Birkin rear shocks measurment needed

[KiwiBirkin]

Hi all I need some info from some one who has built a Birkin and maybe measured there rear shocks before they installed them or are able to measure a set for me prior to there install. I want to replace my rear shocks as I have just replaced my front Spax with some new GAZ adjustable shocks and new 250lb springs and the ride & handling diffrence is amazing.

 

The info I would like if possible is overall length extended, overall length compressed and length with the spring on at the set ride height for a Birkin live axle if possible. This will all need to be measured to underneath the rear plate that the shock pops through at the top of car.

 

Cheers for any help offerd. Kiwibirkin

[11Budlite]

Kiwi,

 

Sorry I don't have all the info you need, but I think the overall extended length should be 17". There were several US cars that had rear AVO shocks with I believe 17.5" extended length, that would let the rear axle hit the frame on full extension. It might be worth a search on the yahoo.birkinowners site.

[KiwiBirkin]

Cheers Budlite I have now been given some info on what they should be.

 

Now my next Qs is what lbs springs are people using in the rear shocks of their Birkins I have new 250lb springs on the front and I need to match the rears to this.

 

Cheers Kiwibirkin

[slomove]

I run 325# front and 175# rear (with ball joint radius arms, no rubber bushings).

 

Gert

[Davemk1]

I'm running the same rates as Slomove - 325 and 175.

 

I've experimented with higher rates and the car transitions very crisply but hooks up not nearly as well. After playing around a lot this is where I ended up.

 

Dave

[KiwiBirkin]

Cheers guys I had a long chat today with a couple of NZ lotus 7 replica builders Fraser Cars & McGregor Sevens and they recommended 250 fronts & 175 rears as they seemed to have settled on them for genral road use on NZ roads and the odd track day.

 

Kiwibirkin

[southwind25]

Kiwi, i measured the length of my rears on my birkin. This was with the wheels on the ground in the garage full tank of gas but nobody in the cockpit. best i could measure they were 12" from the top to the adjustable collar on the bottom.

 

we have 300# for the front and stock rear, which i am guessing is the 175's..

[TheDingo8MyBaby]

If you have a live axle, I would look into getting rose joints for where the shock mounts to the axle. It allows the shock to pivot and prevents it from binding.

[11Budlite]

I'm running 300 lb front and 175 lb rear with the MSI heim joint trailing arms. My car originally came with 150 lb rear springs.

[KiwiBirkin]

Cheers for all the info guys im going with Gaz adjustable rose jointed shocks for the rear that are 16" long with 175lbs springs, im changing the rear over from the normal Birkin top mount to this idea that a guy in Japan used when he changed his rears on his Birkin but using AVO shocks.

 

These are his pictures not mine but mine outcome will be the same.

 

http://i660.photobucket.com/albums/uu326/Hotdognz/bits%20and%20pieces/p1.jpg

 

http://i660.photobucket.com/albums/uu326/Hotdognz/bits%20and%20pieces/p4.jpg

 

http://i660.photobucket.com/albums/uu326/Hotdognz/bits%20and%20pieces/AVOinside2.jpg

 

Kiwibirkin

[KiwiBirkin]

Just fitted the new rear rose jointed Gaz shocks on my car with 175lbs springs I have set the ground clearance which is all good and have added 6 clicks to the rear from full soft however the car seems a bit springy in the rear end when I push the back down and let go, I have seen some info where but cant find it now that Birkin only ran 100lbs springs in the rear on the spax shocks any reason to run the higher springs ??.

[Dave W]

I would try higher shock setting. I have GAZ shocks with 160lbs springs on the rear. I'm running 12 clicks on the rear, or a little above middle way in damping range.

Dave W