Croc

I have had multiple Caterhams with the roller barrel set up but they were all built from new. There is nothing better that I know of for a Caterham. Sound is epic. Instructions for RBTB can be found in here: Set up supplement is here Some recent installation perspectives - start at Ralph's post on November 15, 2023. You will have to cut the bonnet - that is probably more scary than the engine upgrade. Also you are going to have to reflash the ECU with a new tune. Investigating how that will need to happen is important as the down time (i.e. car not operating) could be significant. It may be better (albeit expensive) to buy an unlocked ECU, with a base tune and then tune it locally.

@theDreamer Congratulations! Bureaucracy to get the car and transfer ownership can be annoying. But its winter so by the time you finish it will be Spring and ready for you to drive!

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Those settings are conventional and not likely driving the tramlining. The dampers may make it worse but its at the margins or under really hard acceleration. So I was bored on a 3 hour conference call today so went tire shopping for you. I don't know what your objective for a tire is but assume you want performance and the odd track day. Would assume you want DOT compliance for road use but thats your decision and responsibility. Just doing the front tires. You have 225/50 on 15x7 rim. That gives you a 23.9" diameter. Working backwards using the diameter +/- 1 inch to give me tire sizing and the diameter for that size I get: 225/45/15 23" 205/50/15 23.1" 225/50/15 23.9" 205/55/15 23.9" 195/60/15 24.2" 185/55/15 24.5" I kept within +/- 1 inch as: - You may have wing clearance issues on the upper end - may create an unsightly visual gap on the low end - different profile thicknesses may look goofy when looking at say a low profile rear. Then using the Tire Rack site to give me options by each size I get: 225/45/15 23" https://www.tirerack.com/tires/TireSearchResults.jsp?width=225%2F&ratio=45&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Options here: Toyo Proxes R1R Falken Azenis RT660 Continental Extreme Contact Kumho Ecsta V730 Toyo Proxes R888R 205/50/15 23.1" https://www.tirerack.com/tires/TireSearchResults.jsp?width=205%2F&ratio=50&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Options here: Toyo Proxes RA1 Falken Azenis RT660 Continental Extreme Contact Kumho Ecsta V730 Toyo Proxes R888R Goodyear Eagle F1 Supercar Hoosier Radial wet W2 Dunlop Direzza Z111 Toyo Proxes R1R Bridgestone Potenza RE-71RS Yokohama Advan A052 Nanking Sport Nex CR-S Yokohama Advan Neo AD09 225/50/15 23.9" https://www.tirerack.com/tires/TireSearchResults.jsp?width=225%2F&ratio=50&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Options here: Toyo Proxes RA1 Toyo Proxes R888R Bridgestone Potenza RE-71RS Yokohama Advan A052 205/55/15 23.9" https://www.tirerack.com/tires/TireSearchResults.jsp?width=205%2F&ratio=55&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Option here is the Yokohama Advan Fleva V701 195/60/15 24.2" https://www.tirerack.com/tires/TireSearchResults.jsp?width=195%2F&ratio=60&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Snow tire land - ignore 185/55/15 24.5" https://www.tirerack.com/tires/TireSearchResults.jsp?width=185%2F&ratio=55&diameter=15&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&RunFlat=All Snow tire land - ignore Now filtering that lot down to two primary size options and a short tire list for more serious consideration (with my annotations) for the fronts: Option 1 - 205/50 Toyo Proxes RA1 - How do each of the Proxes RA1/R1R/R888 line up in order? Softest is best for our cars as light weight is gentle. RA1 is race so maybe the stickiest? Falken Azenis RT660 - Dont know these Continental Extreme Contact - Dont know these Kumho Ecsta V730 - Dont know these Toyo Proxes R888R - better sized option than current 225/50 but rolling diameter drops to 23.1" Goodyear Eagle F1 Supercar - Don't know these but tread looks interesting a little too slick like? Hoosier Radial wet W2 - track only - not DOT. Likely not wear well and may overheat. This would be a bold choice! Very expensive. Toyo Proxes R1R - Is RA1 softer than R1R or R888R? Or other way around. Yokohama Advan A052 - Dont know these. Nanking Sport Nex CR-S - People say good things about Nankings on Miatas in performance application? Dark horse candidate? Yokohama Advan Neo AD09 - Someone used these on a seven years ago. Don't ask me to remember who! Option 2 - 225/50 Toyo Proxes RA1 - refer my comments above re Proxes in general Toyo Proxes R888R @Marek You will need to validate my thinking (or lack of) on tire diameter but I think thats your best range of options. Because I used Tirerack to see the broad range of options, Avon does not appear as they do not sell it. Maybe a call to Roger Kraus Tires in CA to see what they have in sizing. A phone call to them would be good as you could ask them what their opinion would be for the two size options you have. They do primarily motorsports -track and autocross - and see a range of cars come through, including sevens. They would have a better idea than the majority of participants in this thread. Have you seen this thread discussing similar thoughts on non-Avon tire options?

I am sure you know this, but only play with rake if all else fails. One adjustment at a time, then test before deciding next adjustment. Otherwise you get lost in your changes and creating new problems. I know my CSR plus Westfields are sensitive to rake and often it is a solution when all else has failed. I will be interested to hear what happens from the experiment.

Yes it has been around way longer than it should be. I assumed it was consignment and the owner was not adjusting down to meet the market. However, after all this time I think @slowdude is more likely right as consignment sellers eventually dump owners if they are not being realistic on price meeting the market as the advertising fees do tend to stack up. $40K for a Westfield is a high amount for that spec. Thats Westfield Seight model territory.

Set up for camber and toe-in spec is where I would expect them. It is toe in and not toe out? You don't mention caster or rake. Some positive rake of 10-15mm is always good. I expect you would have caster in the 5-6 degree range. Even so, I am not seeing anything there that looks to be driving substantial tramlining. The tire size on the front is a flashing red light to me. Given the R888 sidewalls are very much stronger (less flexible) than the sidewalls on the equivalent Avons (which are a lighter weight construction of carcass), I think you have created the convex profile that is likely causing your tramlining experience. The R888s were designed for a much heavier car than a seven. Much heavier than even the Avons were intended. So they flex less. The common way people got around that was to lower the tire pressures to absurdly low levels (think 14psi). So while I run 18psi cold on Avon ZZR/ZZS (which translates to 24-25psi when at ideal target hot temps), the R888 would need to go lower cold psi in order to make the sidewalls flex more and generate more heat into the tire. These cars are sensitive to tire profile squareness and this is a function of adapting a modern saloon car tire onto a car less than half the weight of the regular saloon car. We normally adjust for that by lowering the tire pressures. If I were you I would run an experiment. Drop tire pressures all round to 15psi and (carefully) see what that does to your tramlining. Try again (carefully) at 12-13psi and compare results. If my theory is right then you should see less tramlining as the car weight is flexing the sidewalls to get to a better profile cross section. The concern I have at a 12 psi you can induce enough cornering force to rip the bead off the rim. But as you are testing tramlining (i.e. a straight ahead feel) the risk of that happening should be minimal as you should not be cornering hard for this experiment. This should give some feedback on whether a wheel width size change is needed or not. If it does improve it then that gives us the insight that tire sidewall stiffness is the issue. The its a matter of choosing a Avon for a more flexible sidewall or if you want to stay on the existing R888 front tire sizing then maybe a square set up with 8 inch wide wheels all round? I definitely would not be going narrower wheels with your horsepower.

I will respond here despite the presence of an ongoing menage a trois elsewhere in this thread. Just avert your eyes. I am a little surprised about the tramlining as I have not heard that being an issue on any seven since Avon ACB10 tires were being used. They were a bias ply motorsport (Formula Ford) tire and so had a convex profile across the tire. Other sevens do just fine on 15 inch wheels of the size you mention. Plus they are what I would choose for the horsepower your car has. I don’t get a ton of tramlining unless the road is really bad yet I have same size wheels and engine hp as you have but I have different brand of tire. Reducing wheel width feels wrong to me with what you have said. Applying a process of elimination on the front wheels: a) is it the R888s uniquely having the tramlining characteristic compared to say another brand of rubber? Others have used this tire on many brands of seven and I cannot recall them complaining about tramlining. b) are you squeezing a too wide tire onto the size width wheel you have and inadvertently creating a convex cross section on the fronts? c) is it your set up? What camber, caster and toe are you running? Positive rake? Options b) or c) feel most likely with what you have said so far. Reactions?

Definitely no lowered floor needed. You would be too low otherwise. SV is useful if you plan touring (and want a slightly roomier cockpit), have big feet, or want the wider B6 style Tillets that can fit in there. Its an important decision, so if no one turns up locally then consider making a flight to do a test fit where you can try on both S3 and SV for size. Did you check the USA7s community map to see if anyone has listed themselves in your neck of the woods?

Drivetrain is in now. Oil line and coolant plumbing underway. Integration (completing the wiring up) will be a bear. Other than that I have been disconnected dealing with some distant family issues, traveling, plus the aftermath of my most expensive YouTube video ever - I spun a bearing on the BMW CSL.

Guys, its time to move on. Life is short. This is not important in the bigger scheme of life. There is an ignore button on this forum software so you can avoid each others posts if you so choose.

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Congratulations on making the dream live. I have fond memories of my driving trips in Northern New Mexico - its a nice part of the world to have a seven in.

Ahhhh....I remember this car. Maroon Birkin. George brought it to NJMP once. Beautifully prepared. He did do some sort of modification to take 13 inch wheels as I remember him telling me about the various modifications he had done to make it better as a track car. This is the first of only two Birkins I have ever seen run 13 inch wheels. At 210fwhp you should be fine on a stagger set up. I definitely think you will prefer a 13 inch wheel on track over the 15 inch option which is usually a better road solution. Just aim to keep somewhat close on the rear wheel rolling diameter (i.e. your regular road tire sizing will be a proxy to help match on a 13 inch solution) - there are online calculators to help you with this.

Why not see if I can start the traditional USA7s thread drift by going off topic in the middle of someone else's foodfight. I like your thinking @Cueball1 especially since I feel guilty for starting this little boys pissing contest although I have now had a golden shower and dried myself off. Bruce touches on these points in his earlier comments - I'm just going to reorder and expand slightly. If you are going for an extra set of wheels then the choice between 15" and 13" is open to consider. However, I just realized you have a Birkin and I don't think the calipers/hubs accept a 13" wheel? I vaguely recall Tom Carlin doing some modification to make it work on another forum member's Birkin track car. He does track days in his demonstrator Birkin on 15 inch wheels. The transformation of a se7en's handling going from 15" to 13" is profound. Lighter rotational mass means things spool up quicker and the handling is much better. I find the breakaway point is telegraphed much better as the driver gets a better feel of what grip levels are. In an ideal world I would show you what it is like in a back to back test - it was eye opening the first time I did it. Either way, this is your first decision point - which diameter wheels to select (assuming the Birkin gives you the choice). Decision two is then width of the wheels. Birkins traditionally run a square set up for wheel width. Caterham is square up to around 180hp then they go stagger set up after that where rears are wider than the fronts. The wider rears becomes important with more hp as you are trying to put the power down PLUS control corner rotation. Too wide on a lower hp car and you cannot keep the car nimble to rotate it in corners. By rotate I mean pivot the car not spin it. All cars have mechanical grip so you can throw a se7en into a corner and carve your way around using that mechanical grip. However, that only works up to a certain speed. To add speed beyond that you need to know how to corner beyond the limits of just carving an arc around and starting to adapt the grip at the wheels to pivot the car in a corner. That requires a level of slip that is simply not possible if you stuck fat wide tires on a lower hp car. Some will disagree but I find a se7en handles better and can be faster with a slightly less tire than you think you need. Earlier in my driving history when I was less experienced I preferred feeling safe on mechanical grip but that puts a ceiling on your speed potential which you need to go through to be a better driver. The Speed Secrets series of books by Ross Bentley describes this far better than I can - get volume 1 and have a read. I think you have a Duratec Birkin so should be north of 200hp? The other thing to consider is what fits under your rear wings. Will a wider stagger set up rub the rear wing. I have seen a race/track Birkin with a stagger set up rub a hole in the top of the rear wing, partly from tight clearances, and partly as the traditional road se7en suspension is fairly soft (as it should be) since you use that to accentuate weight transfer around the individual wheels on a light car. Decision 3 is then what tires. A se7en is a lightweight car. The lighter the tires the lower the unsprung weight and the better the handling. Avons traditionally have a light tire carcass compared with the alternatives - roughly a 20% lighter than the equivalents from a competitor like Toyo or Yokohama. Thats why you see a lot of people gravitate to Avons in the UK and even here in the US. The Avon compounds are usually faster. Last year at Spa, on Avon ZZRs in the dry, I could lap seconds quicker than a race 420R that was running on Toyos with a driver. That should not be possible as the race car was much lighter than my road 420R, plus it had a sequential and better gearing and a driver who I rate better than me. Decisions 1 and 2 will inform the population of tires you have to choose from. I have heard Roger Krause Tires reocmmending Nittos and Kumhos from time to time but I don't have experience with those brands although I know Roger and his team know their tires better than anyone else I have found in the US. For track, the fastest option will always be a slick. I use Hoosier slicks on my US Caterham for track work. They hardly heat cycle given the light weight and it is easy to stretch 1-1.5 years of track time out of them. A few I know have been using Michelin formula opening wheel slick tires and like them. I am sure there are other slick choice but I like the Hoosiers. However, if you are not experienced with a lot of track time then I would not recommend a slick tire. They take you up to silly speed grip such that when it lets go its going to be messy. Slicks do not telegraph their break point to a driver as well as a road tire. Track experience helps here. So then you drop back to the road types of tires. The Avon ZZR has three compounds to choose from and all 3 are faster on track than anything else out there that is not a slick. However, it is not a good option on wet tracks as it gives up fairly quickly. Avon ZZS is a road legal tire and is good in both wet and dry and produces roughly similar lap times to the usual choices you will be able to get from Toyo or Yokohama. For my UK Caterham I run the Avon ZZR extreme compound as my dry weather tire and the Avon ZZS as my wet weather track tire. Hoosiers are not available in the UK plus UK/European track day operators ban slicks so they were never an option there. Even so the Avon ZZR is pretty close to the Hoosier from back to back testing - roughly 1-2 seconds a lap slower around a 1.9 mile circuit like NJMP Lightning. I have used the Avon ZZS in all conditions on track - monsoon, rain, snow, ice and dry and they are a very good all rounder. The Avon ZZS is roughly 3-4 seconds a lap slower around NJMP Lightning than the Avon ZZR) and is going to be comparable to what a similar sized Toyo/Yokohama performance tire for a seven can do. Don't get hung up too much on change in rolling diameter. You should measure the rolling diameter on your rear road tire set up now and compare it to what you are going to get on your track tire set up. If it is smaller then yes your odometer will click over quicker but remember you just shortened the gearing so the car is accelerating quicker and you have a lower top speed. Quicker acceleration out of the corners is a good thing. Lower top speed is probably irrelevant. I don't know what your local track will be but it is unlikely you will see Vmax speed down the straight. Unless it is a pro car where the gearing is calibrated to the track to be peak engine speed for optimum lap times or at big straight track like Spa-Francorchamps/banked oval, every other car is not reaching their top speed on the average race track. The average new Corvette will pull 150-160mph down the straight at NJMP but it can do 175mph+. The same applies to a seven. When I go from the 15 inch road wheels with Avon ZZS on my CSR to the 13 inch track wheels with Hooser slicks, the rear rolling diameter comes down less than a quarter of an inch. The improvement in track performance is monumentally improved. I now find the car will almost redline in 6th gear down the NJMP straights. I'm not even close to doing that on the road wheel set up, I was at least 1000rpm short. Theoretical Vmax comes down from 155mph to around 140mph area. Of course if you increase rolling diameter the opposite will happen - slower acceleration and higher top speed. My critical observation here is a seemingly small change in rear rolling diameter will produce a magnified effect on our lightweight cars. Its hard to know until you try it. But it is unlikely to become an important factor in your driving on track. If this was a Caterham with 220hp then I would be going 13 inch wheels, 7inch wide fronts, 8.5/9 inch rears and Avon ZZS all rounders for my versatile all weather track tire. If the Caterham was below 200hp then I would go 7 inch allround width but rest the same. For a Birkin, while you need to validate this, I would be betting you will end up on 15 inch track wheels and likely a square 8 inch set up (or a stagger 7 front and 8 rear set up) with a good menu of Avon ZZS, Toyos or Yokos to choose from that will make you happy with the outcome.

Forgive me for being old, but were you at the the 2022 NJMP where my garage neighbor had an ex-Williams F1 car on track and was attempting to learn to drive it? I will be charitable and say he was doing a lot better than I could have! He flew out a crew of Williams Historic Team technicians and all the kit to run the car for the day. His ultimate goal is to historic race the car - yes there are races in UK/Europe for this. The cost of that one day was heavy 5 figures in cash. One place in Redmond WA I use for various car work - they are rebuilding my latest engine blow up - supports something like 25 ex-F1 cars for track days from 1950s to present. The team and gear needed to put the modern cars out on track is eye watering. Yet for the Maserati 250F they just stick it in the back of a simple trailer, throw some tools, extra plugs, oil, etc and some extra tires and off they go. One guy to support the owner who is driving the 250F. The simplicity of that matches what we do ourselves for a seven track day. Even my 1974 BMW CSL is beyond me easily running it at a track day - it needs a support team. That was the era things started to get complicated in top tier racing in UK/Europe. The rest of the world followed in the 1980s

Whoa! Little surprised at that demographic chart. Does make you wonder where the next cohort of owners will come from since the costs of these cars are not as cheap (relatively) as they once were. I made the 1970s....just....