bumpstops, shock length, and tires size. help me iron out the fuzzy points..

**mudb8** · 03-20-2009, 05:16 PM

and things that need a better or more explanation.

it's something I've been working on not only for a base line, but to show how bumpstops vs. shock length play an important role in a suspension system besides using them to shoe horn in a set of 33's with no lift... for those who feel they don't need the ability to run high speeds on rough terrain.

the issues come up every day.. how long do my shocks need to be? how long will fit?, what size tires fit/can fit a given height?

another edit... this chart is directed at the front shock lengths, since the front is where the rubbing issues mostly occur the rear typically needs around 1" more than the front for the same length shock.

here's some bumptop/spring tech....

Rear Springs are Rancho 2.5" RS616... unloaded length is 15.5". collapsed to coil bind they are 5",

Which means the 2.5" rear lift springs REQUIRE a minimum of 1.5" bumstop extension whith the relocated spring perches, no loss or gain in ride height was made from the relocation, I made sure to set them exact.

A stock 104 rubicon/sahara rear spring is 11 3/4" unloaded, 3 3/8" @ full coil bind...

so, add/clarify a point/measurement, contest a point.... ect.

I'm not trying to prove anything here, just showing what each system and combination can/will do.... good or bad, depending on how one looks at it..

**mudb8** · 03-20-2009, 09:43 PM

edited some, added some....

Rigger007 · 03-22-2009, 09:24 AM

Looks like you've put some time in this, looks good.

01TJMudder · 03-22-2009, 09:35 AM

this may help a little http://manoian.net/jeep/jeep_lift_tire_size_what_fits_what_hits.html

**mudb8** · 03-22-2009, 11:09 AM

Quote:

Originally Posted by 01TJMudder

this may help a little http://manoian.net/jeep/jeep_lift_tire_size_what_fits_what_hits.html

hadn't seen that before, deal is I know pretty much exactly what works and attempted to take out the vagueness and "recommendations" away like this.... (which is stated for running 35's in the link) "4" of lift is required. 6" of lift is recommended. Some rubbing may occur. A small body lift or wider fender flares may be necessary to increase clearance and prevent rubbing." that doesn't tell you that 35's need 3" bumpstops to run the 4" lift, it say's " some rubbing may occur"
the bump stops prevent damaging rub and allow the use of specific or longer travel shocks.

by pointing out the bump stop height required for a given shock length and the tires size that fits as a result of the bump stops.. for example on my chart if you pick a tire size wanting minimal lift, it tells what length bump stops are needed to keep the tires out of the fender, and the shock length that can go with the bump stop height without bottoming out the shock... regardless of lift height.

for example look at the chart for 35's. they need 3" bump stops regardless of lift height to fit stock fenders. if you want up travel that's more than stock suspension without the huge 6" lift, use a 2" lift, 1" bump stops and high line fenders with 23.75" long shocks.. is up travel not a concern? put 35's under a 2.5" lift, 2-2.5" bump stops, 24" long shocks, and a 1" body lift. no guess work and definitely doesn't "require" a 4" lift or recommend a 6"

**mrblaine** · 03-22-2009, 11:34 AM

Quote:

Originally Posted by mudb8

and things that need a better or more explanation.

for those who feel they don't need the ability to run high speeds on rough terrain.

There seems to be a large amount of confusion as to what "high speed" really is. We are NOT talking race speeds here, nor are we talking above average. We are just talking about being able to keep up with the herd when we head out to a trail. What all the PRO LCG mooks keep overlooking in all of this is when you build for a specific purpose, you COMPROMISE a lot of other aspects of your rig's performance to achieve one goal.

Lack of balance is always bad, never good.

Building for what is supposedly LCG is akin to building a mall crawler. You know, the rig that looks good, has all the hooraw crap bolted to it, swing-out, Long arm lift, hi-lift, Winch with steel cable and a big *** hook that's never been scratched, beadlocks, 35" tires, and yet, hasn't been re-geared and locked up.

Everyone oohs and aahs over it, but on the trails it would suck, but hey, it looks great at the mall.

If I build a rig that can handle moderately fast traversing of the fire roads, you can bet your sweet bippy it will do everything else well also and that includes street handling.

**mudb8** · 03-22-2009, 11:44 AM

I under stand that mrblaine,
I'm not trying to push lcg with this, just showing what combo's can work. I have the shock lengths listed with the lift height as they generally come in a fairly well balanced kit without over compression or overextension of the springs.... that's what I intended to show anyhow.

surely using 24" shock with a 2" bb is a problem...

thanks for the input.

**Unlimited04** · 02-14-2010, 06:51 AM

**SHAKEnBLAKE** · 02-23-2010, 10:26 PM

So, I daily drive a 4" SA lift and 33's. I may some day run 34's. According to mudb8's chart, I can run 25-26" shocks. Unlimited04's super fine print above seems to suggest that the ride will be too rough if I go with this maximum length shock. Is that why rough country suggests their 23" 8304 shock? I'm just trying to get myself set straight on what length shocks I'll be happy with.
Thanks guys! Good thread!

**mrblaine** · 02-23-2010, 10:54 PM

Quote:

Originally Posted by Unlimited04

What's the story behind that picture?

**mudb8** · 02-24-2010, 12:21 AM

Quote:

Originally Posted by SHAKEnBLAKE

So, I daily drive a 4" SA lift and 33's. I may some day run 34's. According to mudb8's chart, I can run 25-26" shocks. Unlimited04's super fine print above seems to suggest that the ride will be too rough if I go with this maximum length shock. Is that why rough country suggests their 23" 8304 shock? I'm just trying to get myself set straight on what length shocks I'll be happy with.
Thanks guys! Good thread!

the 23" is too short for a 4" lift.... the 4" is well served with a 15" collapsed shock length. One of these days I'll change the chart to show collapsed length instead of extended lengths since shocks are not created equally on the inside.

Quote:

Originally Posted by mrblaine

What's the story behind that picture?

The pic is what I used to show the importance of and how to measure and figure out the proper bumpstop lengths needed to keep the shock mounts on the axle instead of hanging from the shock when they get busted off after bottoming out the shock one to many times...

the lift in the pic above is an RC 2.5" with the RC 2.2 10" travel shock. (the original long ones)

**Unlimited04** · 02-24-2010, 07:17 AM

Quote:

Originally Posted by mrblaine

What's the story behind that picture?

sorry, should have linked the source. its mudb8's picture from here:
http://www.jeepforum.com/forum/f9/rear-shocks-too-long-rc-2-5-spring-lift-786205/index6.html#post7330627

i figured it would be useful in this thread.

**sardog12** · 02-24-2010, 10:39 AM

Quote:

Originally Posted by Unlimited04

So, upon full stuff, the bumpstop in the coil in the rear will compress completely so you should measure from the pad at the bottom to where the bumpstop goes into the holder? I had figured on the bumpstop compressing maybe an inch or so but not completely into the holder.

**Unlimited04** · 02-24-2010, 10:48 AM

Quote:

Originally Posted by sardog12

So, upon full stuff, the bumpstop in the coil in the rear will compress completely so you should measure from the pad at the bottom to where the bumpstop goes into the holder? I had figured on the bumpstop compressing maybe an inch or so but not completely into the holder.

its got a few thousand pounds on it, so yes the jounce bumper will compress fully into the bumpstop cup. in fact, its designed to do that.

**mrblaine** · 02-24-2010, 10:56 AM

Quote:

Originally Posted by Unlimited04

its got a few thousand pounds on it, so yes the jounce bumper will compress fully into the bumpstop cup. in fact, its designed to do that.

A few thousands times what multiplier for the difference in dynamic over static loads?

If you hit a whoop in the road that bumps your rig up to full extension on the shocks and when it hits it takes them to full compression, how much force will that bumpstop see with 2000 lbs of rig moving downwards at 40 to 50 MPH crossing a distance of 10-12"?

Dave and you are correct, measure to the cup for shock travel because those are your only two hard points that won't compress.

EDIT- also forgot it's a safe way to save your shocks should the jounce bumper fall out or get damaged.