James' Race car build

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gt_james
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James' Race car build

Post by gt_james » Fri Jan 10, 2020 11:41 pm

I realised I never created a thread for my car that I bought back in 2018, but I haven't done much yet!

I've always wanted to use an RX7 for racing, although starting with trackdays seems to be the best first step. I originally planned to use my black S3, Sylvester, as a track car, so I did the 13B conversion, and managed a couple of trackdays in it, although never really converted it to a track car, it has full interior, soft suspension etc. I saw this yellow car come up for sale which looked to be much closer to a track car, so rather than strip apart my black car and molest another of these rare cars, I thought I'd get this one which already has been stripped out! I can't feel bad about stripping one of these into a track car when someone else already did it haha.

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This car was originally built by Dwayne at silverfern performance, he used it for some trackdays, but then his friend drove it and blew it up and it sat in his workshop. Then a guy called chris, who was a customer of Dwayne's with an FC, saw the car in the workshop, and bought it, and got Dwayne to bring it back to life, so it got a fresh rebuilt 12A half bridge, with weber 48 IDA. Chris didn't even get the car finished running in, he discovered a fuel leak and stopped driving it. He then made a move to Spain and sold up.

I bought the car, I called it top cat (got to have a silly cartoon name :lol: ). I suspected the fuel leak was a rusty fuel tank, so I bought a NOS fuel tank, pulled the old one out, realised it was just the sender gasket leaking! I fitted it with the leak fixed, but then I ended up not doing much else with the car for a long time. My excuse is I had a busy year last year buying my first house and renovating it, also I go to Uni part time, and was busy with work too, I went to the manufacturing plant in the Philippines for the company I work for. Oh and I was silly and bought a 1990 Nissan Skyline haha, and I daily drove my black car for quite a bit of last year too so at least I did some driving!

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Anyway I should have a bit more time to spend on this car now the house is finished.

I plan to race this car, I am aiming to run it in the Classic Sports Car Club's "Future Classics" championship which is for 70s and 80s cars. So I have started pulling it apart to be able to get a roll cage made. I want to get a welded in T45 roll cage which will meet MSA circuit racing regs, possibly FIA homologated.

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For some reason the steering shaft dissapeared down inside the column, so I can't grip it well to pull it out and I can't get a steering wheel back on to turn the wheels :thumbdown:
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ian65 (Sat Jan 11, 2020 6:37 am) • KiwiDave (Sat Jan 11, 2020 1:00 pm) • spirit r (Sat Jan 11, 2020 3:13 pm)

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Re: James' Race car build

Post by ian65 » Sat Jan 11, 2020 6:24 am

Really looking forward to reading this thread James, thanks for starting it. Is it going to be road legal for track us or an out and out trailered track car?
If it's purely a track car it would be interesting to learn how much weight you could shed by removing the road car stuff.... loads of sprung weight on a stock road car, it's surprising how much weight is in things like the rear glass hatch and the rear seat back! Luckily, as you say, most of the interior is already stripped for you.
Re your steering column it sounds like the plastic shear pins have failed, see here...

viewtopic.php?f=8&t=1604

a really strong magnet ( speaker magnet or something) might pull it out which would enable you to withdraw it all the way and fit the steering wheel so at least you can move the car around, you'll still need to fix or replace it though before you can drive it.
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gt_james (Sat Jan 11, 2020 1:48 pm)
1986 Series 3 Elford Turbo
http://rx7fb.com/viewtopic.php?f=2&t=2400
New custodian of 'Gus', K plate series 3
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

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Re: James' Race car build

Post by DKWW2000 » Sat Jan 11, 2020 9:25 am

Lovely colour James....I think the FBs look best in yellow....good luck with the build & will follow with envy :clap:
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ian65 (Sat Jan 11, 2020 10:22 am)
RX7 FB S3 - RX7 FC TII Vert
Rotaries Previously Owned:-
2 x NSU Ro 80s - 2 x S2 RX7s - Suzuki RE 5 - DKW(Hercules) W2000 - Norton (Krauser) Commander

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Re: James' Race car build

Post by gt_james » Sat Jan 11, 2020 11:31 am

ian65 wrote:
Sat Jan 11, 2020 6:24 am
Really looking forward to reading this thread James, thanks for starting it. Is it going to be road legal for track us or an out and out trailered track car?
If it's purely a track car it would be interesting to learn how much weight you could shed by removing the road car stuff.... loads of sprung weight on a stock road car, it's surprising how much weight is in things like the rear glass hatch and the rear seat back! Luckily, as you say, most of the interior is already stripped for you.
Re your steering column it sounds like the plastic shear pins have failed, see here...

viewtopic.php?f=8&t=1604

a really strong magnet ( speaker magnet or something) might pull it out which would enable you to withdraw it all the way and fit the steering wheel so at least you can move the car around, you'll still need to fix or replace it though before you can drive it.

It’s primarily going to be a track car, so as you say saving all weight I can will be very important. If anyone has any ideas on weight saving as I go along I’d appreciate hearing them! I have quite a few plans to get the weight right down, and I’ve spoken to a few other racers who’ve managed to get these cars very light. Tony Ellis was very helpful when I phoned him, he mentioned his car with T2 engine and box weighed 850kg, so I’m hoping with a 12A I can get down under 800kg. Also the future classics championship has no minimum weight regulation. I’m going to try and get a trailer, it’s often much better to trailer to tracks rather than driving a track car hours to and from a track and racing around all day. But having said that I might try and put it through an MOT for a laugh.

Thanks for the link about the steering shaft. In the back of my mind I thought that could be the case, but I was hoping it would be something else. I would probably try to use a nylon pin to repair like factory or even better use an S2 box which is supposed to be better for racing. Eventually I would like to convert to rack and pinion, I have a few ideas how to do it with correcting bump steer and roll centre.

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Re: James' Race car build

Post by spirit r » Sat Jan 11, 2020 3:18 pm

Good you find some time posting h[b[ pictures. Thanks for that.
What kind of wheels and front spoiler you are going for?

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Re: James' Race car build

Post by gt_james » Sat Jan 11, 2020 4:49 pm

The future classics championship has a regulation for standard silhouette, so I will run all stock bodywork, although I will likely try and reproduce in composite where I can to save weight. I may get away with running a TWR front bumper and a the elford rear spoiler, as I have seen that there's an RX7 that races with future classics already run by team rassler, and they also use a TWR front and a rear spoiler. Technically I think it should be stock front.

For wheels and tyres I am going to start with using my set of Enkei compe 8s and lotus eclat wheels which are both 14x7 et25. I think I will run a 185/55R14 Yokohama Advan A052 for dry and either uni-royal rainsport 3 or kumho ecsta v700 for wet. I may want to move to a wider tyre in future, but there's not much available wider than 185 in 14s, and moving up to 15" will be a weight and diameter increase. A narrower tyre will make learning car control easier anyway, so I'm not interested in having the widest tyre to start with. In 15" there is much wider, like the Nankang AR1 245/40R15, so maybe something like that will be quicker, although I will need a very short final drive ratio to use a bigger diameter tyre.

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Re: James' Race car build

Post by marksport » Sat Jan 11, 2020 4:53 pm

Diff ratios make a huge difference .
I have tried many different final drives and gear box ratios....

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Re: James' Race car build

Post by gt_james » Sat Jan 11, 2020 5:17 pm

Yep that's something every racer I've spoken to has said. I will try and run a kia 4.77 and an MX5 gearset. My engine isn't dynamic balanced so I don't want to rev it too high, maybe 8000-8500? Tony Ellis said when he had an NA car he needed the mazdaspeed 5.2 diff ratio and he ran 13" wheels. That diff ratio seems to be discontinued, so I'm stuck with a 4.77, so trying to keep the tyre diameter down, but I can't go to 13" wheels with my S3 brakes, and I cant find a smaller tyre than 185/55R14 in a decent tyre. I may have to switch to a Ford English axle to be able to use a 5.2 diff ratio, and they can also be lightened with an alloy carrier and upgraded more easily anyway.

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Re: James' Race car build

Post by marksport » Sat Jan 11, 2020 5:19 pm

You can still find 5.1 if you go hunting

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Re: James' Race car build

Post by gt_james » Sat Jan 11, 2020 6:02 pm

Where? PM me if it's a racer's secret haha. From what I heard they wear out very quickly anyway, so if I can make a longer ratio work for now I will do that, but will definitely need a shorter ratio if I go to a wider tyre and 15".

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