The Morgan Park Track Day Next Friday - 26/11
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Ray Bell said:
Having the springs, shocks inboard would reduces the unsprung mass. On a car that light, reducing unsprung mass by even a couple of kgs would increase performance and handling.
edit: Wow awesome pics btw!
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I am drooling over the Lotus Elan......
Sorry for being rude, but how much does one of these Elans fetch these days?? with the chassis and drivetrain restored
Cheers
Billy
Sorry for being rude, but how much does one of these Elans fetch these days?? with the chassis and drivetrain restored
Cheers
Billy
I think they go for around 30- $35K Billy ! I know of one in the club for sale.
Ironically there now seems to be 3 Lotus owners on Aussie Frogs, Boxhead, Al and myself. Anymore on here ??
cheers JR
Ironically there now seems to be 3 Lotus owners on Aussie Frogs, Boxhead, Al and myself. Anymore on here ??
cheers JR
wow these Elans certainly appreciate over time!!
JR, I didn't know that you also have a Lotus! and please please *begging* let me be a passenger in your Lotus next time I see ya mate
Cheers
Billy
JR, I didn't know that you also have a Lotus! and please please *begging* let me be a passenger in your Lotus next time I see ya mate
Cheers
Billy
Not really... the spring is still the same, and you've added the links that allow the spring and shock to be inboard. And if you use gas shocks you can actually do better with it outboard...
Lotus owners...
Well, the Wuillemin family have one, now Adrian's, but formerly Owen's. And Norm Smith... I don't know if he's registered, but he looks in... he has an Elan S2 or +2 or whatever that bigger model was. Is.
Ray Bell said:
When doing suspension calcs, for the unsprung mass we take the weights of all the wheels, brakes etc, and half the weight of the wishbones, springs, shocks. By having the springs and shocks inboard, you reduce that portion of the unsprung mass. The only extra unsprung mass that is added is half the mass of the one pushrod link that is required to transfer the force to the inboard springs/shocks. The pushrod link weighs far less than the springs/shocks, even gas shockers.
jr20516v said:
Thanks JR!
The only problem now is I have to get back into Australia :disappr: ....I should be back in Oz early/mid Feb for about a week or so.Thanks again JR!!
Cheers
Billy
But you still have to include half the spring and the portion of the shock that's attached. That cannot change. The whole pushrod weight would have to be included... it all moves, after all.
Ray Bell said:
Why do you have to still include any of the spring and shock? They're both inboard and all their weight is supported by the chassis.
With the pushrod, it is pivoted on the chassis and a rocker arm transfers the wheel motion and force to the shocks.
Looking at the attached pic of the inboard suspension layout, moving the wheel up would result in lifting up a weight load consisting of the mass of the wheels, tyres, brakes, kingpin....and approx. half the mass of the wishbones and half the mass of the pushrod (because the other end of the wishbones and pushrod pivot about the chassis and therefore partly supported by it).
With an outboard design, the springs and shocks would be located where the pushrod in the inboard design is located. Therefore moving the wheel up would result in lifting up a weight load consisting of the mass of the wheels, tyres, brakes, kingpin....and approx. half the mass of the wishbones and now half the mass of the springs&shocks.
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I suggest that you don't actually understand what the term 'unsprung weight' means...
It's not a matter of where it's located on the car, it's a matter of whether it moves in relation to the chassis... the term is describing anything that has an inertia effect on the suspension's movement or control.
It's not a matter of where it's located on the car, it's a matter of whether it moves in relation to the chassis... the term is describing anything that has an inertia effect on the suspension's movement or control.
Ray Bell said:
When outboard, the entire body of the damper is lifted (with one end pivoting) when the wheel moves up. When inboard, the entire damper body does not move, but instead the pushrod via the rocker arm translates the wheel movement into a purely axial movement of the damper rod. The associated mass effects in actuating the damper this way is very small in comparison with moving the entire damper body that occurs with an outboard design.
http://www.fraser.co.nz/suspension.html See 2) point 3.
edit: If you look at the attached pic, you can clearly see that with the movement of the wheel, the only part of the springs/shocks that contribute to the unsprung mass (and as you said, have an inertial effect) is the small weight of the damper rod. You can attach a great big 20 kg weight around the main lower body of the shock and it wouldn't make any difference to the unsprung mass because that main lower body of the shock does not move with the wheel. However, consider adding that same big weight if the shock is mounted outboard, and it's obvious that this mass will contribute to the inertial effects because it will be accelerated up and down with each movement of the wheel.
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Not forgetting that with gas shocks you can mount them upside down when outboard?
Overall, there are more plusses for the outboard mount than the inboard, with the inclusion of lost motion in linkages adding to the considerations.
Overall, there are more plusses for the outboard mount than the inboard, with the inclusion of lost motion in linkages adding to the considerations.
I think you're confusing the movement of the shock when it compresses, with the translational movement that the entire body of the shock goes through. Put simply, when mounted inboard there is only the axial movement of the shock as it compresses without the translational movement. With the inboard configuration, the actuating pushrod which weighs significantly less moves in the same translational movement that you would get the spring/shocks moving in if mounted outboard.
You actually get lost motion when the shocks are mounted outboard due to the shocks becoming more and more horizontal as the wheel travels up. Whereas when mounted inboard, proper design of the rocker arm can achieve a linear shock actuation. One of the websites I linked to in the previous post explained this.
Anyway, let's just agree to disagree!
You actually get lost motion when the shocks are mounted outboard due to the shocks becoming more and more horizontal as the wheel travels up. Whereas when mounted inboard, proper design of the rocker arm can achieve a linear shock actuation. One of the websites I linked to in the previous post explained this.
Anyway, let's just agree to disagree!
Agreeing to disagree always leaves someone with wrong information...
The 'lost motion' of which I speak is the total of the slack that exists in each of the joints. Whether they be rubber joints or spherical bearings, new or worn, there will be lost motion, an uncontrolled point when things change direction.
Fewer links means less lost motion.
The 'lost motion' of which I speak is the total of the slack that exists in each of the joints. Whether they be rubber joints or spherical bearings, new or worn, there will be lost motion, an uncontrolled point when things change direction.
Fewer links means less lost motion.