bouncing and washing up track

[outlaw4j]

was watching Eldora some over the weekend and noticed a lot of cars get into some chop and would bounce and wash up the track getting tight. others seemed to be getting through it pretty good. what in a DLM causes this?

we dont run a DLM but have a mod and had the same exact issue at a new track to us this weekend. we were not exactly sure what we had going on...and still exactly dont to be fair

[MasterSbilt_Racer]

The rf is balls deep in a bumpstop and the lr has links at 55 degrees, holding the chassis up. There's nothing to give, but the tires.

[MasterSbilt_Racer]

Aero dependent cars can't handle rough surfaces, because they have purposely limited useable suspension ranges.

[Jking24]

All of what masters said but basically some guys are better any positioning their car to better handle hitting the hole. Or missing it all together

[Kromulous]

Hard pucks over a christmas tree style bump, the ramp up on some of the pucks is just to fast.

[KTMLew]

Only one of you came close to explaining why 4-5 cars float thru the bumps. HTF has always had issues with bouncing which induces a push both in Capitals & Longhorn. Different shock packages.

I believe it's the combo of bump stop AND shock valving. Mainly high-speed rebound.

[MasterSbilt_Racer]

Only one of you came close to explaining why 4-5 cars float thru the bumps. HTF has always had issues with bouncing which induces a push both in Capitals & Longhorn. Different shock packages.

I believe it's the combo of bump stop AND shock valving. Mainly high-speed rebound.

It's pretty close to impossible to effectively absorb the energy input involved with the limited amount of shock travel available. If these cars didn't have such a flimsy tire on them, it would be scary. You can only have so much rebound before you simply pull a tire off the track.

[outlaw4j]

do DLM's run LF limit chains, or other types of LF travel limiters? At times it looked like it would bounce the whole front up dumping all the load to the rear putting them into a straight drive push.

i thought maybe some of them that were getting through better were able to keep the LF on the ground better in the chop.

[billetbirdcage]

Yes, they do^

[billetbirdcage]

Hard pucks over a christmas tree style bump, the ramp up on some of the pucks is just to fast.

While true, many are also just running too close to hitting the frame on the ground. Catch one of the ruts or bumps at the wrong time or way, and the frame can bottom and you lose the front end completely. Even with not bottoming the fame, if your turned far enough right it's possible to hit the right side rack clevis into the ground and lock up the steering for a split second.

A lot of this is getting worse as the years go on? WHY? It's do to the way the cars are stuck from aero and the way the cars are driven now. It starts with qualifying as everyone is in the fastest line letting off or blurping the throttle in the same place on turn in. This digs a hole or bounces the cars and they make a dip or hole in the track as the night goes on. That bounce makes another one right after the first where the cars land and just keeps going, where you have 3 or 4 dips in a row.

Turns 3 and 4 have always been worse then 1 and 2 at eldora because of the lane haulers enter the track to the infield. This hump/dip/area is really close to where you lift, (so if you lift when you get launched from that dip) at the wrong time the front end dives as your car comes down and make the RF travel father and may over travel and hit the ground or become solid from rigid RF spring/bump rate. This totally upsets the car and make it do several hops which in turn digs more holes in track.

Hope that all made sense.

[outlaw4j]

Yes, they do^

out of curiosity how much drop do they run on the LF? Is this something guys adjust much or more of a set and forget on them?

[KTMLew]

out of curiosity how much drop do they run on the LF? Is this something guys adjust much or more of a set and forget on them?

Noticed lot more cars lifting LF last few months. Not like the left side "short/straight panhard rod" days but definitely more prevalent.

I'm gonna say about 6 cars don't have the bounce thru the holes issue. Guess where they run most weeks? Position 1-6.

[billetbirdcage]

out of curiosity how much drop do they run on the LF? Is this something guys adjust much or more of a set and forget on them?

Obviously it varies car to car or team to team but 1" to 2" over ride height is pretty typical with average being closer to the higher number.

Some will set and forget and others may adjust thru the night or with the speed of different tracks.

[Henry Every]

To me it seems like the HTF guys are more comfortable driving adjusting to slick/smooth situations like their home track or All-Tech. It seems whenever its big and fast or the track changes a lot during the night that they struggle to keep up with the changes. The really good teams setup wise, the 1-6 mentioned above know how to adjust the setup, line and driving style to suit conditions the best. But just like explained above, todays so called, "sophisticated" cars aren't really built with rough conditions in mind, too many solid or nearly solid links in the suspension system to handle holes and rutts efficiently. I doubt the LF would help very much to compensate a RF thats just to stiff and too short of travel. The wheel load just spikes so quickly it destroys/sheers the contact patch on the RF and away goes the nose up the track, add in a solid j-bar and they are lucky they don't eat the fence more often. A good ole Rayburn swingarm would eat those holes and rutts up that send Rockets and Longhorns headlong intro the wall these days. JMO

[KTMLew]

To me it seems like the HTF guys are more comfortable driving adjusting to slick/smooth situations like their home track or All-Tech. It seems whenever its big and fast or the track changes a lot during the night that they struggle to keep up with the changes. The really good teams setup wise, the 1-6 mentioned above know how to adjust the setup, line and driving style to suit conditions the best. But just like explained above, todays so called, "sophisticated" cars aren't really built with rough conditions in mind, too many solid or nearly solid links in the suspension system to handle holes and rutts efficiently. I doubt the LF would help very much to compensate a RF thats just to stiff and too short of travel. The wheel load just spikes so quickly it destroys/sheers the contact patch on the RF and away goes the nose up the track, add in a solid j-bar and they are lucky they don't eat the fence more often. A good ole Rayburn swingarm would eat those holes and rutts up that send Rockets and Longhorns headlong intro the wall these days. JMO

Love the reply. Who gonna be the first guy to try swing-arm stuff again? I'd bet the straight axle guy. AK.

Just add some extra brackets and carry the stuff with you for those nights when the track has "character".

Wonder why the canti-lever stuff never seemed to work? Shock was pointed at rear bumper.

[KTMLew]

Rayburn swingarm or a knock-off?


https://www.motortrend.com/uploads/s...ound%7C875:492

[KTMLew]

https://www.motortrend.com/uploads/s...sion-guide.jpg

[MasterSbilt_Racer]

Love the reply. Who gonna be the first guy to try swing-arm stuff again? I'd bet the straight axle guy. AK.

Just add some extra brackets and carry the stuff with you for those nights when the track has "character".

Wonder why the canti-lever stuff never seemed to work? Shock was pointed at rear bumper.

Cantilever cars worked. I run a z link every week. It's swing arm with the coilover on the cage.

Cantilevers suffered from too little understanding, too much adjustment, and no shock adjustment to accompany the wheel rate changes.

[MasterSbilt_Racer]

Rayburn swingarm or a knock-off?


https://www.motortrend.com/uploads/s...ound%7C875:492

Hard to say for sure. My guess is a Rayburn with some extra fabrication.