Shortshift

Well - time for an update?? I keep logging in to see what the progress is, so thought I'd ask directly! James

To add to what Mike has written above. Caterham's ECUs are encrypted, so technically not locked but the effect is the same as they cannot easily be accessed and remapped. In the UK there are one or two tuners who can remap these encrypted ECUs including Steve Greenhalgh of "two Steve's" fame. Most rolling road operators cannot do this, however, with the common work-around being the sale of a new, open ECU that can be mapped as required. Makes it a costly rolling road/remapping session, unless you have other reasons for wanting to change or upgrade your ECU. The SBD/Easimap dongle and connector that Mike referred to will allow you to read certain parameters from MBE ECUs (including Caterham Cars encrypted units) such as lambda, temperatures, rpms, throttle (tps) position, etc etc., in real time. It's a useful tool to help with fault finding and for setting up. But it cannot be used on an encrypted ECU to adjust mapping. James

This is super-interesting, Mike. I am harbouring some similar thoughts but whereas your build is intended to be an ultimate track car, I'm thinking about making the best road-car that I can - so similar approach but with different specs and priorities at component level. You mentioned that CC supplied the car as a glider but in the pictures of the car being built in the factory it seems to have a Sadev fitted and, I presume, at least a block in place as the primaries seem to be fixed to something and pointing in the right direction! Can you shed some light as to the extent that CC were able (happy?) to supply without the driveline mechanicals in place? James

John - no worries. PM sent. James

Mike - I was carrying out my own research into this and, as part of that, I reached out to Mic. He replied with some background and a touch more detail and I have published (above) as much of what he told me as I think is right to reproduce in a private forum without his express permission. But I've no problem in sharing his note on a private basis so I'll send that to you as a pm (actually, it really adds very little to what I've said). James

John - I'm not an expert on this but valve spring failures on early R500D's are pretty well known, at least here in the UK. From what I know there is a mix of usage cases, ranging from people who do very little track-time through to others where trackdays are a common occurrence. I think there have also been issues with the double spring arrangements, too - though disaster can be prevented in the event of the main spring failing by the second spring that saves the day. But then you have to realise that something is amiss as the surviving second spring can mask the primary failure. I will look out what I can, but I think the flaw in the two-spring set-up is due to interference between the two springs. I can vouch for this being an issue as I have personally witnessed the strip-down of an engine where a second spring had failed (this followed an earlier failure of a single spring, requiring a major rebuild that included fitment of the double springs - doohhh). If you search BlatChat (likely in TechTalk) and/or the main Facebook Groups you will pick up this stuff quite easily. James

If it helps, in the UK there have been several failures of valve springs (usually with fairly catastrophic consequences) in 'early' R500D engines. These seem to have been the single parallel Kent springs - they were fine at the very start of R500 builds but later became unreliable. As a consequence, Caterham Cars moved to a Cosworth conical spring and standard cap set-up (around 2010/11, so it sounds as though your engine might be one of the last pre-Cosworth spring ones), and this remains the current build spec for all of Caterham's performance engines - so 420 and up, including all 620s (which, whilst lower revving, are subject to a hard duty cycle). The recommendation from Mic Attree (well known as Caterham's main man when it comes to the build of these engines) is to replace the Kent springs with Cosworth conical springs and standard caps. He is not aware of any failures with the Cosworth springs. Sorry that I don't have part numbers to hand! James

Did it work? James

Yup - it can be taken out of circuit quite easily if you know how. Perhaps not something to post about on a public-access forum, though, so maybe I can PM you. James

Measuring whatever bump steer characterstic you have on your car before doing any modifications is obviously sensible. It will give you a reference or datum point from which you can make and measure incremental adjustments. Methods to do this at home include: (1) Making a gauge (as per the Paul Deslandes pdf/Blatchat article above) (2) Using a laser lamp and projecting onto a surface ahead of the car to plot the characteristic at that forward distance. These results then need to be scaled (schoolboy mathematics/trigonometry) to get back to bump steer at the wheel/hub (plenty on Blatchat about this) (3) Using a laser lamp in conjunction with a mirror to measure the extent of bump steer directly at the hub (a general Google search will throw this up). One small consideration to bear in mind with (2) above is that, strictly speaking, you also need to take into account the lateral movement that your hub will go through as it is swept from full droop (rebound) to full bump, even with zero bump steer (ie: with the wheel and hub always facing perfectly straight ahead). In a Caterham, with double wishbone front suspension, there will be something in the region of 3mm of lateral movement due to this geometric effect and you could argue that this needs to be factored into the results that you will otherwise get. The mirror method avoids this. But, in any case, measuring to establish a base-line and to determine the effect of any changes you make is an essential part of the process. James

Given that your car is a S3, then if it follows the general trend for this type of Caterham it will likely need either the rack raising (9mm seems to be the oft-quoted amount) or, conversely, the outer TREs lowering. The effects of each method are not directly equal and opposite to each other but they are generally like that - so you can either raise the inner joints (the rack) or lower the outer joints (the TREs) to achieve broadly the same effect. You're right to say that Jack's adjustable TREs do seem to have a good reputation and they offer superb ease of adjustability (compared to shimming the rack) but I'd check, before ordering, how much adjustment they offer in each direction either side of the nominal factory spec. They also look cool... I don't know for sure but I suspect that they offer more in the 'increase height' direction than they do in the 'lower height' sense. So you might be a bit tight if you need to lower them significantly (analogous to raising the rack, which seems to be the S3 norm). You might also check the steel specs; if the pin is longer than the standard TRE pin you might reasonably expect to see it subjected to higher levels of bending stress. I think that Jack's pins are EN8 (a conventional engineering grade carbon steel) but I also know that some people prefer to see an alloy steel being used in this type of application. And I think that Jack's TREs are not taper fit and they do require the control arm to be drilled out to take the non-taper pin (not a big deal, so long as you are aware). Finally, from what I have found out on bump steer, if you're driving on road it may pay not to chase the oft-quoted holy grail of zero bump steer. This seems to be universally the way to go for circuit driving but, for road use, it seems to be generally considered that a small amount of toe-out on bump is fine (perhaps even preferred). It certainly appears to be the case that toe-in on bump (particularly for road use) should be avoided. James

Croc's summary is super-helpful. I knew about the offsets not being the same as the info that is cast into the rims on the road wheels but the other information is new to me. Thanks! Over here (in the UK) we get a lot of people advertising 15" rims as CSR wheels when, in reality, they are simply Caterham's 'standard' 15-inch 10-spokers. And actually finding any pukka CSR wheel sets to buy is off the scale in terms of challenge. James

Thanks for the welcome, guys, and in particular to Mike (Croc) for not only helping to get me sorted here but also for sending me separately some links and information on his CSR exploits (and aspirations). I'll certainly get some photos together and post those here to add some pictorial interest. Give me a few days. And I might have given the wrong impression (as in, oversold!) when I said that I had bought my CSR as a project car. I can see now that this conjures up images of converting it into a fire-breathing monster but the reality is far more prosaic - turning a tatty and untidy car into something that looks and drives more like a new one. A few tweaks and mods along the way, and I'm nearly there - with budget blown as usual. Will provide some more detail when I attach some photos, later, in case any of it is of interest. And picking up on the comment about parts - yes, there's a thriving cottage industry and several lively private sales sites/marketplaces for all parts Caterham here in the UK. Not sure how it would go with shipping to the US but if people are really in need of help or stuck then I'd be very happy to see what I could do to help. James

I've only recently found USA7's (I can't see how I missed the site previously) and signed-up in the last week. I'm actually UK based but I hope that won't count against me too much as I know forums to be a great way to share experience and experiences, irrespective of location. By way of background I have been a serial owner of Caterham Sevens since 1997 and currently own an R500D (which is brilliant on track, but maybe a touch too one-dimensional for more general use) and also a CSR260 which is a bit of a project car (bought last year in need of some tlc) which I hope will prove to be a great on-road Seven. I'm a long-standing, keen member of L7C in the UK and have been involved in organising that Club's trackday programme in recent years - still a passion! But more generally I very much enjoy general blatting (particularly with like-minded and like-equipped companions) and simply spending time in and around these great little cars. Looking forward to joining-in as best I can from across the water. James