the DIS advantages to using the FC suspension, besides having to open the hood are these

1. roll center is not as correctable as the FB stuff is.

2. engine mounts change... PITA!

 

The roll center on the FC suspension sucks.

Plus even the fast rack (three port power) is not as quick as the power steering box. It's slightly quicker on-center but it's slower near the stops. I had to relearn my steering because of this - on dirt there aren't really any small steering corrections, with the power box I'd just throw the wheel to about 1/2-3/4 turn of lock and be able to make corrections with relatively small hand motions, with the FC rack it takes more exaggerated hand motions.

The R/C is definitely lower with the FC subframe, which is why if I was going to do it again, I'd relocate something an inch higher. Either mod the subframe or mod the body. The ball joints LOOK like they are 19mm stud (never checked) which means you SHOULD be able to get ball joint extensions for them, which isn't as pretty a solution as the steering arm spacer for the pre-86 stuff, because you're only moving the ball joint pivot and not the steering pivot. That's where the rod end steering comes into play...

It's only money and time, right?

 

yep! we keep talking about doing an upper control arm/double wishbone. paul wants to build it from rx8 parts cause they are actually quite reasonable new, although there are TONS of circle track parts too. the Rx8 mounts the upper arms on the subframe, so the whole suspension is one unit, but the FD and early miatae just have tabs on the body...

 

Sadly, Power Steering wasn't available on Canadian Model FB's If you have it, it would have been dealer installed with a purchase made from the US!

Why not install a welder series universal mustang II front end. It's cheap to purchase, easy to build, parts are easy to find and huge aftermarket for performance upgrades! With the welder series front end, you can use the pinto style front rack in either power or manual.

 

I looked into that briefly in the late 90's.

I had an actual body chunk from a Mustang II (it's not a subframe per se) and the chassis rails from the Mustang were about 6-8" narrower than the RX-7. I didn't think the engine would actually fit down in there, either.

Rotaries are wide engines.

If you were piecing together from aftermarket kits, it'd work with tie-rod spacers (common in street rod world) but I wonder how wide the track would end up being.

 

i think i'm just being clear, but PS was a factory option in 84-85 only on the GSL and GSL-SE, weird that canada was different.....

yeah mustang II would work, but for us it would be easier to use mazda parts, or just buy from coleman/afco

 

I think the issues you are experiencing are related to the kind of racing you are doing. We have built a number of big tube conversions and have had no issues getting struts out or servicing the struts themselves. Since we are using DA Koni's it is necessary to pull the struts to make rebound adjustments until the car is tuned.

Based on the way the spindles are made I would say that using wheels that have allot of offset are a fast way to cause a spindle failure. Running heavy wheel and tire combinations can't help either.

As far as steering quickness is concerned - add a circle track steering quickener to your power steering system. Allot of top level Solo cars use steering quickeners like the Stagnaro C Prepared Mustang. The steering ratio on that car is 1 to 1 just like a go kart.

From a clubracing perspective, the stock manual box is more than quick enough. Allot of the steering happens at the rear end of an agressively driven RX7.

 

agreed however, this is why i suggested a welder's series unit. you can modify it to the width required as they come prefabbed in 56", 58" and 60" track widths.

This may be true. Not 100% sure however I literally have 12-14 GSLs and GSL-SE's in my back yard and not one of them came with PS. Word from the local mazda dealer owner (who made the real targa top cars) said that it was an option that his dealership had to purchase from US dealers and install in Canadian Cars. Meh, doesn't matter anyway...

Perhaps. However, the only reason why I suggested it is that it opens a world of possibilities. They actually are really easy to install and if you are considering removing the subframe anyway, it's not that much more work to put one of these in.

Whichever way is chosen, important parts should be replaced "while your there". Kind of do it right the first time deal. I've learned the hard way.

 

re the PS unit, its not common here either, they kinda vary by region, PJ's hasn't had one without PS! i actually used to have a targa car... wonder if it was from canada

good point about the mustang II suspension, it IS another option. it kind of does look like the miata and FB ball joints are the same size though..

 

my '84 started life as a manual box.

As a general rule of thumb, it seems like if it's silver with red cloth interior, it has power steering. My theory is that people bought the cheapest model that had power steering as an option. I know someone who refused to even try a manual steer RX-7 because the idea of not having power steering was bad, somehow.

I know someone who had seven GSL-SEs and only one of them had P/S, too.

 

My silver 84 GSL SE with burgundy leather has PS FWIW.

 

Not really, the holes are used for holding the parts in the mill during manufacture. Also the current design would not allow to move those holes without moving the surrounding material.

Best bet would be different arms with an offset to the tie rod mount. We just need to decide how much.

-billy

 

lol, total side track! around here, it seems like we either got leather OR PS, but its rare to find both, and its actually rare to find cloth too.

i think my PS gsl-se's are 2 for 7? both were leather and PS. i'm 2 for 7 with cloth, both were manual.

ive had only the 1 gsl i think, leather with manual, the rest of the 84-85's have been white GS's

 

I will make some measurements and let you know what would work with my setup if that would be helpful.

Would it be feasable to offer two or three different steering arms with various offsets, so that customers could get an arm that would provide the most offset that their wheel/tire/brake combination would allow?

I would pay for such an animal!

 

My 84 GSL has a red cloth interior, but no PS. That's the way I like it. No need for PS in such a light car. Your arms get used to the little bit of extra effort needed in tight spaces.

 

I figure this is the best thread these questions.

Could someone explain why the stock caster alignment spec has one wheel about half a degree different from the other wheel? I thought unequal caster caused pulling.

Why does everyone here suggest as much positive caster as possible? To my understanding that makes the steering harder, and the only advantage is faster self centering.

Thanks

 

I believe the stock specs are a bit off due to the extra weight from one side to the other. I personally don't run stock specs and haven't in quite a while now.

Caster provides better stability at higher speed and gives a bit more camber on turns IIRC.

 

Oddly enough the unequal caster is to correct what would otherwise cause a pull.

All roads are ment to have a slight crown in them meaning they are highest in the center and lowest on the edges to help drainage, albeit very small there should be a slight curve to them. By taking a tiny bit of caster away from the driverside wheel this corrects for the slight grade of the road thus allowing the car to drive straight, if you were to take that alignment and put it on a TRULY flat road, the car should pull left ever so slightly.

 

Even if it's not specified, it's standard alignment practice to add a half degree of caster to the right side in order to bias the car to drift left. (Caster will never cause a pull unless the signs are different side to side) This is so the car is more pleasant to drive on crowned roads. I'd imagine that in RHD countries, caster is added to the left side instead.

FWIW - A drift is when the car kinda wants to lead off to one direction. A pull is when the car wants to make a turn unless you hold the steering wheel.

For the amounts of caster that we can get, steering heaviness is a non issue. I had one car that specified one degree, but I showed them I was able to get over seven degrees of caster. No appreciable change in steering heaviness. Added caster does, however, help cut down on wandering and tramlining, which is excellent if you're running tires that are wider and lower profile than the stock 165/80-13s.

You're never going to see much more than four or five degrees of caster without serious alteration to the tub or suspension, and this coincidentally enough is what most factory works setup charts will specify for competition cars.

 

oddly the stock spec for an FB is 4 degrees of caster, and the competition spec is 3.

its really weird when you consider they give you springs, shocks and alignment, but don't mention a word about tires, which is totally backwards.

 

Ah, I had forgotten about road crown. Makes sense.

Thanks

 

Incidentally, my camera is like a dog, it can't look up.



But that is how I bolted a GSL-SE engine to an FC subframe. FC driver's side mount, with some hole redrilling (bolt pattern slightly different), with a piece of 1st-gen mount bracket welded in place. And a 1st-gen motor mount.

 

After I reworked the rear suspension on my '84 Lemons-spec racer I was inspired to do something about the front end. I've been following this thread and thought that if people were adding strut spacers to raise the roll center and alter ackermann geometry, then maybe I could try to build in a reasonable amount of offset too. I measured, made up some drawings, thought about the forces involved and how to safely implement the design, and here's what I came up with-





The 'mod' consists of installing a plate I made that features 20mm offset flathead cap screws between the steering arm and the spindle/strut. This increases track width 40mm and adds about 2.5 degrees of camber without having to use wheel spacers or hacking up the strut towers. Everything clears with just as much space as the stock configuration. I've toiled over the design for a while because I've never seen anybody try this before, but I can't see a reason why it won't work. I'm taking it to the track in a couple weeks so that will be the real test. Till then, what do you think? It certainly looks badass on the ground if nothing else.

 

The casting/forging is of a decent enough material that you can weld on it with no problem. I had two struts that had only half of a bolt hole left after a Sawzall was required to remove the bolts. I placed a strap over the hole, welded another strap over that, retapped 12x1.5, and it worked just fine. Certainly the bolts never came loose before I bent that pair of strut housings too.

What I am getting at is, one could probably make a rotator/spacer plate and just weld the thing to the housing instead of trying to figure out how to attach it with countersunk machine screws. I don't know if trying for more camber would be a good idea since it would really throw off scrub radius, even more so than wide wheels typically will. If anything, I'd want to try to get the ball joint CLOSER to the rotor and then make up the camber distance with an extended control arm.

 

you are not the first to do this, but kudos for coming up with it on your own and building your own, i plan on making some myself, but with less camber and more ackermen.