abtosway

iTrader: (2)

Hey guys! I have swapped in a right hand drive fc crossmember and suspension into my 79 fb. I have the s5 motor and transmission in and a big greddy turbo and re amemiya front mount intercooler. The car is coming along nicely however I just ran into a speed bump.

I bought an S5 lhd steering rack to replace the rhd one that I had.

The steering rack is 44 inches however the distance that the rack needs to be is 49 inches. I cant wrap my head around how this is possible.

The suspension is bolted to the crossmember which has not gotten any longer. Why do I now need a 5 inch longer rack? and what can I do? it is the passenger side that is short by 4 inches and the driver's side is short by 1...can I use a tie rod sleeve and an m12 x 1.25 bolt to extend the rack?

thanks guys!
Chris

bshusted

iTrader: (1)

Is it possible that whoever sold you the new rack threaded in the tie rods as far as they would for shipping purposes? If you added a sleeve, I feel it would create a potential weak point in the steering setup.

The most troublesome part is that the distance on each end is different. Was the rack centered when you made these measurements? I understand that there are two different ratios for FC steering racks. I have the powered S4 version and it's 2.5 turns lock to lock. If you turn the input shaft 1.25 turns from one stop, are the rod ends the same distance at each end?

abtosway

iTrader: (2)

hmmm...i dont think they are threaded in and yes they are the same length on each side. I absolutely agree that it would be a weak point, also I think that having my passenger's side tie rod 4 inches longer than the driver's side would have to mess up the steering right?

does anyone know how long their steering rack is end to end?

I will try unthreading the tie rods a bit and see if maybe you are on to something! thanks so far!

just to clarify, has anyone done the fc crossmember/suspension swap and used the stock steering rack from the fc with success? if so what did you do?

thank you guys!
chris

bshusted

iTrader: (1)

My car is about 2000 miles away, so I can't measure my FC rack for you, but I have done the FC swap in my FB. It does work.

Thinking about it a little more, the rack is not symmetric. The mount on the driver's side is different from the passenger's. Perhaps since the mounts are different, the subframe is specific to whether the car is RHD or LHD.

It doesn't matter if the subframe is in an FB or FC, the steering rack should fit regardless.

If you still have the other rack, perhaps you could lay them next to each other and compare the mounting points.

Lengthening the tie rods will most certainly screw up the steering geometry.

abtosway

iTrader: (2)

Appreciate the input so far, I was actually thinking along the same lines. So I suppose the logical step is to ask fc3s folks to measure their steering racks, from tip of tie rod, to the tip of the opposite. Both RHD and LHD folks are welcome to reply

(possible i was shipped the wrong rack entirely :s )

Thanks!

peejay

Oh yes it is. I remember seeing an FC race thread out of the UK and thinking "Wow, that subframe looks wrong to my eyes!"

if you want an LHD rack, you need an LHD crossmember... or a lot of fabrication work.

LHD rack/crossmember:



A thought: Could someone have sent you a Miata rack? I haven't had one side by side with FC but that would make sense, given that piston engined cars tend to have the pinion much closer to center than RX-7s, so most of the missing length would seem to be on the passenger side.

PS - You do not have an FB. FBs weren't made until 1981MY. You have the far superior 1st-gen, the one that combines lighter weight with better looks...

abtosway

iTrader: (2)

haha yay for "far superior and lightness"! haha that made my day!

it may be possible that I have gotten a miata one, i will have to do some research!

S4 and S5 racks are the same right?

thanks for the help so far guys!

before I go order a 1000dollar flaming river custom rack, does anyone know the stock length end to end of these racks?

thanks again

bshusted

iTrader: (1)

I don't know about the SA's "superior looks," but it's good to see that peejay dug up a picture of a subframe and rack.

Instead of getting a custom rack made, why not just get a real LHD FC rack and LHD subfame.

As far as I know S4 and S5 are the same as far as mounting. Some S4 power racks have an extra pressure port for power steering. The only other difference is a couple of different ratios.

abtosway

iTrader: (2)

haha I dont know about "superior looks" either but I will gladly try to fool myself into believeing it!

I see what you are saying about lhd rack and member. I have already fabbed up mounts and making them solid should not be an issue, so I am not worried about mounting the rack. I guess I just need to know that I have the right one.

from what I understand, it is IMPOSSIBLE for my wheelbase to suddenly have gotten 5 inches wider when I mounted this crossmember in my 79 which must meen that the member that I bought this rack off of sent me the wrong one right? the only thing I am waiting on to confirm is a proper measurement of the right one....hmmmm....

peejay

AFAIK, there are only three FC racks: manual, "slow power" and "quick power". FCs had the quicker power rack until mid-87 or mid-88. The change was late in S4, anyway. The difference is minor.

abtosway

iTrader: (2)

@peejay: That lines up with the what I've been seeing, with the exception that they're is of course a left hand and right hand drive version of each. While the core rack remains the same with the reversal, the mounting changes drastically to clear the opposite side of the oil pan. To compensate, I'd imagine different length tie rods, and perhaps end links would be used, this is the assumption I've been working under to maintain sanity :P

Thinking on it now, maybe i should repost in the second gen threads hey? haha

Thanks again!

j9fd3s

iTrader: (3)

basically.

manual rack is s4 only. it had an FB01 sticker on it

the quick (15:1) power rack is in ALL the PS equipped s4's, and the upper model s5's. its the one with the vehicle speed assist, which was the first car to use such a thing. can be ID'd by the 3rd hydraulic hose. i think these are either FB17 or FB55 numbered

the "slow" ps rack, 17:1 is found on the base S5 models, and is just a normal 2 line system. this one is an FC01.

RotaryEvolution

iTrader: (30)

the s4/5 power unit with 3 lines is FB78, just mentioning it as i have one sitting right here and thought i'd double check.

it's not jacked up and i have to leave soon otherwise i would get some measurements of full length for you.

abtosway

iTrader: (2)

Hmm, I'll have to check how many lines when i get home Karack... if you wouldn't mind measuring when you get a chance that'd be terrific!

I'm trying to knock down all other options before parting with money for a custom rack.

peejay

Interesting.

My '85 GSL had speed-variable power steering, too. I still say that the car only had power steering in order to make it easy to steer at parking lot speeds, necessary due to all of the weight added by the power steering pump bracket.

RotaryEvolution

iTrader: (30)

i forgot it is a RHD rack so the numbers probably are actually incorrect, this one is a LHD.

abtosway

iTrader: (2)

@Karack - nope I have lhd rack so hopefully those numbers do work, I will try and take a look for them...
thanks

j9fd3s

iTrader: (3)

lol, yeah. that's japanese engineering at an extreme, we need power steering because we have power steering.

they should have just added a little negative camber, the steering in peepers is really light, even in the parking lot, with 225's

abtosway

iTrader: (2)

Just going to high jack this thread back for a moment xD

So thanks to everyones assistance, I picked up a actual FC rack today. I do still need to fabricate new mounts for it as the RHD crossmember has them backwards for the LHD rack, but thats not an issue so I consider this problem solved!

It looks like the rack I was sold by a member here, was unfortunately a Miata unit, not an FC as advertised. Appreciate all the help on this one... I'll post pics as soon as its in!