Tomcat Nev Posted May 27, 2006 Share Posted May 27, 2006 Sat in bed this morning (still) as for once i am in England and not working, thinking about Air Bump Stops. I know Steve of this forum has used them, is there any one else?? I am interested to find out whether the kind of donkey kicking i get with rubber bump stops might be eliminated and how best to mount them............... Nev Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted May 27, 2006 Share Posted May 27, 2006 Still in bed?? No wonder you miss so many races. As you know I am a fan, Simon Haycock, last years BORC class 7 winner and former AWDC class 7 winner also has them. Rick Mann, last years AWDC no. 1 winner, was using them on an indy until he changed his shock set up, and speaks highly of them. Less bangs for your bucks Quote Link to comment Share on other sites More sharing options...
Tomcat Nev Posted May 27, 2006 Author Share Posted May 27, 2006 I am up now and about to take the Hooligans to the cinema! So, the thing i am unclear about is the damper tuning. I assume that with the air bump stop having a greater travel the rebound force will be less per unit length and thus dampers set for rubber bump stops will have a greater amount of rebound damping than necessary????? Also, what actually stops them bottoming out? i.e. enough force and your can compress a gas into liquid.......................... bit extreme, but do they have them selves an internal bump stop??? Nev Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted May 27, 2006 Share Posted May 27, 2006 I suspect your right about being able to have less rebound damping, rather depends on whether you had it 'right' in the first place. I had fairly light rebound on the front and ended up with Milners recommended Tomcat settings for the rear in a car weighing 450kg more. My main criteria with the settings on the rear was that it didn't kick up on landing. The bump stops work progressively, the first inch and a half doing very little. They have a piston in similar to a shock absorber. As to what happens on full bump, dunno, was quite content that they worked and I never had a crash landing even when misjudging a jump. There is a little neoprene ring on the outside. I took Wildcat owner Rich Squires on a couple of laps once and he said it was like a magic carpet compared to his. Quote Link to comment Share on other sites More sharing options...
Tomcat Nev Posted May 27, 2006 Author Share Posted May 27, 2006 Hmmm, Sounds like i might investigate these for mine then! Have you patented your mounting system for them? Where did you get yours - Milners??? Are they Fox?? Nev Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted May 27, 2006 Share Posted May 27, 2006 Have you patented your mounting system for them? Where did you get yours - Milners??? Are they Fox?? Nev Sadly I didn't patent the mountings, no doubt they are now available in orange off the shelf. I did get Fox ones from Milners but you might want to speak to King Off Road and see how much theirs are. Are you planning to do Minehead with SCOR, there is a small possibilty I might get there? Quote Link to comment Share on other sites More sharing options...
Tomcat Nev Posted May 27, 2006 Author Share Posted May 27, 2006 Dad is flat out finishing it off ready for Minehead - so yes i should be. I am back the week before so can get on the machine myself and get any last little jobs finished. I will try and remember to get out your way.................... Nev Quote Link to comment Share on other sites More sharing options...
simonr Posted May 27, 2006 Share Posted May 27, 2006 Tell me about air bump stops? Where / what are they from? What do they look like? Si Quote Link to comment Share on other sites More sharing options...
rick Posted May 27, 2006 Share Posted May 27, 2006 Tell me about air bump stops? Where / what are they from? What do they look like?Si Si, go here http://www.foxracingshox.com/fox_offroad/offroad_index.htm and click on bump stops. Quote Link to comment Share on other sites More sharing options...
simonr Posted May 27, 2006 Share Posted May 27, 2006 That's a good idea! Are they expensive? Si Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted May 28, 2006 Share Posted May 28, 2006 That's a good idea! Are they expensive?Si They are about £130 each, so not pocket money. However if you want speed suspension is where you need to spend your money. In some circumstances you can run less or smaller shock absorbers so there can be a saving in overall budget. I initially fitted them to the front of my RR to enable the axle to travel right up to the chassis on full bump. I could therefore get 12" of travel on the front without a significant lift in ride height. Landing at Sidbury, photo by Mark Fell Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted May 29, 2006 Share Posted May 29, 2006 Hi guys, I wondered if you might find this thread interesting. there is a few pages of it to digest... http://www.pirate4x4.com/forum/showthread.php?t=347598 Cheers, Al. Quote Link to comment Share on other sites More sharing options...
LR90 Posted May 29, 2006 Share Posted May 29, 2006 That's a good thread Al though they are jus rubber springs and so I'd expect to get more compression under heavy load (landing) than on low speed articulation so to my mind they would limit articulation? Adn on a heay landing they are just springs so might need stiffer damping. But the air bump stops... are thse any different (cushion of air, undamped) or just an more expensive bling alternative/ Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted May 30, 2006 Share Posted May 30, 2006 That's a good thread Al though they are jus rubber springs and so I'd expect to get more compression under heavy load (landing) than on low speed articulation so to my mind they would limit articulation? Adn on a heay landing they are just springs so might need stiffer damping. But the air bump stops... are thse any different (cushion of air, undamped) or just an more expensive bling alternative/ I guess you would expect different deflections for different dynamic loads no matter what bump stops you used? I can't really imagine a case where they deflect the same amount if the chassis is moving at 1m/s vertically or 10m/s vertically. Unless they are rate sensitive? I don't know if the air bumps have any inherent damping, but I would suppose not? Is that not up to the dampers? Is a bump stop expected to extract energy as heat or just provide a force to decelerate the sprung weight towards the end of the suspension travel in a controlled way (i.e. without a back-jarring *BANG*)? I guess I'm asking more questions than giving answers, sorry! What properties do people normally expect from bump stops? Certainly factory ones are springs rather than dampers. Anyway, glad the thread was of some use - air bumps are on the pricey side, I thought an alternative suggestion might be of use. Al. Quote Link to comment Share on other sites More sharing options...
jules Posted May 30, 2006 Share Posted May 30, 2006 The TMC's run them and Tim swears by them. I have not seen them on Beam axle trucks racing that doesn't meen people don't I have not seen them on club level comp racers only national level. Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted May 30, 2006 Share Posted May 30, 2006 I have not seen them on Beam axle trucks racing that doesn't meen people don't For what it's worth, many people certainly run them on solid axle trucks in the states (racing that is, not just rock crawling / offroad). They seem a bit more of a novelty over here, possibly because people generally seem to spend less on their vehicles? Al. Quote Link to comment Share on other sites More sharing options...
LR90 Posted May 30, 2006 Share Posted May 30, 2006 I was wondering if they might be more similar to the air shocks? Might help justify the cost if they were revalvable and you could change the air volume/effective spring rate. They would also exibit a variable spring rate (almost exponential) which would reduce the variation in final bump stop hieght for varying loads. Quote Link to comment Share on other sites More sharing options...
D9OSV Posted May 30, 2006 Share Posted May 30, 2006 Have been looking at these for sometime They look and sound ace. If you look in the states you'll find universal mountings for as little as fifteen dollars Would love to try them But they ain't cheap Jim Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted May 30, 2006 Share Posted May 30, 2006 I think they would be way down my shopping list if I were building a challenge truck but somewhere near the top for a safari racer. They do have some damping effect and soft bump and less rebound are the main attributes. They also gave me an unexpected bonus when racing at Minehead with the AWDC last year. I lost all the oil and bent a shaft on one of my single Fox shocks on the rear on the first lap. However using just the bump stop on the rear I was able to continue and finish a reasonable sixth overall. As I had no spare shock absorber I would have had to retire or slow significantly. Without doubt I would have fitted them to my Warrior had Ohlins not brought out their progressive damping system, which is effectively an integral hydraulic bump stop. Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted May 30, 2006 Share Posted May 30, 2006 A little more input for you guys... This place does 'short' bumps - from 2", 3" or 4" (this may help as one issue with the regular air bumps is their overall length). http://www.radflo.com/Products.asp?MessageID=9 For info, you can reduce the travel of longer ones by opening them up and putting in a metal spacer to take up internal volume. If you then have space to mount them higher, you make them into a stop with less travel (if you want to). Apparently it's a straightforward operation, but I have never done it. A bit of general info here (note the application and how it differs (probably) from your own): http://race-dezert.com/forum/showthread.php?t=2351 http://race-dezert.com/forum/showthread.php?t=3771 LR90 - good point, agreed. Cheers, Al. Quote Link to comment Share on other sites More sharing options...
jules Posted May 30, 2006 Share Posted May 30, 2006 For speed challenge event I would consider them but as you say there a little steep. but bending a axle is steeper. For comp (I run independent for comp) would say they can only be a improvment. Quote Link to comment Share on other sites More sharing options...
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