Professional Rock Bouncers/Builders - Advice needed

Beyer · Sep 8, 2008

blacksheep10 said:
lower the uppers if its easy. I suggest raising the uppers and lowers on the axle. get that roll center up and gain side hill stability while at it. I would start with going all the way to full bump and raising the upper on the axle til you're out of room. get them links flatter. they should be inverted at full stuff assuming a fair amount of uptravel.

Ok, I looked at the rig for a second this morning, and it looks like I can only get 1-2" from lowering the uppers at the chassis. :-\ I will probably look into raising the uppers at the axle as much as possible before they hit the floor. I might get another 1-2" there as well.
The lowers are currently right at, or slightly above, axle center-line.

CHASMAN9 · Sep 8, 2008

First off, I am no qualified suspension Guru like some of the others here, just a weekend warrior. I did notice that your rear suspension has rubber bump stops that are 5-6" above the pad. I have had Fox Air Bump stops installed and they sit about an inch above the pad that let's them absorb the initial impact and the coilovers do the rest afterwards. My suspension is way more controllable now than it was with the original air bags and air shocks. Just my 2 cents worth. :dunno:

Beyer · Sep 8, 2008

CHASMAN9 said:
I have had Fox Air Bump stops installed and they sit about an inch above the pad that let's them absorb the initial impact and the coilovers do the rest afterwards.

My bumps are set-up to bottom out just before the shock does. If I move them lower, I will lose some of my uptravel. :dunno:

EOR MFG · Sep 8, 2008

Def a separation problem and the timbrien springs do not help, although it does not look like you are hitting them often
Alot of builders use heavy valving and super heavy spring rates to solve these issues, and it works mainly by limiting any axle movement,but its patching a geometry problem which is what you have. If you want call me and I will get the numbers from your rig and try to find the best /easiest avenue for fixing the problem.
1 800 826 1623 Jimmy tue---sat

Beyer · Sep 8, 2008

EOR MFG said:
Def a separation problem and the timbrien springs do not help, although it does not look like you are hitting them often
Alot of builders use heavy valving and super heavy spring rates to solve these issues, and it works mainly by limiting any axle movement,but its patching a geometry problem which is what you have. If you want call me and I will get the numbers from your rig and try to find the best /easiest avenue for fixing the problem.
1 800 826 1623 Jimmy tue---sat

Cool, I will give you a call. I need to get under there and get some good measurements tonight.
Do you think the Timbrens might be creating a rebound that the shock can not control? Would stiffer rebound valving help?
Thanks.

EOR MFG · Sep 8, 2008

Yes it is possible the timbrens are a spring and will cause the rig to bounce off of them, they work but they transfer the energy back to the chassis
rather than absorb it. How old are the Saw's ? and do you know the valving #'s

Beyer · Sep 8, 2008

EOR MFG said:
Yes it is possible the timbrens are a spring and will cause the rig to bounce off of them, they work but they transfer the energy back to the chassis
rather than absorb it. How old are the Saw's ? and do you know the valving #'s

SAW's are 6 months old and came from poly Performance. I would have to ask them the valving.

Edit:
Compression is 8.
Rebound is 12.

BamaTJ · Sep 8, 2008

Beyer said:
SAW's are 6 months old and came from poly Performance. I would have to ask them the valving.

Edit:
Compression is 8.
Rebound is 12.

My old saws were 10/12 and I revalved to where you are now 8/12. I don't think that is your problem but I do think an air bump would help some

SAW uses weired valving numbers that don't match Fox. I found this helpful info on revalving http://azrockcrawler.com/

Under Tech, go to Suspension and Shock Valving

EOR MFG · Sep 8, 2008

Ok I was just checking to make sure you had the updated valving

Beyer · Sep 8, 2008

EOR MFG said:
Ok I was just checking to make sure you had the updated valving

Does that valving sound ok for what I am doing?

BamaTJ · Sep 8, 2008

Beyer said:
Does that valving sound ok for what I am doing?

For crawling and some full throttle bumping yes, for professional bouncing you could probably up the compression valving to .10. If you can covert it over to Fox numbers then 50/90 or 60/90 is a good range for your rig.

TwinStick · Sep 9, 2008

What are your numbers. If you shoot for about 80% AS number you will be in the ballpark. You definately have an antisquat problem.

We were trying something new with our stock mod rig. We tried running 140% AS. There is a reason why people don't run numbers this high. It humped rocks like it was it's job. We LOWERED the lowers on the frame end, to give more vertical seperation. I think we lowered the lowers 2.5" and our AS number went down to about 89% and was an absolute world of difference. It hardly ever bounces unless you are near verticle hard on the throttle with lose traction in the rear.

I was having the same problem with my jeep as well. I was running 104% AS and lowers the uppers at the axle end 1" which brough my number down to 96%. This also made a huge difference.

TwinStick · Sep 9, 2008

With all that said though, it does look like your uppers are too high. Run the numbers and post the spread sheet.

Beyer · Sep 9, 2008

It is just me and the little one tonight, so I will take another look at it tomorrow. I will try to get some numbers, but I thought I remember that by raising the uppers at the chassis, it lowered the AS.??? :dunno:

Jimmy, I will try to call you tomorrow.
I am headed to Clayton Thursday night and hope to start making some changes next week.

vanguard · Sep 9, 2008

Just by eyeballing it, I think you might have a negative anti-squat (instant center behind the axle). That should cause your chassis to lower when you're getting on it. In theory that shouldn't be a problem, it's when it rises and drops that you normally have the bouncing problem. Having said that, a negative anti-squat may be too much of a good thing.

I watched the first video over a dozen times now. I think it's going to be hard to control the bounce with those tires. That's probably the first place I'd look although the links might be part of the problem too. I wish their was a cheap and easy way to test changes but I can't think of one.

Beyer · Sep 25, 2008

OK, I am going to try to get back on this project this weekend.
I know we talked about shooting for a flat upper link at ride height, but is there any problem with it nosing down a little if I can get that much seperation at the axle? I might be able to add 2" at the axle and then drop the front 1"-2" and this might actually put me into a nose down scenario.
Bad idea? Should I go flat and no more?

kid rok · Sep 25, 2008

My uppers are lower at the frame side. It seems to work great as of now.

P · Sep 25, 2008

Beyer said:
OK, I am going to try to get back on this project this weekend.
I know we talked about shooting for a flat upper link at ride height, but is there any problem with it nosing down a little if I can get that much seperation at the axle? I might be able to add 2" at the axle and then drop the front 1"-2" and this might actually put me into a nose down scenario.
Bad idea? Should I go flat and no more?

Have you contacted Jimmy with EOR with numbers ? That cat can fine tune a suspension like whoa , when a guy like that offers to help , jump on it !

Beyer · Sep 25, 2008

P said:
Have you contacted Jimmy with EOR with numbers ? That cat can fine tune a suspension like whoa , when a guy like that offers to help , jump on it !

No, but I will. I just want to be sitting in front of the buggy with a tape and welder when I do. I am just trying to get a feel for what I should be shooting for.