Locofinn's Dmod Seven
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Author:  locofinn [ February 16, 2008, 7:12 pm ]
Post subject:  Locofinn's Dmod Seven

I am officially "all in".

1. I just purchased my donor car. 1982 RX-7 GSL with stock12A, 5 speed, and LSD diff.

2. I am 5 weeks (of 15) into my welding class at the local community college and If I say so, it was certianly worth it. The instructors are good, the equipment is top of the line, and I am progressing quickly on MIG, and TIG very soon. He is even setting up special projects for me to help on my specific fab skills.

3. Scored my first specialy part two months ago. A used but good condition billet Appleton quick ratio rack and pinion unit from a race team closing shop for $75.00 on e-Bay. No need to shorten a rack as it is 18.25" wide

Getting really excited. Plans are to weld the frame summer of 2008, part the car out winter of 2008, and have the drive train fitted by the summer of 2009. On the track 2010. This will be a track only machine. Dmod SCCA. I sold off the Gstock MINI Cooper this year and plan to co-drive the next 2 seasons while the build continues.

I will start posting pics as soon as I figure out how.

Another Locost crazy,

RX7.jpg [ 16.68 KiB | Viewed 25197 times ]

Author:  weconway [ February 16, 2008, 7:35 pm ]
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Good luck!

Man, that RX-7 is almost too pretty to take apart...almost.

Author:  chetcpo [ February 16, 2008, 8:29 pm ]
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Congrats! I agree it is sad to see such a good looking car bite the dust but many more have died for far lesser causes. Not that it's really dying, it's just being born again into a true sportscar. :P

Author:  erturbo [ February 16, 2008, 9:48 pm ]
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Great to see another rotary-powered build, especially so close by. Who knows, we may end up competing against each other @ some future autoX's!

Where in Indiana are you? We (the ohio, kentucky, WV, IN) Locosters are planning a meeting at my house in louisville for sometime in the next few months, you'll have to join if you're close by.

Congrats on the donor and steering rack, bidding on a nice racing rack myself right now, look forward to seeing some progress.

Author:  Rotus7 [ February 17, 2008, 12:31 pm ]
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Couple of questions:
1)are you going to use and modify the front sruts or do you have some other spindle/upright in mind?
2) are you going to stick with the 4x110 wheel bolt pattern?

Thanks and good luck

Author:  erturbo [ February 17, 2008, 2:04 pm ]
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I'm actually using a 2nd gen donor, so my bolt pattern is 5x114. And yes, I'm using the stock bolt pattern, available quite readily.

I do plan on using the front uprights, though I'd assume their different from 1st gen bits. The hardest part I can see so far is making an adapter to mount the upper a-arm to the (I assume, I didn't take the donor apart, bought the parts already stripped) macpherson strut mount. See pic. I'm planning some boxed piece fabricated of 1/8" plate to adapt to a uniball.

The other hurdle is the fact that the rx7 steering arms on the upright are quite long, so I'm compensating with a really quick rack ratio. Haven't calculated that yet, though I assume it will be in about the 2.60 range (don't quote me on this)

File comment: 2nd gen uprights
DSC01658.JPG [ 62.09 KiB | Viewed 25093 times ]

Author:  locofinn [ February 17, 2008, 6:12 pm ]
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I am thinking of two options for the front spindles. Fiero or Mustang II. Lots of "off-the-shelf" performance brake and stuff available for the Mustang II, but the Fiero spindles might better fit the 13" x 10" wheels I will be using. I don't want big heavy brakes for autocross anyway. Waste of money and brake fade is not an issue on autocross.

Front A-arms
The weld yourself upper a-arms kit by Kinetic look good or similar stock car parts with rod ends and screw in balljoints. Lower arms will be custom fab with screw-in ball joints and rod ends "ala stock car parts".

Bolt Pattern & Wheels
Wheels will be custom made or ordered from Diamond racing depending on budget. Diamond has the stock bolt patterns available with any offset I may need. The front and back don't have to match for a track only car. I might change my mind if I can figure a way to do redrill the hubs effectively. Anyone have experience with 13"x10" size wheel fitment?

Rear Suspension Link
Thinking of a 3-link rear like Modernbeat has show elsewhere in this forum. Other friends racing Mazda RX7's have proven this design works well for road racing. Should work for autocross too.

Author:  locofinn [ February 17, 2008, 6:20 pm ]
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Oh, as far as he donor RX-7. Don't feel bad. It is much worse than the pictures. Really bad case of cancer from the back of the door rearward. It would be lucky to last the 3 more years before breaking in half. The drive train is great. Same owner last 16 years who fixed every little thing on the car when it needed it. It was his daily driver the whole time until I bought it. Sad about the body/chassis. THE PERFECT DONOR :D

Author:  locofinn [ May 10, 2008, 11:56 am ]
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Got the steel today. Does it look like $402 worth of steel? My steel supplier says expect another 30% jump by the end of May. I used the cut list BOM from the McSorley site and added about 40 ft for each size. Planning to build a rolling cart/stand for the build table first.

Locost Steel.jpg
Locost Steel.jpg [ 15.72 KiB | Viewed 24493 times ]

Author:  locofinn [ May 10, 2008, 11:58 am ]
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Also got the MIG welder. Picking up the MIGMix gas tomorrow.

Locost welder.jpg
Locost welder.jpg [ 20.95 KiB | Viewed 24485 times ]

Author:  locofinn [ May 10, 2008, 12:01 pm ]
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I was also lucky and got the exact rack I needed off E-bay for $75. I is an Appleton Billet R&P unit. with 2:1 ratio. 18.25" wide.

Locost Appleton Rack.jpg
Locost Appleton Rack.jpg [ 11.4 KiB | Viewed 24481 times ]

Author:  chetcpo [ May 10, 2008, 12:33 pm ]
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I'm going to move this to the builder's log. Looks like that's what it's turning into. :wink:

Author:  Mike Basden [ May 10, 2008, 7:43 pm ]
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I hope that rack works out for you. I bought a similar Appleton rack thinking it would be a great find (18.25" overall but only 2.5-3" of travel lock-to-lock).

With my donor spindles that will only give me 29* of turning either way. For my wheelbase this equates to a 39' turning circle :shock: So...I'm looking for a new rack now. But figure I can use this one once I finally decide to make some billit cusotm uprights or something.

Author:  locofinn [ May 10, 2008, 8:37 pm ]
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What spindles are you using and what are the steering arm lengths?

Author:  Mike Basden [ May 10, 2008, 8:41 pm ]
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I'm using S2000 spindles with an arm lenth of about 5.7".

These spindles with stock rotors and hubs are also very heavy. I'll eventually make my own out of billit and try to use the same pick-up points since I was able to dial that in fairly well (I think).

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