355 Is the FHP Steering Rack the Only Option?

I've had my F355 GTB for about a year now and I just cannot get over how slow the steering rack is in this car. There are many other things I would like to improve upon but they add to the charm of the car. The steering rack is just horrendously slow. I've read the FHP rack is a nice improvement but seems to be near impossible to find, and if you do find, it's wildly expensive.

Any thoughts on this? I'd be surprised if a parts group haven't attempted to bring another option to market given the want for the upgrade and the lack of options out there

 

I know what you mean. Not sure about the rack but have you tried a smaller steering wheel?

 

not interested in a smaller steering wheel

 

Quaife makes a quick rack and pinion kit for the Fiat X1/9, which uses a TRW rack. I have an old standard rack on the shelf and keep meaning to try it, but haven't got round to it yet.

https://www.quaife.co.uk/fiat-x19-steering-rack-kits/

https://shop.quaife.co.uk/shop/steering/quick-rack-kits/fiat-x-1-9-rhd-quaife-quick-rack-pinion-kit-2-4/

 

Non-hydraulic rack kits don’t work for hydraulic racks. Quaife doesn’t make quick hydraulic rack kits.

 

I think the easy way out is a steering rack ratio quickener. A little gearbox plumbed inline with the steering shaft. One would have to be custom-made, but I bet if someone did it there'd be a lot of buyers. I agree, the tall rack ratio is the worst feature of the car. Kind of inexplicable.

https://www.summitracing.com/parts/hre-5225?seid=srese1&gclid=CjwKCAjwpMTCBhA-EiwA_-MsmaSNvs-v0kaGVU3rLNZQjsdkdo4if4iSuuegej7UNzy1Q1G4udlkFxoCk74QAvD_BwE

 

Fair enough, I haven't actually contacted them. When the time comes I will get a new rack and pinion made by a race engineering firm, plenty of them here in England.

 

one of the NSX guys had 30 quick ratio racks custom made by Quaife, really helps the car a lot. I bought two

 

I have chatted with some manufacturers about making a quick ratio rack for the 355 and it's possible...we just need the orders in place for them to justify the build out.

 

Is the 348 rack quicker than the 355 rack? And is the caster on 348 same as 355? If the 348 has more caster because the 348 was somewhat unstable to some until suspension tweeks were made perhaps if the 355 caster is less and using a 348 rack you could get better overall steering feel and less of the heavy manual rack feel with less caster? I'm just throwing things out there...

 

… for non-hydraulic racks correct?


Plenty of companies out there can do non-hydraulic rack kits. More is involved with Hydraulic rack kits, hence the reason Quaife doesn’t do them.

 

Yep non assist racks, much easier for sure.

 

What's the difference between the rack & pinion in a PAS rack vs an unassisted rack?

 

Yes, but you can add an electric assist to a manual rack (which wasn't an option back in the day). This would reduce weight and complexity and allow you to vary assist with speed, only have it at low speeds and manual un-assisted at faster speeds. Generally manual racks are slower than their hydraulic counterparts to make up for the lack of assist, but if you're having it done custom and plan to run it with electric assist you could make it faster.

You'd want to run the manual steering alignment settings - way too much caster by default in power assisted which would make the steering super heavy, especially with an even faster ratio.

 

I don’t really know, sorry. Someone here does though.

 

I remember WSM stating 348 caster at 5º and F355 caster at 7º--my speculation is that this is likely due to higher top speeds*
The 7º was on of the things that pushed Ferrari towards power steering in F355.

(*) but then there is that rear suspension change from pre-Specialé 348 to post-Specialé 348 which calmed the rear end markedly.

As to OP question: I find my F355 steering to be excessively light and often faster than desired. I wish I could put a 348 rack in it.
The closest and easiest solution is: to route PS pump back to itself, and route PS pump inputs at the rack to themselves.
Then, if you like this feel, remove PS pump at next major.

 

I'm not sure if this is what you were suggesting but it's impossible to add PS to a manual rack. Very very different designs. I also don't think anyone would be that happy with a manual rack 355. The steering would be so heavy that it would remover whatever road feel was enhanced (try driving a 964 RS America). Unless someone can figure out how to re-gear the stock rack, I think a ratio quickener is the only realistic way to proceed.

 

Most quickeners on the market are 1.5:1 or 2:1 ratio, which would be too quick for a 355 street car imo. You’d need a 1.25:1 quickener to convert a standard rack (3.25 turns lock-to-lock) to 2.6 turns lock-to-lock, which would be close enough to FHP’s 2.75 turns lock-to-lock.


I stumbled upon this thread doing a search.

https://www.4c-forums.com/threads/quick-rack.66246/page-3


Some interesting comments from the Alfa 4C guys. Alfa 4C is roughly 2500 lbs, manual rack, 2.7 turns lock-to-lock.


Apparently, one guy thought he was fighting the car too much on twisty roads and ordered a power steering rack.

“I have a power steering unit on order and am curious about a faster rack too. On the fun roads I enjoy the 4C is a wrestling match: high effort and crossed-up arms on the really tight turns. Seems I’m not the only one who shifts to 8 or 4 (hand position) to get enough leverage. Yes I have suspension upgrades and alignment. That made the car far more predictable. But the heavy manual steering and the slow rack (2.7 turns) it requires just aren’t well suited to fast street driving on truly twisty roads.

Compared to a Lotus the 4C steering feels like a dead power rack. Numb, and load through the steering wheel masks perception of loads on the chassis and tires. I’m sorry, it’s not a feature. I love the 4C but Alfa spent the whole budget on the glorious tub and had nothing left to sort the steering / suspension.

For perspective I drive the same roads in a Porsche Spyder, M2CS, Miata…and manual rack ‘71 911 and Ferrari 328. Only the Ferrari is as challenging. There’s a reason why power steering / faster racks became the norm.”







Another guy did the 1.25:1 quickener with the manual rack, but ultimately preferred to get a proper rack and pinion kit made.

“I don’t have power steering, just a steering quickener mounted to a used Giulietta column

The quicker steering is just what I wanted but I’m not happy with the clumsy execution. I regard my “quick column” as a cheap and cheerful test rig that was a great success but I want a more discreet, elegant solution.
I’m looking at getting a quick ratio pinion gear cut that will fit the 4C rack and give you 2 turns lock to lock with no other changes. I have one in my Capri and it’s works perfectly.
If anyone o r is interested let me know and I’ll get an extra one done.”

 

I believe the general consensus is the quicker the steering ratio the more effort is required to turn it (on a manual rack), however it might work a lil differently with a quickener? Perhaps a quickener doesn’t need as much effort as an equivalent quicker ratio rack/pinion?

 

348’s and manual rack 355’s (no one actually spec’d) have roughly 3.5 turns lock to lock. Slightly higher than power steering 355, I presume for less effort required.

 

Was more steering force required with the quicker rack on the NSX? What is the ratio?

 

The turning radius is also horrendous but not really an issue (is what it is). The steering rack is just way too slow. Seems like the only solutions are to use a quickener or find a group willing to make a batch of quicker racks if we can get the numbers to make it worthwhile.

Is anyone in for the latter?

 

I’d be interested

 

Yes, more force required especially from center as the stock part has the gearing cut so it’s easier to get going. The quick ratio has same teeth all across.
Ratio was 3.25 stock, now at 2.5 lock to lock

 

“the stock part has the gearing cut so it’s easier to get going.”

I’m a bit confused here. Are you saying stock NSX rack has variable sized teeth?



Has anyone in the NSX community made quicker racks for the power steering NSX’s?