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1971 R75/5 forks

79914

New member
Can I have it all? I love the soft ride from my forks but on a panic stop the front end dive needs to go. Can I rebuild them and have both - the soft ride and minimum front end dive?
 
Do you still have the original front fork springs from '71? May be time for front fork rebuild. A relative cheap up grade is to go to BMW heavy duty fork springs in the rebuild. Another relatively cheap upgrade is to go progressive fork springs. There are a lot of specialists who do upgrades to these forks and can dial these forks in to your exact specs. Be prepared to pay the price. Good luck with your project.
 
Can I have it all? I love the soft ride from my forks but on a panic stop the front end dive needs to go. Can I rebuild them and have both - the soft ride and minimum front end dive?
I rebuilt my front forks about a year ago with the progressive springs. It feels fine to me, but I hope to not have to test them on any panic stop.

I would think progressive springs would be all you would need, as they get progressively stronger as they are compressed.

If you still have the 71 springs in there, they have to go for sure! They don't last forever.

-Don- SSF, CA
 
When doing the rebuild, braze up ONE of the rod holes in each fork side. Continue to use 4 or 5 weight fork/suspension oil.
Use the stock springs. If they are only sagged somewhat, you can make a pvc or metal spacer for the top of the spring, to set the sag you prefer.
Brazing up ONE of the rod holes on each side will still allow nice fork action without excessive stiffening.

BTW....You can control the fork performance in both directions, depending on what you need/want.
Note that I think that these older forks are much better than the ones on the early eighties bikes; quieter, better ride, over both large and tiny bumps....and are better on washboards too.

Note that BMW offers a higher damping performance ring for the forks. Usually called something like: 'ring, more stringent' in the fiche.
If you go any further, you will start loosing the small bumps suppleness. The one exception, IMO, are the springs. I think the stock ones should be tried first, but shim them if you need to set the sag, by adding a spacer at the top.

Be sure that you remove as much stiction from the forks as possible...test method on my site, and it is very simple to do. If the stiction is high due to misalignment, the forks just not perform well. The /5 forks are quite capable of handling small road imperfections such as tar snake rises; and, rather large bumps, but stiction makes things much less so, and I've seen fender and fork braces destroy the nice stock handling, because they were not set up correctly. Shimming or bending of braces/mounts may be needed.

There were plenty of things tried years ago on, it seems, every model of Airhead from 1970 to 1995.... to """improve""" the forks. Stiffer springs, added bottom springs, cartridge inserts, different weights of oil, true progressive springs, etc. Most of these things have drawbacks, and you might not like them, and best to start simple.

A solid understanding of how the forks actually work internally, is a good idea, in particular the details on compression and rebound.

snowbum
 
forgot two things:

1. If you are a heavy guy, you may need to replace the springs with stronger ones.
2. You can eliminate only so much dive. A bottoming spring may be the simplest thing; as you get SOME dive, and then the forks stiffen, fast.
 
Snowbum what is the maximum length of preload spacer one can use without coilbind ?

BTW Thank You for your shared wealth of knowledge !
 
maximum length of preload spacer? Haven't the foggiest idea. I've used to a couple of inches, as I remember
'bum
 
I used RaceTech springs with good results on my /6. They make them in different rates for your weight and they are straight wound rather than progressive (like the Progressive springs [duh]). I prefer them as with progressive springs you get an initial dive on braking and then they go stiff. They will provide a stiffer ride over the small bumps though. Depends on what suits you.
 
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