spring behind axle on lakester

[chambies]

Just starting my belly tank lakester build... I am looking into many different options as far as suspension set up but want to make the most of the wheelbase length. One option I am leaning towards is this spring behind the axle setup by drilling and welding a spring perch into the front wishbones. Does anyone foresee an issue with safety, set up or passing tech?
examples shown here:

http://images.search.yahoo.com/search/images?_adv_prop=image&fr=yfp-t-900&va=front+suspension+rolling+bones

[maguromic]

My 2 cents would be to get rid of the spring and run a torsion bar set up. Build it with off the shelf parts and you an tune it to track conditions. Tony

[Seldom Seen Slim]

Tony:  I think the new photo should be for a different sponsor thanks to location of the logo.  How 'bout "chasm"?

[chambies]

I guess I wanted to stick with a more traditional setup... I am familiar with doing a transverse leaf spring and I know that I would do it safely. However, I just dont want to go that route and later find out that it wont pass a tech inspection for some reason. What about doing a spring behind setup would keep from passing an inspection? I have read that they can ask for magna flux? Rule book doesn't state certain suspensions are banned... seems pretty open.

[Stainless1]

It is special construction, nice thing about those classes is innovation is somewhat encouraged... and mostly tolerated. 
Remember everything you hang out in the air is drag... if you are building to challenge records keep the drag as low as possible.

[kiwi belly tank]

You can pretty much do what you want. If you do a flat spring in the aero shadow of the axle it will eliminate the drag. I actually prefer a solid mount axle, it eliminates pitch & roll.
  Sid.

[WhizzbangK.C.]

I've got no dog in the fight at all, I'm a bike guy. That said, the main problem I see with suicide front ends is the failure mode. If one of the spring perches, spring, or bones breaks or otherwise parts company, the frame drops to the ground and can dig in, hence the moniker "suicide".

The aero advantages of the design are attractive, but the safety aspects need to be addressed.

I think it should be designed with triple redundancy, so that if any 2 parts fail there is still support for the vehicle to roll out to a controlled stop.

Just my .02. 

[chambies]

i seriously doubt I will be competitive as far as records go.... I dont have that kind of money. My goals, for now, is to build the belly tank lakester, get through a tech inspection and make some timed runs at Bonneville. I am not new to building projects but very much a newbie in regards to land racing. I have lots of old for parts and am very interested in the V4F engine class. Thank you for the responses. I will try to start a build thread and keep some pics posted on progress.

[kiwi belly tank]

I've got no dog in the fight at all, I'm a bike guy. That said, the main problem I see with suicide front ends is the failure mode. If one of the spring perches, spring, or bones breaks or otherwise parts company, the frame drops to the ground and can dig in, hence the moniker "suicide".

The aero advantages of the design are attractive, but the safety aspects need to be addressed.

I think it should be designed with triple redundancy, so that if any 2 parts fail there is still support for the vehicle to roll out to a controlled stop.

Just my .02. 

You might want to re-look at a motorcycle front end before you yell "suicide", where's your redundancy there?
A transverse front end is only called suicide if it has no structure above the axle. I've been rodding & racing since the 60's & have never actually seen or heard of a failure.
  Sid.

[SPARKY]

chambies--  pls fill out your profiel  so that we know where you are hiding out 

[WhizzbangK.C.]

I've got no dog in the fight at all, I'm a bike guy. That said, the main problem I see with suicide front ends is the failure mode. If one of the spring perches, spring, or bones breaks or otherwise parts company, the frame drops to the ground and can dig in, hence the moniker "suicide".

The aero advantages of the design are attractive, but the safety aspects need to be addressed.

I think it should be designed with triple redundancy, so that if any 2 parts fail there is still support for the vehicle to roll out to a controlled stop.

Just my .02. 

You might want to re-look at a motorcycle front end before you yell "suicide", where's your redundancy there?
A transverse front end is only called suicide if it has no structure above the axle. I've been rodding & racing since the 60's & have never actually seen or heard of a failure.
  Sid.

Exactly my point, actually. I was just pointing out that he needs to make sure that he has structure above the axle to catch it and prevent the frame from digging in in the even of a failure, and NOT build it "suicide style".

I haven't been rodding & racing nearly as long as you, but I have seen broken springs, shackles, and perches in my time, in custom built and mass produced vehicles.

As far as bikes go, it's a risk that we find acceptable, and if you look at most front end designs, they are way overstressed for the loads they're expected to carry, but I've seen them fail also.   

[jimmy six]

Mine has been that way for 43 years with no problems. Been 216. It's on a roadster. Spring perchs are mounted to holes drilled in the wings welded to the axle, 4-5" dropped tube. Spring eyes are upside down. One side solid. Caster adjusts with the hairpins and tapered shims on the spring mount. Trouble free..................Good Luck