Air bumps for my 35's

[bobbynelson0730]

New here, not to FJ's. here's my rig, el burro. 315/75/16 GY MT/R's, WE all around, Outdoor Logic bumper, yada yada.
Got the 35's (these are very much a 34.8" tire unlike others that run closer to 34) in a bad deal gone good when my 33's disintegrated in less than 2000 miles. Love them since I love rocks, but I do stuff them. No flares, seam pounded flat and a few other spots with the sledge.
I have a snorkel (not in pic) so I'm a little hesitant to do a chop and patch on the inner fenders similar to some other here (also dealing with fitting dual battery in future and still closing the hood). Has anyone used a charged bump stop like kings set a little lower to limit some up travel and prevent blowin the fenders off next trip to Baja? Just unsure how these bumps work, are they meant to reach full compression or will that damage them similar to continually bottoming out a coilover/shock. Ill take the slight loss for the extra girth to roll over rocks and to survive G-ing out in Baja washes. Any input/experience is appreciated
-bobby

 

[Mtbcoach]

The bump stops you are questioning are meant to be used in that manner, that is the intent of their design.

Yet, if you are regularly bottoming out your suspension, you need to re-evaluate your suspension as well as your driving style IMHO...

 

[Delancy]

Here's what I've learned about air bumps on the FJC.

Front

1. They should be used in conjunction with aftermarket LCAs, and really only make sense ( to me ) on an LT suspension.

2. Need to custom order a 2" bump shortened to 1.5" stroke, otherwise they'll be hitting all over town, DDing.

3. Major fab is required for typical bump cans. Jounces are the only "bolt on" solution that don't require.

My opinion is, if maintaining the OE width, get TC LCA/UCAs with secondary shock hoop and run a bypass set up as the bump. Less fab, better overall results, since the bypasses allow for overdriving the platform, where bumps don't.

At least, bypasses should be factored in with bumps. At that point, may as well go LT, which cam tab, coil tower, and LCA mount reinforcement, along with a host of other "adds".

This was a pita, unnecessary in my opinion, and it's on mine.







Rear

1. The rear linkage and shock mount configuration will never be capable of keeping up with the front. Period.

2. Have to French bumps into the rear frame rail with OE width rear axle, so major fab. Jounces can be used inside the coils, or at the frame rail with drops on either.

3. Bypasses, bypasses, bypasses, and if not, coil overs.

My opinion is, bypasses set as bump stop make better sense, but still won't be capable of keeping up with the front, without relinking the rear.

The FJC ain't a frog. Axle housings are prone to bending.

Not my rear, but depicts.

 

[Delancy]

Can't find the WTS ad on Mud, but FJNewb is selling SAW coil overs and bypasses set up for max travel on a Camburg +3.5" kit (would work for +2" kit ) and rear coil overs (major fab to fully utilize).

Will look for link and post, just for somewhere to start researching options. He's be the guy to talk to regarding a "go fast" suspension.

Edited: Ultimate Go Fast Suspension

 

[bobbynelson0730]

By bottoming out I guess I should say "full compression" for I may have left the impression I do a lot of go-fast driving. Totally the opposite, 99% of the trails I run are slow, crawling types, where I am stuffing the 35's under 5mph (not that big of a deal). I do run maybe once a year to Pismo and also down Baja - but being in So Cal, there's always an opportunity to have a go fast run so I’m not looking for a suspension that can perform exceptionally well in the whoops, I'm just adding to what I have to prevent more damage when those blue-moon runs do occur.




I have researched the Jounce set up a little, but I guess what turned me off them (in the front) were two things

1. Bolt on mounting? Why would you ever want a bump stop mount to be attached solely with a few bolts? I would not think you would want the force of a hit to have to be transferred through the bolts to the frame instead of a solid mount that gives that much more strength (just like the stock ones) - yes, you can weld them on but that's number two...
2. Location- from the little reading I did they are ideal for an FJ with the typ. 33's, so they would not contact the LCA soon enough for a larger diameter tire and I would be wasting whatever stroke remains after hitting the fender. (also why I totally bypassed a cheaper rubber stop like Timberens all together) So the fab work already required to make them the correct height is why I am looking at the standard canister setups.

The rear isn't the biggest deal, with my adj. rears set 2 clicks from the stiffest setting it doesn't bottom out fast nearly as much. I still stuff flexing but I can deal with that. I have even looked at just extensions for the rear bumps, I can't seem to find any solid feedback on how well they perform but they are cheap enough I may just give the 2" a try.

I know the FJ isn't the ideal anything - but that's why it's fun, you can do a little bit of everything at a half decent pace. LT sure would be fun, even more a SAS for me. But that's just not my reality at this point. New TC LCA's (I already have TC uppers) MAYBE in the far future, so for now the whole bypass deal can't happen $$
I really appreciate the input guys - hence strolling over here since it definitely has the real know-how members. Please keep it coming if I'm off at all or other ideas are out there

 

[bobbynelson0730]

And I hear ya Delancy on the housings... I run baja with Ryan Millen and the Millenworks FJ... boy do those SCORE race carnage stories make the campfire fun.


hmmm now you got me to thinking with the LCA's since his FJ is a stock mini class, so stock LCA/UCA are required yet he has a bypass squeezed in there....

 

[Delancy]

The bumps I run were installed for 35s and with crawling/ trails the intention.

Better to save the cash and run Timbren's if that's what you're doing, and coming from someone who was told that exact thing, didn't listen, by someone who was told that same thing, and didn't listen.

The irony.

If you're just keeping the tires out of the fenders, a rubber bump is fine, almost better.

On the IFS, at slow speed, it's very hard to force the hydro down, since the corner weight seems skewed on the stuffed wheel, therefore the resistance from the hydro can almost limit up.

When setting my +2" LT up, released the N2 and stuffed 1/4" before hitting the metal inner (not the OE flare) which was ~1/2" before the shock topped, by calculations of a 35" tire, and very close to spindle bolt contact on the inner fender.

Turns out, 35x12.50x17 KM2s on TR bead locks are a 33.75" tire, give or take, so tire contact is irrelevant, BUT when tip toeing through the rocks, I can see very little movement ( visualized by the dust ring on the bump ) of the air bump, running the lowest N2 pressure suggested, yet the LCA contact is very evident.

In contrast, when hitting the rough river bottom at high speed ( or just the crap a$$ OK. Joking) I can actually see the bumps to the intended job, based on same visual inspection of the dust tibg around them.

All you need is a bump that's compression is calculable and will stop the tire from contacting, for crawling.

Look for drops of Timbren's for T4R, FJC, even Taco's since they're prevalent, and save yourself the money of hydro's for the future SAC.

My two cents.

 

[bobbynelson0730]

FINALLY, getting the info I have been searching for

Well back to the Timberens, they are longer..but do they just compress to the "stock" limit? like they do not actually limit the up travel more, they just make it a more controlled stop?

The force applied to the charged bumps makes a lot of sense differing between slow/high speed..never thought about that!

SAS will come eventually

 

[Delancy]

Not my findings on the Timbren's in recent searches for the 80.

They do have an actual compressed dimension, based on x+y-z. The research had been done already for the 120 platform, just takes a little poking around.

The rear is easier, if you don't mind drops. MetalTech has specifically for their extended travel rear set up, but, ultimately, the up is limited before a true 35" tire rubs, so would work on any set up with a shock capable.

Whatever your running should be capable of enough "up" travel to rub the 35" on the rear, so a drop of their dimension would be universal, so to speak.

You'll probably need to dust off the BFH to properly treat the seam on the inside of the front fender wells and the rubber cover on the lower DS inner well.

As for the hydro pressure. I'm assuming that a longer stroke hydro would offer more progressive resistance, but can't say.

 

[bobbynelson0730]

Well I'm trying to avoid that cycle of not listening. I ordered some timberens today with the contingency that my buddy was planing on getting them anyways so if they don't fulfill my needs then I have a buyer for them slightly used. Will have them on and installed for next weekends run to cougar buttes, Johnson valley. Ill update once I get some miles on them. Thanks

 

[Delancy]

Who doesn't love cougar butts? Haha.

Give this to Jeremy please and if Dave's there, make sure to tell him he still can't weld for chit.

 

[bobbynelson0730]

Hahahahahha will do