Birkin IRS setup height for the rear

[KiwiBirkin]

Hi guys I have a mate who has just purchased a new 2010 model Birkin S3 IRS, its sitting very low at the rear and needs to be adjusted up to the right ride height and its probley different to my live axel Birkin. Can some one with a Birkin IRS tell me what you have setup for the height from.

 

Picture for ref of where to measure.

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

 

Cheers Stephen

[11Budlite]

Stephen - I can't help you with the IRS set-up but I think most of Birkins are using appr 1/2" more ride height in the rear compared to the front. With my narrow track front end and AVO shocks we set the front ride height by measuring the distance between shock eyes and setting it at 294mm. I then set the rear ride height so it was 1/2" higher than the front. I could probably lower it all around but I like being able to drive on some of our crappy roads and not bottom out the sump. I think the measurement on my car at the point you're requesting is a little over 6" unladen.

[KiwiBirkin]

Cheers Bruce, I know for a live axel the height at the point in the picture should be around 160-165mm if its the same for a IRS then thats good I can convey that msg to Don with the IRS Birkin

[Croc]

Kiwi - If you do not get any response here then PM Kitcat on this forum. He has an IRS Birkin on road tyres and it handled pretty nicely at the sevens track days earlier this week.

[Kitcat]

Kiwi: I have the new Birkin (2009 w/wide track/IRS, etc.). I measured the spot you suggested yesterday and it was 6".

 

The US Birkin dealer has very specific front suspension set up advice also. I cant find the specs tho will post if I run across. I do know the lower A arms are not parrallel to the ground under the ideal set up (engine side is a bit higher than wheel side).

 

My car has a nicely baffled wet sump. But-I still blew up the engine at a track day. Turns out the stock (raceline?) pan is deficient for aggressive track use. It can be easily modified w/a trap door. If you send me your e-mail address I will forward a photo of the mod.

 

USA Birkin also recommends adding a breather tube/catch can to valve cover, one on exhaust and one on intake side, to keep crank pressure under control, if track use is expected. I ultimately had 4 breather tubes (and still blew up the engine due to oil starvation). My replacement engine just had the stock breather tube and one extra and did fine at last track day (w/modded oil pan).

 

Also, Duratec oil spec 5-20 is too thin for sustained, heavy track use. I would upgrade to 5-50, like the Cosworth Duratecs use for track. For spirited street use, I think the 5-20 is fine.

 

There is a Birkin discussion group on Yahoo that is an excellent source of info. Google "birkinowners yahoo" for details.

Edited July 2, 2012 by Kitcat