RiF Posted April 28, 2005 Share Posted April 28, 2005 Do you think Arch could modify a standard se7en chassis to be independent rear suspension without it costing a fortune? And would it even be worth it??? Thought I would ask here before bothering Bruce. What problems would you forsee? Don't even think about asking what I am planning 😬 😬 😬  Richard in France Flying fast in my very bright yellow 226bhp Duratec 7, with internal kevlar/carbon panels and pushrod suspension 😬 😬 😬.for pictures of 7 and carbon Edited by - richard in france on 28 Apr 2005 21:38:20 Link to comment Share on other sites More sharing options...
rgrigsby Posted April 28, 2005 Share Posted April 28, 2005 hmmm I'm guessing to get the IRS to fit on a standard chassis is going to be a challenge, all the geometry will be different and you're going to have a REALLY small fuel tank or no boot! It can be done as Birkin have done it... Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
Dickie Normuss Posted April 28, 2005 Share Posted April 28, 2005 What's in the pipeline Richard  Seek forgiveness, not permission. Rules are for the interpretation of wise men and the obedience of fools. Link to comment Share on other sites More sharing options...
RiF Posted April 28, 2005 Author Share Posted April 28, 2005 😬 😬 Not telling yet *wink*  Richard in France Flying fast in my very bright yellow 226bhp Duratec 7, with internal kevlar/carbon panels and pushrod suspension 😬 😬 😬.for pictures of 7 and carbon Link to comment Share on other sites More sharing options...
Irrelevant Posted April 28, 2005 Share Posted April 28, 2005 It could certainly be done - it's not even a massive job if the chassis is bare. However, the current CSR IRS is carp and still needs a lot of work. Suffering serious sprint cold-turkey. Must get this finished Link to comment Share on other sites More sharing options...
Jason Plato Posted April 29, 2005 Share Posted April 29, 2005 Thinking about it , if the only basic differences between a SV rear end and a std chassis is the width ( as seen from the SV de dion fitting straight onto the std chassis and increasing the track width )  Then I guess the SVR independant rear end , could also be grafted onto a std chassis . But the chassis itself would be narrower ? photos of the SVR are here but better ones are on Angus' site Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted April 29, 2005 Leadership Team Share Posted April 29, 2005 I would have though the chassis would need "beefing up" in a few new areas to take IRS? Stu. Link to comment Share on other sites More sharing options...
simonbell Posted April 29, 2005 Share Posted April 29, 2005 The thing about IRS is that it is only better than dedion if it is properly designed and set up. To cut and shut the CSR IRS into the std chassis would always be a compromise as the geometry won`t have been designed for the narrow chassis. I`ve even heard it said on blatchat that the IRS won`t work in the std car because of the narrower chassis. Simon Bell - Caterham 7 Duratec R I`ve seen the future.....and it`s powered by duratec Check out the website here Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 29, 2005 Share Posted April 29, 2005 I'd be interested to see the whole SVR chassis undressed. The thing about the design of the Seven is that the rear suspension loads are supposed to be reacted by the tubework at the sides of the car at the rear bulkhead. Simply adding on a framework around the diff could lead to all sorts of problems. I suppose that one argument exists that the mods made to mount the diff for the de Dion beefed up the chassis strength and stiffness down the tunnel and at the diff mounts, but I'm not super convinced. The Watts linkage implementation is even a bit of a stretch for the engineering purist. The rear mounts are essentially dangling in very poorly located space. If you didn't mind sacrificing boot space, you would triangulate rear IRS mounts from the top damper mounts and the A-frame mounts. These are the strongest points. But then again if you wanted a strong stiff chassis, you wouldn't have a geet big hole in the middle for driver and passenger (witness the R400/SLR race car's wishbone brace in the passenger compartment. If you had a mind, you would also improve the scuttles structural contribution by triangulating to a junction with the central tunnel just behind the gearlever. I'm talking about extra tubes, so this would be heavier, right? Erm... not necessarily but in the cost conscious world of Caterhams the answer is probably. In engineering terms, if you have a target stiffness and strength for the chassis, a better optimised spaceframe will be able to achieve the target stiffness/strength for less weight. You might have to get involved with optimising tube wall thicknesses throughout the chassis. While not FEA, I wrote a spaceframe stiffness analysis program in 1991 as part of my final year project at uni. Ten years later it was surprisingly easy to port that program to VBA (in Excel and Visio) where I used it to calculate the surprisingly difficult to analyse front ARB stiffness on the Seven... Now I haven't seen the IRS Caterham chassis to examine it, but it is possible that some or all of these considerations have been taken into account. I'm just telling you how I would do it given a clean sheet of paper. Link to comment Share on other sites More sharing options...
RiF Posted April 29, 2005 Author Share Posted April 29, 2005 All your comments are very interesting 😬 Peter you must get to have a look a a bare chassis, would be interested in your opions. Richard in France Flying fast in my very bright yellow 226bhp Duratec 7, with internal kevlar/carbon panels and pushrod suspension 😬 😬 😬.for pictures of 7 and carbon Link to comment Share on other sites More sharing options...
metal mickey Posted April 29, 2005 Share Posted April 29, 2005 Peter, I have some pictures of the bare chassis at Brands last year. If you want, let me have your email and i'll send them to you. Mike. Link to comment Share on other sites More sharing options...
Nifty Posted April 29, 2005 Share Posted April 29, 2005 When I was last at Caterham they had the show chassis in the front showroom  Keep off the straight and narrow 😬 Link to comment Share on other sites More sharing options...
oi oi Posted April 30, 2005 Share Posted April 30, 2005 one of my lasts posts :( have a look at an early narrow body westfield independant setup (up to about 92ish). westfield made there own casing for the english diff which is really small and light (ali casting). if you can get hold of one of these then that would save a lot of space and mean you can use your existing diff. chassis mods for this diff should be relatively minor. i also think you will be able to use existing fuel tank. email me and i might be able to get some photos. alternatively ask on the wscc boardroom. i know v7 looked into this, but i think he ruled it out 🤔 hth (for now)  Link to comment Share on other sites More sharing options...
Bare Posted April 30, 2005 Share Posted April 30, 2005 Putting IRS into a 7 chassis IS old territory.. Many.. have done this over the years. including Lotus back in Series 2 days. The Chassis has been PROVEN to be adaptible. Look around a bit...there is an entire (and surprisingly Large) subculture of 7 activity: Clones, Builders. Kit makers and DIY'ers.. Many . not unexpectedly, are Crap.. but some are V good indeed...an open mind could be educational :-) Amusing but Myopic arguements re IRS only being slightly better than Dedion... there are those who still carry on the same belief re Live axle vs Dedion Do agree that the 'New ' CRS car/suspension is rather a poor effort. and not worth emulating.. at least not when one is expending personal funds.. note that even a westfield has a decent IRS... in an even simpler chassis... wonder what they learned years ago? Link to comment Share on other sites More sharing options...
Jason Plato Posted April 30, 2005 Share Posted April 30, 2005 Birkin have a reasonably good IRS system in a chassis of the same dimension as caterham .    C7 TOP Powered by Hellier Performance 😬 South Wales AO Link to comment Share on other sites More sharing options...
simonbell Posted April 30, 2005 Share Posted April 30, 2005 I`ve driven the Birkin IRS and it was extremely stable on the road. I never got a chance to drive it in anger on the track though. Simon Bell - Caterham 7 Duratec R I`ve seen the future.....and it`s powered by duratec Check out the website here Link to comment Share on other sites More sharing options...
Ferrino Posted April 30, 2005 Share Posted April 30, 2005 Some CSR chassis pics HERE. Bite me 😬 Link to comment Share on other sites More sharing options...
DavePalmer Posted April 30, 2005 Share Posted April 30, 2005 Just got this months EVO - it's got a feature on the CSR. Seems when they took the roll cage off the chassis wasn't stiff enough so they've made some last minute mods this year. There's a good if small diagram of the chassis showing the additional tubes and modified tubes (increased thickness). Link to comment Share on other sites More sharing options...
Normans_Ghost Posted May 1, 2005 Share Posted May 1, 2005 Given the constraints on space and cost I think CC's IRS is not too bad. Like all commercial designs it will improve over the years as the money comes in. If we wanted to design the perfect anything it would never see the light of day. Designs evolve and improve (thats sometimes debatable) as the money is available. Now, my project for next years retirement is to fit Freestyle front & back. But thats not all. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here Link to comment Share on other sites More sharing options...
RiF Posted May 1, 2005 Author Share Posted May 1, 2005 so I should take the stripped chassis to Westfield or Birken for IRS 😬 Norman: all arranged now, just a long wait  Richard in France Flying fast in my very bright yellow 226bhp Duratec 7, with internal kevlar/carbon panels and pushrod suspension 😬 😬 😬.for pictures of 7 and carbon Link to comment Share on other sites More sharing options...
simonbell Posted May 1, 2005 Share Posted May 1, 2005 Some pictures of the Birkin rear wishbones and uprights here Simon Bell - Caterham 7 Duratec R I`ve seen the future.....and it`s powered by duratec Check out the website here Link to comment Share on other sites More sharing options...
Simos Posted May 1, 2005 Share Posted May 1, 2005 James Whiting did an IRS Caterham years ago which he said worked. He may still have the designs, who knows. Link to comment Share on other sites More sharing options...
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