Can a 4" Radius arm Lift kit stretched to 6-8"

[craggio_2001]

I recently purchased a 2007 F250 HD crewcab shortbed. It looks to have an RCD 4" suspension on 33x12.50x20's. I need to put new tires on it and know that 35" tires would fit nicely but would like to run 37x13.50x20 with a 6-7" lift. I have a friend that is selling a set of 22x10 Mazzi rims with 37x13.50x20
Toyo's.

I want to know if anyone knows if I can remove the 4" RCD coils and install 6-8" coils? I know I will need longer shocks and a carrier barring shim but does anyone know what else I might have missed?

Thanks,
Chuck

[HeMiSlAyEr]

Besides putting in a longer coil you can put a leveling kit on top of the coil like the Skyjacker 2.5" polyurethane bushing. Thats the route I went with when I put my lift on. You might also have issues with the trac bar, you might need one with more of a drop.

[FarmF350]

Yep ought to give you the same results as a leveling kit on a stock truck.

[tvandyck7]

If you lift it that much more you are going to have a few issues if you go the cheap route. Your track bar will need to be extended a bit or it will pull your axle over to the driver's side and your coils and control arms won't line up right. Also you will need to add a drop pitman arm to lower your drag link. I can already tell you that your bump steer is going to be rediculous no matter what size stabilizer you put on. You'll also have to make sure your steering doesn't bind anywhere. If you don't get the drag link parallel with the track bar, you will have the bump steer and "death wobble".

[FarmF350]

Originally Posted by tvandyck7

If you lift it that much more you are going to have a few issues if you go the cheap route. Your track bar will need to be extended a bit or it will pull your axle over to the driver's side and your coils and control arms won't line up right. Also you will need to add a drop pitman arm to lower your drag link. I can already tell you that your bump steer is going to be rediculous no matter what size stabilizer you put on. You'll also have to make sure your steering doesn't bind anywhere. If you don't get the drag link parallel with the track bar, you will have the bump steer and "death wobble".

I would disagree with that. Alot of people say that stuff - dont mix leveling kits with lift kits or your truck will be destroyed. I suppose that would be true of stacking leveling kits. But if the lift was originally designed properly to relocate everything to stock parameters, then a leveling kit would have the same effect on that lift as it does on my stock truck for example.
And I have never had "rediculous" bump steer or any of these problems. BTW Im pretty sure the "death wobble" is assosciated with the factory steering stabilizer and is a truck to truck thing that doesnt really ever get fixed and is a problem the day it is made on.

[HeMiSlAyEr]

yeah i never got the "death wobble" after I put on my dual stabilizers. After getting the scare once or twice I put it on and that was the last of it.

[caryt]

Both of you guys have smaller lifts..going from a 4" to a 6-8" is a big difference on these trucks.

[FarmF350]

Originally Posted by caryt

Both of you guys have smaller lifts..going from a 4" to a 6-8" is a big difference on these trucks.

Its the principle not the height I think. Adding 2 or 2.5 inches to a lift or a stock truck is the same. If he doesnt already have death wobble hes not going to get it. The suspension angles will be the same as a stock truck with a leveling kit, assuming the lift he has now was properly designed.

[DCSpecial]

Adding lift gives you a more negative caster setting.
The amount of rake the truck has also plays into caster.

Too negative and the truck will handle very, very poorly.


FWIW, death wobble is generally due to a loose trac bar or trac bar bracket or too negative of a caster setting.

The stock stabilizer can cause excessive feedback through the steering wheel while going over bumps....but that is much different from death wobble.


To say that if you don't have death wobble now that you won't get it, is incorrect. Increase the lift to the point that your caster reading is negative (close to or below zero) and you will get it.

[caryt]

X2!!!

[brice250]

does your friend still have the rims and tires? Im looking for some 37'' tires. elledgechris@yahoo.com

[KYmxracer52]

What's a proper amount of caster to have on a 5" lift kit? I have tossed around the idea of adding a 2" spacer kit to mine, but want to make sure I can get the handling details ironed out first. What parts on the truck do you adjust to fix the caster? Can most competent alignment shops adjust this on a lifted F-250?

[DCSpecial]

Originally Posted by KYmxracer52

What's a proper amount of caster to have on a 5" lift kit? I have tossed around the idea of adding a 2" spacer kit to mine, but want to make sure I can get the handling details ironed out first. What parts on the truck do you adjust to fix the caster? Can most competent alignment shops adjust this on a lifted F-250?

With a 5" lift you either have a) radius arm drop brackets b) new radius arms or c) a 4 link.
When properly designed these correct your caster back to stock specs or slightly more positive.

If your current lift allows you to adjust the 4 link or the lower mounting of the aftermarket radius arm to axle you have some adjustment for caster to possibly compensate for the additional 2" height that you'd be adding. The additional 2" of height shifts your caster more negative (closer to zero or actually below zero) if you don't make any other changes.
Now, if you can't adjust your radius arms or 4-link you can use alignment cams that go on the upper ball joint to shift your caster back positive. However, you are limited to the amount of change you can get out of an alignment cam.

Beyond that, you can purchase an adjustable 4-link, different radius arms or larger radius arm drops.

With a 5-7" lift I'd prefer a +2* to +4* caster setting.

I run my stock height 07 F-350 +3.5* to +3.7*....technically "out of spec" but it handles much better than stock.

[KYmxracer52]

I have the OEM radius arms w/ drop brackets. 99% sure its a Pro Comp lift. I'd like to get mine on the positive side of caster just to slow the steering action somewhat. I may upgrade to a 4-link setup. Can an alignment shop tell me what degree my caster is set at now?

[DCSpecial]

Yes, if you get it aligned (I always recommend this once a lift is installed) they can give you a print out showing your toe, caster, camber, thrust angle, etc..

They also may have cams in stock or can quickly get them if you need a change.