MikeR
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| posted on 18/2/05 at 10:47 PM |
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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.
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TheGecko
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| posted on 19/2/05 at 01:10 AM |
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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]
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britishtrident
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| posted on 19/2/05 at 08:01 AM |
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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
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MikeR
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| posted on 19/2/05 at 09:25 AM |
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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?
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TheGecko
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| posted on 19/2/05 at 12:00 PM |
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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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MikeR
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| posted on 19/2/05 at 12:12 PM |
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ok, i'll bite.............
so what do people think about using a mono shock on a road car?
(which would be my intended application)
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NS Dev
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| posted on 19/2/05 at 12:49 PM |
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very little point, main advantage being weight loss, which won't have much effect on a road car
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britishtrident
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| posted on 19/2/05 at 01:19 PM |
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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.
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britishtrident
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| posted on 19/2/05 at 01:25 PM |
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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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Matthew_1
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| posted on 20/2/05 at 12:27 AM |
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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 ?
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clbarclay
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| posted on 20/2/05 at 01:14 AM |
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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.
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MikeRJ
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| posted on 20/2/05 at 04:17 PM |
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quote:
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.
If you read the text that is exactly what it was designed to do, trading ride comfort for roll stiffness.
By the way, the Dax design does not separate roll and bump stiffness AFAICT, it simply incorporates camber compensation to maintain camber in roll.
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chaos999
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| posted on 21/2/05 at 11:34 AM |
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I have the GTS Challenger on the road with the monoshock!
Simon
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MikeR
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| posted on 21/2/05 at 11:50 AM |
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Simon, do you have a rear anti roll bar or is all the roll 'managed' (not sure of the correct term) via the front?
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chaos999
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| posted on 21/2/05 at 12:15 PM |
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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
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mandy69
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| posted on 21/2/05 at 02:51 PM |
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Don't forget to tell them how it sounds.
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chaos999
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| posted on 21/2/05 at 02:54 PM |
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Oh yes, what a noise... triumph engines rock.. what an intake noise!
Simon
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NS Dev
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| posted on 22/2/05 at 12:41 PM |
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quote:
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
Yep, summed it up perfectly I think there! Single wheel bump IS a big issue on crappy British roads, and systems which work on heavily downforce
oriented cars on the track will not work on the road, where bumps need to be catered for at the same time as cornering!
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