(I searched keywords squat, launch, spring, rate)

I know,
I know...
the E36 isn't a drag car
BUT

if/when I decide to travel the straight track
I'd like to be prepared.

Is squat good for a launch?

:dunno

As stiff a spring as possible in the rear will get you what you want.

When I had stock suspension, I was getting way better 60 ft times than other m3 powered e36s at the strip who were mostly on aftermarket suspension.

Maybe because with stock suspension I had less camber and a better contact patch? I did have wider tires than most who were there.

So why would a stiffer spring be better? I really don't know much about drag racing physics. I have a 600 lb spring in the rear now.

When I had stock suspension, I was getting way better 60 ft times than other m3 powered e36s at the strip who were mostly on aftermarket suspension.


I have a 600 lb spring in the rear now.

Have you had similar 60ft times w/ your new springs?
or have been back out?

Have you had similar 60ft times w/ your new springs?
or have been back out?

Have not been back out yet.

We used to run 50/50 shocks in the rear with either 90/10's or 80/20's in the front. This will give you a good weight trasnfer... Probably a medium spring in the rear with a LONG soft spring in the front

When I had stock suspension, I was getting way better 60 ft times than other m3 powered e36s at the strip who were mostly on aftermarket suspension.

Maybe because with stock suspension I had less camber and a better contact patch? I did have wider tires than most who were there.

So why would a stiffer spring be better? I really don't know much about drag racing physics. I have a 600 lb spring in the rear now.

probably not because of camber settings. Altough extra negative camber in the rear doesn't help standing starts.

I think it's tire deformation, on aftermarket suspention you transfer weight to the rear a lot faster. If the tire doesn't get the chance to build up these forces it will spin.

We used to run 50/50 shocks in the rear with either 90/10's or 80/20's in the front. This will give you a good weight trasnfer... Probably a medium spring in the rear with a LONG soft spring in the front

generally on the money in my book, added point if you can adjust the rebound in the rear, will make a large difference when you can get that dialed in...at least it did on the mustang...

Mike

generally on the money in my book, added point if you can adjust the rebound in the rear, will make a large difference when you can get that dialed in...at least it did on the mustang...

Mike

so
soft setting for the rear?

As stiff a spring as possible in the rear will get you what you want.

No, not even close. You need compression in the rear when you are launching. A softer spring with an adjustable rebound shock would be good. Look to see if the 318i has a softer spring rate and use those on the back when you go to the 1/4 mile. I know alot of my F-body friends would use V6 Camaro rear springs because they were softer and allow more weight transfer durring a launch.

No, not even close. You need compression in the rear when you are launching. A softer spring with an adjustable rebound shock would be good. Look to see if the 318i has a softer spring rate and use those on the back when you go to the 1/4 mile. I know alot of my F-body friends would use V6 Camaro rear springs because they were softer and allow more weight transfer durring a launch.


There you go...adjustable rebound will let you control how quickly the weight that has been transferred to the rear on the launch is returned from the rear to the front (just remember when you have a spring that is compressed, it wants to return to it unbiased position, additional rebound control let's you control how quickly the spring returns to its unbiased position). I had really nice Koni drag shocks on the mustang, at one setting you could pull the fully compressed shaft out of the body by hand, at another you needed significant force to do so (i.e., could not do so by hand).

Good luck,
Mike

No, not even close. You need compression in the rear when you are launching. A softer spring with an adjustable rebound shock would be good. Look to see if the 318i has a softer spring rate and use those on the back when you go to the 1/4 mile. I know alot of my F-body friends would use V6 Camaro rear springs because they were softer and allow more weight transfer durring a launch.
But what about IRS on our cars?

But what about IRS on our cars?

It still needs to compress otherwise there will be very little weight transfer. You need the weight transfer to keep the rear tires loaded so they don't spin off the line so you can get a good 60'. Also for every .100sec you improve on your 60' time you can improve your ET by about .200sec, and for every 100 pounds you remove from the car you usually see a .080-.100 reduction in ET.

I know its not a BMW but the new GTO has IRS and you can see how it compresses here.... http://www.youtube.com/watch?v=LkD-bxhxUDc

It still needs to compress otherwise there will be very little weight transfer. You need the weight transfer to keep the rear tires loaded so they don't spin off the line so you can get a good 60'. Also for every .100sec you improve on your 60' time you can improve your ET by about .200sec, and for every 100 pounds you remove from the car you usually see a .080-.100 reduction in ET.

I know its not a BMW but the new GTO has IRS and you can see how it compresses here.... http://www.youtube.com/watch?v=LkD-bxhxUDc

Damn that thing is fast.