355 Ferrari F355 Challenge Steering rack

The smaller steering wheel does not compute for me?

Regardless of the size of the wheel, the steering column needs to rotate 360 degrees, times by the number of turns to go from lock to lock. Only by increasing the size of the teeth on the rack can that lock be reduced, i.e less teeth to from from one lock to the opposite one.

 

Don't tell me that!!! My new quick-ratio wheel just arrived.
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The real options are:

a) Quicker rack (the subject at hand)
b) Shortening the pickup points on the uprights
c) Intermediary steering quickener in the steering shaft​

I investigated (a) a couple of decades ago for an Audi, and haven't been able to find the company that would custom-machine components to fit inside a factory housing from that time. Cost wasn't cheap, and I can't recall how I found them.
I've done (b), most notably on a Datsun by using 240 struts (and I think the steering arms may have been a separate piece), per instruction from Electramotive, also for the purpose of changing the scrub radius, among other things. The 355 doesn't have this option.
Investigating (a) eventually lead me to (c), but I never had it done, which mk e installed in his V12 308 project along with the EZ Power Steering kit to make the higher effort manageable. We already have the PS part, so splicing a ratio changer into the shaft at the firewall is all that would/should need to be done, but will require some fabrication. Different ratios are available.

 

Agreed, the only practical way is to find another trw rack from that era that had a lower ratio, in the hope that the internals may fit into the 355 case. Having pulled a number of these apart over the years, it does seem that TRW kept to a standard type of sizing for internals, and the bespoke parts were simply the outer casing to suit each manufacturers needs.

Problem is that quick racks only tended to be used in higher performance models, what is really needs is a rack reconditioner in Europe to take apart a 355 rack and then compare it to the more mundane ones they see far more often and hope they can match up to something they have to hand.

After that it is more straightforward as the trw racks are easy enough to strip apart and service anywhere around the world.

Its likely to be something from Saab/BMW/Jaguar/Ford etc what will supply the donor internals.

I have a spare lhd rack here in the UK I will offer up to the cause if anyone wants to do the legwork to find a company that will strip and inspect it/ try to match up a quicker rack and pinion.

 

Juice isn't worth the squeeze on this - add more caster if you want more feel/effort, but honestly the stock steering feels about perfect to me. Light at normal speeds, weights up nicely when pushed. The seating position is the far bigger issue for me, I can't get close enough to the wheel for ideal seating position without either my knees hitting things or my head touching the headliner. I need the wheel about 2" closer to me or the seat another 2" lower, neither of which is easily achievable.
If this were an off the shelf upgrade or parts readily available to upgrade the stock rack, it just might be worth the PITA that is R&R'ing the stock rack, but if any more effort or money than that is required, not worth it at all.

 

So Jeff Segal says the single most important upgrade he did was the quick steering rack (starts at 4:10).

 

@RudyP

 

I agree. on the track yes absolutely needed. Street car not worth considering. Perhaps just a little quicker then the challenge especially if you have a better suspension and more power then a "stock" challenge car.

 

Are you saying 2.5 turns as opposed to 2.75 turns is the way to go?

 

Yes track only not for a street car. I may go further I love a quick steering box and adjust with a bigger steering wheel if needed

 

I'm not sure that 2.5 turns would be a problem. Not apples to apples, but I drove a Giulia QV before the 355. Steering ratio of 11.8 and 2.3 turns was never a problem on the street and perhaps one of the best features of the car.

 

OK been under a rock for a while, who can we get to make these?

 

Do we know who bought this rack?

 

Yes it doesn't change the rack ratio of course but smaller diameter does decrease leverage.

Results in a bit heavier steering feel and more degrees steering movement vs inches traveled of circumference.

(turn a 380mm wheel 90 degrees your hands traveled 298mm, 320mm wheel 90 degrees your hands traveled 251mm) No?

Another idea is, it appears the tie rods are swept forward a bit from the rack.

What about maching/re-drilling the steering knuckles to put the tie rod end closer to ball joints.

Would result in more overall steering angle lock to lock but I think could be brought back to stock with a collar clamped on the rack, inside the inner tie rod ends to limit travel.

 

That's exactly what I've been thinking. Would interfere with the heat shield mounting but other than that should work. I was also toying with the idea of billet hubs...

 

Billet hubs would be nice because you could lower it and keep the control arms in their original position. Would need rears too

Could also build them to push the wheels out a bit. (would need a spacer same distance between the CV's and trans outputs)

 

Wasn’t me that’s for sure. It’s gone now. Forever.

 

Maybe send a stock rack to these guys?

http://www.woodwardsteering.com/PDF/1.Power%20Steering%20Racks%20for%20Road%20Racing,%20type%20CF.pdf

 

Oh nice and they are on the west coast. I just need to find a bad rack now to send them or 3D scan mine

2.09 and 2.36 YUMMY


"Each model in the CF series can be machined for one of seven pinions, to provide a wide choice of steering ratios. Expressed in inches (mm) per turn, these are: 1.57 (40), 1.83 (46,5), 2.09 (53), 2.36 (60), 2.62 (67), 2.88 (73), and 3.14 (80)."

 

Here's a busted rack on ebay: https://www.ebay.com/itm/114178433871?hash=item1a9590a34f:g:Y-4AAOSwnXReji8o

 

I would contribute to this cause.

 

Fwiw they do say on that page they do not do street car racks.

Tims car is a race car though so maybe they will build one for him, then we can all order one

 

Same here - lets make this happen.

 

This is an in-cockpit view of a 1995 F355 Challenge with a 380mm steering wheel at Lime Rock Park. I'm not sure if this car ever got the quick-steering rack...





The driver handles and shifts that car perfectly around that 1.530 mile track. When I first tracked my car at Lime Rock, my instructor used this as an instructional video.

 

I also want to change my steering for a track only F355: I contacted Sportech in the UK and they can do the job:

using the OEM rack and designing new rack, pinions and pistons to the specs (I would thin of a ratio of around 2.25)

Cost (approximately)
design 2500€
first order 4000€
if more than 3 units build: 3000€

If I can find 3 other people interested it would cost around 3875€ to modify the rack.
Anyone interested?

 

If you guys are serious then I would suggest contacting Tim at Walkersport in the UK. He already has a contact for machining uprated propeller shafts for the gearbox at a very competitive price, and manages 355 challenge cars on behalf of clients, so no doubt would get the ball rolling for a quicker ratio rack and pinion to be machined for the stock casing if the market was sufficient. I can see it being for better priced than above.

I have a standard, complete and undamaged lhd rack here I can lend/ drop up to him for strip down and mock up if he does not have one one stock, he is less than a 2 hr drive from me as well.