shm21284

Well, my imagination kicked in again and I decided on what suspension to use for my independent rear suspension project. I decided on FC suspension since a buddy of mine has a parts car rotting in the parking lot. I am basically getting this for free.

I read a while ago on the internet that FC suspension was used on an FB test mule. Then, I read a book written by Jack Yamaguchi that it indeed was used on an 82 FB to test the design. I copied the 11 page write up on it, which includes pictures (always good for seeing how they mounted it in the car). I parked my FB next to my friends FC, and, as far as I can tell, the sub frames look like a NEAR bolt in procedure, with some minor drilling, possibly a little welding. Its not as bad as it initially sounded.

Its going to take a while for me to get this project moving since I will have to fab an engine mount for my 12a to have something to rest on (I was thinking possibly the frame rail). I will also have to come up with an LSD. Does an 82 LSD work with 87 axles? do any of the internals swap over?

tjgosurf

....

I have no clue. But I wanted to keep this post going, because it sounds like a good idea!

rotor vs. piston

My prayers are with you.

nevarmore

Where is Alexandria? It sounds like some small town I've driven through once or twice but I can't place it. It sounds interesting and if you're close I'd be happy to help.

RX7145

iTrader: (1)

Alexandria = Speed trap of Ohio

Your car sounds cool you should come to a meet sometime

nevarmore

They renamed New Rome?

http://www.ohiorotaries.com and http://www.columbusracing.com

ioTus

iTrader: (5)

whats his name... some dude on here is doing it.. bcrx7

http://www.bcrx7.com/omid.php

explore around that site for a bit

jutny

if this works, i WILL do this.

cause i know where i can get a 2nd gen parts car for free.

peejay

Linndale is awful. My radar detector plays the theme song from "Gone with the Wind" every time I drive through there.

But anyway: Why bother with the IRS, it has many disadvantages esp. the FC setup.

shm21284

Simply put, solid axle sucks. The only thing its got is less weight. But its unsprung weight. From an engineering standpoint, independent suspension is superior. From a racing standpoint, its superior. From a smooth ride... well, i wont even go there, cuz my car is like riding a go kart on potholes.

The second gen has the overall advantage over a solid axle. The only thing I dont like about it is the weight gain, but most of it is unsprung weight, which translates to better control at the limit of grip. I love corners, and a well balanced, easily controlled car is what i want.

shm21284

By the way...Alexandria is the worst place for cops. I got a loud exhaust ticket when i was ******* around with a true duel exhaust (dont waste your time, it sucks) when i worked at the only gas station/shop in town (where the cops get there coffees and donuts) and the mayor has a harley. Avoid this shithole at all costs

peejay

From an engineering standpoint? You're forgetting that the solid axle is inherently stronger, you CANNOT have any useable degree of anti-squat with an IRS (this is the force that drives the rear tires into the ground under acceleration, *generating* traction by its additional downforce to the tires), and swing arm type suspensions like the FC has have a very nasty amount of anti-dive in the back - basically, braking tries to pull the tires off of the ground, since the arm length is so short.

Let's not forget the *inherently* much more stable suspension geometry.

IRS has two advantages: unsprung weight, and more interior room available. I would say the advantages of the solid axle outweigh the advantages of IRS.

purple82

Agreed.

Also, during body roll, a trailing arm suspension changes the wheel's orientation with the road. Not good for cornering grip. A solid axle ALWAYS has it's wheels perpendicular to the road.

A good multilink suspension can overcome this, but the 2nd gen aint got that.

The only advantage that I can see to a trailing arm rear suspension is the reduction of "skipping" through bumps in corners and probably a better ride. Ultimate grip, however, is probably better with the solid rear end.

shm21284

you cant control camber, caster, toe, or any of the other necessary factors when facing suspension. Why did all modern race cars go IRS? (i know trailing arm is not the IRS of choice, ill get to why im doing it)

You dont always want your tires perpendicular to the ground. Example: when cornering. You want your outside tire to camber more negetively, while your inside tire should stay closer to flat. A well designed IRS does this, including the FC's. It also has toe control (the toe in while driving is going to be scrapped, but you can still adjust the toe in/out).

Granted, trailing arm has more squat under acceleration which was a major problem in designing the FC suspension. There were so many problems with the FC at first that many people wanted to ditch it and go with solid axle. The IRS was pushed, though, and they finished with something better than ours. Its simply an upgrade from the FB. Theres more control when considering driving, theres more control on how you can tune the suspension (instead of basing tuning on only spring rates, bound, rebound, and swaybars you also have toe and camber), theres more control on how the suspension is supposed to react under certain conditions.

shm21284

Stronger? i dont plan on off roading.

More stable suspension geometry? explain, i dont understand

shm21284

The FC has increasing camber as it increases suspension travel, much like unequal length suspension arms

FirstGen7

Hmm, shm, I've got an 82 as well...and she's just in time to get a little suspension replacement...

Interesting idea, I like it, I like it a lot.

MosesX605

Doing an IRS swap doesn't seem to be worth the trouble, IMHO. Even if the parts are free, you still have to engineer the swap, deal with fitment issues, custom driveshaft, etc. Once you're done, you have a rear suspension with a different bolt pattern than the front, so off to the boneyard to find SE front struts and spindles so you can have the same bolt pattern, assuming that you installed the rear suspension from a GX, not a GXL. If the suspension's from a GXL, you have to get wheel adaptors for the front, and then you're still stuck with piddly little brakes in the front and huge brakes in the back.

That doesn't include new dampers and springs, because there's no point installing old worn components from the donor car.

All of that work, for what?

For a car that may or may not handle as well as a properly set-up car with the stock rear axle.

Doesn't sound worth it to me.

FB II

shm21284

The suspension is from an 87 SE, im using both the front and rear suspension. I already have a t2 transmission, so a custom driveshaft is 35 dollars to have the t2 driveshaft spliced with the fb driveshaft and balanced.

I like challanges, and this is certainly a challange in engineering and fabrication. I go against the mold, like mazda goes against the mold with their engine.

peejay

With a Panhard or Watts linkage, the roll center doesn't go all over the place like in most IRS's.

Strength is imporant for all vehicles.

shm21284

Strength is important, but why would a solid axle need to be used? The FC's rear suspension is pretty strong.

By the way, the trailing arm on the FC is more of a multilink. Ill see if i can scan some pics of the 11 page thing for everyone to view.

TwEaK

iTrader: (6)

shm i was thinking of doing the same thing for my futur FB but dont know weather or not to do it im gonna have my FB as a daily driver / weekend track car dont know if i should keep the solid rear axle and just get a good suspension??
TwEaK

peejay

It's a swingarm with camber control. Basically crap.

1984special

Hey, more power to you. Just remember that Mazda had a whole damn group of engineers working against the mold...