Birkin rear ride height need a measurment

[KiwiBirkin]

Hi any chance some one with a Birkin can measure there ride height of their car at rest with no one sitting in the car, I have just replace my rear Spax shocks with new GAZ Gold shocks and 175 lbs springs and I think I have the ride height set a tad high.

 

Can you measure at this spot indicated in the photo which is where the aluminum meets the guard and goes under the car please and if possible provide me with a metric size

 

Picture for ref of where to measure.

http://i660.photobucket.com/albums/uu326/Hotdognz/bits%20and%20pieces/RideHeight.png

 

Cheers KiwiBirkin

[Davemk1]

Ride height on these cars is not set this way. It's set by setting the front shock eye-eye number to 294 mm and then setting the rear part of the chassis a certain amount above the front to establish rake. This way stuff like tire and wheel diameter won't influence the number and the suspension angles will all be correct.

 

As I recall the front shock eye-eye is 294 mm and there should be 15 mm of rake. So you would measure the ride height under the front of the chassis and add 15 mm to get the rear. I'm working off my not so good memory on this so someone else should chime in if I'm wrong.

 

I hope that helps.

 

dave

[slomove]

Memory is good enough....that is what I have seen as recommendation. Works for me.

[KiwiBirkin]

My front shocks are at 294mm eye to eye centers, so all I need to do is be 15mm higher at the rear ?? if that is so where do I measure the front height from and then where do I set this 15mm for rake because as I move back further down the chassis the height will increase so there must be a spot too measure from.

[Davemk1]

I measured from the spot on the other chassis rail where the rear section of the front A arm attaches. It seems to be the lowest point up front.

 

Then I measured the rear right in front of the rear fender - right where you indicated on your drawing.

 

Of course like all settings it should be done with weight in the seat.

 

Dave

[KiwiBirkin]

So im correct in thinking the 15mm difference should be with my body weight on the drivers side or should that be with the weight of both a driver and passenger ??, can you also explain in a bit more detail why you have rake as my thoughts would have been to have a level car with the weight in it.

 

Also dave any chance you can supply me your ride heights you have for those 2 spots as a ref for me.

 

Cheers

[Davemk1]

So im correct in thinking the 15mm difference should be with my body weight on the drivers side or should that be with the weight of both a driver and passenger ??, can you also explain in a bit more detail why you have rake as my thoughts would have been to have a level car with the weight in it.

 

Also dave any chance you can supply me your ride heights you have for those 2 spots as a ref for me.

 

Cheers

 

I just measured mine for you and I think my front shocks are 290 mm eye - eye and my front height is 5 5/16" and the rear is 6 3/16" without my 190 pounds in the car.

 

I hope that helps.

 

Dave

[KiwiBirkin]

Cheers Dave when you look at your car from the front does the front arm of the bottom A arms rise up on a gentle slope up from the tire end to the car body or do they look parallel to the garage floor ?? with those settings.

[Davemk1]

Cheers Dave when you look at your car from the front does the front arm of the bottom A arms rise up on a gentle slope up from the tire end to the car body or do they look parallel to the garage floor ?? with those settings.

 

With my settings the lower A arm rises slightly as it goes from the wheel to the chassis. In other words the chassis end is a just a bit higher.

 

Dave

[KiwiBirkin]

Cheers Dave I have mine now set up the same way now and im really happy with the results. Thanks for your help.

 

Next I have to start setting up the shocks as I have 30 clicks of adjustment on these Gaz shocks, I tried 15 clicks all around but the car felt very stiff and it seemed the rear jumped over some bumps. Anyone have any recommended settings for starting off.

 

Cheers Kiwibirkin

[Davemk1]

Cheers Dave I have mine now set up the same way now and im really happy with the results. Thanks for your help.

 

Next I have to start setting up the shocks as I have 30 clicks of adjustment on these Gaz shocks, I tried 15 clicks all around but the car felt very stiff and it seemed the rear jumped over some bumps. Anyone have any recommended settings for starting off.

 

Cheers Kiwibirkin

 

Have you been able to corner weight the car? If not it can work wonders for the on-the-limit handling. If you don't have scales (few do, some friends and I went in on a good set) see if you can borrow some. It's worth the effort.

 

It's also important to make sure that all the setting are done in the right order and with weight in the car. The weight in the car changes things in a rather large way. I set mine in this order -

 

ride height

thrust angle

front camber

front toe

corner weight

recheck ride height

 

If you like doing this kind of stuff it's good fun. If you don't it seems silly and unnecessary. I hope it's fun for you.

 

dave

Edited October 14, 2009 by Davemk1

[slomove]

Don't know about Gaz shocks but with my old Spax as well the current Protech I needed few if any clicks at all. With too many clicks the rebound sometimes took a second or more which leads to a very hard ride. On the other hand even with no clicks the rebound was not oscillating (swinging up and down) so I ended up with 2 out of 12 clicks and that unscientific method gives me a pretty good ride.

 

Gert