. I had 1600 lb/in springs for a while that were a little too stiff, but not by much. 1100-1200 lb/in is probably perfect, at least for the 4 door Tahoes. Not sure if the trucks are lighter on the front.

However, that's only part of the problem. Spring stiffness will help a little, stiffer shocks will help a lot. You need to control the dynamic motion of the suspension more than the static force (spring) if it's really hitting the wells hard. I wish I had an off the shelf shock to point you to, but everything I tried was too soft so I went to coilovers. There's probably an Aldan/QA1/Ridetech drop in that would work, maybe with some extra valving help. I have ridetech in mine now and they are good, but they need stiffer shim stacks and less stack float to be truly great.

 

[96TahoeDoug]

I know nothing about lowered trucks but curious if the passanger side inner fender has been opened like this and if its blowing road grim into the air filter? or has the oem air filtration been altered?

Good eye sir. It's identical except for a cold air scoop focusing the intake plenum continously forward to the radiator support and dedicated CAI port. Like a knucklehead I chopped the **** out of the box were discussing see photos:

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The box is still there and I need to repair the bottom. Without the complete well it is open to the tire. I haven't noticed extra debris even did some flooded street monsoon driving. All is dry.

 

[someotherguy]

Man...hearing "spring stiffeners" in the original post scares me.

It caught my attention as well but without more info it's hard to know what's really going on. I assumed (maybe incorrectly) he's talking about the spacers that come with the BellTech springs these days - since they started offering their 2" springs as really a 3" spring with a 1" spacer so you choose which drop you want by omitting/including the spacer. Not my favorite setup but I guess it keeps people from cutting a 2" spring for a 3" drop.

However, that's only part of the problem. Spring stiffness will help a little, stiffer shocks will help a lot. You need to control the dynamic motion of the suspension more than the static force (spring) if it's really hitting the wells hard. I wish I had an off the shelf shock to point you to, but everything I tried was too soft so I went to coilovers. There's probably an Aldan/QA1/Ridetech drop in that would work, maybe with some extra valving help. I have ridetech in mine now and they are good, but they need stiffer shim stacks and less stack float to be truly great.

I ran the old Nitro Drop shocks on that truck and they did fine. Also, they lasted long enough that the urethane bushings in them crumbled to dust which was a little disappointing beyond the otherwise good lifespan on the shock itself. Anyway I'm glad you brought up the shocks because I don't recall which specific ones he had being mentioned although I did ask.

Richard

 

[Dc8610]

Sorry I haven’t replied I put on some bigger bump stops off the rear of my buddys gmc it don’t rub unless I hit a really bad dip. So I let it sit but I recently ordered some coilovers and rear shocks with adjustable stiffener knobs. I will be installing today my only Q is I cannot find torque specs anywhere for sway bar, ball joints exc… any spend that have to do with what I have to torque back down. Anyone know? Thanks guys all your feedback really helped and hopefully these coilovers help this issue and get rid of it for good.