The S2000

[Shadowden]

I'll see if it pops again. If so, I'll wait till Saturday and we can run the code. I'll bring my book.

Played under the hood last night with a cheap strut bar I bought off of craiglslist (10.00). It doesn't fit the car due to my intake, but works to give me an idea of dimensions and where clearance issues may be. Hoping to finalize a drawing by Saturday then hopefully get to start fabricating it.

[Shadowden]

After the meet on Saturday, ECAM helped me flush the old brake fluid and clutch fluid from their independent systems using a vacuum bleeder. I rather liked the device and it could be done by one person. We then bled the brakes and clutch by the conventional method.

If this was a proper thread, I would have taken pictures of the old nasty fluid, but I didn't. However, the coffee/oil colored fluid that came out was evidence that mileage is not a good indicator of when to change fluid.

CEL/MIL continues to stay off.

Washed the car and hit it with some Prima Banana Gloss on Sunday since the weather is supposed to stay nice.

[ecam8000]

I'll see if it pops again. If so, I'll wait till Saturday and we can run the code. I'll bring my book.

He didn't bring the book......

[kingtut]

He didn't bring the book......

Ha ha. He not only forgot his book, but his wife too:D

[Shadowden]

He didn't bring the book......

Ecam, Ecam, Ecam...

No light, no book.

Thankfully, you are either smart enough to know where the bleeder valve on the transmission is or have worked on enough of these vehicles.

I scoped out your garage pretty well while I was there...I was planning to start inviting myself over to learn how to do some fabrication in the near future.

[ecam8000]

Anytime!

[Shadowden]

Anytime!

Question about materials and methods.

Seeing your supports you built for the arms on the rear axle got me to thinking. I would like to do something similar with the bracket for my bar. This will reduce the width of the connection at the strut tower leaving more space by the SRI box. I also like the cosmetics of it.

Seeing the 3/8" heims, you were using, I figured those would work great and eliminate fabrication for attachng the rod to the towers. However, I am unsure of what to run the heim to. I was originally thinking that using some aluminum piping, then welding a section of aluminum rod drilled and tapped for the heilm (LH on one side and RH on the other) would work great as long as a jam nut was placed so that it could be tightend up against the bar. However, if there is some sort of thread in junction then that would mean that the only real fabrication would be for the towers of the bar. I am looking on speedway motors and haven't seen exactly what I was looking for, but I could have sworn there was one in the catalogue. I was thinking the aluminum rod could be tapped to fit this heim receiver.

I was thinking of centering this over the strut and this would require space under the tower of the strut bar to get into the future strut top to make firmness adjustments. I have a couple ideas there, but essentially one would look like a simple handle. The other would whale tail out towards the fender side to increase the surface area and distribute more force. The latter would be more difficult to put together, but stronger and more aesthetically appealling.


What should I be looking at as far as plate to build the supports and the flat that attaches the strut bar to the strut tower? I was thinking 0.125" thick. Too much or not enough? 6061 for everything?

I was leaning towards aluminum because of weight, but it may not be the easiest material for me to learn how to weld.

I'm going to mock up a support tonight out of card board. I'll see how it comes up and will send you a picture.

[ecam8000]

Those joints that I have are 3/4! The do make many sizes, but I think you should look at clevis's (not sure if LH thread is available). Simple and lighter. You don't need the bearing, just the joint. Chromoly and steel often have advantages over aluminum, in some applications even weight to strength. Chromoly is often the most expensive, and can be more difficult to weld (correctly) than aluminum. We'll have to do some disigning and fitting. Check out Jegs and Summit Racing too. Search Heim joints and clevis, I'll bet there are plenty of suppliers out there.

Simply; you need a straight rod two clevis/heims and jam nuts with opposing threads (RH & LH) and mounts. What we'd need to know is the force we expect to be dealing with. If your S has double a arms (not McPherson) I'm not so sure this bar is needed.

[Shadowden]

Those joints that I have are 3/4! The do make many sizes, but I think you should look at clevis's (not sure if LH thread is available). Simple and lighter. You don't need the bearing, just the joint. Chromoly and steel often have advantages over aluminum, in some applications even weight to strength. Chromoly is often the most expensive, and can be more difficult to weld (correctly) than aluminum. We'll have to do some disigning and fitting. Check out Jegs and Summit Racing too. Search Heim joints and clevis, I'll bet there are plenty of suppliers out there.

Simply; you need a straight rod two clevis/heims and jam nuts with opposing threads (RH & LH) and mounts. What we'd need to know is the force we expect to be dealing with. If your S has double a arms (not McPherson) I'm not so sure this bar is needed.

All reports say the bar is not needed. There is a lower frame brace very close. It is a mcphereson system from my understanding, but the way the frame lays out, it is reported that sytrut bars do very little if anything besides add something to the engine bay and make a place to put a hand while working on the engine. For me, it is about making something unique and nice.

I was meaning 5/8", not 3/8" for the heims. I will look into clevis joints.

Given a curb weight of 2800lb (m=w/g=2800lb/32.2 ft/s^2=86.96lbxs^2/ft) and a skid pad rating of 0.99g (S2000 CR test by Road and Track) Force = mass x acceleration. a=32.2*.99=31.88), I would calculate the sideways force acting on the car to max out at 2772 lb.

That is a very simplistic look, but does represent a maximum in my opinion, As the car rotates with body roll, the forces will act but horizontally and vertically and the extent of the force acting vertically would act in the suspension. I think at no point will there be a bending force on the bar itself. The point of concern for me would be the loading of the bolt system holding the clevis/heim or the welds holding the bar itself. In any event, the cheap bar I have at home has 4 small tack welds holding the supports...

[ecam8000]

Given a curb weight of 2800lb (m=w/g=2800lb/32.2 ft/s^2=86.96lbxs^2/ft) and a skid pad rating of 0.99g (S2000 CR test by Road and Track) Force = mass x acceleration. a=32.2*.99=31.88), I would calculate the sideways force acting on the car to max out at 2772 lb.

There is where the confusion is. Tower bracing has little to do with car weight or G force. Instead it is designed to give the body rigidity where it flexes. 65-73 Mustang (and many other cars) had a brace (braces) that ran from the towers to rear of hood opening to brace the front sheetmetal/engine bay. The Miata's have double A arms transmitting cornering forces to points lower in the body (frame area) A McPherson car uses the top of the strut mount to deal with these forces (and the lower contol arm). Because of leverage the Mac cars see less force at the top of the tower, but significantly more than a A-arm car. The Miata towers carry the weight. The towers on the Miata still move some because of the loads father down the tower. This leverage point on the Mac cars is also the reason there is little camber change available for alignment (top of strut needs to move a significant amount for camber change). Another point in the McPherson strut needs to move for big camber moves (usually where the bottom of the strut meets the knuckle).

The forces I'm asking about is between the towers. Sounds like the S2000 has little movement. If so, your cosmetic, hand hold will be an easy project. Will you be bringing neons for undercar lighting too?

[RX-7 Chris]

Will you be bringing neons for undercar lighting too?

Neon is old news. Everyone is doing LED lighting now.

[Shadowden]

There is where the confusion is. Tower bracing has little to do with car weight or G force. Instead it is designed to give the body rigidity where it flexes. 65-73 Mustang (and many other cars) had a brace (braces) that ran from the towers to rear of hood opening to brace the front sheetmetal/engine bay. The Miata's have double A arms transmitting cornering forces to points lower in the body (frame area) A McPherson car uses the top of the strut mount to deal with these forces (and the lower contol arm). Because of leverage the Mac cars see less force at the top of the tower, but significantly more than a A-arm car. The Miata towers carry the weight. The towers on the Miata still move some because of the loads father down the tower. This leverage point on the Mac cars is also the reason there is little camber change available for alignment (top of strut needs to move a significant amount for camber change). Another point in the McPherson strut needs to move for big camber moves (usually where the bottom of the strut meets the knuckle).

The forces I'm asking about is between the towers. Sounds like the S2000 has little movement. If so, your cosmetic, hand hold will be an easy project. Will you be bringing neons for undercar lighting too?

Certainly, I'll bring some lighting for underglow! I tend to disagree with the thought that the weight of the car and its acceleration in a corner has little to do with the forces generated between the towers or I am misunderstanding your reply. If the car were always going in a straight line, the rigidity between the towers wouldn't be as important. Instead, the lateral loading in a corner generates a force across the towers which causes rotation of the top of the struts. The bar ties these parts together and allows them to be stronger in this scenario. Otherwise, the bracing in the car would be fine. The bars and bracings I tend to think only really matte at the cars limit. Cosmetic or not? I am not absolutely certain and wouldn't be until I try one for myself. The reports from people say that they felt no difference in the handling of their cars with a strut bar are out there, though even a marginal benefit in the car would be great since this project provides me an opportunity to learn to weld without it being critical to performance or of real structural significance. Plus, I read these reports from track cars mostly. Didn't read much from autocross folks. My feeling is that we are generating far more lateral forces on an autocross course than track cars do simply because of how tight the corners are. Fluid homework kept me from building my mock up last night, but i may work on it at liunch today. I made some assumptions that may be invalid for space and may cause my some issues with my most recent thoughts though.

I had an email conversation with an autocrosser swapping back to his AP1 transmission due to classing. Apparently, swapping an AP2 tranny isn't allowed in STR. Says it would put me in BSP at best, but potentially SSM or FP/XP. That is fine since I am not out to win, but get better at driving. However, it is interesting. His tranny has a lot more mileage than the other I was looking at though and is at the same price.

[Shadowden]

going back to geek mode:

We should assume the forces at the tires are static as the tires are not moving lateral across the road/course. So the force of friction acting inward is equal to and oppostie to the lateral outward force of the car.Assuming the center of the hub is the rotation point (bad assumption I am sure) for the strut then the force of friction would be acting inward at the bottom of the tire imparting a clockwise rotational force. Above the hub, the center of mass of the car would also be imparting a rotational force clockwise. Direction is based on my mental image, but both of these forces would serve to rotate in the same direction. Anyway, assuming the bottom force acts 2/5 of the length andd the top acts 3/5, we would then know force required to prevent the movemnt at the top of the tower.

Tsubh=Fsubf(2/5*2 ft)+Fsubcar(3/5*2ft)-neutralizing force(3/5*2ft)=0

Solving for the neutralizing force would tell us how much resistence the bar would need to add to eliminate all movement from the top of the tower using these haphazard numbers.

Consultation with another geek, we have determined that: Yep, it's cosmetic. I'll start fabricating a mock up and securing supplies!

[ecam8000]

Given a curb weight of 2800lb (m=w/g=2800lb/32.2 ft/s^2=86.96lbxs^2/ft) and a skid pad rating of 0.99g (S2000 CR test by Road and Track) Force = mass x acceleration. a=32.2*.99=31.88), I would calculate the sideways force acting on the car to max out at 2772 lb.

Yes G force and car weight are numbers that are important...

When it comes to building the strut bar I'm curious about the force on the tower (between towers). 2772 lb. is not what the top of the tower would see. Leverage, lower control arm angle, chassis height, roll centers and other factors are in play. My guess is the top of the tower would flex a bunch if it saw half that number max (and about half that 2772 lb is on the rear axle - and the inside tire on each axle as well). My guess it the top of the tower see somewhere in the 500-700 pound side loads. Some cars are flimsy and need to be beefed up when sticky tires and horsepower are added. Others can take a fair amount of upgrades needing minimal "beef". I drove a factory V8 Triumph (1980 TR8) with a manual tranny in the early 80's. A couple of hard launches and the driver's door became difficult to open.

[Shadowden]

Yes G force and car weight are numbers that are important...

When it comes to building the strut bar I'm curious about the force on the tower (between towers). 2772 lb. is not what the top of the tower would see. Leverage, lower control arm angle, chassis height, roll centers and other factors are in play. My guess is the top of the tower would flex a bunch if it saw half that number max (and about half that 2772 lb is on the rear axle - and the inside tire on each axle as well). My guess it the top of the tower see somewhere in the 500-700 pound side loads. Some cars are flimsy and need to be beefed up when sticky tires and horsepower are added. Others can take a fair amount of upgrades needing minimal "beef". I drove a factory V8 Triumph (1980 TR8) with a manual tranny in the early 80's. A couple of hard launches and the driver's door became difficult to open.

Excellent. Given the high skip pad of the car, I assume Honda made the body and such pretty rigid. It is notorious for its stock handling characteristics. I would assume the force between the towers to be pretty low as well. Probably even sub 500lb. My guess is that building for 500# and building for 750# would yield very minimal difference in weight. I like the looks of beefy components when it come to strut bars. Other than the fit of the current bar, I also don't like the looks of it because of its look of flimsiness. Is there problems with over engineering the bar (perhaps breaking off strut studs)?

Mock up of tower complete: