Solid "spherical" bushings

[asylum]

I don't know how to call them exactly : "solid", "spherical", "non-compliance"... I would like to replace them all. I already have the non compliance rear beam bushings and toe links. That means there are still 5 each side to replace (front upper and lower, rear upper arm front, rear upper arm rear, rear lower arm front). It is for my track only car running full slicks. What benefit can I expect ? Did one of you do that change and can comment ?

Thanks for your feedback.

 

[BrakeExpert]

Solid bearings, heim joints or speherical bushings are harsh, they transfer all noise vibration and harshness. Though you say this is for a track car, sometimes replacing ALL of them are going to remove some of the cushion for the tires to do its job. I'd suggest talking to someone who has done this before, as the benefits are likely to be marginal compared to the added possible maintainence depending if yours are gonna have to be greased or refitted over and over. I'm not trying to sound like a dick, but if your goal is say "best possible lap time", the benefit of firmer bushings could net you possibly fractions of a second while spending all that money on say magnesium wheels or lighter chassis bolts could be far more cost effective and take off a complete second. This is a track only car, IS it a pure race car, ie your on full slicks, no interior, no airbags, etc?

 

[asylum]

Full slicks, no interior, cage, lexan windows, brakes, KW Clubsport, splitter ... For sure now I can put a supercharger and gain 2-3 seconds. But if I begin this way, this is a never ending story. Plus I want to keep the reliability high and cost low.

I just want to reach the best chassis settings. Now I encounter a "weak" front grip in certain circumstances (fast corners when not on deceleration phase) which I have not been able to eliminate with different settings (sways, tire hardness, ...). But it is not a surprise with 210 front and 260 rear slicks.

There are not a lot of things left to do. That is why I am asking about the benefits of these spherical bushings. The other last mod I would like to do is wider front fenders to be able to run 240 on larger wheels.

 

[Honcho]

@asylum For your purposes, these bushings will make a significant difference in the responsiveness and stability of the chassis under dynamic cornering loads. The rubber in the OEM bushings will take up some of the chassis movement and release it in unpredictable ways. It's even worse if the rubber is old and/or damaged. This behavior is most noticeable in fast corners as you mention (due to the high load on the bushings) and the best way to describe it is "floaty" or "nervous". Think of it as if the car is wiggling around in its bushings when it is supposed to be set on a stable cornering load. The rear beam non-compliance parts solve a lot of this (due to eliminating dynamic toe change during cornering), but remember they were developed back when NSX OEM bushings were still in good shape. Now, with 30 year old rubber, the rest of the suspension needs attention.

Most people never drive their NSX fast enough to experience this, but you do. Thus, I would replace them all. You can go with the Prothane polyurethane kit, but that needs custom fitting, ideally with a lathe. While the higher durometer rubber will mitigate a lot of the issues, it won't completely solve it. To do that, you need the pillowball spherical product. T3TEC and RFY sell kits. Also, I think Cedar Ridge and possibly Pride have options.

 

[asylum]

Thanks both for your input !

 

[docjohn]

your understeer in fast sweepers means you need more front tire and better aero, maybe a bigger front bar...

 

[asylum]

Yeah that is why I was thinking of wide fenders to go wider front. Then I will adapt the front bar setting. But for me stiffer front means less grip. And I also need some roll to have the tire surface sitting flat while cornering as I have 3° front camber. Well, for sure I am still looking for the right settings.

 

[docjohn]

what is your toe/ castor?

 

[asylum]

A slight toe out. 9° caster. I think I will reduce it.

 

[docjohn]

do you have a big rear wing?

 

[asylum]

Yeah but set very flat. I am more interested in increasing the front grip rather than decreasing the rear one... But this could be a temporary solution.

 

[docjohn]

my personal opinion on rear BAW(big ass wing) unless wind tested they may do more harm than good...

 

[Heavymetals]

Spherical bearings are the only way to go if you want to get rid of a "rubber band" suspension.

Do the shock amounts first.

I would assume that either the PORSCHE or Corvette offerings would work or be adaptable.

They are not cheap either.

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[asylum]

Already have solid top mounts (KW Clubsport).

 

[Honcho]

Understeer or lack of front grip is, like docjohn mentioned, a function mostly of front tire size and aero. The control arm bushings aren't going to have a lot of influence there other than unpredictable effects on handling. For example, if the bushings flex at corner entry and the toe setting changes, the car can go from understeer to oversteer very quickly. Reducing or eliminating the flex will make the car feel much more stable when under a cornering load. It's the #1 thing most track-focused drivers do- they change the rear beam bushing since it has the most effect on dynamic toe change. Changing the other bushings will further increase the stability. @stuntman can probably explain better, since he's a pro.

 

[asylum]

Fronts are done. Rears... ... when I find the time.

 

[stuntman]

Have a pic of your car? What's your rake? (Measure from the ground to the bottom of the center of the front and rear jack tabs.

What's your rear camber and toe? Have you measured tire temps when you get off the track?

Without seeing what wing you're running, you most likely need stiffer front and rear springs to offset the downforce you added to the rear of the car.

 

[asylum]

Work is going on slowly. Finaly I have the rear lower front bushing pieces apart. This front beam is a pain in the ass to take out. With an aftermarket header, the front motor mount nut is unaccessible and the three bolts on the motor are marginally better.

 

[asylum]

Have a pic of your car? What's your rake? (Measure from the ground to the bottom of the center of the front and rear jack tabs.

What's your rear camber and toe? Have you measured tire temps when you get off the track?

Without seeing what wing you're running, you most likely need stiffer front and rear springs to offset the downforce you added to the rear of the car.

High Stuntman,

My last mods to get more front grip, especially when not decelerating or when accelerating was to set the front a bit lower, soften the front sway and put more compression rear. I think it helped a bit. But with the front so light (no front beam, no condensators, small battery, ...), it is hard to get grip.

My future plan is wider fenders to go 240 on 9'' instead of 210 on 8'' and vented hood to go with my splitter. I think this is the only way to really have an increase of grip.

 

[asylum]

I did the rear lower front beam bushing on the press. Quiet easy. The bushings on the rear upper arm are align and I was not able to find a position to use my press. I had to use my big c-clamp. But it works. These bushings do not require that much pressure. The biggest challenge is to have the right sockets and be expert level at Tetris.

I am amazed of how light the stock bushings are. They feel weak.

 

[stuntman]

Have a pic of your car? What's your rake? (Measure from the ground to the bottom of the center of the front and rear jack tabs.

 

[asylum]

I will measure the rake when I will be able to put it to the ground.

 

[stuntman]

You have a significant amount of rear angle of attack in your wing. Even without knowing your camber, toe and alignment, your understeer is probably mostly from your wing.

Place a straight edge on the center of your wing and measure how many degrees the angle of attack is.

 

[asylum]

Yeah I already reduced the angle from the time I made this photo.

 

[stuntman]

Place a straight edge on the center of your wing and measure how many degrees the angle of attack is.