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Another RX7 in the mix

Posted by MeCalledEvan 
john vanlandingham
John Vanlandingham
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Re: Another RX7 in the mix
July 23, 2012 11:29AM
Quote
MeCalledEvan
I found a Toyota rear end, but it's got drum brakes. Before I go and buy it, does anyone know how hard it is to convert it to rear discs?

Yes somebody knows how hard it is to convert to discs.

Shirley you should be able where to search (who pushes the idea?)



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MeCalledEvan
Evan Horner
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Re: Another RX7 in the mix
July 24, 2012 03:17PM
Quote
john vanlandingham
Quote
MeCalledEvan
I found a Toyota rear end, but it's got drum brakes. Before I go and buy it, does anyone know how hard it is to convert it to rear discs?

Yes somebody knows how hard it is to convert to discs.

Shirley you should be able where to search (who pushes the idea?)

Yeah yeah. I had looked on this forum and couldn't find nuthin, which is why I asked. Then I had the bright idea to look on that magical place called Google. Took me to a bunch of Toyota forums with a ton of the info I needed. Funny how that works isn't it?



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eyesoreracing
Dave Coleman
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Re: Another RX7 in the mix
July 24, 2012 05:27PM
Might as well put what you learned here for the next guy who googles the same question and just finds this thread you saying you found it (plus, I'm mildly curious, but not enough to search myself).

-Dave
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MeCalledEvan
Evan Horner
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Re: Another RX7 in the mix
July 25, 2012 02:04AM
It's pretty easy to do the swap. There are full kits for around $450, but those are for people who really are afraid of DIY work.
The DIY is almost as easy at a fraction of the cost:
You need a caliper mounting bracket (found them on eBay for $24, or I'm a machinist so whoop-de-shit), rotor, caliper. Rotors to use are '86-'89 Chevy light pickup 4x4 vented rotors, measuring 1 inch thick. You have to modify the hub and bore it out more for axle clearance. Caliper can be whatever you want to use (if you make your own mounts), but if you want to use the purchase caliper mounts, use 79-85 Cadillac El Dorado rear calipers w/ e-brake.

That's all I've got so far.



"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011
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john vanlandingham
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Re: Another RX7 in the mix
July 25, 2012 10:19AM
Quote
MeCalledEvan
It's pretty easy to do the swap.

Then what's the question?



Quote

There are full kits for around $450, but those are for people who really are afraid of DIY work.
The DIY is almost as easy at a fraction of the cost:
You need a caliper mounting bracket (found them on eBay for $24, or I'm a machinist so whoop-de-shit),

You are?
I thought you were a student at Western in the Auto design program.





Quote

rotor, caliper. Rotors to use are '86-'89 Chevy light pickup 4x4 vented rotors, measuring 1 inch thick.

Wait.
Stop.
You are saying on a little weenie RX7 you are suggesting putting a 1" thick rear rotor on the BACK AXLE?


Quote

You have to modify the hub and bore it out more for axle clearance. Caliper can be whatever you want to use (if you make your own mounts), but if you want to use the purchase caliper mounts, use 79-85 Cadillac El Dorado rear calipers w/ e-brake.

And what pray tell are you worried about "with ebrake".
What is the piston size?
If you say any caliper, that is the "what".
Dude, I'm helping you here, learn to say the "why".

The 'what' is a useless assertion without a stated "why".

What the fawk, aren't they Ttrying to teach you anything up there?

You still have that absurd and nonsensical quote in your signature...seems you believe it.
.

Well you can make assumptions, but they are useless to share without "why" and "why" is size, diameter, costs, ..precedent...

How do people Google search images?
Search this:




John Vanlandingham
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MeCalledEvan
Evan Horner
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Re: Another RX7 in the mix
July 25, 2012 11:26AM
Jon,
I am a student at Western in the Vehicle Design Program. I also have interned at a machine shop all last year and am proficient in both manual and CNC machining (both in operation and programming in CAM and/or G and M code).

Dave asked me to type up what I learned is being done. That's what I did. This is what people do for the Toyota Tacoma. All I wanted to know was if I could do it with that axle, and that the drums weren't integrated into the drive system. I found out that they aren't and I can knock that system off and put a disc on there. So here I was looking at the 'what' and the 'how'.
I hadn't put much thought into the 'why' yet. Thank you for bringing that to my attention.
Calipers: once again, what I typed up is only what I've read is being done. Any caliper? Sure you can use any caliper. Is it a good idea and will it work well? No. I'm well aware of that. But thanks again for questioning me on it and making me think.

As for the 'why'. I hear ya man.
Here's my plan and my 'why'?
1) Measure caliper piston area/swept radius/etc and calculate effective stopping power for the front axle.
2) Measure CG height and roughly calculate dynamic axle forces.
3) Roughly calculate out needed stopping power for rear brakes
3.5) Look at the rotors that are friggen huge and measure diameter, top hat offset, etc and look for an appropriately-sized alternative.
4) Do the same for calipers.
5) Figger out how to my mount calipers.

Good for 'why' and thinking? Would you do anything different? I know you have a ton of experience in reverse engineering shtufsh like this.

And no, they aren't really teaching us too much. I'm mostly self-taught. Kinda lame for a college education. I'm just trying get that piece of paper that says I'm smart now. One year to go and have tuition covered with scholarships so I won't waste any moolahs.

Those are pretty, but almost definitely out of my current budget.



"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011
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zack13277
Zack Rondeau
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Re: Another RX7 in the mix
March 29, 2015 07:46PM
I know this is two years old, but how did this whole project go? I'm currently starting to do almost this exact same build.



-Zack
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MeCalledEvan
Evan Horner
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Re: Another RX7 in the mix
March 29, 2015 09:07PM
The car got torn apart and turned into a parts donor for a Chumpcar instead.
Now I'm kinda regretting doing that with the FB even. It's not much of a capable chassis at all in any racing setting - overweight, underpowered, terrible suspension geometry, terrible steering geometry, tons of steering play, shitty brakes, awful cabin space. You'll notice that many of the members here were telling me that and I was disregarding their suggestions - that was a mistake.



"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011
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zack13277
Zack Rondeau
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Re: Another RX7 in the mix
March 29, 2015 09:41PM
Oh ok. Just wondering. I loved rallycrossing mine so once I change suspension and steering stuff it should be a good stage rally car, I hope.



-Zack
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john vanlandingham
John Vanlandingham
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Re: Another RX7 in the mix
March 29, 2015 11:48PM
Have you thought about maybe this:







A bit more:








2013 and 2014 Champin in the hardest 2wd series in the world:




Seems more and more are thinking that this simple, available, basically good car is a sensible choice...
Nothing fancy, just good...



John Vanlandingham
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Gravity Fed
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Re: Another RX7 in the mix
March 30, 2015 08:04PM
ill give you everything but overweight. how is it overweight???



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mekilljoydammit
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Re: Another RX7 in the mix
March 30, 2015 08:37PM
I have to kind of object to the "not at all in any racing setting" bit, and just have to say that compared to what for those? Most production cars are crappy for racing purposes without work.
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john vanlandingham
John Vanlandingham
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Re: Another RX7 in the mix
March 30, 2015 08:46PM
Quote
mekilljoydammit
I have to kind of object to the "not at all in any racing setting" bit, and just have to say that compared to what for those? Most production cars are crappy for racing purposes without work.
Gotta agree. A stock POS road car Escort is nothing to write home about..

EVERYTHING got work, and nearly always the same stuff as Group 4 Escort if they were in Group 4 and the MFG had the foresight to homologate the parts.
Or in National classes where rules were sensible...not always the case...

Millen's RX7 was Mazda shell and motor...Everything else was Group 4 Escort.

And it was a thing of beauty to watch him dance with that car..



John Vanlandingham
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MeCalledEvan
Evan Horner
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Re: Another RX7 in the mix
March 31, 2015 07:32AM
Quote
Gravity Fed
ill give you everything but overweight. how is it overweight???

For the size of car it is, it's pretty damn heavy since practically everything on it is massively overbuilt. On the plus side, you can use that to your advantage and pull out a ton of weight. For example, last week we pulled nearly 20lbs out of the rear bumper alone on our Chumpcar.


Quote
mekilljoydammit
I have to kind of object to the "not at all in any racing setting" bit, and just have to say that compared to what for those? Most production cars are crappy for racing purposes without work.

I'm not disputing that most production cars don't make good race cars out of the box. Though some cars are more capable in any form of preparation than others. In terms of the FB suspension/steering, it's a glorified pick-up truck, though with maybe even worse geometry. Or look at the front rotors - tiny, hardly any venting, and integral to the wheel hubs. Trust me, they dump a ton of heat into the bearings.

Quote
john vanlandingham
Gotta agree. A stock POS road car Escort is nothing to write home about..

EVERYTHING got work, and nearly always the same stuff as Group 4 Escort if they were in Group 4 and the MFG had the foresight to homologate the parts.
Or in National classes where rules were sensible...not always the case...

Millen's RX7 was Mazda shell and motor...Everything else was Group 4 Escort.

And it was a thing of beauty to watch him dance with that car..

Bingo. But to get an FB there is heaps of work. If you're going to put that much work into something, why not start out with a decent chassis to begin with, and then that level of work puts you ahead of the playing field, rather than trying to pull even with them?

Don't get me wrong guys. I still love the 1st gen RX7. I'm glad I'm racing in one currently. I'm even more glad of how damn simple the things are to work on. But it has its inherent flaws, and some of them are pretty major. I was only suggesting to zack13277 that he look into using a different car as a stage rally car.



"The more I learn, the more I realize I don't know and have so much more to learn." - Claude Rouelle, Optimum G lecture June, 2011
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zack13277
Zack Rondeau
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Re: Another RX7 in the mix
March 31, 2015 02:42PM
I actually thought it handled ok for stock struts and shocks. I'm still going to build it, RX7's are part of rally history and it shouldn't be that much work or handle that bad. We'll see I guess.



-Zack
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