understanding geometry for 38s

[Muffin Top]

Mudlight is running 38s with the following set-up. I saw this in someone else's build thread, so I'm asking my questions here not to hijack :

1.5 perch collars & RC leveling kit in the front, 1.5 top hat spacer rear, 1" body lift, 1" wheel spacers, JKS Max tire clearance kit

I'm trying to visualize which types of spacers extend downtravel (wondering what the limits are on downtravel for the front CVs).


Do the perch collars and top-hat spacer both re-locate the struts downward, so that downtravel is increased? What's the CVs' limit on increasing downtravel?


Did you need the 1" body lift to clear 38s? I guess this is a different way of re-asking my question about whether the perch collars and top-hat spacer increase downtravel?

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[andersman02]

Perch collars do not change anything other than where the strut rides. No change in rubbing.

Top hats effectively take away up travel and gives down travel or droop. (Which would allow more tire before rubbing upper fender.

Body lift increases space from fender to tire, same effect as a top hat without any increase in cv angle.

I think, think, 1" top hat(read that as increased droop) to SAsq is about the max. 2" without SAsq.

Imo 1" body lift is better than putting a top hat on. But no more than 1" otherwise it looks goofy

 

[Muffin Top]

Thanks, awesome! Since it seems the high-end struts can increase travel, I guess one would have to ask the vendor whether it's safe to use a top-hat spacer or perch collar (or whether the vendor's strut has already used up the 2" of extra droop that we have to work with).

 

[Reidt131]

Perch collars do not change anything other than where the strut rides. No change in rubbing.

Top hats effectively take away up travel and gives down travel or droop. (Which would allow more tire before rubbing upper fender.

Body lift increases space from fender to tire, same effect as a top hat without any increase in cv angle.

I think, think, 1" top hat(read that as increased droop) to SAsq is about the max. 2" without SAsq.

Imo 1" body lift is better than putting a top hat on. But no more than 1" otherwise it looks goofy

One guy on here did a 1" body lift, then mounted a lightbar between the grill and bumper. It closed out the gap really well, and I am usually body lift hater #1.

 

[Fordified1]

I think general consensus is, do not exceed 2” of extra down travel. (I don’t know if that includes Sasquatch or not). Beyond that a diff drop can be used, and I feel is a good idea with any extra down travel (droop). There is a member here who has a really well done diff drop kit available, either pre-welded or ready to weld.

 

[Muffin Top]

Does pre-welded mean bolt-on?

 

[Fordified1]

Does pre-welded mean bolt-on?

Yes

 

[Fordified1]

Does pre-welded mean bolt-on?

This is the member.

@TeocaliMG

 

[Muffin Top]

Thanks, awesome !


Now that I think I understand what perch collars are, it looks like Mudlight increased his front droop by 1" with the RC level kit. The 1.5" top-hat spacer out back is ok, because of the solid axle out back.


I'm still kinda surprised that he needed the 1" body lift, when he already had 2.5" of spacer lifts.

 

[Muffin Top]

If I'm reading the words correctly, then Mudlight did it exactly right. A person who increases ride height 1" with a perch collar would also want to use an external 1" top-hat, to restore the front tires to the factory's equal amounts of uptravel and downtravel.


Since he lifted with factory shocks, he wanted equal parts of internal perch lift and external top-hat droop lift up front, so there's not a change in ratio of tire uptravel vs downtravel.

 

[Muffin Top]

Suppose before installing the perch collars you had 8" of travel, 4" up and 4" down. After you lift 1" via perch collar, now that 8" travel is divided 5" up and 3" down?


I'm pretty sure that's how the perch collars work. The only way to absolutely ensure clearance for larger tires is to extend the bumpstops.


Even though bumpstop extension is required for a guarantee of tire clearance, I don't think that means perch collars are worthless without bumpstop extension.

 

[Bradley Thornton]

This may help

https://www.bronco6g.com/forum/threads/the-ultimate-37s-38s-tread.65684/

 

[1st 75th ranger]

Perch collars do not change anything other than where the strut rides. No change in rubbing.

Top hats effectively take away up travel and gives down travel or droop. (Which would allow more tire before rubbing upper fender.

Body lift increases space from fender to tire, same effect as a top hat without any increase in cv angle.

I think, think, 1" top hat(read that as increased droop) to SAsq is about the max. 2" without SAsq.

Imo 1" body lift is better than putting a top hat on. But no more than 1" otherwise it looks goofy

i run 36x12.5x17 no lift no level no spare tire 3rd light probs 0 issues with rub crawling & pre running

 

[broadicustomworks]

With my 38's I still can stuff the tires and have rub.
I've trimmed the fender liners in strategic places and gotten rid of 99.9% of it under reasonable articulation.
Now the issue is the actual fender radius if I were to need or want to articulate the tires all the way up (mainly on the rear, front seems ok, but barely).
My setup:
-Max tire chop
-0 offset Icon Wheels
-38/12.50/17 Patagonias
-Icon Stg. 4 (Remote resi coilovers, roughly 6 turns left of lift for the rear, 8-10 turns left for fronts to max out the lift they offer. Icon tubular UCA, track bare relocate)
-.75" Body lift homemade
-Heavy winch and mount up front and heavy 38 hanging off the rear with the TOR reinforcement/brace and tire carrier, so weight added to both ends ballpark equally.

I do have a bit more lift I can eek out of those coilovers, can always go another .25-.5" of a Body lift and it still look ok.
Clearance is good for most normal trails, highway use. When you get into those flex situations where you are using all the travel you can muster, that's when the size and shape of the wheel wells pose an issue (at least with the fender liners still in place).
With the front I also chopped a half-inch off of my rock rails, and any more trimming will be getting into the metal parts of bracketry used for the fender liners, so avoiding that with more lift on the coilovers when I feel frisky enough to do it.

 

[87-Z28]

With my 38's I still can stuff the tires and have rub.
I've trimmed the fender liners in strategic places and gotten rid of 99.9% of it under reasonable articulation.
Now the issue is the actual fender radius if I were to need or want to articulate the tires all the way up (mainly on the rear, front seems ok, but barely).
My setup:
-Max tire chop
-0 offset Icon Wheels
-38/12.50/17 Patagonias
-Icon Stg. 4 (Remote resi coilovers, roughly 6 turns left of lift for the rear, 8-10 turns left for fronts to max out the lift they offer. Icon tubular UCA, track bare relocate)
-.75" Body lift homemade
-Heavy winch and mount up front and heavy 38 hanging off the rear with the TOR reinforcement/brace and tire carrier, so weight added to both ends ballpark equally.

I do have a bit more lift I can eek out of those coilovers, can always go another .25-.5" of a Body lift and it still look ok.
Clearance is good for most normal trails, highway use. When you get into those flex situations where you are using all the travel you can muster, that's when the size and shape of the wheel wells pose an issue (at least with the fender liners still in place).
With the front I also chopped a half-inch off of my rock rails, and any more trimming will be getting into the metal parts of bracketry used for the fender liners, so avoiding that with more lift on the coilovers when I feel frisky enough to do it.

nice ride and great compromise of suspension lift, minor body lift, and minor body work. This is a great solution for those wanting good articulation and 38/37s.

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