Jump to content

Simply shocking questions.. (Birkin owners especially)


southwind25

Recommended Posts

The ride height of our se7en has seemed a little high...Ok so i took off the front AVO shock to measure it eye-to-eye and i

got a dimension of 328mm, The printable manual says 294. I am guessing

this is supposed to be the unladen free length.

We can see that the collar will set the ride height but it is

already "unscrewed" as far as it will go and still have full thread

engagement on the shock. So at this point is spring length the limiting

factor at lowering the car so it doesnt look like we are doing a baja

run? The suspension simply looks way too high. As far as we know these are all stock parts -springs-shocks but the assembled parts wont give the

stock dimension we are looking at in the manual. what am i missing

here?http://usa7s.com/aspnetforum/upload/817045054_shock2.jpghttp://usa7s.com/aspnetforum/upload/1643005117_shock1.jpg

Link to comment
Share on other sites

Yep...looks like the springs are the wrong size. Best way to lower the car (more than a fraction of an inch) is by changing to shorter springs. Then use your spring perch to fine tune ride height and cornerbalance the car.

Link to comment
Share on other sites

Robert,

 

Are your lower 'A' arms parallel with the ground or do they angle up to the pick up points on your frame?

 

Jack

Link to comment
Share on other sites

8" oh cripes.:eek:

 

.I measured mine at about 9 1/4" between the top & bottom shock collars with the car on jacks.

it's probably a bit longer free length. The bottom arm angles UP to the body at about 5 degrees. sooo,,uhhh....it came with the wrong springs?...oh great.:banghead:

 

what rate-length should i have on this thing wth the 1600 x-flow in it?.

Who is a good source for the correct springs?

 

the rears seems to be in spec with the manual from what i see for collar height.

Link to comment
Share on other sites

I don't know about how your engine weight compares to the Zetec I've got but I can tell you I've settled on 350# in the front and 175# in the rear and it's wonderfully balanced and not harsh.

 

Put some 8" springs on it and you'll be fine. If they are over 9" installed they must be 10" free length.

 

dave

 

 

 

Link to comment
Share on other sites

Dave, who did you use for a supplier? what model # springs? (anyone is free to answer this query)

There seems to be ALLOT of cornfusion on the birkin yahoo group over all this. people bending A arms with the wrong spring-shock combo?...but it seems very few correct answers mostly wrong ones.

 

 

Link to comment
Share on other sites

I got my springs from Woody at MSI. He should be able to give you good advice concerning the spring rate and A arm bending.

 

As I recall (I'm not the expert) the bent arms were a result of the spring/shock bottoming out resulting in a big spike load to the A arms. St the ride height correctly (294 mm) and you should be fine.

 

dave

 

 

 

Link to comment
Share on other sites

Robert, I partially answered on the Birkin list before I saw this thread, but to recap:

 

1. Give Woody a call.

2. The 294 mm measurement eye-to-eye is with the shocks on the car and driver's weight in the car. It sounds like your springs are too long, so this may not be possible. This sets the correct front ride height, then adjust the rears to get the car level.

3. My Zetec Birkin has 300# springs front, 175# rear, by Woody's advice (I got them from him).

4 Give Woody a call! :)

 

 

 

 

Link to comment
Share on other sites

Perhaps try Dick Brink at Texas Motor Works? He's listed at the links section of this Forum under "dealers & distributors". He sells Birkins and seems knowledgeable regarding all aspects of the make.

Link to comment
Share on other sites

Dick would be a good contact. He has a wealth of knowledge about Caterham (being former dealer) and Lotus as wel as Birkin. Also, he has been racing and doing track days with on Se7en for quite some time. He was at 777 and has been at many LOG's. I've always had good dealings with him.

 

Link to comment
Share on other sites

how difficult is it to get ahold of Woody? i have placed several unanswered calls (voicemails) and theres not an e-mail i can find. Any suggestions? i am not close in ohio. I looked into the Eibach springs website but there seems to be several options if i go that way.

Link to comment
Share on other sites

Robert,

 

I sent you a PM.

 

On my Birkin, the front springs were 300lb, 8" free length, with I think a 1-7/8" ID. In fact on the springs themselves they were ID'd as such (less the ID dimension).

 

Bruce :7drive:

Link to comment
Share on other sites

Cool thank you SO much for the info!

 

((hey kudo's to this site, i seem to get faster-more info from the members here than the same from other places thanks guys!!))

 

I found both a set of eibach and afco springs this size-length-rate, but until i am more knowlegeable it's awesome getting confirmations that i am looking at the right stuff.

 

Thank you!:thumbs:

Link to comment
Share on other sites

  • 2 weeks later...

As a follow up, we got our 8" springs on (after a hassle getting the 10" off!)

surprisingly...maybe it's our imagination but the car just seems to have a tad bit better ride taking the abrupt bumps.

 

we set the shocks at 300 MM not the 294 just for good luck.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...