Ron_F Posted August 12, 2003 Share Posted August 12, 2003 Following the Build manual very carefully, I fitted the lower front wishbone to my SV with the spacer washers aranged in a 2-2-2 pattern, i.e 2 under the front bolt and two each side of the rear arm. However, the PBC report from Caterham Midlands says that the wide-track on my SV should be setup with washers as 0-4-0, i.e none under the front, 4 at the front of the rear bolt and none at the back of the rear bolt. This would move the lower wishbone rearwards by the thickness of two washers, and presumably increase the Castor angle by a small amount. Does this sound correct? If so, any handling experts willing to take a shot at the likely effect on steering feel, handling etc? Will such an effect be noticeable? The car has 15 inch R300 wheels with CR500s so it does like to "follow the white lines" a bit too much. I'm not ready yet to strip down the front suspension, I've only down 700 miles! Link to comment Share on other sites More sharing options...
mav Posted August 12, 2003 Share Posted August 12, 2003 Just been out to the garage. Mine (Factory Built 2001)has 0-4-0 Link to comment Share on other sites More sharing options...
Tony C Posted August 12, 2003 Share Posted August 12, 2003 I did mine as per the build manual 2-2-2 and it seems to handle OK. It does dance about a bit on bumpy roads, but I thought they all did that Sir 😬 There was no mention of this in the PBC report from the Factory and I've just checked and it's still 2-2-2. FWIW, when I built mine I set the rear anti roll bar on the stiffest setting and set the toe slightly toe-in, but at the factory they reset it to slightly toe-out. Because of the wandering I set it back to slightly toe-in to see if that helped and I found it did. Seperately, I set the rear anti-roll bar to the softest setting and this also seemed to help the general ride qualities. BRG SV 😬 It is only with the heart that one can see rightly; what is essential is invisible to the eye. (The Little Prince by Antoine de Saint-Exupery) Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted August 12, 2003 Area Representative Share Posted August 12, 2003 Ron_F, By running 2-2-2 you have a greater castor angle than running 0-4-0. The greater the castor angle, the greater the self centring effect, and the greater the weight of the steering. I've just had a look at an electronic copy of, what I believe to be, the latest assembly guide, that makes no mention of the wide track car's standard setting of 0-4-0 as opposed to the standard track setting of 2-2-2, which is quite clear in my Feb 02 paper assembly guide! The Caterham assembly guide looks quite professional and each update corrects some of the errors, but adds a few more errors! Edited by - Richard Price on 12 Aug 2003 22:02:38 Link to comment Share on other sites More sharing options...
jingars Posted August 12, 2003 Share Posted August 12, 2003 Get that socket set out; you know you want to............. Link to comment Share on other sites More sharing options...
Mr Locust Posted August 12, 2003 Share Posted August 12, 2003 I had the same report from Cat Mids at PBC i.e. built 2-2-2 and they recommended 0-4-0. My car is an '02 roadsport with widetrack. When I spoke to the factory I queried this and they said stick with the 2-2-2 as the best all round compromise (or at least for a starting point). My first impressions were that I would probably have gone for a bit more castor (3-1-3 perhaps?) to give more weighting up and more self centring but after about 2k I'm used to it and it feels 'right'. I certainly wouldn't have gone for less castor as recommended by Cat Mids. According to CC there was no distinction between wide/std/SV for this setting. Link to comment Share on other sites More sharing options...
Graham Perry Posted August 13, 2003 Share Posted August 13, 2003 Personally I would leave it where it is , get used to the car fora few months and then change it and see if you like the difference. Some find it twitchy with 4 washers in front, whereas others say they couldn't notice the difference. Link to comment Share on other sites More sharing options...
Asklepios Posted August 13, 2003 Share Posted August 13, 2003 Graham is correct . Suck it and see. My experience was that a small castor angle produced a very darty car, but this was down at 1.5 degrees, due to retrofitting modern wishbones to an older chassis (the chassis seems to change a lot over the years in subtle ways). I rescued things by shimming fully forward (max castor) , and this was perfect at 3.5 degrees ( from memory ), or so. So drive and enjoy or otherwise, and consider a proper measurement at a specialist garage if you must know the numbers and how they relate to feel. Link to comment Share on other sites More sharing options...
Ron_F Posted August 13, 2003 Author Share Posted August 13, 2003 All, Thanks for the advice and guidance. It seems clear that the recommendation (0-4-0) from the PBC would decrease the caster angle, making the car more "responsive" or "twitchy" depending on you point of view. Mr Locust's suggestion of 3-1-3 would seem a good next step. Has anyone changed these washers "in situ", i.e without stripping off the uprights and spring/shocks? With the car on stands and the weight of the suspension supported on a jack, do these bolts have any tension on them? Tony C, a check of the toe-in set at the PBC would also seem to be a good idea. Thanks again Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted August 13, 2003 Area Representative Share Posted August 13, 2003 Has anyone changed these washers "in situ", i.e without stripping off the uprights and spring/shocks? With the car on stands and the weight of the suspension supported on a jack, do these bolts have any tension on them? Yes! I jacked the front of the car up so that the wheels were just in contact with the ground but bearing no load. At this point, nothing springs with any force, but you will need to guide the pins back in by a bit of pushing and shoving! Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 13, 2003 Share Posted August 13, 2003 the std car has 2-2 for narrow track and then a note that wide track needs 0-4. i wonder if this is the source of the confusion 🤔 HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Ron_F Posted August 13, 2003 Author Share Posted August 13, 2003 Hoopy, where is the note that suggests wide-track should be 0-4? I don't believe it is in the current build manual. Perhaps CC have taken it out, or as perhaps as Richard suggests it has been left out by mistake! Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 13, 2003 Share Posted August 13, 2003 not sure. I'm sure its in my manual though.... HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Steve-B Posted August 13, 2003 Share Posted August 13, 2003 it's listed as 0-4-0 in my SV bould manual Steve B Faster than the Speed of Dark Join us on the USA 2005 tour......HERE Link to comment Share on other sites More sharing options...
mav Posted August 13, 2003 Share Posted August 13, 2003 Checked mine tonight and it reccomends 040 for Widetrack Link to comment Share on other sites More sharing options...
Ron_F Posted August 15, 2003 Author Share Posted August 15, 2003 After some research (thanks, Jingars ), my understanding is that the physical effects of caster on steering feel and handling are caused by the gyroscopic forces of the rotating wheel/tyres acting fore (or aft) of the line of the axle. Now the size of these gyroscopic forces are determined by the rotating mass. This would indicate that a very light wheel/tyre combination (such as the R300/CR500) would produce less caster "effect" at a given caster angle (i.e washer positioning in build terms). It follows that a greater caster angle is needed with a light wheel/tyre to produce the same steering feel, all other things being equal. If this logic is correct, does the difference in rotating mass of different wheel/tyre combinations have a significant effect on the actual effects felt? Is there anyone with any relevent experience (or engineering maths !) that could quantify this difference? Any thoughts would be much appreciated. Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 15, 2003 Share Posted August 15, 2003 Don't think its gyroscopic - its the interactiob of KPI (kin pin inclination) and the weight of the car that act to try and pull the wheel straight again. hmmm.... homework - everybody go and read staniforth or millikan and millikan.... HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
jingars Posted August 15, 2003 Share Posted August 15, 2003 An American site Build Your Own Race Car! suggests that caster/castor is a gyroscopic effect. This site here gives a Mickey Mouse guide - please note that I am not comparing a Caterham to a Volvo!!!! 😳 But I am not sure whether castor is Ron_F's problem - I reckon it's his toes..... 😬 Solution - get that socket set out, put the castor to Caterham's suggested setting and see how she goes Anyone got access to the tomes that Hoopy mentions 🤔 Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 15, 2003 Share Posted August 15, 2003 wish i had access to them. M&M is the bible - problem is it costs 70 quid ❗ HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
scooby dooby doo Posted August 15, 2003 Share Posted August 15, 2003 i did buy Tune To Win about 18 months ago and have just opened it - WOW ❗ The answer will be in there but theres a LOT of stuff digest. One gem I saw was regarding sliding pillar suspension: "If you have a morgan then fit better koni dampers. if you don't then there's no reason to know anything about SPS" And one on dedion: "DD suspension hasnot been used in racecars for 20 years - I see no reason for it to return" 😬 HOOPY R706KGU Hoopylight R Link to comment Share on other sites More sharing options...
Ron_F Posted August 16, 2003 Author Share Posted August 16, 2003 Jingars, you leave my toes alone 😳 You could be right, I do need to check the toe-in set by caterham Midlands at the PBC. I am coming to the conclusion that a bit more castor would help the "nervousness" at the front end. Driving along a uneven road at some pace with another vehicle coming the other way could be described as *eek* !! Link to comment Share on other sites More sharing options...
Steve-B Posted August 16, 2003 Share Posted August 16, 2003 ron, you don't state which tyres came with your car, so i'm guessing they're avons... our SV was almost the same way with factory tyres(Avons) on it. went to 21r's and 0-4-0 setup and bob's now our co-pilot. so what tyres does your motor have 🤔 Steve B Faster than the Speed of Dark Join us on the USA 2005 tour......HERE Link to comment Share on other sites More sharing options...
jingars Posted August 16, 2003 Share Posted August 16, 2003 I'm in Stunt Ron mode here, as Ron has just left for a week's trip to the US. I think he's taking a shipment of batteries over there to help them out with their current troubles. Current troubles; geddit?? Yes, you're right that was pretty lame - I apologise. Ron's car does indeed have Avon CR500's on 15" lightweight wheels. Link to comment Share on other sites More sharing options...
Ron_F Posted August 18, 2003 Author Share Posted August 18, 2003 Well the power's back on and this Internet thingy is still working all across the big wide world! Yes, as Jingars said , the car has R300 wheels and Avon CR500s. I;m a bit confused now as Steve-B suggested that 0-4-0 would help. I was thinking of going the other way!, i.e 3-1-3. My confusion could be that increasing cASTER (US spelling!) angle could be either +ve or =ve. Also it would depend on how moving the Lower wishbone forward would move it relation to the Axle centre, i.e where is it starting, in front or behind it? Does anyone have a definitive guide to setting up caterham front suspensions, or recommend some one at CC or elsewhere who knows their stuff? Thanks Stunt Ron, Link to comment Share on other sites More sharing options...
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