IRS Conversion

[pts805]

Hey all, I recently picked up a 69 sports and wanted to know where I should start with the IRS conversion, I understand to some this might not be worth it, but it's what I plan on doing. I realize this is a big job, but that's exactly what I am looking for. I am currently enrolled in my local city college automotive program and I am also taking a welding/metal fabrication class. I want to use this car for my final in the fabrication course(which would be in a couple of years) so this isn't just something that I found to be cool, I really couldn't think of another project to do. I plan on doing an SR20DE swap among other things, but these are more for my personal desires. Any help will be appreciated, I'm new to the car modifying game and if someone could point me in the right direction I'd be as happy as could be. Thanks, Patrick Schmitt

[Alvin]

I know of two IRS setups.
1) Carl Jaeger adapted an entire S13 IRS, google for pics
2) Michael at Roadsterwerx adapted an entire RX-7 IRS
pics here:
http://311s.org/phpBB3/viewtopic.php?f= ... 15#p168023" onclick="window.open(this.href);return false;

[youtube][/youtube][/quote]

hope that is a good start!

[fj20spl311]

There was a 24 hr of LeMons roadster listed for sale with a Miata IRS
I would stick to a smaller set-up. I was looking at a WRX system.

[Gregs672000]

Didn't Skyman purchase that gray car out of Seattle (Guy Selly?) that had the CA18 and an RX7 IRS (I think it was?). Later sold again? Guy was a racer and I believe he did a good job, but I never drove the car.

[Alvin]

Didn't Skyman purchase that gray car out of Seattle (Guy Selly?) that had the CA18 and an RX7 IRS (I think it was?). Later sold again? Guy was a racer and I believe he did a good job, but I never drove the car.

Selle's car had a 1st gen. RX-7 axle with 4-link setup.

[fj20spl311]

Selle's car had a 1st gen. RX-7 axle with 4-link setup.

NOT AN IRS

There was a car / project with a KA24 and a 240SX rear axle.......don't remember the name....maybe Craig??????

[Gregs672000]

Selle's car had a 1st gen. RX-7 axle with 4-link setup.

NOT AN IRS

There was a car / project with a KA24 and a 240SX rear axle.......don't remember the name....maybe Craig??????

Yes, indeed not... i never crawled under it... nice car though...

[RCMike]

Phil, are you thinking about the 1500 with the SR/s-13 rear end that the car was sectioned down the middle?

[st3ph3nm]

I know you specifically didn't want this question, but I'll still ask it: Why?

You mentioned "is it worth it?" My response is "no" but not for the reasons you might think.

Thing is, if you want it as a fabrication exercise, that's fine. But you're unlikely to make the car handle so much better than the live axle setup that's it's "worth" the effort. Live axles are easier to get to handle well. IRS is better, yes, if it's done properly, and it's hard to get the geometry right, and requires a dual uneven wishbone to do so. Mcpherson strut rear ends are prone to so many dynamic caster and camber changes that you may as well run a solid axle with a watts linkage.

The other thing I'd mention is the value of the car. Is it a basket case? Then by all means do what you like. If it's in good order, though, these things are starting to be recognised as a classic in their own right. They can be worth good money, and finding good original examples is getting harder. So my question of "worth it" is this: Is it worth butchering a classic car for a fabrication exercise? You may well find that you've made a great, quick car with (arguably) less character than the original, and worth less than an original car as well - after spending more effort and money than a good restoration would cost... You do have to cut into front crossmembers to mount an SR, for example.

Just my opinion, of course, and ymmv, etc. etc. But good luck whatever you decide to do. And feel free to call me conservative on these things, because I probably am.

[pts805]

Alvin: Thanks for sharing, I appreciate it!

fj20spl311: Do you know of any videos and/or threads regarding this car?

Stephen: Thanks for chiming in! I picked up the car for $800, it's in need of some serous work anyways so I don't view it as too sacrilegious =), I definitely agree with you regarding the character of the car after said modifications, though. Too me, As a younger car enthusiast, I just look at leaf springs and live rear axles as obsolete, to me the perfect car has IRS and I want to build what my opinions would call "The perfect roadster". I don't mean to knock anyone running stock or the people running live rear axles (some of the live rear axle builds on this site are immaculate!), this is just what I want, and I really don't know why I want this but I guess I'm just following my heart.

[fj20spl311]

Phil, are you thinking about the 1500 with the SR/s-13 rear end that the car was sectioned down the middle?

I have seen pictures of a car sectioned down the middle, but it had a V8 conversion....coffee and cars in irvine IIRC.
I have not seen the SR / s-13 rear end.....

Always wanted to do a sectioned car with drive train from a G35 or G37 salvage car.....a GTR would be even more fun, but that's too big a project for the room at hand.

[fj20spl311]

Here is a picture to the LeMons car



Here is the text from the add....The add is expired.

Our Team is ready to pass the baton to the next one. You are looking at a 1968 Datsun 1600 "Fairlady" that has been slightly modified for racing. Bill Of Sale, no title. Finished the last 24H through the night at Buttonwillow. THE CAR IS FREE!! * I`m just asking for money for the cage ($1700) and the fuel cell ($500).. THE GOOD: * Starts on first try all the time! * Good for 24H Of Lemons of ChumpCar Endurance racing. * Roll Cage overbuilt by John Pagel at Evil Genius Racing (He is the chief Technical Inspector at the Lemons) so you can be sure it was built right. * Lights for night racing. * 15Gal Fuel Cell, FIA certified * Quiet custom built exhaust * Race Seat / Race Harnesses * Cut-Out Switch * Hardwired for Radio * Miata 1.6L Engine * Miata 5-Speed transmission * Miata Rear Subframe * Miata rear Differential * Miata rear brakes/suspension * 2 sets of wheels/tires * Miata front end subframe, Power steering, brakes not installed on the car but will come with the sale THE BAD * Belts expired * Radiator has a small leak that got fixed (good now but ideally a new rad for piece of mind) * Could use a lower point for the rear suspensions. Wheels are rubbing when fuel cell is full THE UGLY * Well, the paint job could use a refresh

[fj20spl311]

Why?.........."is it worth it?"
"no"

Well said

IRS is better, yes, if it's done properly, and it's hard to get the geometry right, and requires a dual uneven wishbone to do so.

If you not installing a sub-frame from a know "handling" model....IMHO, you are wasting your time. Especially for a first fabrication exercise

ymmv, etc. etc.

Your money, your car......
If I can help, I am here....

[st3ph3nm]

Actually, playing "Devil's Advocate" it's not necessarily true that you need to grab parts from a "known handling car". Look at all the British sports cars that run Triumph Herald front ends!

That said, a friend of mine who makes sports cars from scratch (literally) prefers building his own wishbones because "you don't have to deal with anyone else's measurements or mess ups". The trouble with taking a wishbone from a different vehicle and shoehorning it in to a different application is it's easy to get it set up wrong. Start from a blank slate and you only have yourself to blame.

My last point is a little tongue in cheek, but if you're going to make the "perfect" modern roadster, why the hell would you put an SR20DE in it? Shouldn't you at least use an SR20VE? Or a 3SGE Beams? The SR20DE is great bang for your buck, but it doesn't make it onto my list of all time great engines...

Anyway, also happy to help. Seems like it's an interesting project for a car that wasn't going to be saved otherwise. Hope I haven't hijacked things too far.

[fj20spl311]

I agree that once you have done a few, start from scratch.

First, I would start with a sub-frame and either narrow the frame or A Arms to get the width desired, test, test, test.....

I am doing just that with tubular upper A Arms.....I am starting with a "standard" set-up and modifying it to fit as a prototype.