79/80 RX7's good choice for IT7?

[sevenracer]

Are there any major disadvantages to using a 79/80 model chassis as a basis for an IT7 car? I have heard that the bumpers are heavier, is this true? I know the front struts need to be swapped to get the later style brakes. Anything else?

Thanks,
Neil

[Speed Raycer]

Disadvantages??? Not really if you change the struts and brakes over to the later stuff. IIRC, the 79/80 strut housings are taller and most shocks seem to fit the 81 up housing.

The only other real "drawbacks" are the 79/80 only thread pitch on the brakelines and clutch hydraulics and the fact that the shifter hole is a couple of inches further forward than the later years. Also, 79 has a one year only points ignition

Oh... and you only have 2 years of brake lights to pilfer at junkyards.

If it's got the motor, then you've got the early intake which is a little more desireable.

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Scott Rhea
It's not what you build...
it's how you build it
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[instigator]

i have spare stock 82 thru 83 smallbearing front struts assemeblies with calipers let me know if you want them.

[Ron Earp]

Neil,

Is this you from down at CMP last weekend? This is Ron, silver and black Miata of Jeff's. Shoot me an email if this is you,

Ron

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Ron Earp
http://www.gt40s.com
Ford Lightning
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Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[dyoungre]

Neil,
I've been racing an '80 chassis, and I had to add ballast to make minimum weight; While the bumpers may be heavier, they have proven to be quite, ah, forgiving when people try to divebomb into a corner. If you compare to the later chassis, the 79/80s have bracing right behind the seats, which is removed on later chassis. I think this bracing was lighter than the reinforcing that Mazda did in the later years so that they could take the braces out (and make the car a 2+2 in some markets?)

There is a wiring difference from 80 to 81 distributors, as well, due to the igniter design - the 80s are remote, 81 on the distributor.

One more warning about the brakes lines, though; The master cylinders have different mountings to the firewall, and are not interchangeable - so don't think you can just swap later stock parts - I turned back, after realizing that it isn't a clean swap.

Good luck - but I think it's a good choice.

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Dave Youngren
NER ITA RX7 #61

[Emisare]

Originally posted by rlearp:
Neil,

Is this you from down at CMP last weekend? This is Ron, silver and black Miata of Jeff's. Shoot me an email if this is you,

Ron



Ron,

It wasn't me who posted, but I saw this browsing the board. We're heading to Roebling on the 10th for school. Hopefully we'll see you guys at VIR this spring.

Neil, but not the OP

btw - I don't have your email address. I'm at [email protected].



[This message has been edited by Emisare (edited January 30, 2005).]

[miketrier]

I have been racing a 1980 since 1999 and I don't feel it has ever been a detriment. If I were building a new car from scratch I would prefer an 84 or 85 due to more of them still being around and a few better pieces, most of which can be put on the 80, however, through the updating rule. I wouldn't hesitate a bit to buy a prepared 80.

[sevenracer]

Thanks for the replies. I have a couple of questions about updates.

1. The struts are definitely longer on the 79, but the brake calipers and brackets look pretty much the same. I had heard that the early cars had "wedge" style brakes that aren't suitable for racing. How do I verify this? Can I update the calipers without changing the master?

2. Can I update to the later style distributor and ignition? Is this allowed in the rules?

Thanks.

[Speed Raycer]

Originally posted by sevenracer:
1.... How do I verify this? Can I update the calipers without changing the master?

2. Can I update to the later style distributor and ignition? Is this allowed in the rules?

Thanks.
Not sure on the visual differences. I believe someone (mazdatrix maybe) sells stainless lines that make the swap, or just swap the hardline fitting over to the 81+

Both swaps (brake and ignition) are allowed with the update/backdate rule as all 12a RX7's are on the same spec line

[dyoungre]

I put '83 struts on my '80 (to deal with the 'tall strut' issue) but kept the '80 brakes, due to the thread problem. If I recall correctly, it required that the backing plate (the big, thick one), the brake caliper brackets, and the brake calipers had to be changed. I'm not sure, but I believe the brakes perform very close to identically, although the 81-83 may have a SLIGHTLY larger swept area or effective diameter. If I recall, the caliper rebuild kits are identical.

The one thing I'm not positive about is the backing plate; I'm pretty sure what I said is true, but I'm reaching back 8 years ...

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Dave Youngren
NER ITA RX7 #61

[instigator]

I have an 84,85,and a 79 that was rebodied on a 82 model tube.The brakes pads are the same. In order to up grade the calipers from the 79 to the 82 I had to buy a fitting from mazda's race program to adapt the brake line to the new caliper. Also the caliper braket had to be changed. It was easy once I got the right parts.

The later model calipers make it easier to change pads in a hurry if you are under the gun at the track . The swap was well worth it.

[Boswoj]

Instigator!

A very nice and easily understandable post! Deep down, I knew you had it in you!

Seriously, good post - thanks for joining in the IT forum's tradition of helping the newbies with the benefits of your experiences.

Boswoj