[JamesL]

I'm curious though... everything I've read about this chassis for the last 9 years, as well as generally understood behavior of macstrut suspensions, suggests camber loss with compression. Unless I'm reading this wrong, you're suggesting the RSX gains negative camber w/ compression? That's an entirely new assertion. It makes me weary of the model.

I was under the impression most McPherson strut system gained a little negative camber with compression, but just very little camber in comparison to other suspensions(ie: dbl wishbone, etc)...

Positive camber gain during compression would be horrible for handling, be it a street car or a race car. :dontknow:

 

[jmercado567]

I hear u matt. I've seen those posts too. On my many attempts to maximize neg camber I found the same... but was quickly told I was wrong by some.... Measuring was done at alignment shops. Whe the war was lowered neg camber increased.

Thanks speedengineer... can't wait to read this tonight

 

[lando]

I definitely agree it's horrible, but I always understood that that was what happened, and a primary reason for maximizing static neg camber in our cars. If I'm wrong then great

 

[Bath Tussue]

I think it only gain positive camber if you lower the car too much

 

[speedengineer]

I definitely agree it's horrible, but I always understood that that was what happened, and a primary reason for maximizing static neg camber in our cars. If I'm wrong then great

When people say that it gains positive camber, they are likely meaning that it gains positive camber relative to the ground (body roll included). MacPherson Strut suspensions definitely do have some negative camber gain. They will continue to gain negative camber until the angle between the strut and the control arm becomes obtuse (aka greater than 90 degrees). That will never happen on our cars no matter how much you lower it.

 

[JamesL]

Regarding the bump-in that occurs on the front suspension.... Ive been thinking about this for the past few hours.

At what point does the angle of the tie rod cause binding within the balljoint and limit/restrict movement during steering operation??

Also, does anyone have a good approximation of the stock tie rod angle? Or a picture of tie rods(from inside the engine bay) at the stock ride height?

 

[vash_the_stampede]

interesting read

 

[speedengineer]

Regarding the bump-in that occurs on the front suspension.... Ive been thinking about this for the past few hours.

At what point does the angle of the tie rod cause binding within the balljoint and limit/restrict movement during steering operation??

Yeah, not sure when that would be an issue. I bet it would be pretty huge angle though.

Also, does anyone have a good approximation of the stock tie rod angle? Or a picture of tie rods(from inside the engine bay) at the stock ride height?

It is somewhere around 6.3 degrees. At stock ride height with BC RSD's, it was 6.3 degrees. As far as I know, buddy club and oem struts have the tie rod attach in the same location, but I don't know for sure. Either way, 6.3 gets you in the ballpark.

 

[Temptazn_Mark]

It is somewhere around 6.3 degrees. At stock ride height with BC RSD's, it was 6.3 degrees. As far as I know, buddy club and oem struts have the tie rod attach in the same location, but I don't know for sure. Either way, 6.3 gets you in the ballpark.

Do you think stock tie rod angle is optimal? Or more angle?

If I lower my car 1.75 inches but the steering rack bracket raises the inner rods by 1.25 inches, doesn't that mean my tie rods should be about stock angle or maybe a little greater?

 

[speedengineer]

Do you think stock tie rod angle is optimal? Or more angle?

If I lower my car 1.75 inches but the steering rack bracket raises the inner rods by 1.25 inches, doesn't that mean my tie rods should be about stock angle or maybe a little greater?

Yeah, that sounds like your angle should be right about stock or a little more then. I would tend to think that you certainly don't want more toe-in than stock. I have no clue how much of a difference it will really make to lap times though...

 

[Temptazn_Mark]

Yeah, that sounds like your angle should be right about stock or a little more then. I would tend to think that you certainly don't want more toe-in than stock. I have no clue how much of a difference it will really make to lap times though...

So because my angles are a little bit greater than factory, it should have a little less toe-in under compression than factory right?

 

[speedengineer]

So because my angles are a little bit greater than factory, it should have a little less toe-in under compression than factory right?

Yes.

 

[Dr.Honda]

Buddyclub RSD has lower tie rod end mounting points then factory to compensate for the lowered ride height. 6.3 degrees with RSD at stock height would not be the same as stock struts at stock height (essentially the 6.3 angle reading you got is less then what it is stock).

 

[Temptazn_Mark]

Buddyclub RSD has lower tie rod end mounting points then factory to compensate for the lowered ride height. 6.3 degrees with RSD at stock height would not be the same as stock struts at stock height (essentially the 6.3 angle reading you got is less then what it is stock).

 

[lando]

Wow... looks like RSD + steering bracket will be overcompensating unless you're seriously slammed.

 

[speedengineer]

Buddyclub RSD has lower tie rod end mounting points then factory to compensate for the lowered ride height. 6.3 degrees with RSD at stock height would not be the same as stock struts at stock height (essentially the 6.3 angle reading you got is less then what it is stock).

Shit. In light of this information, looks like I'll have to remake the bump steer plot for the front. I measured the nominal angle at the buddy club height, not the oem height. Basically, add "with BC RSD" to all the lines on that plot. At stock, all those lines will come down a little bit then... sorry guys.

 

[Dr.Honda]

So with stock the toe in would be even less severe under compression?

And Mark, since you have the suspension out of the car and an extra RSD bracket, why don't you measure the height difference for us.

 

[cobra7]

this is very useful for suspension tuning, thank you

now, take the specs, put it in Adams and do some dynamic analysis for us

 

[Temptazn_Mark]

So with stock the toe in would be even less severe under compression?

And Mark, since you have the suspension out of the car and an extra RSD bracket, why don't you measure the height difference for us.

Note: Pictures taken are of the old version RSD brackets. They may be different, but I believe the steering arm is mounted at the same height and that the only change was beefing up the bracket itself.

I mounted from the top of the steering arm to the middle of the first hole where the bracket meets the knuckle. I got the numbers by trying to keep the measuring tape parallel to the shock and then taking a thin envelope to help provide a visual reference point on the measuring tape to the strut.

The RSD brackets measured in at about 4.25"

OEM suspension measured in at about 5.5"

It would probably be safe to say that the RSD steering arms are about 1.25" lower than OEM.

However, one must remember that the actual angle of the tie rods will be determined by how much the car is lowered.

Edit: I won't be able to check back for awhile since I'm flying out to NYC tonight and will be gone for a week.

 

[speedengineer]

Ok, thanks for the info. Have a good trip!