Spring rates

[MartinClan]

I have found the formula to calculate spring rates. Using it it seems my front springs supplied by Marlin are about 270lb/ft. The rears - which I had made are more like 430 lb/ft - it confirms my suspicion that they are too hard. I have put the formula in a spreadsheet if anyone wants a copy!

So what is everyone else doing about their rear springs?

[Patrick]

Yes please can you send me a copy of the spreadsheet!

I have two options right now:

1) custom made spring

2) rear coil over conversion (not sure the strut towers are strong enough for this without addition modification)

I'm keep the AVO road sport spring on there for now - probably until I've sorted the bodywork so I can see how everything sits.

[Patrick]

Thanks Robin got your email

[Alfie]

Haven't really thought about this yet although I know I can't ignore it forever. Still sitting high on originals at the moment. Just concentrating on getting the thing up and running. Once I'm happy that it's actually going to work, , then I'll invest money in suspension. So, sorry, don't have much to offer in the way of help.

Alfie.

[GreatOldOne]

Well - Marlin say collapse a coil on the standard spring, but no-one seems confident enough to do this. Would Marlin do it for you, if you sent them the springs? They must have done it loads of times for turnkey cars they've built for customers.

Even if they charge you for it, it's probably worth it as you'll have the right height and spring rate then. I can't see why they'd say no... They modify the front struts for you anyway...

Just an idea.

[Patrick]

Its not so much confident, but safety - not sure I would be happy driving around on collapsed or cut springs.

[MartinClan]

What we need is a survey of sucesfully completed BMW Sportster builds to ask what other builders have done - anyone???

Robin

[Patrick]

I've put a post on the owners club forum as it might attract more attention there.