Whizbang

check it out, i gave a quick go over on how i mounted up mine.

http://www.youtube.com/watch?v=1NmCfxRR_EQ

IanS

iTrader: (4)

Good stuff. Its amazing how much easier doing stuff is when you have a welder lol (on my to buy list).

Whizbang

my next major tool purchase is either a tig or mandrel bender

dantheman

iTrader: (4)

Very nice. Doesn't look to hard overall other then the steering. I always thought it was a good bit more difficult then that.

Would it be smart to use metal backer plates for your sub frame bolts that you had to drill holes for just to distribute the load a bit better?

Dltreezan

iTrader: (3)

interesting. i just sold a front subframe to a dude with an FB.

Whizbang

i suppose you could, but i figured that would require there to be more downward force applied (meaning something having to pull the subframe down away from the frame). I figured there would be more upward force (subframe pushing into the chassis) or shear (buy good bolts). This is for my rally car so im certain ill find out

Crit

iTrader: (6)

Be careful guys. What's often overlooked here is that the subframe sits too far forward when installed this way. This adds a huge amount of caster and will require the front edge of your fenders to be cut to clear the tires. It'll fit, but it's not particularly good geometry.

If anyone has locals close that include a tight stock box, FC subframe kit, and a respeed rack kit, I'm curious how they feel. Everyone's always impressed by their own work, and the cars nearly always drive better than the sloppy box ever could, but it would be cool to see one butt planted in all three seats to see how they drive.

Please don't take this as crapping on your thread - you've clearly done a lot of good work. It's just worth talking about, I think.

thunkrd

iTrader: (1)

might do the fc subframe swap on another fb.. this current one will get the respeed rack..

one thing about fc subframe swap is that it makes it harder to put a non fc engine in...

BigIslandSevens

iTrader: (4)

By how much is it too far forward? Can camber/caster plates be used to overcome the geometry change?

Is it as easy as moving the entire assembly back by X amount and just re-inventing the mounts? Such as what was done with the bolts being welded into his set-up. Seems as though using the stock bolts are more of an "easy way out" guide.

As to engine choices once the FC swap id done. Doesn't it make a 13B-RE and a 20B much easier of an affair? The RE Would be as drop in as a T2 I would think.

A REW engine requires a lot of fab work regardless of how you go about mounting it.

Thanks for the ideas though Alex. Good stuff.

Dave

Whizbang

perfectly valid, since i am running a rather unique purpose of rallying so things like the fender touching dont matter to much for me. ill just cut it. Once the front suspension is finished and comes in (dampers / spring coilover rally thing being made at the moment) well see how it all works out. If its sketchy, its not to big an issue for me to relocate things.

peejay

Get down with the sickness!

The steering shaft is the hardest part. The rest is ridiculous easy. It's almost as if Mazda reused much of the FB when they made the FC.



Between the FC front and the three link rear, the car is different. Crazy different. Awesome different.

peejay

The first person I'd heard of doing it (Abe Omid) mounted the subframe so that the wheel centerline stayed the same, in other words he had to relocate all four mounting points. He also used the FC steering column somehow, FB strut tops somehow, and the FC engine dropped right down into place.

I did the inch-forward method, which required some beating of the inner fenders (some was necessary anyway, to clear 60cm rally tires at max compression), trimming of the fenders (they will get flares later; again: bigger hoops) and I had to redrill the passenger side FC engine mount bracket and fabricate a weird FC/FB hybrid bastard "looks like a really bad idea" mount for the passenger side.

For strut tops I made spring perches (washers and 3/16 plate) and used ZX2 units (file the D-hole to fit FC strut, drill strut tower holes for 10mm studs vs. FB 8mm) but if I wasn't so keen on using off the shelf coilovers and getting as much bump travel as possible, as well as continued use of my CP strut-firewall brace, I would have just tried to redrill the strut towers and gone full FC. As it is, the captivated-strut-shaft bearing arrangement means I can unbolt the strut from the top without air tools and change springs in a flash.

I WANT more caster. With the FB suspension, I was already dialing in a lot of caster with the tension rods, which does unpleasant things to the control arm bushings. (I have seen cars with so much caster that the control arm rubbed the subframe!) I also wanted to move the wheel centerline forward in order to get weight off the front end. I'd ideally like 45/55 distribution but I've never had an RX-7 that wasn't 100lb heavier on the front than the rear, and adding an oil cooler and 13B engine makes this worse.

Oh yeah - major plus - removing the steering box from the left side really helps get rid of the heavy L/F problem that FBs have. The FC subframe/engine combo also centers the engine a lot more so that helps get weight off the L/F as well.

I'm not too keen on the FC brakes as of yet - the 12A brakes had much nicer feel and I could brake a lot harder with them. I'm going to experiment with different pads, but I know it can't be a hydraulic issue since the FC (single-pot) calipers and GSL-SE rear calipers have the same piston diameters as 12A disc. In theory, larger brake rotors SHOULD mean better braking, but theory and practice rarely intersect.

But, it's SO nice to have so many fewer bushings, struts that can be swapped out without screwing with the brakes, and a much wider set of wheel options.

Whizbang

woot

Hyper4mance2k

iTrader: (40)

pics pj?

peejay

http://www.ohiorotaries.com/smf/inde...topic=2487.175

mellow65

iTrader: (2)

awesome stuff, and good to see another FB going to be rallied.

are you talking full out rally car?

if so, i got some "must dos" if you want that thing to live a long happy life onstage. I have been spending the last year with an 82 learning it's weak points (IE parts of the frame) that buckle under full blown stage rallies.

other then a few key things, the car when i got it had been on stage for about 7 years and over 40+ days of stage days and she has held together very nicely. better then some rally cars out there.

but if you want some pointers on what need some reinforcing PM me and I'll fill you in.