no complience is fine for the track, but real bad for the street.

And if it's an old track with lots of patches, then no complience isn't that good their either.

Matt

 

They have really convoluted scallops cut out of them for compliance. The newer urethane foam ones can be even more compressible, but of course have the disadvantage of varying rate based on temperature and humidity!

 

Okay, we're sort of off topic. But these were developed for road cars and specifically for compliance. I feel they may have an application on the street as well. Twas my only reason for bringing these up. These are in fact in application all over the world currently - I'm told.

 

I don't think it's really OT given the title and original post:
My stock height MCS has about 1" from the top of the front strut housing to the solid rubber part of the bellows under the bump stop. So if you've lowered your MCS more than that you are probably riding on the bumpstop all of the time and don't know it. The compliance part is why you don't know it. Fortunately, the original post also offers a way for you to find this out for yourself: We can probably conclude from this limited free travel that the MCS is designed to corner on its bumpstops like nearly all other modern sporty cars.

 

BFG9000, you are spot-on, thank you. It's nice to see you participating, along with the likes of Dr O, Petrich, meb, 002 and others who I've learned so much from! The original title of this thread read something like 'Are you bump-stopping... and are you aware of it?', but I guess it somehow got edited...

The PSS9's have internal bumpstops, so the putty test no longer does it for me, unfortunately. While I know I'm doing better now than with the Ledas, I plan to increase travel about .75" when I go with the new H-Sport camber plates. I might also go with a slightly stiffer, linear springs (350#). The PSS9 progressive rate front springs are rated at 320# I think, so this increase in spring rates won't really help that much. I do so really to get more negative camber as the barrel springs are the limiting factor here...

 

Hey tony,

I've never used putty, but a zip tie works very well...and is typical racing equipment for such experiments . Install the zip tie just below the bump stop - touching it. Take the car for a ripping ride. check the new location of the zip tie...this will tell you how much travel you are using. But like BFG9000 wrote, the Mini is designed to ride these. The Megan bumpstops by contrast are very hard!

 

Thank you Michael. Tried searching for a photo so I can have a visual of this, although it sort of makes sense. In my situation though (PSS9's), the bumpstops are inside...

 

Just curious.
There is also a school of thought that well designed bumpstops are actually an important aspect of suspension tuning.
Overly rigid springs have their own issues and running springs firm enough to prevent that may actually be too high a rate. Allowing the suspension to settle onto a compliant bumpstop allows a softer spring but prevents any coil stacking.
This is not an endorsment one way or the other but is worth discussion I think.

This doesn't reference both stops bottoming under severe braking.

Just curious meb. Was this a rough corner where you may have experienced rebound stacking due to a too slow a rebound rate?

 

The left hander at Lime Rock - not rough unless contact is made with the considerable rumble strip...since I do not race for a living, nor am I a suspension engineer, I had to drive a few laps before I could determine what was happening. I kept questioning myself while driving, "am I running out of camber, where's all the grip?" Then suddenly I realized this was not so much a progressive loss of grip as it was sudden. So I focused and really hammered the turn to repeat and sure enough...

Before the next session, I upped the Megan damping by 6 notches - from setting 20 to setting 26 - and I could have gone higher. Setting 32 is max - these have obviously worn a bit.

michael