Best camber and pressure for 91-93 stock size RA1’s?

[1BADNSX]

Please don’t reply and say to run stock alignment. Does anybody have actual track laps and pyrometer data to support optimal alignment and hot pressures for the stock 91-93 size wheels with RA1’s?

The inside temperature should be 15 to 30 degrees hotter than the outside and the pressure should produce a linear profile in between.

If you don’t have hard data, but run this setup, what are you running?

My guess is that the optimal alignment will require more negative camber than I want to use, but I would like to know what it is. Thanks,

Bob

 

[Andrie Hartanto]

Bob,

I don't have data with stock wheels but have data with 17/18 wheels combo if you are interested. Shoot me an email and I'll send it your way.

 

[Dave Hardy]

It's also going to depend on what kind of driving you're doing. Street, Road Course, and AutoX all have different optimum alignments.

 

[DONYMO]

Hey Bob,

Here's my setup and it works well for me with the RA1's.
235/40-17 front and 275/40-17 rear
I run about 2.8 degrees of negative camber in front and 2.5 in the rear.
Yes, I have the Comptech camber bushings and they are a must for good even tire wear up front (as well as performance!).
I run the NSX-R suspension.
I've found that 35psi hot on all 4 corners works best, for my car.

Note: I run 1/8" toe out in front and 1/8" toe in for the rear.

Don

 

[1BADNSX]

It's also going to depend on what kind of driving you're doing. Street, Road Course, and AutoX all have different optimum alignments.

I'm sorry. If I wasn't clear, optimal for a road course.

 

[1BADNSX]

I've found that 35psi hot on all 4 corners works best, for my car.

Note: I run 1/8" toe out in front and 1/8" toe in for the rear.

Don, interesting that you run less toe both front and back compared to stock. This is good to know because it will help with tire wear when increasing the camber.

I am surprised you run the same pressure front to back. I would expect a lower pressure with less weight up front. Does this just feel better or have you taken data?

Andrie, email sent.

Keep up the needed discussion.

Bob

 

[ncdogdoc]

Bob,

Run the max negative camber in the front, but as Don noted, you will get uneven wear until you get the Comptech bushings. I have seen Don cord his tires doing a three day BMW event (RA1's). Then again, Don drives like a mad man

I run negative 1.8 degrees with Khumos, Dali 1" bar up front with Koni 3012?(grey double adjustable)1000#Eibachs on the rat. It is ~350# lighter than most. Did well at Roebling with wear, but mild understeer at the limit. Tire temps were perfect but the racers say that is not ideal, as the NSX corners better with greater negative camber, giving you higher inside temps than "typically accepted" since you will measure temps after a straight. See the DAL Motorsports site for more info. I have not played with toe at all.

 

[Andrie Hartanto]

Hey Bob,

Here's my setup and it works well for me with the RA1's.
235/40-17 front and 275/40-17 rear
I run about 2.8 degrees of negative camber in front and 2.5 in the rear.
Yes, I have the Comptech camber bushings and they are a must for good even tire wear up front (as well as performance!).
I run the NSX-R suspension.
I've found that 35psi hot on all 4 corners works best, for my car.

Note: I run 1/8" toe out in front and 1/8" toe in for the rear.

Don

Don,

that the exact camber that we run using similar tires! Different toe setting though. Also, I use 39 psi hot on all 4 corners.

Now with the slicks, we run much more camber.

 

[DONYMO]

I am surprised you run the same pressure front to back. I would expect a lower pressure with less weight up front. Does this just feel better or have you taken data?
Bob

Just from experimentation. I've run as high as 40 hot, which is what I believe Toyo recommends. This just was too high...I did not have good grip. I don't think one should take a recommendation that represents one tire pressure for all cars. I'm thinking it was DocJohn that recommended 35psi all the way around and I tried it and it seemed great so I stuck with it.

I am kinda the opposite of you, Bob. You're extremely analytical and I just want to "make it go", like those fat characters on Star Trek, The Next Generation

 

[DONYMO]

Also, I use 39 psi hot on all 4 corners.

Yes, you need to run 4 extra psi due to all the pollution out there! :biggrin:

 

[docjohn]

Re: Best camber and pressure for 91-93 stock size RA1’s?

Hey guys,I like the ra1's at about 38 hot all around,but 40 was definately slower and 35 was really similar in lap times just a little more "loose" feeling.However I still don't have the camber plates so I'm running about 1.5-1.8 - camber up front and 2.2 rear on the R susp.My toe settings are a similar to 91 spec.I don't stagger hot temps on tires at the track. I use whatever max hot temp feels good and gives best balance and times.

 

[DONYMO]

Hey guys,I like the ra1's at about 38 hot all around,but 40 was definately slower and 35 was really similar in lap times just a little more "loose" feeling.

Ah HA! I'll try bumping it up a little and see how that works.
Maybe this contributed to my not being able to catch you at the Glen!
Notice I say contributed...there were many factors, no doubt! :smile:

 

[docjohn]

Re: Best camber and pressure for 91-93 stock size RA1’s?

Hee Hee,whatever it takes to keep you behind me! :wink:

 

[1BADNSX]

Run the max negative camber in the front, but as Don noted, you will get uneven wear until you get the Comptech bushings. I have seen Don cord his tires doing a three day BMW event (RA1's).

Don, I assume they were cording on the outside. I can see Hoosiers cording quickly, did the RA1's cord this fast?

 

[DONYMO]

Don, I assume they were cording on the outside. I can see Hoosiers cording quickly, did the RA1's cord this fast?

Yes, a thin strip on the outside shoulder of the tire (left front, of course...this was at Road Atlanta).

Ya gotta do the camber bushings or you'll be fighting uneven wear on track tires.

 

[PaulL]

However I still don't have the camber plates so I'm running about 1.5-1.8 - camber up front and 2.2 rear on the R susp.

Camber plates? Do you mean camber bushings?

 

[docjohn]

Re: Best camber and pressure for 91-93 stock size RA1’s?

Yes,push push in the bushing! :biggrin:

 

[nsxtasy]

Yes, a thin strip on the outside shoulder of the tire (left front, of course...this was at Road Atlanta).

That's exactly what I've got on my left front. All the tracks I run regularly go clockwise, so the left edge gets more wear than the right. And my left front is just starting to show that thin strip of belts, even though the center of the tread still has 4/32" of tread depth and you can still see the lateral tread grooves in the middle area (and right edge) of the tread. This is on my '91, with the original aggressive factory alignment settings, after 1,391 total miles including 1,161 actual track miles (on Watkins Glen, Putnam Park, and Mid-Ohio). The right front has more tread and more even wear.

If I were only using this size tire on the NSX, after 500-800 track miles, I would flip them to even out the wear - either have them re-mounted/balanced on the wheels, or just using them on the opposite sides of the car without remounting (even though the directional tire would be reversed, this is okay, according to Toyo). This time, though, I forgot to flip them partway through. (In my particular case, when I flip the front tires, I have them re-mounted on wheels for my other track car, which uses the same 205/50-15 size tires as the NSX front.)