Quaife quick ratio manual steering rack

There is definitely no prototype yet. It’s still in “finding a stock rack” phase. Nothing has materialized so far. I reached out to [MENTION=21305]jvtec95[/MENTION] and he could be the savior there. Otherwise my plan was to buy a new rack and install it in July / Aug, then ship my old one.

Fwiw, there will likely not be a single or small batch of prototypes. There would be a first batch of ~30 rack kits at the chosen ratio
 
[MENTION=36953]bogle[/MENTION] I messaged you back, I'm fine with sending my old rack out to Quaife to keep things moving.

From what you've looked into it sounds like 30 parts is minimum order quantity, and we have ~1/2 that interested at this point. If anyone is interested please drop a reply in this thread or out to [MENTION=36953]bogle[/MENTION] to add to the list. I believe there is no money needed up front at this point and no firm commitment, but it would be good to see if we can get at least 30 people on the list. That way Quaife can at least see that there is a reasonable demand for putting in the work.

I replaced my rack with a lower mileage one with the brass steering rack bushing installed. It drastically improved steering feel and reduced play, but still has that huge lock-to-lock ratio! I really think this would improve the feel and response of the steering system at a minimal increase in effort.
 
Depending on the cost and whether or not I can buy for LHD and RHD I might be down for multiple.

Probably only going to be LHD huh?


Sent from my iPhone using Tapatalk
 
Yeah the plan is only LHD at this time. Maybe it’d be less effort than this to eventually have the do a RHD one. But for now it’ll be built around the LHD rack.

Quaife confirmed all the sending info this morning, and [MENTION=21305]jvtec95[/MENTION] is in, so this should be moving again. Really looking forward to their analysis
 
Great [MENTION=36474]cuneo[/MENTION]! You've been added to the list in the OP

A little update: [MENTION=21305]jvtec95[/MENTION] sent the rack (THANKS!), and it has been delivered to Quaife! Quaife said they will let me know when it has been 'processed' and they start analyzing it.
 
I got a "Sales Acknowledgment" from Quaife this morning saying they got the rack and will start the quote process. He said it will take up to 4 weeks to get the quote back to me. The quote will include the possible rack gains / ratios they will be able to achieve with the stock housing.

I sent him the desired range, basically somewhere in the 20-30% increase in gain / revolution, with ~25% (16.7:1 at center) being the sweet spot. We'll be able to pick the ratio when we make the final order. Once we have a quote, there will be a concrete price and ratio. Then I'll run around and drum up more interest on FB, etc. I'll also ask anyone interested here to let their NSX friends know at that point!

Thanks again [MENTION=21305]jvtec95[/MENTION] for unsticking this with your rack!
 
Small update on this. I’ve been pinging my guy every now and then. There is still no quote, but he did send this:

We should be able to achieve the ratio you requested (48.1mm/rev). This is achievable with 7T pinion up from 5T at 12DP 14.5° with 5° housing angle.
Click to expand...

For reference that would be a 25% increase in gain from stock for a ratio of: center 16.7:1 - end 14.6:1. I figured that would be a good ratio workable on the street and track and probably be at the acceptable limit of increased effort.

He said he is chasing the quote. I’ll ping him again at the end of the week.

Once we get a quote, I’ll share it here, then start drumming up enough interested parties to cover the quote.
 
I'm assuming that we will be getting the rack and pinion kit, not a full steering rack, correct? I know they offer both but the kits are significantly cheaper although they require a little bit of work to get them installed.
 
bogle said:
Small update on this. I’ve been pinging my guy every now and then. There is still no quote, but he did send this:



For reference that would be a 25% increase in gain from stock for a ratio of: center 16.7:1 - end 14.6:1. I figured that would be a good ratio workable on the street and track and probably be at the acceptable limit of increased effort.

He said he is chasing the quote. I’ll ping him again at the end of the week.

Once we get a quote, I’ll share it here, then start drumming up enough interested parties to cover the quote.
Click to expand...
I'm currently on a 13.8:1 ratio on my NA1 and it's quite nice so a 14.6 should be totally good and given it's a manual rack.. any more would likely require too much effort. Can you remind me, this is a progressive ratio right? Did they say what's the starting ratio? Like 20:1?

In prep for this, i've also done quite a bit of research with implementing a piggyback BRZ/FRS EPS motor on the column. It's a popular mod on the internets (they use Prius', 86's, and various other column mounted motors). I chose the BRZ/FRS/86 because there is a company that makes a digital controller for it. UNFORTUNATELY, I can't seem to find a way to fit the motor under the dash anywhere (visual inspection only). I even contemplated buying a junkyard NSX steering column assembly. There just seems way too many pivots and the column itself seems way too short to fit any type of EPS motor under the dash.

Has anyone else looked into this? The steering feel of the BRZ I owned was very impressive, even for an EPS.
 
The ratio depends on knuckle geometry, so they don't (can't) actually know the ratio cause all they have is the rack. All their changes will affect the rack gain, which is how much the rack moves laterally for a given 360deg column revolution. I've mapped the gain onto the ratio from the user manual (20.8:1 (center) - 18.2:1 (end)) to get the 16.7:1 - 14.6:1 ratio. The old gain is 38.5mm / revolution, and the 25% increase would put it at 48.1mm. The ratio doesn't really matter in all this other than to give an idea of how it will change from stock.

The rack itself wont be variable, it's just a variable ratio because (I think) the knuckle moves through an arc.

I agree that a > 25% increase in effort might be a little much. I really wish we could try 20, 25 and 30% increases.

Interesting, so the 86 uses a motor in the column, then effectively a manual rack? I wonder if splines and stuff would line up. Seems like maybe you'd need the entire 86 column, based entirely on 30 seconds of looking at ebay pics of the motors.
 
bogle said:
The ratio depends on knuckle geometry, so they don't (can't) actually know the ratio cause all they have is the rack. All their changes will affect the rack gain, which is how much the rack moves laterally for a given 360deg column revolution. I've mapped the gain onto the ratio from the user manual (20.8:1 (center) - 18.2:1 (end)) to get the 16.7:1 - 14.6:1 ratio. The old gain is 38.5mm / revolution, and the 25% increase would put it at 48.1mm. The ratio doesn't really matter in all this other than to give an idea of how it will change from stock.

The rack itself wont be variable, it's just a variable ratio because (I think) the knuckle moves through an arc.

I agree that a > 25% increase in effort might be a little much. I really wish we could try 20, 25 and 30% increases.

Interesting, so the 86 uses a motor in the column, then effectively a manual rack? I wonder if splines and stuff would line up. Seems like maybe you'd need the entire 86 column, based entirely on 30 seconds of looking at ebay pics of the motors.
Click to expand...
Good point about the knuckle arc sweep.

Yes, the 86 steering rack resembles ours very closely. If I had more time, i'd buy one and see if I can retrofit it to the NSX. BRZ is a 13.5:1 steering ratio, but to your point not sure what it truly is if the knuckle sweep is removed from the equation. It's so cheap i'd be willing to try it one day if your project doesn't push through. Bummer about the EPS portion of the 86 retrofit though. I had high hopes until I actually stuck my head under there to inspect. There's like zero room unless you change the steering column entirely which would lose the tilt and telescopic function. It's one of the most complicated column assemblies i've ever seen (the NSX).
 
I think they just changed the 86 rack for the new car but I can't remember the differences. Some noted below, but I thought they moved the position of the EPS components? Maybe the new layout would work?

“The EPS has been improved quite drastically, so the steering feels tighter and more precise,” he says while twisting through the notch and bending it into the turn. “It’s very predictable, you know exactly where the wheels are pointed as you enter the corner, mid corner, exit corner.” Improved bushings that attach the steering rack to the crossmember help, Gushi says, and the revised power steering system is quicker, more compact, lighter, and lower to the ground.
Click to expand...
 
Quick update here, I have an official quote from quaife as of yesterday for 30 racks. I'm still waiting for more details from them, and I'm talking to a vendor who could maybe handle the pre-order process, shipping individual racks etc. It's still going, but extremely slow. Quaife is very slow to respond to questions, but it is moving!

I'll update with details as I get them...
 
Big McLargeHuge said:
How much for them to mirror the CAD file and entire production process for RHD racks? I'd put my name down in that case :biggrin:
Click to expand...

I'll ask today, though, I feel like I know the answer: they would need a RHD rack to know exactly what is mirrored. Then it'd probably be another 30 racks... I'll ask to make sure. This is a small deal for them and they seem only moderately interested. They unfortunately don't seem super keen on accommodating anything out of the box. I need to figure out a way to be more charming or something.

Another note: the stock rack is variable ratio (!!). Quaife said it was faster in the center than at the ends. They were unable to give me gain numbers in the center and at the end. They basically told me "it's complicated" and gave me an average gain through the whole range (37.8mm). I ended up getting a brand new rack from Acura in anticipation for this landing, and I did some quick measuring yesterday to confirm. By my measurements, the rack is also very slightly slower in the center than was reported in the pole-2-flag thread: 38.5mm (p2f) vs 38.1mm (my caliper from center). I measured 35.65mm for a rotation from the end. I will measure again with a rotation around center (rather than from center) where it's possible that I match the p2f measurement.

I want to do a bit more measuring, then update all the calculations to account for this. To be clear, the Quaife rack would be fixed ratio. So whatever ratio is chosen it will be more effort change at the ends than in the center. Right now thinking of shooting for slightly under 25% more travel in the center, then it'll be like between 25 and 30% more at the ends.
 
Quaife's analysis of [MENTION=21305]jvtec95[/MENTION]'s stock rack indicated our rack is a variable gain / ratio. This was surprising as the analysis done by the previous effort to build a quicker rack said it was a linear rack. But Quaife said it was quicker in the center than at the ends, and the new rack would be linear.

The fact that it is variable changes the thinking around how a new gain changes the effort, angles, and the ratio. I did all the original calculations based on the linear pole-2-flag analysis, so I needed to do them again for the variable situation.

The first step was to understand exactly at given angles, how much the rack moves linearly. Quaife didn't / couldn't tell me what the gain was in the center or at the ends. So I decided to measure on my own.

Measurement

I printed out a degree wheel and laid it over the pinion. I made a sharpie mark, then rotated the pinion, making sure to locate the sharpie mark in the same place on each notch. I spent a lot of time trying to make these measurements repeatable, and measured each notch several times, especially between 0 and 360.

ab4a55af79f7edcde3d890e72dd33c45.jpg


Here's my last pass at measurement. 60.25mm is how much the rack sticks out of the housing on each side at center. Then I'd spin X degrees, and measure again with the caliper.

0: 60.2mm
30: 57mm
60: 53.66mm
90: 50.3mm
180: 40.14mm
210: 36.95mm
240: 33.85mm
270: 30.82mm
360: 22.1mm
450: 13.45mm
480: 10.6mm
585: 0mm

I spent most of my time measuring 0 to 360 as it is the area we want to improve the most, and I was trying to figure out exactly where the ratio started changing.

It looks like the ratio is fixed at about 40mm/rev for the first 180 degrees from center. After 180 degrees, it starts dropping, ending with a gain of around 35mm/rev at the end.

It looks like a linearish drop in gain from 180 to 360, then linearish again from 360 to the end.

After some tinkering, measuring, and some working out gain (not so staightfowrard at the end as it changes) I ended up with this table:

1. deg: 0, travel: 0, gain: 40
2. deg: 180, travel: 20, gain: 40
3. deg: 360, travel: 38, gain: 36
4. deg: 585, travel: 60.25, gain: 35

Analysis

I wrote a new script to handle the variable ratio and the table from above to work out new angles and change in effort. Some notes:

* I asked Quaife to quote the rack for a 48.1mm gain, a 25% increase in quickness. However, measured gain in the center is 40mm/ref, but the last calculations were done at 38.5mm, so 48.1mm is less aggressive than originally thought in the center: 20.2%.
* The pole2flag thread indicated there was like 98mm of rack travel. But there is really 120.5mm of travel. I measured this, Quaife confirmed it, and even the manual states this 120mm figure.
* Because the rack is slower toward the end, a fixed rack with a more aggressive gain, will make quite a big change in effort toward the ends (full lock).
* Our manual states a variable ratio (18.2 - 20.8). Using 18.2 as the center and 20.8 as the end in the calculations as original ratio makes the new ratio _the same_ at the center and end in the new calculations. This feels like a nice check on the measurement work.

My questions for you:

* Which of these options looks interesting to you? Why?
* Note the change in effort toward the end of travel (360 & 540 degrees): the change in effort is very large. How do you feel about this?

The original proposed gain: 48.1mm

$ node nsx/steering-ratio/gen-changes-variable.js 48.1
Ratio: center 15.1:1 - end 15.1:1 (note: the same center & end)
LTL: 2.51 (current 3.25)
Angles:
15 -> 12.5 20.2% increase in effort
30 -> 24.9 20.2%
45 -> 37.4 20.2%
60 -> 49.9 20.2%
90 -> 74.8 20.2%
120 -> 99.8 20.2%
180 -> 149.7 20.2%
225 -> 183.4 23.3%
270 -> 217 26.6%
360 -> 284.4 33.6%
540 -> 417.6 36.6%

Going a little more aggressive

$ node nsx/steering-ratio/gen-changes-variable.js 49**
Ratio: center 14.9:1 - end 14.9:1
LTL: 2.46 (current 3.25)
Angles:
15 -> 12.2 22.5% increase in effort
30 -> 24.5 22.5%
45 -> 36.7 22.5%
60 -> 49 22.5%
90 -> 73.5 22.5%
120 -> 98 22.5%
180 -> 146.9 22.5%
225 -> 180 25.6%
270 -> 213.1 28.9%
360 -> 279.2 36.1%
540 -> 410 39.2%

Going a little more aggressive

$ node nsx/steering-ratio/gen-changes-variable.js 50
Ratio: center 14.6:1 - end 14.6:1
LTL: 2.41 (current 3.25)
Angles:
15 -> 12 25% increase in effort
30 -> 24 25%
45 -> 36 25%
60 -> 48 25%
90 -> 72 25%
120 -> 96 25%
180 -> 144 25%
225 -> 176.4 28.2%
270 -> 208.8 31.6%
360 -> 273.6 38.9%
540 -> 401.8 42%

I'm thinking of sticking with the 48.1mm TBH. Between 48.1mm and 50mm, 50mm gain gives only a couple degrees of reduced steering wheel angle between 0 and 120 of original angle, but is more effort at the end.

48.1mm/rev
15 -> 12.5 20.2%
45 -> 37.4 20.2%
120 -> 99.8 20.2%

50mm/rev
15 -> 12 25%
45 -> 36 25%
120 -> 96 25% only ~4.8 fewer degrees

What do you think?
 

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