Boost69
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| posted on 1/10/06 at 09:36 PM |
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Help, New build. Chassis, Wishbones, Sierra
Help, Been reading 'the book' for ages and finally got round to starting, then found your Locost site, its splendid but blew my head to
bits with all the extra info.
Almost finished stripping a 1990 Sierra 1.6L as the donor, I am intending to use a bike engine aswell.
A couple of questions spring to mind:
1) There seems to be some discrepencies with the book chassis/wish bone dimensions, Can I still use the sierra uprights, and do the wishbone mounting
points need altering?
2) I know it might be daft but whats the difference between De Dion and IRS?
3)I intend to use the sierra rear end - diff/drivshafts/drums etc, Does the chassis need to be made wider than the book to suit this? If so will the
front need altering so the front wheels line up with the rear?
4) I have been offered a cheap(ish) Suzuki TL1000S, will a V-twin engine be ok?
Sorry for all the questions, just want to get off on the right foot!
Thanks.......Boost.
[Edited on 1/10/06 by Boost69]
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Catpuss
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| posted on 1/10/06 at 10:03 PM |
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I think the book is cortina uprights only. Check the McSorley (?) or locost.info (?) sites for all the corrections to the book.
I would suspect a TL thou motor would be too lumpy. Espesh with its almost off/on power delivery. I ride a VTR1000 but the inlaws have a TL thou based
Raptor and my mate has a TL thou. They all say the TL engine is very off the power on the power.
But then people have used 2CVs for engines. Personally I'd go for an inline 4 if using a bike engine or a V4 if you can get a big enough one.
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mistergrumpy
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| posted on 1/10/06 at 10:07 PM |
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Hello mate. All questions I asked not too long back so I'll answer them best I can.
1) Discrepancy with book wishbones is in the castor angle. Do a search but its basically the offset of the threaded part of top wishbone from centre
and its to enable better centering really. You can still use Sierra uprights and your mounting points possibly may need moving. Best to tack them on
when you triangulate everything up. For best castor angle (offset) do a search I can't quite remember off hand but there's loads on it.
2) De Dion axle is sold by GTS and I believe Caterham use it. Its a solid type axle with trailing arms attached to it like the book. IRS is
independant rear suspension i.e. wishbones just like the front. Lots of opinions on this but best I read was that IRS is better for on track english
type axle like in the book can be better for road and De Dion is a bit of a play off between the two.
3)I and many are using Sierra rear end, you don't necessarily need to alter the arse end of the chassis unless you want to, just fit slightly
wider raer arches which are readily available, but its up to you, some people just don't like that wider rear look. To be honest from looking at
some pictures I really can't tell much.
4) Dunno. Sorry.
Hope this helps and as usual its open to the usual helpful comments by anyone else in case you feel I'm talking out of my arse anywhere along
the line 
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scotty g
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| posted on 2/10/06 at 07:10 AM |
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Hi Boost,
Most people now use sierra parts due to the rarity of mark2 escorts.
Companies like GTS can supply you with the correct wishbones and parts needed as well as the de-dion tube you need to retain the sierras IRS, you can
go with rear wishbones if you like but this will deviate significantly from the book design.
Wider rear arches are widely used, many people including myself think that it makes the car look better anyway, more aggresive!
Bike engines that tend to get used the most are large 4 pots like R1, Blackbird, ZZR and Hyabusa. The only V that gets used is Hondas Pan-European,
not as powerful as the others but very torquey by bike standards.
Cheers.
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procomp
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| posted on 2/10/06 at 07:26 AM |
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Hi mistergrumpy has got it the wrong way round with the suspension IRS is better for road use and the live axle/dedion is better for the track with
the axle being lighter than the de dion setup.
cheers matt
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mistergrumpy
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| posted on 2/10/06 at 08:32 AM |
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 Sorry
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procomp
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| posted on 2/10/06 at 02:12 PM |
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Hi keeps em on thier toes cant make it to easy for them .
cheers matt
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NS Dev
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| posted on 2/10/06 at 02:24 PM |
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quote:
Originally posted by Boost69
Help, Been reading 'the book' for ages and finally got round to starting, then found your Locost site, its splendid but blew my head to
bits with all the extra info.
Almost finished stripping a 1990 Sierra 1.6L as the donor, I am intending to use a bike engine aswell.
A couple of questions spring to mind:
1) There seems to be some discrepencies with the book chassis/wish bone dimensions, Can I still use the sierra uprights, and do the wishbone mounting
points need altering?
2) I know it might be daft but whats the difference between De Dion and IRS?
3)I intend to use the sierra rear end - diff/drivshafts/drums etc, Does the chassis need to be made wider than the book to suit this? If so will the
front need altering so the front wheels line up with the rear?
4) I have been offered a cheap(ish) Suzuki TL1000S, will a V-twin engine be ok?
Sorry for all the questions, just want to get off on the right foot!
Thanks.......Boost.
[Edited on 1/10/06 by Boost69]
Depending on what comes with it I would be very interested in buying the TL motor though!!!!
For a 7 you would indeed be better with a 4 cyl bike engine but for my grasstrack car I need a pair of TL 1000's with injection etc still
attached (+ ecu's etc)
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 2/10/06 at 02:32 PM |
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quote:
Originally posted by mistergrumpy
Sorry
let me just briefly interject with an explanation:
the reason the live axle is good on the track is that a car equipped with it can be very light. The main reason for this is that the chassis was
originally designed for a live axle and so has strangth in the right areas for the job.
The big downside of the live axle is what you meet on the queen's highway.....bumps!!!!!
The live axle itself is quite heavy, meaning high unsprung weight, which when it is attached to a very light car makes sortind damping out extremely
difficult.
Remember that the perfect setup would have an infinitely heavy car with an infinitely light axle attached. the further away from this you get the
worse it is to damp as a mechanism.
On a 7, the axle weighs not that much less than the bit of car it is attached to, and in very simple terms, the spring doesn't know whether it
is boinging the car or the axle..............result is lots of axle "skipping" over bumps etc.
The compromise is de-dion, this still feeds the loads into the right bits if the chassis that Colin Chapman intended, whilst giving a much lighter
unsprung weight and moving the weight of the diff etc to the car, thus making the spring to unsprung weight ratio much more favourable.
Wishbone rear IRS is a whole different ball game, and VERY variable in terms of quality and effectiveness on 7's from various manufacturers.
basically, for a "bookish" car, go for de-dion for road use and live axle for track.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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mistergrumpy
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| posted on 2/10/06 at 03:20 PM |
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Aye. ^That^ sounds better. I thought I was right in De Dion for road use or should I say I thought that I'd read that De Dion was better, not to
cause any arguments.
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NS Dev
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| posted on 2/10/06 at 03:37 PM |
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but remember that live axle makes for the lightest car (just not less unsprung weight)
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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kb58
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| posted on 2/10/06 at 07:47 PM |
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The one big advantage of the live-axle (simple installation) tends to drown out all of its real disadvantages.
For a track car it's important to place roll-centers (RC) where the design dictates; it's not possible to do that with the typical panhard
rod. Staniforth goes into great detail about the importance of proper roll-center placement. A live axle has the problem of an RC that moves up and
down with the axle, not a way to have good handling.
One reason people say to use the live-axle on a track is because of how smooth the track is. I guess you guys across the pond have smoother tracks
than in the U.S. Here the tracks are very much like the public steets with bumps and cracks. I've had cars car skip sideways hitting broken
concrete on our not-so-smooth tracks.
I have no problem with the live-axle being toted as the practical solution to a problem - cheap and simple counts for a lot. But it always bends me
the wrong way when it's claimed to be the same as IRS on track. The fact that the outside edges of the tires wear first on a race track should
tell us the tires are rolling and that camber compensation is needed. A live axle can't do that. Yes it can be bent to add static camber, but
that harms straight-line acceration and braking. It's always something.
And finally, most home-built cars are driven far more on the steet than on track, and the street is very bumpy. I completely agree with Rorty, trying
to make a heavy live-axle work under a car with such little weight is worse than difficult. I also agree with Rorty about it not being easy to fit an
IRS into a 7 chassis.
[Edited on 10/2/06 by kb58]
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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NS Dev
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| posted on 3/10/06 at 02:46 PM |
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I'm not Rorty!!! LOL!!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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whittlebeast
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| posted on 3/10/06 at 03:34 PM |
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All live-axle (simple installation) rear suspensions have issues with the rear axle always putting down more force on one side of the car. It is a
function of the rotation direction of drive shaft. The degree of this issue depends on the torque of the motor times the gear ratio of the
transmission. In my case this is about 1500 ft-lbs of torque. Look at any typical drag race car on launch and the twist of the chassis and how much
one of the front tires comes off the track. Independents and DeDion designs don't have this issue. See the Caroll Smith books for more
info.
AW
[Edited on 3/10/06 by whittlebeast]
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Boost69
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| posted on 3/10/06 at 09:05 PM |
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Nice one gents, thanks for all your advice/comments.
Think i've settled for the de-dion back end, will this fit straight onto a book chassis or does it have to be altered? How wide are the driver
and passenger cells? I'm not all skin and bone! So I might Go for the Mcsorley +4, don't suppose anyone has a book chassis and lives near
Scunthorpe so that I could try my rear end in one?
Just thought I'd mention that I got the TL1000 tonight, couldn't refuse it for the money. So it might be interesting to drive to say the
least.
[Edited on 3/10/06 by Boost69]
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MikeRJ
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| posted on 4/10/06 at 09:38 AM |
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I onlt have experience of the GTS De-Dion:
Some modifcations are required to the rear chassis to provide some extra clearance, but they are very straightforward. Darren can supply a PDF showng
the mods required.
The top shock mounting brackets also need to be fitted 90 degrees from the book position, i.e. the shock mounting bolt points to the front and rear of
the car rather than from side to side.
Also you need to weld some diff carriers onto the frame behind the transmission tunnel to suport the Sierra diff, again not a difficult job and the
plates to be welded can either be fabricated at home or bought from GTS, MK etc..etc.. This applies to all De-Dion axles.
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Boost69
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| posted on 4/10/06 at 10:14 PM |
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Thanks who's darren? How do I contact him?
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JoelP
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| posted on 5/10/06 at 05:10 PM |
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darren is darren george from gts tuning.
Some say you need a high calibre voodoo witch to summon him, others just use the workshop phone number.
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