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Discussion Starter #1
When figuring out wat front springs to use with the bump stops are they typicly softer springs or harder springs?
 

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this must be a highly secretive topic, Area 51 stuff, there must be intrest in this cause i got well over 100 looks in 12hrs.
 

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Not sure it's so secretive..jut not really a clear-cut conclusion they they're better. Like the sway bars from 4-5 years ago, it was something that surfaced last year and some guys tried. If you're going to experiment, I'd start with softer springs than you normally run and be careful with the sag. It's tough to pinpoint how much work the bumpstop is doing and to what degree you want it to "impact". You can use firm o-rings or nylon stops on the kingpin, graphite/screw method that hinders the upward travel of the upper arm...or whatever you dream up.
The most agreed upon impression was that your car must be pretty close without it and only use the bumpstop for the final tweak.

JMO

dk
 

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Not sure it's so secretive..jut not really a clear-cut conclusion they they're better. Like the sway bars from 4-5 years ago, it was something that surfaced last year and some guys tried. If you're going to experiment, I'd start with softer springs than you normally run and be careful with the sag. It's tough to pinpoint how much work the bumpstop is doing and to what degree you want it to "impact". You can use firm o-rings or nylon stops on the kingpin, graphite/screw method that hinders the upward travel of the upper arm...or whatever you dream up.
The most agreed upon impression was that your car must be pretty close without it and only use the bumpstop for the final tweak.

JMO

dk
Dusty pretty much nailed this one on the head. There are several different way's of going about it. And there is no clear way that is better then the other. It's just something your going to have too play with and learn for your self.

Jason
 

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There is a good thought that harder springs would allow for a less of abrupt change. I like this theory, as it has merrit, at least on paper. If you were to look at the resistance graph, a harder spring would have a more gentle curve.

I've done a lot of track testing with bumpstops, and I've found that it doesn't seem to matter much as you'd think, even if the bumpstops are rigid. This is because there is some flex to the chassis. When you push up on your suspension, you can see the flex in 3 areas: where the lower arms connect to the 8-32 chassis screws, chassis area between the LF and RF, and also the lengthwise flex of the chassis (when the belly of the chassis bows).

Bumpstops can be used for 2 things.
#1. They can be engaged slightly, just enough to prevent the chassis from bottoming out. This alone is worth having bumpstops. When you get black on the bottom of your chassis, you are scrubbing speed, either through the added forward resistance, or loss of side bite.

#2. Bumpstops can be engaged harder to be used as an added tuning aid. You can use them to help individually control the specific point in the corners where each tire is pressing hardest on the ground. They can also help control chassis roll, but should not be used as a crutch for a poorly set up car. (ride height, wedge, weight distribution, side shocks, tire compounds, RF springs, among other things are all factors in chassis roll)
 

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FWIW -- there is another way to have a "bump-stop".

Take the stock Associated springs, the small ones, and run them on the inside of the bigger Wolfe, RC4Less, Windtunnel or whatever flavor spring you are running. This is not near as abrupt as the stops on top of the A-Arms.

All in all, do yourself a favor and only play with these when the sled is dialed and you are looking for that little bit more. NOT when that puppy is out in the weeds and won't turn in a 40 acre field.
 

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as james said chassis flex comes into play withe the bumpstops .if your car is real rigid and doesnt have much chassis flex then you will find it harder to tune the bumpstop.also as scott said dont even mess with it if your car is not dialed.if you do you will be out to lunch until you back it completely off and rethink your overall setup.i have been using one for a while now and when the car is good i only run about .30 to.40 thosanths of travel on the right front i ran it on a le future and now on a hd 3.1 and my brother also runs the same on his mcpappy seems to work pretty good.personal prefrence mostly.just my .02
 

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this must be a highly secretive topic, Area 51 stuff, there must be intrest in this cause i got well over 100 looks in 12hrs.
i would like to explain why we run bump stops in nascar so all will understand. when Nascar started implementing both high and low ride hight rules around 1999 thats when all learned that the tire data could start incorperating downforce for the grip of the tires. they learned that the attitude of the body out waid the mechanical grip...so they invented what was called coil binding a spring. wich meant traveling till all coils bottomed out. wich was done by having soft springs and a ton of rebound in the shocks wich would hold the cars down. so the car when at speed would stay nose down ass up and make a ton of down force more grip than they could get from even having the chassis right put both together and you are gaining maximum grip. now they cant run the same springs to soft and to much change in speed during a tire run so travels changes and kills downforce (COT)so Nascar lets them have bump stops to stop the travel wich is better than coil binding springs where they were one run at 5000$ at a time go Hendrick lol. they would colapse but good for pre tech and good for after tech because tire pressure would raise the front. just a little inside scoup. so back to bump stops wich is a bunch of rubber shims stacked around the shock shaft to hold ride hight as it bottomed out all the way around the track a lot LESS GRIP but down force made more grip than the right spring rate low front high rear = more down force wich over rides chassis grip. we can already run low front high rear and make better grip so you make your own decision hope this helps and save someone some money .
 

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i looked at G honeys ride at the birds and seans...no bump stops....i saved some money...the damn geico theme song started playing and it threw a tire at me!
 

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Another reason I'm happy to have a job in Grand-Am... we don't have to deal with stuff like that with DP's... LOL
 

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Discussion Starter #14
Wow great insight Roman Pemberton, I feel special having a Nascar Official coment on my topic, thx for the insight and feedback, and thanks to evreybody.
 

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The big thing to keep in mind, is, while some things carry over from real
to scale cars, everything does not carry over.
Nor are they necessarily done for the same reason.
 

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when in rom..an do as the romans do!
 

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bumps stops

ive worked on DP's too and we ran bump stops everywhere:) the indycars are a different story and probly dosent apply at all. on the ovals we run no bump stops at all but on the roadcourses we are constantly changing packer gaps...hard nylon shims as well as the softer bump rubber. but what was said about the cot cars and the coil bind probly is the most relavent to rc.
 
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