2nd gen RX-7 rally car - brainstorming anyway

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mekilljoydammit
Problem is, with everything I know is wrong with the suckers on a fundamental level, I figure I'd have probably 3x the man hours into the car. 2nd gen front subframe swap

Took me a day at work. Most of that day was wasted in trying to use the 2nd-gen steering column instead of just using the 1st-gen power column that I already had. I kept the original dashboard and all of the electronic gimcrackery which is not compatible with the 2nd-gen column for a variety of reasons.

Unbolt the old steering and suspension, oval the front subframe holes inboard a little, reinforce, shove the new subframe up, make brackets for the rear mounting (three chunks of 1" angle iron and one of the now-unused tension rod bracket bolts, per side), install 1st-gen power column, slice the steering shaft midway between the U-joints and lengthen it, and you're done except for struts. That part is easy too.

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adapted over 2nd gen or Wilwood brakes...

There's nothing to "adapt", really. And if you use the slider brakes because you like 14" wheels, the 12A calipers fit the 2nd-gen hangers. I have a 12A caliper on the left and a FC caliper on the right. I forget what the flex hoses are from, could be either one, they're just about identical.

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equal length 4-link rear with Escort style tunnels for the links, or 3 link... non-Mazda diff...

3 link is easy but the floor eventually will give way at the lower link mounts. Still debating on if I want to do a spot reinforcement in anticipation of changing chassis, or if I want to do a wholesale changeover mount-wise and use longer links, which should allow for more droop travel before the driveshaft bottoms out in the transmission. (Angles thing, the longer the links the less the driveshaft plunge is) And you can't get a $100 junkyard set of 4.78s for the 2nd-gen.

Just sayin'...

OH and 2nd-gens have no headroom in 'em, either.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Okay, taking a step back... is there any major performance advantage one way or the other? It's been pointed out to me Dave Hintz did pretty well in a 2nd gen. I know it's come up on the rallycross stuff (I'm going off the top of my head, and yeah of course it's your car) with the 1st gen that the anti-squat you can dial in is helpful at low speed, but I was thinking semi-trailing-arm rear would be better at higher speed stage rally... and the Supra diff on the 2nd gen makes it less of a pain in the ass for diffs. I recall mention at some point about the 1st gen live axles bending under abuse too; is that exaggerated?

I'm at least somewhat agnostic one way or another; it just really does seem like the FC chassis is less screwing around.

Quote
mekilljoydammit
Okay, taking a step back... is there any major performance advantage one way or the other? It's been pointed out to me Dave Hintz did pretty well in a 2nd gen. I know it's come up on the rallycross stuff (I'm going off the top of my head, and yeah of course it's your car) with the 1st gen that the anti-squat you can dial in is helpful at low speed, but I was thinking semi-trailing-arm rear would be better at higher speed stage rally... and the Supra diff on the 2nd gen makes it less of a pain in the ass for diffs. I recall mention at some point about the 1st gen live axles bending under abuse too; is that exaggerated?

I'm at least somewhat agnostic one way or another; it just really does seem like the FC chassis is less screwing around.

Rememeber just recently I suggested to a newbie guy thinking about a diesel Rare-bit to make a chart with 2 columns Car A and Car B or 1st Gen vs 2nd gen
Then whatever's more or less the same cancels out if its in both columns
Then the remaining things you can concentrate on.

If you do that I am fairly certain you'll see there is no particular advantage in the 1st gen....and a lotta the junk-n-stuff you will eventually need or want to do is already done on the second gen..
Specifically: pretty good steering, pretty good brakes,, conventional struts (not old school were the tubes are welding into that spindly little spindle--which break--or broke 20 years ago--an somehowz I dun't think they've gotten better in the intervening years, do you?)

There was talk of towers, well maybe, if the trailing arms are short--and its a good chance they are---then maybe not towers...Maybe ask The Old Dave Clark if they did coilovers on the rear and how much travel they had...

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

For the record, I hate the 1st gen style struts. Hate hate hate. And I hate that the rules we run under in roadracing don't let me change to a conventional style strut. We've been living with shitty inserts in the suckers forever; I'm planning to finally make new tubes and bore out the spindle bits for them, and weld the new tubes in this winter so I can use halfway decent Koni inserts instead, because I'm tired of running shitty street stuff that doesn't quite work on a race car.

Anyway.

The comparison chart dealie's pretty much why I ended up with "hay, I should do a 2nd gen" and started the thread in that direction, frankly - but I might be missing things. And changing my mind at this point is nice and cheap.

either or. Glad to see more Rx7 folks. My first gen is basically an FC anyway at this point...

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Quote
mekilljoydammit
For the record, I hate the 1st gen style struts. Hate hate hate. And I hate that the rules we run under in roadracing don't let me change to a conventional style strut. We've been living with shitty inserts in the suckers forever; I'm planning to finally make new tubes and bore out the spindle bits for them, and weld the new tubes in this winter so I can use halfway decent Koni inserts instead, because I'm tired of running shitty street stuff that doesn't quite work on a race car.

Anyway.

The comparison chart dealie's pretty much why I ended up with "hay, I should do a 2nd gen" and started the thread in that direction, frankly - but I might be missing things. And changing my mind at this point is nice and cheap.

Save yourself some work and call on the fawkin phone.
I'm here home wif the girlies tomorrow so call.
It's me birfdee so I'll be in a good mood.
(get some tubes from me and weld them in, use Bilstein inserts so we know what the valving is and you're golden.

koni!!?

Echcht

And write up yer chart then and post it , maybe you did forget sumpin, but I think I know the conclusion in advance.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.



Edited 1 time(s). Last edit at 12/29/2012 11:29PM by john vanlandingham.

Quote
mekilljoydammit
Okay, taking a step back... is there any major performance advantage one way or the other? It's been pointed out to me Dave Hintz did pretty well in a 2nd gen. I know it's come up on the rallycross stuff (I'm going off the top of my head, and yeah of course it's your car) with the 1st gen that the anti-squat you can dial in is helpful at low speed, but I was thinking semi-trailing-arm rear would be better at higher speed stage rally... and the Supra diff on the 2nd gen makes it less of a pain in the ass for diffs. I recall mention at some point about the 1st gen live axles bending under abuse too; is that exaggerated?

I'm at least somewhat agnostic one way or another; it just really does seem like the FC chassis is less screwing around.

The 2nd Gen RX-7 is pretty darn good right out of the box. If you gotta do an RX-7 it really is the best choice. You already gave a laundry list of fairly major fabrication projects just to get a 1st gen up to the level of a 2nd gen. Hintz's car was remarkably stock in many regards. Stock suspension and steering with DMS shocks and good bushings. Stock brake system with good pads and fluid. Lots of power (probably 300+hp at full boost, we never went over 11psi) with the stock transmission that never gave any problems. Won a lot of rallies with a skilled yet conservative driver. It worked pretty darn good but took a lot of maintenance (just like any rally car, I guess.)

If you were starting from a clean slate I would recommend a Volvo or a Merkur first, just because there's so much more rally specific parts available for those. It's very easy. Plus they have more room inside.

Knobs would be nice on roadrace shit, and getting those on Bilsteins is apparently pretty nontrivial, is all - the Koni 8611s are about the cheapest halfway decent way to get what I want. Was looking at doing something similar to what you're doing with the 50mm Bilsteins, but with ebayed Penske guts, but had too much other crap to do to get anywhere on that past buying tubes, bushings, and a smallish assortment of guts. Also got some 40mm Bilsteins I was screwing around with too (the 84-88 300ZX ones) but not sure what valving is in those either, and there's just something attractive about using the Konis to get the damping to do what I want it to first without having to revalve the thing for every change.

(I don't pretend to know what rally damping curves should look like)

When's a good time to call? Don't wanna interrupt anything fun.

John, various crap came up today that needed doing - next week(end?) sometime?

Road racing and rally have very different suspension requirements. Trying to make a setup that works for both will end up being a less than ideal compromise for both. Better to have a road race set of springs and dampers and a rally set. Also keep in mind that a rally legal cage is going to end up putting you into a pretty open/unlimited level of road racing classification.

Oh yeah, don't misunderstand, I have no intent of trying to use the same springs/dampers/etc on both surfaces. I got sidetracked to bitching about the 1st gen RX-7 struts in a roadrace context, where I'm looking at cramming Koni 8611 inserts into them by the expedient of modifying the struts to fit new tubes. Separate car from the actual subject of this topic.

As for roadrace cages... the only (SCCA roadrace) class where there's a maximum cage build level is Improved Touring, which the car wouldn't be legal for anyway unless I pulled the whole driveline out too. STU, which I was shooting for (again, as something where the car would more-or-less fit, not as something to be a top flight runoffs-winning car) runs on Dot-R tires, but allows engine swaps (good because I was planning on an RX-8 motor anyway), any gearbox ratios (Miata ratios aren't stock) unlimited cage stuff, some suspension pickup movement, etc. Incidentally a rally legal XR4Ti would fit into the class too, though it would have to throw a restrictor on.

Now, a rally legal cage has more tubes than are required for roadrace, and the diameters and wall thicknesses are a bit bigger too, but that's just a bit less ballast that's required.

Oh yeah, not like anything made of metal has progressed (other life priorities right now) but was poking around and figured out another gearbox option. The early RX-8 6 speed is cheaply available, but has a dumb 4th gear; 1.645:1, 1.187:1 and 1:1 for 3rd-5th sucks. The 99-05 Miata box is the same thing but with a different bellhousing (and possibly needs the input shaft cut down a bit, if the 5-speed Miata boxes are any sign, but whatever) and a 1.257:1 4th, which leaves much better splits. Given how relatively cheap both are (especially compared to Quaife gearsets or any sort of dogbox) and how the 6 speed box has a reputation for being stronger than the 5 speed, it seems like a nice way to have a box doing 2.269:1 for 2nd up to 0.843:1 for 6th... and a useless stump pulling first gear but whatever.

04 05 Rx8 gear boxes will need the 2nd gear shifter lever replaced with the "new version" was made a little long and tends to cause premature death. and by tends i mean i think everyone i know with an 04 or 05 has a replaced transmission, but a guy on rotarycarclub.com figured out how to make the boxes worth while

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Hm, interesting. I was planning on just using the Miata box and keeping any RX-8 boxes around for parts donors. Any URL handy? Last thing I want is to be sitting around screwing with gearboxes that have recurring problems - had enough of that with the 80s vintage crash box in the roadrace car.

nothing handy, just talking to the guy over there. dont think he ever made an offical thread about it, showing the details.

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023