Help identify fork springs?

[Allred]

In addressing some of the maintenance ills on my new-to-me 1983 R65, I noted that the fork springs are different than I have seen in BMW's before.  While they are the correct length (19.5" un-compressed) they are tightly wound at both top and bottom, such that the first inch of length, top and bottom, there is absolutely no space between the coils.  So, all spring action is happening in the center 17" or so of the spring.  Also, at the bottom of each spring, there is an orange paint mark about 1/2" long.

There were no spacers snstalled top or bottom, no spring caps, etc.   I refilled the forks with BMW 10 wt synthetic oil to the proper level, but I think the bike's ride is still quite stiff.  Could these be Heavy Duty Springs?  What should a stock BMW R65 spring look like?  Should there be spacers instlled.  Note, this is a standard model, not an LS.


Thanks in advance  

[Justin B.]

I don't believe factory used any spacers.  Are the coils progressively wound or do the coils have the same distance between them once they get started?  Maybe you could try using a bit lighter fork oil, maybe 7.5W.

[Barry]

Allred

My springs (which I think are stock) are like yours including the paint mark.  They should be progressively wound both ends and have a wire diameter of 4.25mm.  They are stiffer than earlier airheads which used 4.00mm wire and were longer (more coils of thinner wire = a  lower spring rate). Best thing to do is measure your sag. If you don't have enough sag then maybe stiffer springs have been fitted.

[Allred]

Thanks for the response, Barry.  The local BMW shop thinks maybe a spring like I described, and you apparantly have in your bike, is aftermarket, but maybe not.
I did not think to measure the thickness of the coils, but next time they're out I will.

Interesting, to be sure.  Do you know of any internet available information to help identify BMW springs?

Thanks again

[Barry]

To be honest I only assumed my springs were original. The bike had only done 6200 miles when I got it and seemed to be 100% original down to the last nut and bolt. I don't think the forks had ever been stripped before because  I found that it had the early type of damper valve body which hadn't been replaced or even shimmed to cure the clonk which I understand was quite common on the very first bikes.

The link below has lots of information on most airhead springs but not so much on our model. Your spring length is spot on though.

http://mysite.verizon.net/vze4dp63/bmwmotorcycleparts/forks1.html

[Chris_in_BC]

. I don't think the forks had ever been stripped before because  I found that it had the early type of damper valve body which hadn't been replaced or even shimmed to cure the clonk which I understand was quite common on the very first bikes.

Barry,
Do you have any link to further information on early damper valve bodies (compared to later) and the shimming you mentioned?

Cheers,
Chris

[Barry]

Chris

There is some good information in the BMW club journals. You can down load them as pdf files from the link below. You need April 1982 and Feb 1991. The various online parts fiches diagrams will show the old and new valve bodies and some US suppliers still stock the shims. Of course the diagrams are not very clear and there is no substitute for having the parts in your hand to understand how the damper valve works and why it might be noisy. I wish I could buy shims in the UK. I made my own which are less than perfect. I'm going to have another go as I've made some nylon valve washers to replace the steel ones. So my forks will be stripped again soon.


http://www.bmw-club.org.uk/~archives/1980s.htm

[Allred]

Barry,

Thanks for the reference to the two archived articles from GB BMW Club.  I found them to be very informative.  I must say I admire the organization that has produced, and preserved such useful information!

[Chris_in_BC]

Thanks Barry,

 Great link with lots of info.

Cheers,
Chris

[tagordon]

The stock springs, I have read, are not flat on the ends.
There is a small part on the end, listed as the absorbing piece, that the spring will chew up.
Thus if its flat on the ends then after market, if it ends bluntly with a radial cut of the spring wire then its stock.
I checked the progressive springs I have wait to install & they are flat on the ends.
Have not removed my stockers yet.
Just my two cents worth on the subject.
Troy

[Allred]

The stock springs, I have read, are not flat on the ends.
There is a small part on the end, listed as the absorbing piece, that the spring will chew up.
Thus if its flat on the ends then after market, if it ends bluntly with a radial cut of the spring wire then its stock.
I checked the progressive springs I have wait to install & they are flat on the ends.
Have not removed my stockers yet.
Just my two cents worth on the subject.
Troy

I had just about concluded that my springs are stock, but Troy's post makes me think otherwise.  They are definetly ground flat on both ends, and there is no other small part.  Got vacation coming up for the rest of this week, but next week, I think I'll pull a spring out, clean it, measure the coil diameter, photograph it, and post a photo and better description.  Until then, thanks for the continuing feedback.