gys
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| posted on 22/6/04 at 07:37 PM |
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McPherson struts...
Just wondering, has someone used McPherson struts for the rear suspension of a 7?
[Edited on 22/6/04 by gys]
Man kann ein Auto nicht wie ein menschliches Wesen behandeln – ein Auto braucht Liebe...
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Jon Ison
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| posted on 22/6/04 at 07:42 PM |
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would have thought finding springs soft enough may be a problem,
maybe not ?
dunno, bit big n ugly though, all IMHO.
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JoelP
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| posted on 22/6/04 at 07:52 PM |
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well, it offers 4 wheel steering at least...
pros, simple enough. Off a 4x4?
cons, would need bracing as they would be the driven wheels. maybe ugly. spring rate.
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pbura
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| posted on 22/6/04 at 08:29 PM |
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You should look up user TheGecko. He's building a middie with struts.
Pete
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JoelP
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| posted on 22/6/04 at 09:08 PM |
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id almost recommend it with a car-engined middy, theres more weight to spring and the donor struts will save a lot of effort. Plus more height at the
back.
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Noodle
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| posted on 22/6/04 at 09:24 PM |
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Could you be all be talking about the Chapman strut? Now, I wonder why it's called that ...
Cheers,
Neil.
Your sort make me sick
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Mark Allanson
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| posted on 22/6/04 at 09:32 PM |
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Who was McPherson then?
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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andyps
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| posted on 22/6/04 at 09:50 PM |
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quote:
Originally posted by Mark Allanson
Who was McPherson then?
Some bloke who invented a strut suspension system
Andy
An expert is someone who knows more and more about less and less
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gys
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| posted on 22/6/04 at 09:55 PM |
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quote:
Originally posted by Mark Allanson
Who was McPherson then?
Earle S. MacPherson of General Motors developed the MacPherson strut in 1947. GM cars were originally design-bound by accountants. If it cost too
much or wasn't tried and tested, then it didn't get built/used. Major GM innovations including the MacPherson Strut suspension system sat
stifled on the shelf for years because innovation cannot be proven on a spreadsheet until after the product has been produced or manufacturered.
Consequently, Earle MacPherson went to work for Ford UK in 1950, where Ford started using his design on the 1950 'English' Ford models
straight away.
IIRC The 'Chapman strut' (yes, after the guy that invented those funny sportcars ) is a McPherson strut without the rotation bearing.
In a rear application it then must be 'Chapman Strut' (or you add a rack)...
[Edited on 22/6/04 by gys]
Man kann ein Auto nicht wie ein menschliches Wesen behandeln – ein Auto braucht Liebe...
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Mark Allanson
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| posted on 22/6/04 at 10:01 PM |
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GM cars were originally design-bound by accountants.
Not much changed then
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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andyps
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| posted on 22/6/04 at 10:30 PM |
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I seem to remember that a Chapman strut uses the drive shaft as part of the linkage somehow. Wil check when i get chance unless someone beats me to
it.
At least I was right about Mr McPherson!
Andy
An expert is someone who knows more and more about less and less
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timmy
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| posted on 23/6/04 at 03:31 AM |
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The original Chapman strut appeared on some of the early Lotus sports racers. In simplest form, it contained:
The driveshaft to locate the wheel laterally (and drive, of course)
Spring & damper unit
A single trailing arm to locate the wheel longitudinally.
So it obviously puts a lot of load on the driveshafts. Lotus strengthened the system later to include a bottom wishbone to take some of the load.
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TheGecko
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| posted on 23/6/04 at 07:51 AM |
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As Pete Bura said, I'm building a middy struts at the rear. The following picture shows the drivetrain with the (unmodified) struts in
place.
The biggest problem is the size of the spring seat. However, kits to convert to coil-overs are common. Here's a pic of an unmodified strut
(different type to mine) and some conversion sleeves (the blue and gold bits).
And here's the same strut with the factory spring seat removed and the sleeve in place (and a nice new paint job).
Those sleeves (ACME thread alloy body with alloy collars) are AU$38.50 each (about GBP14.50) so hardly expensive.
The biggest problems could be the height of the strut and the need for a fairly rigid top mount. The height isn't as big a problem as you might
think - my Corolla struts tops (at normal ride height compression of the strut) are 850mm off thr ground. That's only ~100mm higher than the
normal rear bay in a book Locost (from memory - I'm at work and The Book is at home).
The frame strength is a seperate issue and important because the strut is providing suspension location in three directions. In the back of a front
engine Locost it would be fairly straightforward to brace I would think.
Strut rears have been used on plenty of performance cars since Chapman's efforts too. Obvious examples are Lancia Stratos, Lamborghini Urracco,
Toyota MR2 etc etc.
The ubiquity of struts also makes than a very inexpensive choice now. On the weekend, I also decide that I will reuse the Corolla front subframe
which has two engine mounts and the suspension arms all attached. Will need about 10 bolts to hold it to my chassis and then most of the rear
suspension is built and aligned for me
Best regards,
Dominic
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rusiq
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| posted on 19/3/05 at 04:07 AM |
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THE CHAPMAN STRUT
I Could you be all be talking about the Chapman strut? Now, I wonder why it's called that ...
The 'Chapman strut' (yes, after the guy that invented those funny sportcars ) is a McPherson strut without the rotation
bearing. In a rear application it then must be 'Chapman Strut' (or you add a rack)...
 
Rescued attachment TheChapmanStrut.jpg
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kb58
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| posted on 19/3/05 at 05:28 AM |
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Good grief... that mount above will have terrible bending loads in bump.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Volvorsport
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| posted on 19/3/05 at 12:04 PM |
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if its good enough for lotus , then ..........
www.dbsmotorsport.co.uk
getting dirty under a bus
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jestre
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| posted on 19/3/05 at 01:31 PM |
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Has anyone used the Macpherson's on the front? perhaps replacing the top wishbone?
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clbarclay
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| posted on 19/3/05 at 02:20 PM |
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Robin Hood use a 'mini McPherson strut' on there cheapest kit.
Below is a pic of as much of the strut as they show on thier website.
[Edited on 19/3/05 by clbarclay]
 
Rescued attachment robin hood 2b.JPG
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britishtrident
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| posted on 19/3/05 at 03:28 PM |
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The Robin Hood set up is actually sliding pillar much as used by Morgan. RH called a mini McPherson strut either because sliding pillar has such a
(justfied) bad reputation or I suspect more likely (having seen examples RH suspension expertise) they didn't know any better.
McPherson didn't invent strut suspension the inventor was a Rolls-Royce and later GM engineer Maurice Olley. MacPherson took it with him to
Ford GB (then almost entirely seperate from the main Ford company)and symplified combining the anti-roll bar and track control arm to form the lower
wishbone. For obivious reasons Ford dubbed the revised aranagement a McPherson strut.
Olley along with Fred Lanchester was the foundng father of automotive suspension and a major influence on Colin Chapman.
On aircraft landing gear struts are still called after Olley.
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britishtrident
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| posted on 19/3/05 at 03:44 PM |
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As in one of the pictures the original Elite and Elan used struts. The Elite had a fixed length drive shaft the Elan rotoflex joints.
The lower end of the strut was a special alloy casting to accomodate the wheelbearing --- The height of the upper mounting wasn't much
different from the upper shocker mount on a Locost because Chapman did a very clever wheeze and didn't put the strut centre line in line with
the wheel bearing axis but moved it forward by about 4 inches, this was enough to allow the bottom end of the damper tube (from a Ford Anglia) to
sit alongside the wheel bearing and drive shaft, this being the key difference between a Chapman strut and MacPherson strut. This of course allowed
the strut top mount to be several inches lower and suitable for use in a small sports car. Elans were great handling road cars but could be a
handful on the track much I suspect due to the strut suspension.
I have seen Elan struts transplanted on to the rear of a racing Imp (John Fyda's "Agra Imp" and can't say it gave any
advantage over the more usual semi-trailing arm Imp suspension.
Also Davrian tried using Fiesta struts on the rear of the Davrian Dragon (a Fiesta power Davrian Mk8) but Adrian Evans concluded they didn't
work and reverted to using semi-trailling arms.
[Edited on 19/3/05 by britishtrident]
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britishtrident
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| posted on 19/3/05 at 03:48 PM |
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quote:
Originally posted by rusiq
I Could you be all be talking about the Chapman strut? Now, I wonder why it's called that ...
The 'Chapman strut' (yes, after the guy that invented those funny sportcars ) is a McPherson strut without the rotation
bearing. In a rear application it then must be 'Chapman Strut' (or you add a rack)...
Interesting to note that the picture shows a Spyder Engineer replcement Elan chassis with mountings for Sierra based Spyder double wishbone rear
suspension to replace the struts.
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MikeRJ
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| posted on 19/3/05 at 04:34 PM |
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quote:
Originally posted by britishtrident
The Robin Hood set up is actually sliding pillar much as used by Morgan. RH called a mini McPherson strut either because sliding pillar has such a
(justfied) bad reputation or I suspect more likely (having seen examples RH suspension expertise) they didn't know any better.
The 2B originaly used the sliding pillar system, but it's cheaper sibling called the "SubK" actually uses small McPherson struts,
which is probably why RH called them mini McPherson struts!
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MikeRJ
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| posted on 19/3/05 at 04:37 PM |
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quote:
Originally posted by kb58
Good grief... that mount above will have terrible bending loads in bump.
Exactly what I thought. The suspension tower is extrememly robustly made with considerable triangulation and it's them mounted on a couple of
bits of unsupported RHS. Should flap around nicely, perhaps it's a cheap way of reducing spring rate (until it fatigues and falls off).
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gazza285
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| posted on 19/3/05 at 08:46 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by kb58
Good grief... that mount above will have terrible bending loads in bump.
Exactly what I thought. The suspension tower is extrememly robustly made with considerable triangulation and it's them mounted on a couple of
bits of unsupported RHS. Should flap around nicely, perhaps it's a cheap way of reducing spring rate (until it fatigues and falls off).
To be fair the photo does not show the full picture as the section hidden behind the rearmost tube is not just 25x25 box, it is constructed out of
much larger section tube.
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stephen_gusterson
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| posted on 19/3/05 at 10:51 PM |
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quote:
Originally posted by Volvorsport
if its good enough for lotus , then ..........
i disagree.
lotus and chapman desings have killed more F1 drivers due to mechanical failure than any other team. addinf a brace would have added 8 oz of weight in
that design, so thats why it wasnt fitted.
atb
steve
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