Group Buy Variable Manual Rack - Feel a little F1 tech in your hands

[liftnot]

I've been trying to get a time with Erik for weeks but everytime he has an open slot he gets called away to a race or is under the weather or something. Super nice guy though. I didn't know Ryan has the latest Penskes on his car??? I thought he's been running the same old Penske he's always had (which are still awesome).

Ryan has the 8300 series(its not the latest Penskes) with the remote which is necessary for the rear as it really can use the last bit of piston space for travel(most won't know that). Otherwise, we were gonna settle for the 7500 DA. FWIW, PC told me the Real Time NSX had Penskes not sure who set it up. Erik is hard to track down and too nice to say no but thats because he knows what he is doing once people recognize his value.

He had double pneumonia recently and before that was in an accident so he is quite banged up and backed up and the long/crazy Pantera build and a 750 hp Viper ACR that came with all the wrong settings of the Bilsteins and +++. You need to have Ninja skills to pin him down. Dido, you don't find many classy guys like him around. It will be a small miracle when we have our Penskes in hand:smile:. He agreed to work with us to give him some breathing room as he is only work half day now from 7 to 7 unlike before. For once we want to try a properly valved Penske b 4 we kick the bucket and there is no better car to have it than the very analog, capable old NSX we have and no one better than him for the damper set up.

 

[Stephen@NCAutoUSA]

Only a few more to go!

 

[jrnsx]

Count me in for sure.

 

[Mac Attack]

We have little experience in this area. We just want a higher tech, quicker, variable ratio rack to improve the overall driving experience. We are the "client" in this case and the client only "think" they know what they want but don't "know" what they should have in terms of the math/vehicle design parameter in steering. IMO, better wait for MVO recommendation. We are depending 100% on their feedback. At least we know we have the right vendor and the battle is half over.:wink:

$25 for an initial feasibility study is one thing: $~1500 for a rack when this is done is another thing.

FYI, per the SM, the OEM M/T rack is variable ratio'd from 20.8:1 to 18.2:1, with 3.24 turns lock-to-lock.

For most of the people on here, they probably won't want to deviate much from that. No offense to MVO, but the Honda folks that did our designs were no slouches either. I would personally want to keep the 20.8:1 ratio just off-center the same, and change the 18.2:1 ratio to something like 15:1 for quicker reaction in mid-turns. If people already complain about steering effort when trying to park then this probably isn't for them.

Also FYI - A European owner has already retrofitted a Quaife R/P into our M/T NSX rack. Quaife commercially provides quite a few designs to choose from. Maybe your efforts to get a better rack would be cheaper and easier if you worked with them. Quaife is a pretty good outfit....

Dave

- - - Updated - - -

Ryan has the 8300 series(its not the latest Penskes) with the remote which is necessary for the rear as it really can use the last bit of piston space for travel(most won't know that). Otherwise, we were gonna settle for the 7500 DA. FWIW, PC told me the Real Time NSX had Penskes not sure who set it up. Erik is hard to track down and too nice to say no but thats because he knows what he is doing once people recognize his value.

He had double pneumonia recently and before that was in an accident so he is quite banged up and backed up and the long/crazy Pantera build and a 750 hp Viper ACR that came with all the wrong settings of the Bilsteins and +++. You need to have Ninja skills to pin him down. Dido, you don't find many classy guys like him around. It will be a small miracle when we have our Penskes in hand:smile:. He agreed to work with us to give him some breathing room as he is only work half day now from 7 to 7 unlike before. For once we want to try a properly valved Penske b 4 we kick the bucket and there is no better car to have it than the very analog, capable old NSX we have and no one better than him for the damper set up.

Penske's are great because of their quality, endless configurations, and employee knowledge/helpfulness. Otherwise, they have no magical designs or valving.

I've worked in the past on getting their regressive valving into a cheap 7500 DA body. However, because of the decrease in stroke from my air lift cup kit, I would have to go with an external reservoir system to maintain enough travel. Furthermore, the regressive design decreases shaft travel even more than your traditional shim stack (most wouldn't know that either).

In order to keep adequate travel with moderate spring rates, I've pretty much convinced myself to go with a custom Ohlins DFV setup. It's a comfortable ride on the street, as well as an extremely competent track performer. That balance works for me. If you are purely into tracking or have very smooth roads (I'm jealous if you do), then you can't go wrong with the Penkse....

Dave

 

[liftnot]

Thx for the info Dave. This is only for folks who wants something faster than 18.2 as many won't mess with Mother Honda. We don't know anybody at Quaife.
MVO is top notch and a lot closer only 2-hour difference, perhaps we will learn a thing or two about their special design that set them apart(?) and that will be one of the main reasons we are going with MVO. The choice is clear. Cheaper price is what we want but not what we are after. If the gearbox/diff. breaks, the car stops and smokes. If the steering breaks, OMG!

The secret to go quicker is be able to keep that as a secret and the secret is: there is no secret. Heck, why bother to do anything to our car to have a good lap time, the car in oem form is very good. just throw a set of sticky tires and you're done. We want to be able to say the car is capable to do 1:39 at Laguna w/ a near stock motor. Whether the driver can do that is another story.

 

[Mac Attack]

I can still replay the scene of events more than 20 years ago just like it was yesterday... I was in a shifter kart doing 70MPH into a turn and the steering shaft somehow disconnected itself at the bottom of the mount. I've had a lot of other butt-puckering off-track adventures in motorsports, but I can vividly recall the only time I had a problem with steering.

 

[liftnot]

That sounds like an anomaly. maybe you were going so fast, all the vibration/harmonic reached the natural frequency and let it self go to be free. Who was the "crew chief' doing the "pre-race" check? You've scared us. Better keep yours OEM.

 

[Mac Attack]

No need to be scared now....

Oh - my steering setup is modified OEM. I've already added a 1.25:1 ratio quickener with the ultimate goal of retrofitting in Quaife components... or possibly MVO based on what you find out!

 

[prym8]

Thanks p2f.. Put me down for 25.

 

[liftnot]

Guys,

More PM answers:

Just sign up for now.
Don't send any funds yet. We'll wait until we have a larger count and make your contribution one phase at a time as to keep track accurately of this many people is a nitemare. BTW, this is a NONE-refundable proposition. If the 1st phase of assessment does not show much promise, we will not push forward and there is no refund. Thats why the larger the number(regardless the outcome), the lower of your contribution. If we don't reach the desired number, this may not happen but we believe there are good things to come.

As with any after-market product, This is for OFF-ROAD USE ONLY.

 

[Albert86]

I'll go for $25

 

[stuntman]

No need to be scared now....

Oh - my steering setup is modified OEM. I've already added a 1.25:1 ratio quickener with the ultimate goal of retrofitting in Quaife components... or possibly MVO based on what you find out!

How did the quickest change the steering response and effort (at speed and when parking)?

I have been thinking about installing one of those for s while now.

 

[Ponyboy]

$25 for an initial feasibility study is one thing: $~1500 for a rack when this is done is another thing.

Considering the OE rack was around 1k, I don't think it unreasonable for an upgraded steering rack at a $1500 price point. Especially when you take into account that the part is not available anymore and the expertise of the supplier in question. How much $$ do you have in your modified OE?

I'm not sure I understand the tactic of disparaging the idea of variable steering rack, question the choice of vendor while introducing another, and then assert the the non-stock status of your own variable system. At least that's the perception which may be something you did not intend.

 

[greenberet]

FYI, per the SM, the OEM M/T rack is variable ratio'd from 20.8:1 to 18.2:1, with 3.24 turns lock-to-lock.

For most of the people on here, they probably won't want to deviate much from that. No offense to MVO, but the Honda folks that did our designs were no slouches either. I would personally want to keep the 20.8:1 ratio just off-center the same, and change the 18.2:1 ratio to something like 15:1 for quicker reaction in mid-turns. If people already complain about steering effort when trying to park then this probably isn't for them.

What you want is probably just what a variable ratio rack would offer. To quote the article on variable ratio steering racks from the September 2008 issue of Racecar Engineering:

... the steering ratio produced from a constant ratio rack is anything but constant. Because the linear motion of the rack is driving the rotational motion of the upright, the input-to-output ratio reduces with steering lock. In other words, it becomes closer to one to one, meaning the increase in steering angle or steering gain increases with lock. Put simply, it means the more you steer, the faster the steering becomes.

Broadly speaking, this is the effect you want, but unfortunately it doesn't happen fast enough or with the right profile to be useful.​

 

[Mac Attack]

I'm not sure I understand the tactic of disparaging the idea of variable steering rack, question the choice of vendor while introducing another, and then assert the the non-stock status of your own variable system. At least that's the perception which may be something you did not intend.

Perhaps you should re-read my previous posts then, keeping in mind the following facts that were available to you but you chose to ignore:
1) As stated by the vendor in the first post, this is the "R" as in research phase - not a purchase thread that you insinuate I am crapping in.
2) I've never been disparaging of the variable steering rack idea - in fact, I listed the variable OEM ratios as well as a suggested ratio that I would personally like to have. I thought it would be helpful to this "R" thread.
3) Yes, I did introduce an alternate parts supplier that could help with this endeavor. If you did your research, you would know that this alternate vendor does not make a drop-in rack. The alternate suppliers R/P would still require sourcing specific bearings, bushings, possibly machining of our OEM housing. P2F would hopefully take this up if MVO didn't work out. However, I understand the MVO initial selection (reputation and proximity to P2F), and have absolutely no issue with their decision.
4) I do not make parts to sell and profit from; I am not a vendor. If I introduced another alternative that apparently others have considered (look a few posts above), then that is in keeping with the spirit of this "R" thread that P2F could continue forward with.

I don't appreciate you trying to instigate something that is not there. You can point out your last sentence to try and maintain a high ground, but your accusation of a sleazy tactic in the first sentence is completely unfounded. Hopefully I'll see less of this in the future from you with Lectio Divina.

Dave

- - - Updated - - -

How did the quickest change the steering response and effort (at speed and when parking)?

I have been thinking about installing one of those for s while now.

As you probably already suspected, I don't recommend it because of these drawbacks:
1) Even with precision manufacturing and hardened gears, it still introduces additional "slop" in the system. I don't like this. I've even checked into replacing my "U" connection to the rack just because there is a little bit of slop after 125k miles on it.
2) It's a direct multiplier to the steering input... The on-center OEM feel with a slight bit of front tire toe-out is perfect for me as far as responsiveness and comfort. The quickener makes that more sensitive obviously, and is why I just went with a 1.25: ratio instead of the more common 1.5 or 2:1 ratios.

In hindsight taking into account the cost and modifications involved, I shouldn't have done it. It's one of those things I had to try... live and learn!

My $0.02.

Dave

 

[Ponyboy]

If you didn't mean what you wrote then you have my sincerest apologies. Perhaps you should reconsider the tone and context of your posts so that there isn't any ambiguity.

 

[Mac Attack]

What you want is probably just what a variable ratio rack would offer. To quote the article on variable ratio steering racks from the September 2008 issue of Racecar Engineering:

... the steering ratio produced from a constant ratio rack is anything but constant. Because the linear motion of the rack is driving the rotational motion of the upright, the input-to-output ratio reduces with steering lock. In other words, it becomes closer to one to one, meaning the increase in steering angle or steering gain increases with lock. Put simply, it means the more you steer, the faster the steering becomes.

Broadly speaking, this is the effect you want, but unfortunately it doesn't happen fast enough or with the right profile to be useful.​

That is a good point and something Honda had to consider when designing our OEM variable ratio rack.

Another thing is the Ackermann effect. Unfortunately, our NSX's have a pretty significant difference in front tire angles at full lock, which contributes to a lot of scrub in really tight turns.

- - - Updated - - -

If you didn't mean what you wrote then you have my sincerest apologies. Perhaps you should reconsider the tone and context of your posts so that there isn't any ambiguity.

No, I meant what I wrote. If you have a problem with it I suggest you let it go and enjoy the rest of this Holiday weekend.

Have a good one,

dave

 

[TURBO2GO]

Good info Dave.

 

[rizzo]

im in

 

[02#154]

I'm in for funding the R&D

 

[liftnot]

Thank you those who show faith and believe in us and in MVO to make our cars more special to drive all the time.

PM Q answer:
>What ratio would be more ideal?
We are thinking in the range of high 15s or low 16s. We will propose this to MVO and see what they say after the assessment. Not saying the oem is inadequate, we like to have a more direct steering feeling and more feedback of what the tires are doing & at 18.2 oem, its a bit high but perhaps that fits the design parameter of being a luxury sports car. we are not sure about the variable part and what it should be.

 

[darock]

I am happy to contribute to this by donating $25.

Bernhard

 

[havoc_UK]

I'm interested in a RHD version

Me too.

Seen this on Facebook and shared with NSXCB...but can you clarify whether this would be LHD only or whether a RHD variant could be built?
(Given RHD cars outnumber LHD cars, if this part can be certified for Japan then the potential market has more than doubled...)

Thanks,

Martin.

 

[liftnot]

Martin,

The 1st step is to have the LHD oem rack assessed (cuz this is what's avail. here in the US). Pending the assessment from MVO, we then can move forward which means the number of folks signing up make a big difference in terms of price(a typical inverse relationship in manufacturing cost). We would love to have at least 100 folks so at $25 USD each, the cost is very little. If we don't reach 100, P2F would pony up the rest so Step 1 can complete as we believe in what we do.

It IS our plan and intention to provide the new rack for the RHD folks as well. AFAIK, the LHD and the RHD is a mirror image so once the new rack is designed(Step 2, another $2.5k), to program the machine to do RHD should be piece of cake.

We will close the GB by the end of June so we can get things rolling collecting money. Pass the word on to NSXCB Martin and Thx for signing up. Logically speaking, this upgrade will improve the driving feel between the car and the road with better feedback and it will be made by a world class steering rack specialist.

 

[BATMANs]

Add me to the list..... since day one of my owning the NSX, I've considered it 2nd to the RX7 FD on steering feel and response and thought there was room for improvement.