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16 Jan 2014, 19:48 (Ref:3354864) | #26 | ||
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Well, fingers crossed, nothing to show yet, but to get Gp1 off the ground properly the right tyres are going to be needed. With the 'Goodwood initiative' hopefully resulting in more cars getting out to play (elsewhere) afterwards, it is important that it happens sooner rather than later!
What axle ratio choices do you have with the Dolomite? With an RS2 it would be possible to adjust ratio to suit tyre diameter- within reason. |
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17 Jan 2014, 11:20 (Ref:3355099) | #27 | ||
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Hi Guys,
have a look at my blog and if you have any pictures of your cars or other period pictures it would be great that you send them to me so I can ad them to my database. http://touringcarmadness.tumblr.com |
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17 Jan 2014, 16:43 (Ref:3355224) | #28 | |||
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I think the normal ratio is around 4.1:1 and there is I believe a 3.9:1 and a 4.5:1 available. |
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17 Jan 2014, 17:19 (Ref:3355248) | #29 | |||
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Avon do two standard treaded patterns for slicks, their block pattern being the norm, plus an 'allweather' pattern that looks similar to a period Dunlop. Usually the latter are harder compound so can be used wet or dry. What sort of diameter are the tyres mentioned? |
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17 Jan 2014, 19:50 (Ref:3355325) | #30 | |||
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17 Jan 2014, 20:37 (Ref:3355365) | #31 | ||
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So in old money we are looking for a 21 to 21.5" diameter tyre. Avon list a 7.0/21.0x13 which is pretty close. Question will be if it is available and in a suitable compound! FF2000 run 6.5/21.0x13 fronts on 6" rims so will see how one looks alongside a 185/60x13 road tyre on same width wheel.
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18 Jan 2014, 08:18 (Ref:3355518) | #32 | |||
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18 Jan 2014, 12:12 (Ref:3355578) | #33 | |||
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The tyres they have supplied me in the past for Gp2 and FF2000 are from the "crossply slick" list rather than the "historic" one, so....... Edit- FF2000 from historic list. Seems to be specific tyres for specific applications, and looking at 15" tyres higher profile than others! The 6.5/21.0x13 mentioned previously would, given all other boxes ticked, be useable on an Escort. That is a start! Last edited by Mike Bell; 18 Jan 2014 at 12:22. Reason: Addition |
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18 Jan 2014, 13:31 (Ref:3355594) | #34 | |||
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18 Jan 2014, 16:34 (Ref:3355646) | #35 | ||
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Mike. Presumably you have to run the english axle on the Mk 1. What about the Mk 2? Was it the english in Gp1 and an atlas option in Gp2?
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18 Jan 2014, 18:30 (Ref:3355671) | #36 | |||
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Ant, am sure now that the "historic" Avon list is specific tyres and compounds that are for certain formulae and applications. |
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20 Jan 2014, 21:50 (Ref:3356411) | #37 | ||
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P
I'm going to pop in and see Paul at BMTR and take an old period slick tyre with me. Hopefully we'll find something suitable in size and application and we can learn what we need to be working towards for the future.
I don't think there is anything that's 100% exact and ready to go at the moment for any of us in Gp1, so it may just be that we find something that is near enough and simply go testing with it and learn what's what. |
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21 Jan 2014, 07:05 (Ref:3356528) | #38 | |||
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Give Paul and Peter my regards! |
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21 Jan 2014, 07:35 (Ref:3356534) | #39 | |||
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The point being that even if your diff ratio isn't quite right for a particular track, does it really matter? I'd be quite happy to stick to Toyos simply because as far as grip levels are concerned they probably represent similar levels to the period slicks. Of course this is a somewhat pragmatic view but let's not lose sight of the fact that we are amateurs and thus tyre construction is probably the least of our worries. |
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21 Jan 2014, 07:55 (Ref:3356539) | #40 | ||
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I've used 185/60 x 13 tyres for years but when I was doing a series alongside the BTCC I had the opportunity to do a fair bit of testing with Avon who put me on the crossplies that were being used on the front of FF at the time but were lower profile.
In the end we did get it to do similar times but it took a lot of experimenting and testing (and I mean a lot !) with camber/caster/spring rates so it's not all plain sailing with just fitting a set on the car IMHO |
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21 Jan 2014, 09:48 (Ref:3356576) | #41 | ||
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Fellas, this is all great stuff…
I hear exactly what you are saying Peter and Gordon and it makes a great deal of sense. The truth is that there are no tyres available any more that are available in the sizes we need. The construction type for heavier cars (touring) and period bias nature are available, but not in our sizes until you get to 15 inch and apparently some very small size 13 inch. Great for those who have the option… on this are their any Group 1 cars with 15 inch rims homologated? This therefore leaves us with trying to find something that is suitable that is a sensible substitute. I agree with you Peter in that finding the exact size is probably the least of our issues, the construction is more concerning. I am told a touring car slick tyre is of a 6 ply construction to cope with the weight and enable a stiffer tyre wall. With only a 2 ply (single seater tyre) being currently available there are obvious concerns of how to get the tyre to work on a touring car, the tyre wall deforming is obviously the greatest of these. However, there is a potential suspicion that maybe the period tyres were equally only a 2 ply as the Dunlop recommended tyre pressures were pretty high. There is some period documented evidence (Dunlop fact sheets) that show these. This is why we are going to cut an old period Dunlop slick down (I have several examples of the period Dunlops) and see as to its construction. If they are 2 ply (a possibility, but unlikely I think) then were in the right area for period correctness and we are then just playing with the labour of getting it to work. If of course it is 6 ply and much stiffer it may spell the end to trying slicks for the time being as no 6 ply are available. Ultimately what I'd like to see is that if we cannot get a slick tyre that is currently available to safely operate then I'd like to see an acceptance by the organisers and growing European movement that is Historic Group 1 that we can use a tyre that is as near as dammit to the performance of the period slick, which in my mind is the Toyo R888 or Yoko AO48. Essentially and as far as I understand it these tyres are of the correct construction, but simply have modern looking treads cut into them and are the nearest thing (in construction and lap time) to the slick we would otherwise be running. However, I fear that there would be outcry that they are not period (due to the tread patterns and not available in period) and we would therefore be pushed back to the Dunlop D84J which are in my mind little more than a road tyre of 1970's design. There is obviously a view that would suggest that if we are all on the same tyre, what does it matter? I agree, it probably doesn't, but in the interests of trying to allow the cars to run closer to the intensity of lap time that they did in period it would seem a correct thing to do. Plus also if we are to be running with Group 2 and Group A it would seem to at least be kinder to us to be running a little closer to them than even further away than we are at present. |
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21 Jan 2014, 12:00 (Ref:3356637) | #42 | ||||||
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21 Jan 2014, 12:42 (Ref:3356662) | #43 | |||
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The downside to which you and Gordon have alluded… slicks may well be the correct type of tyre to use, but they will probably be more expensive and will take many hours of suspension tweaks and set up development to get them to work in positive way. That's if we can get them to work at all! It is for these reasons that I think the research is both interesting and possibly necessary. |
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21 Jan 2014, 12:55 (Ref:3356671) | #44 | ||||
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I'll watch the developments with interest. |
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21 Jan 2014, 13:25 (Ref:3356685) | #45 | ||
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Removed
Last edited by andy97; 21 Jan 2014 at 13:38. Reason: Comments overtaken by others with more knowledge! |
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21 Jan 2014, 13:41 (Ref:3356696) | #46 | |||
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We do use Avon CR6ZZ and the tyre is a soft compound compared to a Dunlop historic, Avon slicks are not very soft but kind of and the Avon "Historic All Weather" is basically the slick but with a tread of the period. But why don't you look at Michelin ? Maybe they have the slick for you ? I think the main word has to be "period tread" then construction is a different thing and that has more to do with testing and setting up your car to suite the tyres. |
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21 Jan 2014, 14:04 (Ref:3356701) | #47 | ||
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If the tread is the only criteria then modern construction slicks will apply. No need to use Avons if Michelin, Dunlop et al have a current tyre.
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21 Jan 2014, 15:45 (Ref:3356718) | #48 | |||
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As a slight aside but hopefully a relevant example, the PCGB series switched to Pirelli slicks this year, having used Michelin List 1B tyres for several years. Lap times fell, but the tyres were "off" after one race to the tune of a second a lap, so some of the front half of the grid were buying a new set of tyres for each meeting at £1K a go. Set up was crucial and "old" tyres had handling impacts so some of the front running guys were also testing on new tyres. The stress on components meant that many were needing new brake discs at every meeting too. In contrast a set of Dunlop Dirrezzas on the same car will probably last half a season and so will the brake components etc. I accept I am not comparing like with like by looking at Group 1 cars against 996 and 968 or Boxster and different manufacturers will have slicks with different characteristics but unless you are going to have batches of tyres made that are to 1970s technology and compounds then you will not be able to replicate the 1970s tyre performance so why not accept that and run on a freely available tyre that does not over stress components. |
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21 Jan 2014, 16:33 (Ref:3356736) | #49 | ||
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Equally ZZs are pretty expensive and not really suitable for cars that ran on slicks. It really comes down to the simple matter of nominating a tyre or tyres that are; suitable for the majority of the cars; and, that are readily obtainable. Trying to re create the actual tyres will be prohibitive for many and won't actually achieve anything but small grids.
I would love to run slicks but if others can't at a reasonable price then there's little point. Rather be sensible and run a modern competition tyre irrespective of tread pattern. |
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21 Jan 2014, 17:06 (Ref:3356746) | #50 | ||
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I don't like using non-period tyres. I do like to have an even playing field. A lot of historic series that run slicks specify Avon. As you can't have adjustable dampers, adjustable ride height, adjustable camber etc on a Gp1 car, there can't be that many hours to spend setting it up for particular tyres. |
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