Track test of non-compliance toe links and rear beam bushings from Ti Dave

[CB72]

After many modifications to my NSX, I finally decided to upgrade the rear suspension with non-compliance stuff from Ti Dave.
To be honest, I was a little doubfull that it would improve the roadholding but given that the car would sometimes go in an almost uncontrollable oversteer I decided to give it a go!
Last W.E. I went to my local track to test the setup.
The conditions were quite treacherous specially with my Avon ZZR semi-slicks under pouring rain.
Luckily the rain stopped in the afternoon and the track started drying.
As you will see in the video, the rear broke loose quite a few times and the car remained perfectly controllable.
Next time, I"ll upgrade to Michelin Pilot Sport Cup 2's to at least keep up with the Cayman GT4!

https://www.youtube.com/watch?v=zYgMhHaazqU

 

[Mac Attack]

Was the rear toe-in the same before/after the non-compliance parts?

I recently swapped to the non-compliance rear beam too and have been playing with rear toe-in settings. Everything from zero toe to 10 mm toe-in.

10 mm toe-in feels the best to me but will eat my tires too fast. I can live with 4 mm total toe in and that's what I run.

 

[Mac Attack]

Edit - I just checked my spreadsheet and I have gone up to 11 mm total rear toe-in during testing. That's the equivalent of 1 degree total toe-in!

 

[CB72]

Edit - I just checked my spreadsheet and I have gone up to 11 mm total rear toe-in during testing. That's the equivalent of 1 degree total toe-in!

I didn't change the rear toe-in after fitting the non-compliance bits.
It's set at 4.1 mm.
As I drive to the track and because the roads over here are sometimes in poor condition with different levels of traction left to righ causing the car to wander, I prefer to run with little toe-in.
The camber front and rear is set at 2°30'.
The front swaybar is from Dali in the middle hole and the rear is the OEM bar.
The balance seems right to me.

 

[Mac Attack]

I didn't change the rear toe-in after fitting the non-compliance bits.
It's set at 4.1 mm.
As I drive to the track and because the roads over here are sometimes in poor condition with different levels of traction left to righ causing the car to wander, I prefer to run with little toe-in.
The camber front and rear is set at 2°30'.
The front swaybar is from Dali in the middle hole and the rear is the OEM bar.
The balance seems right to me.

That's what I like as far as rear toe-in with the TiDave rear beam bushings too.

Did you ever try completely removing the rear sway bar? That's what I've done. DAL Motorsports and Dali used to do that too on their track cars.

 

[docjohn]

They did but with very stiff front bars ...

 

[CB72]

That's what I like as far as rear toe-in with the TiDave rear beam bushings too.

Did you ever try completely removing the rear sway bar? That's what I've done. DAL Motorsports and Dali used to do that too on their track cars.

Yes, I saw that but I don't understand the logic: stiffer front bar means more understeer, weaker (or no rear bar) also means more understeer!
I once drove a full racing NSX that understeered a lot at my driving speeds.
The only explanation I can think of is that the car must be driven eitheir at full throttle or throttle off but never in between???
Doesn't you car understeer a lot?

 

[Mac Attack]

Short answer is no.

At speed you can get front downforce with a splitter. It doesn't look like you run one so that would be something cheap to try.

Running without the rear sway makes it more easy to trailbrake too, but it seems most people like slow in, fast out style.

 

[stuntman]

11mm of toe is excessive.

 

[Mac Attack]

11mm of toe is excessive.

Yes. It was all part of testing (including minor rear toe-out) to get a feel for MY ideal alignment. Everybody is different.

Like I said earlier, I settled on 4 mm rear toe-in total with TiDaves non-compliance adjustable camber bearings.

 

[stuntman]

11mm probably causes more problems than anything beneficial it may do. 4mm is also a lot (and the factory settings), especially in a car with non compliance bushings.

 

[Mac Attack]

11mm probably causes more problems than anything beneficial it may do. 4mm is also a lot (and the factory settings), especially in a car with non compliance bushings.

Not all of my five rear suspension corner rubber bushings have been removed for bearings. I've only swapped the rear beam bearing and the toe control arm. There's still three old rubbers left with 130k miles on them.

If you do simple free body diagrams on the rear suspension pivot points, it appears that you'll get the most "bang-for-your-buck" slop elimination through [MENTION=9035]titaniumdave[/MENTION] rear beam bearing and toe rod bearing. HOWEVER, there's still three other bushings in the rear allowing dynamic geometry changes, so for a race car, those are a good investment too. At that point, further reducing rear toe would be beneficial.

Good info to know:
The 1991 SM says rear toe in spec is 6mm total +/- 1mm. We all know that was reduced later not because of handling complaints but because of poor rear tire life. I'll personally take the hit on tire life as opposed to reduced handling performance, but everyone is different.

During bump travel, the OEM-design rear toes IN. That means during heavy braking, any increase in rear ride height will lead to slightly less toe-in. Combined with the slop in the bushings leading to less toe-in under heavy braking, then at some point you may be toe-OUT total depending on your initial static toe settings. Not very stable under these simultaneous conditions, and can quickly reduce your confidence in the rear if you encounter a bump. That's one of the reasons why I removed my rear sway.

 

[titaniumdave]

I didn't change the rear toe-in after fitting the non-compliance bits.
It's set at 4.1 mm.
As I drive to the track and because the roads over here are sometimes in poor condition with different levels of traction left to righ causing the car to wander, I prefer to run with little toe-in.
The camber front and rear is set at 2°30'.
The front swaybar is from Dali in the middle hole and the rear is the OEM bar.
The balance seems right to me.

Looks like you are driving well in the video, car has bit more to give with the current set up. If it was my car, I would would increase the front sway bay stiffness, go to the shortest setting and decrease the rear camber to 2 deg. Both of these will increase rear traction and put off the point where the rear wants to let loose. The trade off is the car will like a quicker transition as you turn in, meaning you will need to use the throttle AND brakes to get the car to rotate as you set up for the corner. From the video, you are already doing this in some corners. It might help to get a coach to ride along and help with timing as you advance. I love getting another set of eyes in the passenger seat, any time I can get a coach I jump at the chance!

I am assuming you have compliance joint clamps on the front of the car already?

Dave

 

[Mac Attack]

Looks like you are driving well in the video, car has bit more to give with the current set up. If it was my car, I would would increase the front sway bay stiffness, go to the shortest setting and decrease the rear camber to 2 deg. Both of these will increase rear traction and put off the point where the rear wants to let loose. The trade off is the car will like a quicker transition as you turn in, meaning you will need to use the throttle AND brakes to get the car to rotate as you set up for the corner. From the video, you are already doing this in some corners. It might help to get a coach to ride along and help with timing as you advance. I love getting another set of eyes in the passenger seat, any time I can get a coach I jump at the chance!

I am assuming you have compliance joint clamps on the front of the car already?

Dave

Have you tried no rear sway? Like the Lotii?

 

[titaniumdave]

On The race car I have a DAL 1 1/4" front sway and no rear sway...I can imagine there will be time having a small rear sway could help, especially in the wet.

 

[CB72]

Michelin Pilot Sport Cup 2's

Good news, I fitted PSS Cup 2's in 265/35 R18 at the rear for the next track day!
The front will run with eitheir the P Zero Corsa's in 205/45 R17 or the Avon ZZR's in 215/40 R17 as I can load an extra set of front wheels in the car.
I know it's not ideal but there's not much choice for the front.
If the 205/45's don't rub too much, I could go for Pirelli Trofeo R's considered as the ultimate semi-slicks over here?

 

[CB72]

Looks like you are driving well in the video, car has bit more to give with the current set up. If it was my car, I would would increase the front sway bay stiffness, go to the shortest setting and decrease the rear camber to 2 deg. Both of these will increase rear traction and put off the point where the rear wants to let loose. The trade off is the car will like a quicker transition as you turn in, meaning you will need to use the throttle AND brakes to get the car to rotate as you set up for the corner. From the video, you are already doing this in some corners. It might help to get a coach to ride along and help with timing as you advance. I love getting another set of eyes in the passenger seat, any time I can get a coach I jump at the chance!

I am assuming you have compliance joint clamps on the front of the car already?

Dave

I appreciate the feedback!
The guy in the 997 GT3 phase 2 in the attached video took me for a ride the same day and uses a lot of trailbraking to get the car to rotate so I understand what you are saying.
With my new PSS Cup 2's at the rear, I'll gain a lot of grip I'm sure, so I'll leave the chassis as is until the next track day.
BTW, I have your non-compliance joint clamps but haven't installed them yet...
What should I expect from that?
Here's the video where the Porsche is following me:

https://www.youtube.com/watch?v=M12mEPpD1CI&list=FLoe6PovyXNTYPQBX7V3_yeA&index=2&t=0s

John

PS: I forgot to mention I'm using Brembo 330x32 front disks with the hats I bought from you.

 

[titaniumdave]

The clamps will make the front end more stable at corner entry, especially when you are at threshold in your brake zone. In that situation, especially with those big front calipers, the front wheels move backward under heavy braking and will move forward as grip is reduced on the inside tire as weight transitions to the outside tire. This creates a vague feeling in the steering. I expect you will be surprised how much more crisp and confidence inspiring the car will be with the claps installed, plus it only take 15 minutes to install the set!

 

[CB72]

The clamps will make the front end more stable at corner entry, especially when you are at threshold in your brake zone. In that situation, especially with those big front calipers, the front wheels move backward under heavy braking and will move forward as grip is reduced on the inside tire as weight transitions to the outside tire. This creates a vague feeling in the steering. I expect you will be surprised how much more crisp and confidence inspiring the car will be with the claps installed, plus it only take 15 minutes to install the set!

I understand the logic, I will get them on before the next track day.
To be honest, I'm not 100% confident with the brakes as in the rear I'm using NA2 size disks with AP Racing 4 pot calipers ( same size as used by Lotus Exige in front).
I already exploded one disk while decelerating from 125 mph and my latest pads ( Pagid RS 14 black) partly disintegrated near their life end...
Time for an upgrade I suppose.

 

[CB72]

NSX upgraded with Ti Dave's non-compliance front clamps

I got them on the car today!
Here's what the front looks like now with DF large fenders, 330x32 Brembo disk, Porsche 993 turbo calipers, Pagid RS 28 pads, Comptech camber kit, KW V3 clubsport dampers, Dali 22 mm sway bar and Ti Dave's front clamps.
I wonder if Soichiro would appreciate???

 

[titaniumdave]

I understand the logic, I will get them on before the next track day.
To be honest, I'm not 100% confident with the brakes as in the rear I'm using NA2 size disks with AP Racing 4 pot calipers ( same size as used by Lotus Exige in front).
I already exploded one disk while decelerating from 125 mph and my latest pads ( Pagid RS 14 black) partly disintegrated near their life end...
Time for an upgrade I suppose.

I trust you are not using NSX NA2 rotors on the rear of the car with those calipers? NSX rotors a 23 mm wide and the caliper is designed to run a minimum rotor thickness of 25 mm. This combination can have catastrophic results since the pads can become dislodge from the caliper when the pad is worn!

 

[CB72]

I trust you are not using NSX NA2 rotors on the rear of the car with those calipers? NSX rotors a 23 mm wide and the caliper is designed to run a minimum rotor thickness of 25 mm. This combination can have catastrophic results since the pads can become dislodge from the caliper when the pad is worn!

AP Racing states that the CP 7600 family suits 295x24 mm disks so I'm only 1 mm short...
On top of that, I'm using the deepest pads (16 mm) that are available for these calipers.
https://www.apracing.com/product_de...mm_mounting_centres-suits_ø295x24mm_disc.aspx
I'm tempted to go with a Stoptech BBK kit but I will need 30 and 34 mm caliper pistons to match my Brembo/Porsche front calipers.
https://www.zeckhausen.com/catalog/product_info.php?cPath=24_425_5017_7288_7292&products_id=22491
This will deliver the 60% front bias I'm currently running with.
Now, I'm not sure Stoptech would be willing to sell this setup?
The other possibility is to go with K-Sport BBK that are almost half the price but I'm a little wary about their performance under racing conditions???
https://h-tune.co.uk/ksport-k-sport-big-brake-kits-calipers-front-rear-bbk-6-8-pot-cylinder/

 

[jwmelvin]

1 mm could make a difference. I had a pad fall out of my track car (Civic) yesterday. I knew the pad was low but didn’t realize it would fall out. The pedal went to the floor and it made for an interesting corner; fortunately one where I only needed to brake lightly. I won’t be running them that low again.

 

[titaniumdave]

Yes, I have seen this happen. Be careful out there!

 

[Mac Attack]

I trust you are not using NSX NA2 rotors on the rear of the car with those calipers? NSX rotors a 23 mm wide and the caliper is designed to run a minimum rotor thickness of 25 mm. This combination can have catastrophic results since the pads can become dislodge from the caliper when the pad is worn!

Wow, great catch Dave!

Are you making any more brake upgrade kits for the NSX?