Went to my 2nd Mud Drags last week and noticed a HUGE difference in the way the racers had their suspensions tuned.

Most were, IMHO, set up way too stiff and virtually bounced down the track. One even bounced out of the ruts, got sideways, and rolled (Driver crawled out, he's OK).

The faster trucks squatted when they hit the power and stayed there all the way through the traps. So, it's a no brainer on what it takes to stay planted.

As a muscle car motor head, that tells me they've got virtually no damping on bump, and lots on rebound...

I'm thinking of building a truck to mud race with, so I did some searching online. Where can I find bump/rebound specs for various shocks? Or are there obvious choices that the other guys just didn't use?

Thanks.

 

those bilsteins with the remote reservoirs are sweet but a lil pricey. check with monsterbaby he does mud races!

-cutts-

 

time for 4 link and coilovers....but yeah check with monsterbaby

 

Go to the junk yard grab a few different sets of worn shocks for your truck, That's the low budget way!! http://store.summitracing.com/partde...5&autoview=sku
or you can do it this way!! which is the way I would go and make sure you have a lot of droop in the rear springs you want the rear end to drop into holes(to maintain traction) and the front end to float over holes(making a smooth skid/skim plate for the underbody area) For the rear end you would want say 6 inches of up travel and 8 inches of down travel for a total of 14 inches of travel. You may have to c notch your frame to get the travel you need, But it would be worth it!! You are right most of those guys over spring and over shock thier rides and wonder why it won't cut it! Get a real remote control truck and play with spring rates, shock oil weights, piston hole diameters and shock angles even play a part in the handling of the vehicle. The Rc trucks are just as complicated and everything you use on the big ones can be used on the little ones and versa vice!! Or get a dirt bike and that race tech revalving kit for the front forks and change out the shims and see the difference they make!! Actually just use some motorcycle forks for your shocks you could get that kit and different weight oils to customize the handling. That would look wild some giant shocks(forks) stuffed under your truck!! I got a set off ebay for my Yz because I lost a tiny part that at Yamaha was like $200.00 for the damper rod assembly, I got both forks off ebay for $75.00 that is a big price difference!! I am going to revalve those forks for motocross since mine are set up for hare scrambles!! Jeez see what you get me talking about shocks and handling and I can't shut up!! It can really make a difference, In dirt bike racing if the bike isn't set up right. You will be tired before the race is over, because the bike worked you, instead of the bike working for you!!

 

Squating under accceleration is probably not the way to go. It may appear that the suspension is soft, and there could be some truth there. However, the decrease of heigth in the rear of the truck is not an indication of traction. The fact that the back goes down does not mean that the truck is "hooking up". This is an indication of a vehicle that the axle is lifting and is out of control.
Think of this; Is the vehicle pushing the axle down, or is the suspension compressing and removing traction from the rear end?

Dampers have very much to do with a combination of spring rates, traction, and vehicle weight. There are wheelbase and terrain considerations to consider, so trying to narrow down an exact shock will be difficult.
I would be willing to bet that most of the guys with a suspension that is too stiff, would really not gain too much by decreasing rebound or compression. Too much spring negates a decent damper.
Interesting deal trying to find a compromise between suspension pre-load and the proper damper.

 

Now, I may be a noob/wannabe when it comes to mudding, but not when it comes to racing.

When a vehicle accelerates weight is transferred to the rear whether you want it to or not. That weight is going to cause the springs to compress, or what I describe as "squatting." RWD racers on drag strips have suspension setups that 'encourage' this weight transfer with shocks on the front with little rebound damping that allows the front to lift. FWD racers do just the opposite. Road racers want stiffness on the front so the suspension 'sets' quickly while turning, and typically soft (at least in rebound) on the rear so that the inside rear tires stay planted (loose is fast).

I tried to describe in words what I saw on the track, and maybe 'squat' isn't accurate enough. The important part is that the fastest trucks did "hook up" and didn't bounce down the track. The slower ones seemed to be on either stiffer springs (and I mean MUCH stiffer springs) or were over damped on the bump side because they virtually "bounced" down the track.

Stiffer springs and shocks may help on the highway, when racing a car on a road course, or when towing, but certainly not on an off road track. Watch a professional off road race where the trucks get significant 'air time.' When they land they 'stick' to the ground, not 'bounce' back into the air. They are heavily damped in rebound.

So how does one discern the difference when buying shocks online? Where are the bump/rebound specs, and what should they be for off road racing (vs. off road touring)? And, if the information isn't readily available, what are the types being used by the veterans?

Thanks.

 

If you are talking about CORR type trucks, then you are stepping up the $$ big time. They spend a LOT on their shocks. The shocks on those trucks are coilovers with multiple valving adjustments for both droop and uptravel.

I would get a good set of adjustable shocks for your truck and you can set it up however you want.

I have been running a set of Procomp MX6 (the only good thing PC has made) on my rock crawler and love them.

 

Whoa. Look what I found...

http://www.4x4review.com/feature/shock-genius.asp

Wonder what types of arguements you could stir up with this??

 

I've been running mud trucks for years and a big key is being able to flex the frame/suspension to keep traction to the ground. There are some people that add crossmembers to their trucks to stiffen the frame only to find that they loose traction in the hole. Where in the street drags, suspension travel is limited due to the smooth surface. In the mud, no hole is perfectly smooth, so you need to keep that travel. It doesn't need to be a huge amount of travel, like a rock crawler, but enough that you keep all the wheels on the ground. I run the Pro Comp ES9000 shocks on my F-150, and have no problems keeping traction. Over the winter, when I build my new racer, I am going to coil overs at all corners with 79 F-150 radius arms front and rear as they act as ladder bars, but allow me to stay in a "stock" class. This will be on a full size Bronco frame so I can keep the frame flex. If you can get away with it, go with either a 3 link or 4 link setup (just like a street drag car) as it will still give the good traction and some suspension movement. Another key is obviously wheel speed. The faster you can get those tires spinning, the more you can get on top of the mud and get through the hole. There are some people that run different ratios front to rear (the front being a higher/numerically lower ratio) so that the front "floats" pulling the truck through. It works, but you have to be careful if the truck is in 4wd on hard dirt or bad things will happen.

 

You need to get shocks with both compression and rebound adjustability!! Did you check the link? That is the most cost effective way to go for a mostly street truck. Optimal would be what I said with c notch and 14 inches of travel!! You need to have sag a truck sitting at the top of it's travel looks like it could do anything, But get him out in some rough fire roads and he will be crawling complaining he can't see straight. Look at a baja race truck or a stadium truck, I bet you can take one of those and fly through any mud pit in this country!!

 

That is EXACTLY what I was talking about.

 

mx6's suck ***** compared to other adjustable shocks out there about the same price....chit even the ranchos are better...that **** dont barely do chit...

 

Hummm.....maybe the difference is the weight of the vehicle. I put them on my Jeep and they are perfect. The Ranchos were horrible....

 

i only had mx-6's for about a week and decided they were not worth the cost so i traded them for somthing....id realy like to try the bilsteins, ive heard good...

 

Yeah, I have heard the 5100 series were pretty good.....but $$.