Professional Rock Bouncers/Builders - Advice needed

[Beyer]

Sometimes when I am getting on it to climb a hill with a ledge that I have to bump/bounce over, it starts a chain reaction of bouncing that SUCKS! I will post a few videos of what I am talking about and pics of my 4-link. I run SAW coilovers with stock valving. I run about 5 psi in the rear tires and 6 in the front.
I watch videos of the southern boys and alot of them take the initial hit and then the rear tires plant and either dig or hook up, but don't bounce like they are on leaf springs.

Do I need new valving in the shocks to slow down the rebound and/or compression?
Do I need to change my 4-link?
Do I need to get a tire with less sidewall flex?

Video of Rollover Hill at Disney. The beginning shows it very clearly, but worse than normal:
http://www.youtube.com/watch?v=3uOkmXul0LY

Video of 6A at Falt Nasty (T.C. popped out of gear 4 times):

Pics of the rear Suspension...

Front (if it matters?)....

 

[BamaTJ]

Where did you get the shocks? Stock valving from SAW is pretty stiff as it is. But some vendors like Poly get custom valving

 

[rock mafia]

Based on your pics, it looks like you have more vertical seperation on your links at the chassis, than you do at the rear axle.

 

[1TONZR2]

it looks like when you suck down the front end, it didnt bounce as much....dunno why though. definately would want to get that taken care of, thats a parts breakin bounce.

 

[Cole]

I know one big thing Bryan Cole always talks about is the Valving in his FOX shocks. He swears by Fox Shocks and talks about how it makes a lot of difference.

 

[Beyer]

I know one big thing Bryan Cole always talks about is the Valving in his FOX shocks. He swears by Fox Shocks and talks about how it makes a lot of difference.

Wonder if he could tell me how to make the SAW's work like the FOX's?

 

[Beyer]

Based on your pics, it looks like you have more vertical seperation on your links at the chassis, than you do at the rear axle.

Yes, they are very close to parrallel. Would this cause this scenario? It made my numbers better in the 4-link calculator and I had room, so I did it.
I asked Triaged on Pirate about parrallel upper and lower links, and he said it did not cause any ill effects, but I have always wondered why I NEVER see any other rigs built like this. There must be a reason, but I have never heard it talked about. I know some people have problems with too LITTLE vertical seperation at the chassis, but never heard anything solid about too MUCH seperation.

I do not mind moving the mounts down on the chassis or putting taller tabs on the axle (I have a little room to spare), but do not want to waste my time if it will not help my issue.

Thanks.

 

[Beyer]

Where did you get the shocks? Stock valving from SAW is pretty stiff as it is. But some vendors like Poly get custom valving

Yes, POLY. I would rather have the shocks a bit stiffer and not bounce than have a softer ride. :-\
Maybe I can call poly and ask them about the valving.

 

[BamaTJ]

Call Poly and ask them about the valving on SAW's they use.

 

[InDaShop]

I dont think that has anything to do with the coilovers. On that 1st vid on Rollover Hill that thing goes into HUMP mode immedately. Just looking at pics it is so hard because they throw everything out of whack. But I would think you need a LOT less vertical seperation on the front and rear axle.

 

[rock mafia]

I dont think that has anything to do with the coilovers. On that 1st vid on Rollover Hill that thing goes into HUMP mode immedately. Just looking at pics it is so hard because they throw everything out of whack. But I would think you need a LOT less vertical seperation on the front and rear axle.

I agree. Valving is not the problem, it may contribute some, but not that much.

I have never used any of those calculators, I doubt most big time builders do either. I just go by what I think looks right, no complaints yet. I generaly want less seperation at the frame than at the axles. Anywhere from 30-50% less. I would not worry about the front, yet. Looks like you could lower the upper chassis mounts pretty easily, I'd start there.

 

[Beyer]

Thanks guys, I will start with lowering the uppers at the chassis.

MAtt O, didn't you just add vertical seperation at your chassis. Did Dan mention what he shoots for at the chassis when you were there?

Also, is there such thing as too much horizontal seperation (too much angle)?

When I built thius buggy, I went with as much seperation as I could get vertically and horizontally. I think now I FAILED on the vertical seperation on the chassis end, but what about too much horizontal seperation. Such thing?

I have heard you need at least 40 degrees to hold the axle in place, but how much is too much?

 

[kid rok]

I would lower my uppers at the frame. Make an adjustable bracket then you can set it where you want.

 

[rock mafia]

Also, is there such thing as too much horizontal seperation (too much angle)?

When I built thius buggy, I went with as much seperation as I could get vertically and horizontally. I think now I FAILED on the vertical seperation on the chassis end, but what about too much horizontal seperation. Such thing?

I have heard you need at least 40 degrees to hold the axle in place, but how much is too much?

I don't like the way your lowers are mounted, but that's just my opinion. I don't think that has anything to do with your humping problem. Jimmys, BTF and others do it that way. I prefer to have the lowers angled less so they slide up/down rocks instead of hitting them more sideways.


You don't have to have 40 deg, esp on both sets of links. My personal buggy had nowhere near that on the front, top or bottom, and it worked ok. The joints just have to work harder to keep the alxe straight, and when they get loose, side to side movement of the axle is more noticable.

 

[BamaTJ]

Beyer I had no vert sep at the frame on mine so I had to add a few inches. Mine has about 5 inches now and it made a huge difference. I have more at the axle end on mine

 

[wngrog]

Them there Monster Truck tars on 15" wheels are a cause for some bounce. It is hard to work the tire wrap/bounce out of a swamper on 15" wheels.

That said, that is not your sole cause, but even the best setup will get you some bounce with those "Big Naturals"

 

[blacksheep10]

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.

 

[Josh Bishop]

Put ya a tight limit strap on there and it wont let the suspension unload like its doing. Bryan runs tight limit straps on all his rigs.

 

[Beyer]

Put ya a tight limit strap on there and it wont let the suspension unload like its doing. Bryan runs tight limit straps on all his rigs.

I run a limit strap, but with 3-4" of slack. I like to have the droop when crawling over obstacles, especially with 115" wb and 23" belly.
I also like to have the whole axle be able to drop when going fast through the whoops, so I can take advantage of more of the suspension.
Does he run the limit strap tight soley for the purpose of eliminating hop?

 

[Beyer]

Them there Monster Truck tars on 15" wheels are a cause for some bounce. It is hard to work the tire wrap/bounce out of a swamper on 15" wheels.

That said, that is not your sole cause, but even the best setup will get you some bounce with those "Big Naturals"

Yeah, that is why I threw that possiblility in there. May be something I have to live with until a deal on some 17" wheels and sticky Iroks comes around.