Quaife quick ratio manual steering rack

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.
I'm a bit confused. How is it 40mm/rev for the first 180* but starting at 60.2mm goes to 40.14mm at 180*? (20.06mm change).

If the ratio is slower past 180*, then its likely to reduce steering effort at low speeds in parking lots, since you never really go past 180* on track.

In this case, using a linear rack will make steering effort a lot higher in parking situations.

Will the rack have the same same overall travel as stock? If not, then there will be rubbing at full lock.




Good data from the other thread:

I must admit that I too felt like the NSX's steering was subjectively slower than many other cars. I decided to look at the in-car videos of various cars around Buttonwillow raceway and compare their steering inputs to a few different NSXs of varying degrees of build. I took a screenshot of each car in two different corners at the point of their maximum steering angle.

The cars I looked at were:

-NSX - Mild build: My personal car: 235/40-17, 275/35-18 NT05 street tires, KW V3 coilovers, and NSX-R rear wing
-NSX - Extreme build: FXMD's record holding Time Attack car: 305/35-18 345/35-18 racing slicks, KW 3-way motorsport dampers, MASSIVE aero
-NSX - Moderate build: BellWilliam's car: 235/40-17, 275/35-18 NT01 R-comps, coilovers, big splitter and wing
-2015 Mustang GT - Mild Build

-S2000 - Mild Build: Stock Aero: 255/40-17 Dunlop ZII StarSpec, HKS Hipermax IV SP coilovers
-S2000 - Extreme Build: Evasive's record-setting Time Attack car: 275 street tires? and massive aero
-Lotus Elise - Moderate Build: Manly's record-setting Time Attack car with massive aero
-Lotus Exige - Mild Build: Relatively stock with Hankook Ventus Z214 tires



Turn 2 "Buttonhook" is one of the slowest (<50mph) corners that you'll find on any racetrack. It requires a lot of steering input at low speeds and while trailbraking can reduce understeer, the corner as an up-hill right at the apex that causes almost any car to understeer at the apex. This is a great corner to determine how much steering lock is needed in a technical and quirky haripin.

BW%20T2%20Steering%20Angle.jpg

-All of the NSX's required ~180-degrees of steering input at the apex of this hairpin.
-The 2015 Mustang GT also required ~180-degrees of steering input.

BW%20T2%20Steering%20Angle%202.jpg

-Both S2000s required ~160-degrees of steering input, slightly less than the NSX -by 20 degrees
-Manly's yellow Elise required the same ~180-degrees of steering input as the NSXs.
-The Exige required ~150-degrees of steering input, about 30 degrees less than the NSX. Keep in mind he was turning 2:03s, which was much slower than the rest of the cars in this group other than the Mustang doing 2:06s.


free_degree_wheel.jpg


Turn 4 "Grapevine" is a pretty standard corner with very little camber/banking. I chose this corner because it does not require much braking or lifting of the throttle, so the balance and steering inputs aren't affected as much by differences in driving styles and trail-braking, and singles out the setup and balance of the car and the steering inputs needed.


BW%20T4%20Steering%20Angle.jpg

-My NSX required ~95-degrees of steering input
-The FXMD NSX required ~100-degrees of steering input
-William's NSX required ~80-degrees of steering input - quite a bit less than the other NSXs.
-The 2015 Mustang GT also required ~80-degrees of steering input.

BW%20T4%20Steering%20Angle%202.jpg

-The stock S2000 required ~75-degrees of steering input and was quite loose and oversteering through this corner
-The Evasive S2000 required ~80-degrees of steering input
-Manly's yellow Elise required ~85-degrees of steering input
-The Exige required ~55-degrees of steering input, about 40 degrees less than the NSX. Keep in mind he was turning 2:03s, which was much slower than the rest of the cars in this group other than the Mustang doing 2:06s.
free_degree_wheel.jpg



I will let everyone draw their own conclusions on the difference of required steering input between the NSX and a cars like the S2000 and Elise/Exige which are considered to have very quick and responsive steering. The Elise/Exige are the only cars without power steering (like the NSX) but they also have much smaller wheels and tires, and the car is about 1,000lbs less than an NSX.

Keep in mind that the driver's inputs and setup/balance of the car does affect how much steering input that is needed. Which is why I took samples of moderate to extreme car builds, as well as varying levels of driver ability. Overall, I think the required inputs between all of these cars are very similar.


0.02
 
Last edited:
I'm a bit confused. How is it 40mm/rev for the first 180* but starting at 60.2mm goes to 40.14mm at 180*? (20.06mm change).

The rate of Xmm / rev is linear travel over 360 degrees. So from -180 to 0 (say left 180deg to center), it's ~20mm linear travel, then from 0 to +180 (center to right turn 180) it's another ~20mm, which is 40mm linear travel over 360 degrees -> 40mm / rev.

This is more complicated to measure beyond 180 as the rate is variable from 180 -> end. i.e. Measuring the total travel from 180 -> 360 will give you the average rate over that span, but not the rate at some point in the travel. For that, I measured smaller increments, then extrapolated, e.g. measure 30 deg, Xmm*12 gives you rate at that point in the travel. Ideally I'd be able to measure in like 1 or 5 degree increments, but 30 degrees was about the minimum I was able to accurately spin the shaft. And any measurement errors in angles say ~5deg are extra amplified.

If the ratio is slower past 180*, then its likely to reduce steering effort at low speeds in parking lots, since you never really go past 180* on track.

In this case, using a linear rack will make steering effort a lot higher in parking situations.

Yeah, that is def the downside here. For me personally, I'm happy to strong arm around a parking lot for 30 seconds if it feels awesome while driving. If we could do a variable ratio rack, that would be cool, but Quaife said they will only build a fixed ratio rack kit. This is a good reason to not go over 20% so as to keep the change at the ends semi-reasonable.

Will the rack have the same same overall travel as stock? If not, then there will be rubbing at full lock.

Yep, it's 120mm travel now, and will be 120mm with the new rack kit, no matter the ratio/gain chosen.

Good data from the other thread

With this data, the 15:1 / 20% option should put the NSXs at similar steering wheel angles to the faster ratio cars. i.e. 100 -> 83, 180 -> 150. ~180 deg steering angle on the new rack would give you the equivalent of 225 deg with the stock rack.

stock -> quaife 15:1
15 -> 12.5
30 -> 24.9
45 -> 37.4
60 -> 49.9
90 -> 74.8
100 -> 83.2
120 -> 99.8
180 -> 149.7
225 -> 183.4
 
20% looks similar if not more aggressive than the S2000. I probably wouldn't go any quicker than that.

20% increase in effort is appreciable. What options are they below 20%?
 
The 20% / 15.1:1 option is still less aggressive than the s2000, and it'd be much less aggressive than the 'fast' s2k rack, both in an s2000 and in an NSX. There is some data on this in the s2000 rack thread. s2000 racks are either 13.8:1 or 14.9:1 depending on year / model. nsxmugen measured the linear travel of a fast s2k rack, accord rack, and an NSX manual rack in this post. His results:

* S2000 traveled 2.34" per each full wheel turn (59.4mm / rev)
* Accord traveled 1.91" per each full wheel turn (48.5mm / rev)
* NSX traveled 1.4" per each full wheel turn (35.6mm / rev)

The way he measured these in the videos is not so precise: eyeballing a vice grip and measuring with a tape measure. But even if he is +/- 5mm, it's still 54mm on the low end with an s2k rack, much higher than the 48mm in the 20% option. Matching that ratio in the NSX would require a 52.6mm rate, and a 31.5% increase.

$ node nsx/steering-ratio/gen-changes-variable.js 52.6
Ratio: center 13.8:1 - end 13.8:1
LTL: 2.29 (current 3.25)
Angles:
15 -> 11.4 31.5%
30 -> 22.8 31.5%
45 -> 34.2 31.5%
60 -> 45.6 31.5%
90 -> 68.4 31.5%
100 -> 76 31.5%
120 -> 91.3 31.5%
180 -> 136.9 31.5%
225 -> 167.7 34.9%
270 -> 198.5 38.4%
360 -> 260.1 46.1%
540 -> 381.9 49.4%


Here are some other options, though I am still leaning toward the 20% option.

A 10% option, 16.5:1


$ node nsx/steering-ratio/gen-changes-variable.js 44
Ratio: center 16.5:1 - end 16.5:1
LTL: 2.74 (current 3.25)
Angles:
15 -> 13.6 10%
30 -> 27.3 10%
45 -> 40.9 10%
60 -> 54.5 10%
90 -> 81.8 10%
100 -> 90.9 10%
120 -> 109.1 10%
180 -> 163.6 10%
225 -> 200.5 12.8%
270 -> 237.3 15.8%
360 -> 310.9 22.2%
540 -> 456.5 25%

A 15% option, 15.8:1


$ node nsx/steering-ratio/gen-changes-variable.js 46
Ratio: center 15.8:1 - end 15.8:1
LTL: 2.62 (current 3.25)
Angles:
15 -> 13 15%
30 -> 26.1 15%
45 -> 39.1 15%
60 -> 52.2 15%
90 -> 78.3 15%
100 -> 87 15%
120 -> 104.3 15%
180 -> 156.5 15%
225 -> 191.7 17.9%
270 -> 227 21.1%
360 -> 297.4 27.8%
540 -> 436.7 30.7%

A 17.5% option, 15.5:1


$ node nsx/steering-ratio/gen-changes-variable.js 47
Ratio: center 15.5:1 - end 15.5:1
LTL: 2.56 (current 3.25)
Angles:
15 -> 12.8 17.5%
30 -> 25.5 17.5%
45 -> 38.3 17.5%
60 -> 51.1 17.5%
90 -> 76.6 17.5%
100 -> 85.1 17.5%
120 -> 102.1 17.5%
180 -> 153.2 17.5%
225 -> 187.7 20.5%
270 -> 222.1 23.7%
360 -> 291.1 30.6%
540 -> 427.4 33.5%
 
The 20% / 15.1:1 option is still less aggressive than the s2000... s2000 racks are either 13.8:1 or 14.9:1 depending on year / model.
15.1:1 and 14.9:1 are VERY close. Personally, I don't think we should go that far since the S2000 rack is power-assisted and known to be twitchy.

A 15% option, 15.8:1

$ node nsx/steering-ratio/gen-changes-variable.js 46
Ratio: center 15.8:1 - end 15.8:1
LTL: 2.62 (current 3.25)
Angles:
15 -> 13 15%
30 -> 26.1 15%
45 -> 39.1 15%
60 -> 52.2 15%
90 -> 78.3 15%
100 -> 87 15%
120 -> 104.3 15%
180 -> 156.5 15%
225 -> 191.7 17.9%
270 -> 227 21.1%
360 -> 297.4 27.8%
540 -> 436.7 30.7%

A 17.5% option, 15.5:1

$ node nsx/steering-ratio/gen-changes-variable.js 47
Ratio: center 15.5:1 - end 15.5:1
LTL: 2.56 (current 3.25)
Angles:
15 -> 12.8 17.5%
30 -> 25.5 17.5%
45 -> 38.3 17.5%
60 -> 51.1 17.5%
90 -> 76.6 17.5%
100 -> 85.1 17.5%
120 -> 102.1 17.5%
180 -> 153.2 17.5%
225 -> 187.7 20.5%
270 -> 222.1 23.7%
360 -> 291.1 30.6%
540 -> 427.4 33.5%
I'm liking these options. Maybe the 17.5% one.
 
I have some exciting news, we have a pre-order page live for the Quaife quick rack! It's happening!

The NSX Rack Repair you know and love has agreed to handle the pre-order and fulfillment of the Quaife quick rack kit. There is obviously no one more natural to handle this than the people who rebuild NSX steering racks.

You can pre-order it here:

http://nsxrackrepair.com/services/quick-ratio-for-manual-rack-pre-sale

We need 15 pre-orders to make this happen. Once there are 15 paid pre-orders, Quaife will be paid which will kick off the build process. The kit build process will take 12-16 weeks, then the racks will be shipped to NSX Rack Repair, and he will handle fulfillment to you.

* There are 30 total available rack kits (ahem, 28, I'm getting 2)
* Price is $500 per kit all in and includes shipping to you. This is about a 30% discount from what it will be once these initial 30 have sold.
* You have the option to send your rack to NSX rack repair to have your rack rebuilt and the kit installed at additional cost. You don't need to make the decision to rebuild your rack now. Charles will contact you when the rack kits have been built.
* You can obviously receive the kit as is for a DIY install.
* The exact final ratio has not been confirmed with Quaife yet, I will do that next week. It will be equal to or less than 20% effort and around a 15.x:1 ratio.

I will be reaching out to individuals who have expressed interest, and both I and Charles from NSX Rack Repair will be posting the pre-order link elsewhere in the coming days / weeks. The faster we get to 15 pre-orders, the faster these get built!

Some Q & A

* What if 15 are not sold? Everyone gets a full refund.
* What if >= 15 but < 30 are sold? NSX Rack Repair will buy the remainder and sell them as an add-on to a rack rebuild.
* What if more than 30 people are interested? Right now there are only 30 available slots.
 
Put in my pre-order! I had read a post on NSXCB forum with someone who worked at Quaife. They had developed an NSX specific rack, but it was a full motorsports rack (not just the rack & pinion). They had used 2.6 turns lock-to-lock, so sounds like the 15% would be closest to that. I run a ps rack on my integra with a looped line and reservoir (no pump), that is 3 turns lock-to-lock @16:1 ratio. Quaife makes a rack and pinion kit that shortens this to 2.83. Sounds like these options are in that ball park, I would vote for one close to 2.6 if it's still up for choice.
 
Put in my pre-order! I had read a post on NSXCB forum with someone who worked at Quaife. They had developed an NSX specific rack, but it was a full motorsports rack (not just the rack & pinion). They had used 2.6 turns lock-to-lock, so sounds like the 15% would be closest to that. I run a ps rack on my integra with a looped line and reservoir (no pump), that is 3 turns lock-to-lock @16:1 ratio. Quaife makes a rack and pinion kit that shortens this to 2.83. Sounds like these options are in that ball park, I would vote for one close to 2.6 if it's still up for choice.

Great! We're only a couple away from the 15 threshold, then we can pay Quaife and are off to the races.

Interesting on that whole rack, I wonder what happened to it. I also wonder if the total travel would have been the same or more at 2.6 turns. Their EF civic kit is 3.8 -> 2.85 IIRC, which is a 25% increase, but not sure if the travel is the same. It's tough to compare without knowing the specifics though...

I'm still pretty sold on the 20% option at 15.1:1 putting the ratio in the same ballpark as several generations of miatas, the E46 M3, the later model s2ks, etc. I guess there is a question of threshold: where ideally should that extra 3% be? In angle or in effort. Which will you notice more? I dont think we'll know until we get these made.
 
One last steering rack related tip, the small rubber mounting bushings in the Energy Suspension kit 16.10103 (Integra) fit the NSX rack and collars (the small ones that the bolts go through). You can't use the large bushing that goes around the rack body, but the whole kit is ~$10 vs $6-$10 each for the oem rubber ones. They are a higher durometer urethane, so firmer mounting of the rack and better feedback/feel. They worked great for when I rebuilt and installed my rack as my old bushings weren't far from dust.
 
I know we are pretty close to the 15 minimum to make this happen, spoke with Charles at NSXRackRepair.

Can’t wait and this seems like it is really going to happen! Thanks to everyone that helped make this a possibility and huge thanks to Charles and the OP for putting in all the work for us NSXers to bring something new and exciting to the market.


Sent from my iPad using Tapatalk
 
We have crossed the 15 pre-order threshold! Quaife just got back to me with answers to some questions, and is in the process of transferring the account from me to Charles. That means quaife should get paid the first installment this week or beginning of next to kick it off [emoji322]
 
now watch the nsx start cleaning up in local auto-X.......Lol.....
 
We have crossed the 15 pre-order threshold! Quaife just got back to me with answers to some questions, and is in the process of transferring the account from me to Charles. That means quaife should get paid the first installment this week or beginning of next to kick it off [emoji322]

Yoooooooooo thanks for the update!

I’m CRAZY excited


Sent from my iPhone using Tapatalk
 
Anyone in SoCal getting this? Would love to hook up with you!

(I've already spent my budget on steering mods so I couldn't get in on this one)

If you want, I’m getting mine installed into a fresh rack by Charles, you could test it back-to-back in your car. Just gotta install and remove yourself


Sent from my iPhone using Tapatalk
 
Back
Top