Guys,

Just seen some pics of a mono shock from the GTS challenger....

I'm curious, why use a mono shock? Whats the advantage? whats the effects with regard to handling? How does it affect the shock? Why has no one else done it on a IRS seven? Why not use it in the front instead of twin shocks?

It seems to me that the mono shock has built in anti roll. Another advantage is that it can easily be designed as rising rate. It also has weight advantages.

I too am interested in how it drives--specifically how it behaves in roll and extreme bumps.

--Chris

Can anyone give a more detailed explanation. I just don't get this monoshock idea.
If my (poor) diagram is about right, then the spring / damper unit should resist bump that affects both wheels at the same time (eg speed bump or squat due to acceleration).
It should provide absolutely no roll resistance at all.
I think that this should give good grip at the rear and possible understeer as the front is providing all the roll resistance.

[Edited on 18/2/05 by JonBowden]
Rescued attachment Monoshock.gif

Jon, I asked this question myself on another thread.

Where does the roll resistance come from as none is apparent from pictures?

Edit:

This thread....

http://www.locostbuilders.co.uk/viewthread.php?tid=19793

[Edited on 18/2/05 by Alan B]

there are a large number of ways of doing a monoshock, some useful and have point, others less so with little point other than the "because I could" value!

A Trishock arrangement with two normal pushrod operated shocks plus a third for antiroll is a more interesting arrangement, as it gives very tuneable roll characteristics, but adds weight.

The system that I can not fathom out is the Dax antiroll system, which seems to be completely solid in roll but also when 1 wheel moves separate to the other (over a bump and not in roll!)

Alan,
I read your previous post. Even without an anti-roll bar, normal suspension resists roll. This design does not do that. As far as I can see, if this setup was used at both ends, the car could be pushed over with one finger. Or am I missing something - some F1 cars use a single spring / damper

Jon, exactly my point....this set-up with the single spring not anchored to the chassis anywhere can move freely in a roll situation....it needs an anti roll bar or some means of resisting roll.....

I understand the dual roles of bump and roll resistance in a conventional set-up and that an anti-roll bar is not always required.

NS Dev...

Yep, I've seen the arrangements you describe....all provide some roll resistance.
The question here is what provides roll resistance in THIS set-up rather than how it is usually done.

[Edited on 18/2/05 by Alan B]

[Edited on 18/2/05 by Alan B]

Based on the diagram above, it looks like the shock is tied to the frame through the pivots. When there is body roll would not the shock/spring combo resist roll based on the spring characteristics?

Cory

quote:

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Originally posted by Alan B
Jon, exactly my point....this set-up with the single spring not anchored to the chassis anywhere can move freely in a roll situation....it needs an anti roll bar or some means of resisting roll.....

I understand the dual roles of bump and roll resistance in a conventional set-up and that an anti-roll bar is not always required.

NS Dev...

Yep, I've seen the arrangements you describe....all provide some roll resistance.
The question here is what provides roll resistance in THIS set-up rather than how it is usually done.

[Edited on 18/2/05 by Alan B]

[Edited on 18/2/05 by Alan B]

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Alternative setup used in Formula Renault




[Edited on 18/2/05 by chunkielad]

found this diagram and description for a swing-axle suspension with a similar transverse mono-shock in formula Vee
http://www.fvee.org.au/handbook/rearsusp.html
They say there is no roll resistance

....................and best left on a formula renault I think!

not much use if it goes over a bump!

damn, i was looking for a more positive view as it would fit nicely over my brand new (well new to me) audi transaxle....

looks like two shocks next to each other pivoting against the chassis would be better.

Works on a single seater as the roll resistance comes from the rear and race tracks are generally smooth.

Gents:

Understand that I offered my understanding of the system. By no means was I trying to proclaim and absolute truth. As it turns out, I am wrong. I'm still interested in how it drives.

--Many apologies for the propaganda, Chris

Chris all propaganda is welcome, as long as the truth is found in the end! )

(disclaimer - I am not responsible for any blood letting in the finding of the truth!)

This look more logical for a mono shock setup. taken from the drysdale motorcycle site.


[img]http://home.mira.net/~iwd/openwheeler/dh-7.htm[/img]

quote:

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Originally posted by MikeR
damn, i was looking for a more positive view as it would fit nicely over my brand new (well new to me) audi transaxle....

looks like two shocks next to each other pivoting against the chassis would be better.

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off this week to push that along!

you don't want to push it, you need an engine!!!

I saw a set up like this on a 2F 1R trike he claimed it does work .
photo below , a wild machine by the way
best wishes
Iain
Rescued attachment rides03081804.jpg

and here is a discription of how it works from "Motorcycle sport" magazine
best wishes
Iain

help if I include the pic
Rescued attachment Radial susp003.jpg

help if I include the pic
Rescued attachment Radial susp003.jpg

Going back to the qestion of what the advantage is, its obvious you half the cost of coil overs which start at aroud £300 for a set of 4
A set of 2 would only be £150

That Formula Renault, the suspension looks rock solid in effect it would be like using a solid (not spring steel) roll bar. precisly the oposite of what we are all worried about.

I was curious if it had otheer effects i couldn't obviously see. A bit like the old hydroelestic suspension, one wheel hits bump, pushing other wheel down to smooth the ride. From the comments now i'm guessing now

Shame really as I spent my afternoons team review figuring out how to fit a mono shock to the front and rear of the next car....... looks like i wasted some pencil graphite.

The transverse mono-shock is nothing new. Len Terry describes his use of the layout on the Terrier Mk6 (1962) in "Racing Car Design and Development". There, he correctly states the actual advantage - the layout separates the bump and roll springing. Bump springing and damping is provided solely by the mono-shock. Roll springing is provided solely by the anti-roll bar. They can be adjusted completely independently of each other, unlike a conventional arrangement.

Any claims that a transverse mono-shock is "inherently anti-roll" are bunkum. Simple visual analysis will quickly show that the system has zero roll stiffness as many have stated above. The system shown on the little Drysdale racer has a very obvious anti-roll bar connected directly to the suspension rockers.

The system shown in Chunkielad's Formula Renault is a completely different kettle of fish. That is the layout used in many (most?) formula cars currently, with the suspension push-rods connected to a T-piece that pivots to actuate the spring/damper. Visual analysis shows that the T must pivot up and down with simple bump and rebound (hence acting on the spring) but would try to move sideways on roll. The anti-roll springing is arranged along the pivot-axis of the T, inside the alloy casing visible in the photo. The adjustments for roll stiffness can even be seen on the ends of the casing. This layout even allows different roll-stiffness for left and right roll (if that takes your fancy ).

Hope this helps,

Dominic

[Edited on 19/2/2005 by TheGecko]

A lot of designers have played with seperating roll and bump in suspension. In the kit car world Fairthrope ad more recently Dax have successfully built cars in which the camber change in bump and roll modes were seperated.

http://www.carfolio.com/classifieds/show/?id=1

forgive my ignorance but....... if you add an anti roll bar have you really separated bump and roll?

One wheel goes over a pot hole, it drops, twisting the anti roll bar which is linked to the other wheel - hence they are not separated. Or am i completely missing the point?

Yes, single wheel bump is equivalent to roll, so seperation of bump and roll is only in the formal sense when talking about two wheel bump. However, there aren't a lot of potholes on F1 circuits so the single wheel bump issue isn't as big a deal. Whether monoshock makes sense for a road car is another question......


Dominic

ok, i'll bite.............

so what do people think about using a mono shock on a road car?

(which would be my intended application)

very little point, main advantage being weight loss, which won't have much effect on a road car

One big disadavantage I can see is zero damping in the roll mode --- normally because it shares its damping with the road spring the roll mode is way over dammped but zero damping could lead to a rocking oscillation.

Looking at the trike pictures I am really puzzled it appears to have a Watt's linkage which keeps the horizonal coil spring damper unit centralised - this would give 100% roll stiffness which might make some kind sense on a trike as for obvious reasons all the roll stiffness is at one end of the vehicle.

Slightly off topic, but looking back at the trike pics, the front lights appear to be attached to the wishbones - is that legal ? I assume he's got lights to drive on the roads so it must have passed SVA ?

Mind you, where's the front number plate go ?

Talking of the trike, look closely at the left hand side of the coil over. the looks to be a linkage going diaganally up and right from behind where the coil over is bolted on.

Does any one no if this is part of the suspension, or some thing else unrelated.

quote:

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Originally posted by britishtrident
Looking at the trike pictures I am really puzzled it appears to have a Watt's linkage which keeps the horizonal coil spring damper unit centralised - this would give 100% roll stiffness which might make some kind sense on a trike as for obvious reasons all the roll stiffness is at one end of the vehicle.

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I have the GTS Challenger on the road with the monoshock!

Simon

Simon, do you have a rear anti roll bar or is all the roll 'managed' (not sure of the correct term) via the front?

HI,

Rear ARB, yet!. The car rides very firm and done 500 miles so far. Great traction from the off and generally feels okay. Currently the car needs to be setup, in terms of camber/castor and toe correctly, I guessed it to be honest. GTS are going to do this properly and then I am doing a test day on track to see what happens, progressively and on/over limits of traction in corners entry and early power on.

Initially it all feels okay just damn stiff. The spring is a 400lb spring and I think this is to stiff, it's wound up with a lot of preload to get the ride height correct. Probably needs different length shock/spring and lower lbs..

I did back off the spring to minimum preload and then jumped around on back and yes the spring compresses and if on one side it allows it to move more than the other.

Looks to be that, say OS Rear wheel rises then force transfered along the rod to the rocker (the longest part) which acts upon the shock length. Now all the force can not be going over to NS Rear as the shock is connected half way along the longest side of the rocker thus using mechanics the lever effect is less than that applied at other end, fulcrum in same pos but smaller lever with same force. Rebound is thus damped and with the severe pre-load would the connecting rod to rock then provide some anti-roll??

As all is so stiff the whole chassis is a big arb as far as I can tell. Front suspension is inboard cantilever and again very stiff too.

It needs sorting out geometrically first and then I will test at speed on track.

It feels very twitchy at moment (single seater quick rack) but I have been happily driving to from work and cornered happily at 60-70mph without any worrying washout or too bad bump steer.

SImon

Don't forget to tell them how it sounds.

Oh yes, what a noise... triumph engines rock.. what an intake noise!

Simon

quote:

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Originally posted by TheGecko
Yes, single wheel bump is equivalent to roll, so seperation of bump and roll is only in the formal sense when talking about two wheel bump. However, there aren't a lot of potholes on F1 circuits so the single wheel bump issue isn't as big a deal. Whether monoshock makes sense for a road car is another question......


Dominic

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