Crazy Jay
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 posted on 12/2/04 at 10:43 AM |
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IRS and stuff
Hey all, just wondering, how much different is the westfield chassis to the book 1? Also, wat kinda stuff do u need to do the chassis to make it IRS?
Cheers
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Findlay234
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| posted on 12/2/04 at 12:03 PM |
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Are you intending to weld your chassis together or buy one?
weld: shouldnt be too hard but will take a lot of time (ask james about moding the chassis)
Buy: if you buy you can get an irs chassis for 500-1000 pounds no effort and leaving yuo loadsa time to get cracking on your donor car. companies to
look into are luego, mk, gts, mac1, to name a few.
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Bob C
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| posted on 12/2/04 at 12:06 PM |
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IRS
There doesn't seem to be an "standard" IRS design, Checkout de dion (nearly as good as wishbones) - dozracing does a kit, checkout
the tiger avon book by Jim Dudley. Eventually a "best practice" or de facto standard will emerge, meanwhile home chassis builders do what
seems right to them & (hopefully) live with it!
I'm now committed to wishbones but if I were starting again I'd probably do de dion.
cheers
Bob C
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Simon
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| posted on 12/2/04 at 12:10 PM |
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CJ
Another thing to do is buy the Tiger Avon book (and a tub of glue to stick the pages back in with) and graft their IRS onto Ron Champion's
"locost" plans.
That's what I've done!
ATB
Simon
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Mix
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| posted on 12/2/04 at 06:25 PM |
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scoop
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| posted on 13/2/04 at 08:14 PM |
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Guys, someone out there must have a tried and tested design for an IRS set up. Im looking to go this way with my first attempt with a sierra donor.
Any pictures or sketches?
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dblissett
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| posted on 13/2/04 at 09:05 PM |
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irs
first you will have to chose standard width or a plus 4
the plus 4 plans i have used have come off mcsorleys site they are very good i beleve this suits the wider sierra track but others will disagre
the irs i have used is a mix of the avon and my own it takes ages to do anything your self and get it right so i would advise the de dion set up as it
looks easy to fit and a very good compromise
if you do go your own way it takes 5 times as long to get anything you will be happy with
good luck dave
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Julian B
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| posted on 13/2/04 at 09:07 PM |
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Scoop
This may seem a silly question but why do you want to go IRS? Are you going to track race your car?
Cheers
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Bob C
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| posted on 13/2/04 at 11:10 PM |
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irs
Why IRS - to be honest tracks tend to be smooth enough for a truck axle to work OK! IRS = low unsprung weight which comes into its own on rough
surfaces. SO you win cornering on bad roads. I have an mx5 & it is a heap better with OZ superleggera wheels in place of same size MIM wheels.
Only difference, about 1kg per corner. So I'm OTT about unsprung weight on my '7' - I'm even worried about the unsprung weight
contribution of cycle wings at the front !
cheers
Bob C
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type 907
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| posted on 14/2/04 at 08:52 AM |
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Hi All
Most of you shy away from making your own IRS and I wonder why.
Wishbones arn't a problem. Top one is the same as the front on mine ( and RC's prototype ). A few bits of box to brace the dif area is not
rocket science. Dif mounting plates I think you can buy if not make, ( I did make my tranny tunnel to fit the dif ).
So it's down to uprights then, it certainly was the bit that made me scratch my head. I made a profiled plate that fits the Sierra brake
backplate, drilled & tapped to fit the drive shaft, on which could be welded mountings for the W/B's & shock.
(See my photo archive for finished, fitted item.) This was just a loose copy of the plate on the Sierra axle.
If something like this was commercialy available would it solve a problem? (for those who havn't got access to a profile cutter)
I'd like your thoughts on this one.
 
Rescued attachment Sierra upright back plate 003s.jpg
Too much is just enough
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stephen_gusterson
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| posted on 14/2/04 at 12:10 PM |
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type 907
suspension is genrally a bastard subject.
its full of angles, geometry, techniques and pitfalls.
There are specialist books written on the subject alone. KPI, camber, ackerman, roll centre, blah de blah all are in there to screw up your
design.
I went with IRS and its added months to the build.
the original seven used irs. Trawl this site and others to see if you can find the statement
'my live axle locost handles like crap - im gonna convert to irs'.
In 3 - 4 years on the net using sites like this its NEVER come up as an issue.
IRS sounds like a nice idea - but unless your gonna race (is irs race legal?) I wouldnt bother.
If you are gonna drive so hard on the road that you think you need IRS, look at Alez recent post to see how easy it is to trash a car.
Think hard before you go IRS - It can add complexity, masses of time, and in the end you may end up with something WORSE in terms of handling than a
std book live axle.
atb
steve
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Julian B
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| posted on 14/2/04 at 01:41 PM |
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I was talking to some of the Guys at DAX who incidentaly can sell you either an IRS or DeDion Chassis, about which set-up to go for. The long and the
short of it was as previously said an irs system only comes into its own in race situations. A drawback with IRS is when pulling away from a stand
still: The car squats and cocks up all of the rear geometry just when you want maximum rubber on the road. That problem is non-existent with a Live
axle system. I think beam axles are still used (front and rear) on some American oval racers but i might be wrong about that. So unless you intend to
get the extra that IRS gives you by racing your locost save your time and effort and keep with the old fashioned Live / dedion set-up
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pbura
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| posted on 14/2/04 at 09:21 PM |
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I think live axle and de Dion are perfectly fine, and have only started to look at IRS in order to use 500+ lbs/in bike shocks. These would have to be
mounted inboard in order to put leverage on the shock.
I am thereby adding needless time and complexity to my build, but WTF?
This should be a picture of a Leitch with inboard shocks:
Pete
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Wadders
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| posted on 14/2/04 at 09:47 PM |
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excuse my ignorance, but whats a leitch?
looks rather tasty, do you have any more pics?
ta Al.
This should be a picture of a Leitch with inboard shocks:
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pbura
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| posted on 14/2/04 at 11:32 PM |
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quote:
Originally posted by Wadders
excuse my ignorance, but whats a leitch?
looks rather tasty, do you have any more pics?
The Leitch is a higher-quality 7 built in New Zealand, I believe.
I stuck what pictures I have in my photo archive. Wish I could see how they do the lower shock mount!
There's also a pic of a Donkervoort IRS in my archive, with traditional shock layout. Very elegant and strong-looking, IMO.
But, like I said, I wouldn't arse with IRS or inboard shocks if it weren't for cheap/excellent bike shocks. Credit to Steve Graber for
planting the seed and Steve Carter for cultivating it.
Here's one I bought on eBay for about UKP 14, including shipping:
 
Rescued attachment c8_1.jpg
Pete
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JoelP
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| posted on 15/2/04 at 12:45 AM |
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pete, i like that pic of the donkey. would that style of suspension be 5 point or does the spring counts as a 6th point? looks pretty tidy anyway.
point remains anyway, make a choice and do any! pros and cons all round.
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type 907
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| posted on 15/2/04 at 12:52 AM |
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Hi again
Just to clarify a point or two:
I'm not saying that IRS is better, I'm certainly not saying my version is better than any other IRS, Dedion or conventional axle.
I just get pleasure out of building it. If it takes longer to build or ends up as being slower, or handles worse than others I don't mind,
"it's mine". If I can help anyone along the way, that too is a bonus.
I definitely won't be racing it, I'm to old for that.
Paul G
Too much is just enough
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JoelP
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| posted on 15/2/04 at 12:57 AM |
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If you choose to do IRS it can only help to have a nice cut plate available, so i think its all good myself. a good offer anyway paul, if i ever
upgrade my car i'll give ya a shout!
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pbura
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| posted on 15/2/04 at 04:54 AM |
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quote:
Originally posted by JoelP
pete, i like that pic of the donkey. would that style of suspension be 5 point or does the spring counts as a 6th point?
Couldn't say! I don't think the shock does much to locate the suspension, though.
Glad that you liked the donkey pic, Joel, so I put up a couple more. That car is extremely well thought out. Look at all the boot space and where
they put the fuel cells.  Wouldn't try that at home!
Oh, some of the Leitch pictures in my archive are unreadable due to the "+" in the file name, so I put them in again with different names.
Will have to ask Chris to delete the baddies, as I can't.
Paul, that's a beautiful job you've done on your chassis. If you were to add in a few more pics, I'd be grateful
Pete
Pete
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stephen_gusterson
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| posted on 15/2/04 at 11:09 AM |
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i did irs on my car cos i wanted it to be different.
I wouldnt do it again.
atb
steve
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dblissett
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| posted on 15/2/04 at 02:45 PM |
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being different
being different i chose to do irs at the first attempt that means a lot longer build/wait to get on the road without much of a noticeable benifit when
it gets on the road ( and the more i learn about suspension the more complicated it gets and i wont know if mine is ok until its on the road)
if i were to do it again dedion would be my choice
cheers dave
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dblissett
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| posted on 15/2/04 at 02:46 PM |
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being different
being different i chose to do irs at the first attempt that means a lot longer build/wait to get on the road without much of a noticeable benifit when
it gets on the road ( and the more i learn about suspension the more complicated it gets and i wont know if mine is ok until its on the road)
if i were to do it again dedion would be my choice
cheers dave
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James
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| posted on 15/2/04 at 11:34 PM |
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Gotta agree there.
James
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