custom suspension question

[autox19]

so working on my locost planning. I noticed that most Formula cars (and quite a few locost) have the heim joints horizontal. with a few locosts and most off road that them vertical for the A-Arm to frame mounting. I know people here seem to be able to word things that makes my old brain understand. so any one know the answer which way should I do it? this will be a low street car.

Odie

 

[Rupunzell]

Note the long suspension arms on many open wheel "formula" cars, this coupled with not a lot of suspension movement and long suspension arms means the angles at those spherical rod ends are not going to be much. Typically a few degrees at the spherical rod end. This horizontal mounting of the spherical bearing bracket is related to the bracket anchoring points to the chassis which tends to be an advantage with the bracket configured as horizontal.

Also note, majority of small formula cars use a 0.250" diameter AN/MS/NAS bolt in double shear with a bracket sheet thickness of maybe 0.90" thick material. This joint calculates to about 4,000 pounds pull out (figure about a 1,000 pound car), which will not happen unless the car hits something solid and hard... resulting in limited damage to the chassis.

And spherical rod ends are not created equal, the good ones have a fiber reinforced liner (typically teflon or similar), staked to limit free play and meets aero specs. The common industrial/commercial spherical rod ends are Poooo for this application as they have WAY too much slop/play for accurate suspension movements.


Bernice

 

[autox19]

Note the long suspension arms on many open wheel "formula" cars, this coupled with not a lot of suspension movement and long suspension arms means the angles at those spherical rod ends are not going to be much. Typically a few degrees at the spherical rod end. This horizontal mounting of the spherical bearing bracket is related to the bracket anchoring points to the chassis which tends to be an advantage with the bracket configured as horizontal.

Also note, majority of small formula cars use a 0.250" diameter AN/MS/NAS bolt in double shear with a bracket sheet thickness of maybe 0.90" thick material. This joint calculates to about 4,000 pounds pull out (figure about a 1,000 pound car), which will not happen unless the car hits something solid and hard... resulting in limited damage to the chassis.

And spherical rod ends are not created equal, the good ones have a fiber reinforced liner, staked to limit free play and meets aero specs. The common industrial/commercial spherical rod ends are Poooo for this application as they have WAY too much slop/play for accurate suspension movements.


Bernice

First, I was hoping you would be one to reply (along with others) . so it sounds like As a plan this I need to know if the bracket is going to be horizontal or vertical and I need to know the amount of expected play before I decide to go one way or the other. I also will need to look for the high quality ends as you pointed out. I think there are lists on the losost forum, but honestly I trust the people here more.
I am still bouncing around what I am going to end up with. I have looked for used formula cars and they are higher than my entire budget or really close to it and that is without doing any modifications to the car to make it street legal. Building is the way I am going. It also will occupy me for a longer time. That tends to make my wife happy as I get twitchy without projects.
Current ideas:
Single seat like a formula
Longitude mounted (but hard to find a transmission)
Transverse mounted using FWD
Dual Seat Front to back
Triple Seat (saw one with a google search) front center, 2 passengers side by side behind driver in a "Y" pattern
Standard Lotus locost Front engine.




Odie

 

[Lowtechprime]

Spherical joints, even expensive Teflon lined ones don't last long on the street. I've learned that the hard (costly) way.... For a street car, you're probably better off with urethane or Delrin bushings.. I still have spherical joints for my front suspension and steering in the 128, but just know that they need to be replaced often. The Delrin bushings in the rear suspension are 7 years old now and unchanged from when they were installed....

 

[Steve Thomas]

If the bolt thru the rod end is vertical, you only have 10 to 15 degrees of articulation before the joint binds/dies. If the bolt thru the rod end is horizontal, you have unlimited articulation - full 360 degrees. In the case where the bolt is vertical, detail design is critical. The articulation limit the OEMs specify is within the rod end geometry - no provision for how it might get mounted. The body of the joint has to have room to move and the outer diameter of the ball at the mounting face is also a limit. This is why you see tapered and or stepped mounting spacers and bushes..

 

[Rupunzell]

First, I was hoping you would be one to reply (along with others) . so it sounds like As a plan this I need to know if the bracket is going to be horizontal or vertical and I need to know the amount of expected play before I decide to go one way or the other. I also will need to look for the high quality ends as you pointed out. I think there are lists on the losost forum, but honestly I trust the people here more.
I am still bouncing around what I am going to end up with. I have looked for used formula cars and they are higher than my entire budget or really close to it and that is without doing any modifications to the car to make it street legal. Building is the way I am going. It also will occupy me for a longer time. That tends to make my wife happy as I get twitchy without projects.
Current ideas:
Single seat like a formula
Longitude mounted (but hard to find a transmission)
Transverse mounted using FWD
Dual Seat Front to back
Triple Seat (saw one with a google search) front center, 2 passengers side by side behind driver in a "Y" pattern
Standard Lotus locost Front engine.




Odie

Instead of building from ground up, consider converting a Spec Racer Ford (SRF) or Sport Renault roller (no power train) chassis to convert to a street car. Typically street cars needs fenders to be road register/licensable.. Open wheel cars become a challenge to do this, bodied race cars already have "fenders"...

Spec Racer Ford - Wikipedia

en.wikipedia.org

Bernice

 

[autox19]

Instead of building from ground up, consider converting a Spec Racer Ford (SRF) or Sport Renault roller (no power train) chassis to convert to a street car. Typically street cars needs fenders to be road register/licensable.. Open wheel cars become a challenge to do this, bodied race cars already have "fenders"...

Spec Racer Ford - Wikipedia

en.wikipedia.org

Bernice

Please see what I already wrote. I have been looking and nothing in my budget. I would much rather convert.

Odie

 

[Steve Thomas]

Converting a circuit car for road use is also easier said than done. You would have to raise the ride height a fair bit which will destroy the suspension geometry and may well result in rod ends outside their limits too. Will certainly put you outside whatever the designer had in mind so all bets are off as far as roll centres, camber change etc are concerned. That sexy bodywork will look very odd when the wheel centres shift down as you raise the car The path you are already on is probably best