Help with Rear Spring Rate

[JRD56]

I recently purchased an un-assembled MarkIII originally shipped in 2007. It came with the Solid Axle Coil-over kit and Bilstein F4-BE3-A274-Ti shocks. However, the springs were missing (the only thing missing in the whole kit :) ). According to the parts list they should #250 springs and 1.875" ID. I understand from Factory Five they are now using Koni shocks and recommend 350 lb spring, but the Koni springs are 2.5" ID. I'd like to stay with the Bilsteins but want to make sure I use the right spring rate. Any suggestions? Also does anyone know why the move from Bilsteins to Koni. Are there any issues with Bilsteins?

[David Hodgkins]

Welcome to the forum!

Being the Admin it may seem funny that I'm sending you to another site but there was an issue with Bilsteins of that era and this is a Direct post from Dave Smith.

Take a look at this thread:
http://www.ffcars.com/forums/21-ffr-type-65-coupe/196809-bilstein-report.html

The unit ID is very close to what you have, and it's worth a call to Bilstein at the very least to determine if you should perform an upgrade on your shocks. Do this before determining if you should bother getting springs at all for those shocks. I have Koni's on my car, BTW.

:)

[edwardb]

I recently purchased an un-assembled MarkIII originally shipped in 2007. It came with the Solid Axle Coil-over kit and Bilstein F4-BE3-A274-Ti shocks. However, the springs were missing (the only thing missing in the whole kit :) ). According to the parts list they should #250 springs and 1.875" ID. I understand from Factory Five they are now using Koni shocks and recommend 350 lb spring, but the Koni springs are 2.5" ID. I'd like to stay with the Bilsteins but want to make sure I use the right spring rate. Any suggestions? Also does anyone know why the move from Bilsteins to Koni. Are there any issues with Bilsteins?

Congrats on your purchase, and welcome to the madness. Yes there are issues with Bilsteins. It was slightly before my time with this hobby, but I've heard the story enough. There was an issue in 2008 with the Bilsteins breaking. Multiple instances and potentially catastrophic because the entire suspension would collapse. Bilstein provided a solution, and owners could send the shocks to them for rework. They upgrade to 14mm shafts and upgraded Heim joints compared with the prior 11mm shafts. (Hopefully I got that right...) The program is still active from what I've heard. But through it all, there was a falling out with Factory Five and they switched to Koni. The Koni's have been the mainstream long enough that all the parts are based on them. Personally, I would recommend considering a change.

Edit: David beat me to it.

[CraigS]

The info you have re; 250# spring is correct to match the Bilsteins. The 350 springs work w/ the FFR Konis although, if I had them, I would probably go to 300.

[JRD56]

Dave, Ed and Craig,
Thanks for quick reply's. This is not my first project and like the others there are always "hidden costs". Let the $pending begin. I'll likely go with Koni's to stay current.
Looks like a great forum and I'm sure I'll be using it a lot.

Jim D