im going about putting my Fc knuckles on my fb without changing up to rack and pinion. does anyone have a writeup on what i need? i cant remember what balljoint and other things i need to swap it all on.

 

I haven't done this myself, but I believe it was the early 90's 626 balljoint that makes it work (checked rockauto and the pic looks correct). You would need FC strut assemblies as well.

 

What's the benefit to doing this?

Thanks!

 

fc brakes and the ability to run fc coilovers

 

Ah ok, I see. Thx.

 

This is tempting man! Would be easy for me to just swap to FC front strut assemblies and leave my freshly-done FB front suspension in the car as-is...

 

Yeah it's a decent "in between" solution for those who don't want to do all the work involved with the full FC subframe swap. Again I haven't done it, but from what I can see, it's basically just a matter of using that 626 ball joint and then putting the FC knuckle/hub/strut on top of it... If you're doing this on a GSL-SE you could use FC 4 lug parts and it should all work quite nicely.

 

I'm probably going to be doing this over the winter because the FB motor mounts are better and the FB suspension geometry is VASTLY better. I mostly did the FC swap because FC have much stronger snouts.

So yes I'm going to be converting my FB from FC back to FB front end.

The FC steering arms are only ~130mm long versus ~145mm for FB, so the FB steering won't be quite so slow. I'm looking for an FB box with a bad locator pin so I can splice in a steering quickener as well.

 

All of this sounds awesome.

I wonder if I should just but the FC knuckles I have on, and sell my big bearing FB struts with my FC brake conversion for some cash and get nice coilovers for the FC knuckles. I wonder what the roll center is like with the FC knuckles...

 

Wouldn't it just be easier to move the FB strut towers back ~25mm to fix the castor/roll centre concerns with the FC subframe swap?

 

Could be against the rules for his class, wasn't there someone that grafted the entire FC strut towers onto an FB?

 

Moving the strut towers back will do zero for roll center, it will just increase caster.

The problem is the control arms are way too short and are mounted too low. So the roll center is low and it moves around a lot.

 

Yeah there was a guy on here who put the FC towers on, can't remember his name though. I actually rebuilt the frame rails on my FB to move the FC subframe upwards 1" and it did wonders for the roll center. Certainly not a quick job, nor would it be something everyone can do but I'm very happy with the result. Engine still fits under a stock hood too! lol

 

I saw your build and you did a great job! I would go FC subframe but that would require me redoing my whole swap...

It will be interesting how my car will drive with the FC knuckles and powersteering

 

Do you have any pictures of this? It's something I may have to do if the roll center doesn't match up with the IRS particularly well. I'll be moving the struts back anyway I think, but if I can get the subframe up higher that will help too.

 

If you're going to an IRS then the FC geometry will probably be fine.

The big issue with the FC suspension in an FB is the FB has a fairly high rear roll center by necessity. Mazda had to use a Watts for packaging reasons, and the pivot had to be fairly high up also for packaging reasons. (I have the numbers somewhere, I'd like to say it is 40mm above axle centerline. Not as bad as a swingaxle VW but close ) So the front roll center is also decently high so the roll center axis isn't all out of whack.

When you put the FC suspension in, that axis goes all out of whack and the car starts to drive a bit like a Reliant Robin. Lowering the rear roll center would be the proper fix but that isn't very neatly done if you like having quiet exhaust systems, or stock mounted fuel tanks.

 

This is pretty much what I thought. I have the Nissan Skyline IRS in the FB at the moment and the diff sits so low it's hard to get a trolly jack between it and the ground when the coilovers are fully wound up. I couldn't understand why the FC front subframe introduced such a problem with roll centre until I realised that the original watts linkage is really the problem when viewing roll centre as a combination of front and rear centres.

I think I'll still move the strut towers back on the FB to counter the castor problem (or see if I can get a couple more degree with modified bushes or something) and see how it drives with the FC front and Nissan IRS before worrying about roll centre again. Thanks for the info

 

I don't have any at the moment, I will have to go digging as I'm sure I took a few. I've been meaning to post more info about it, but haven't had the time, and am hesitant to because I'm no engineer - it's just something I decided to do (the current rails were rusted to hell anyway) and it seems to have worked out well. Well enough that I did it to my other 2 fb's afterwards lol. I like metal work, what can I say....

 

I'll come to the rescue, but not take any credit: