This information comes directly from Matt Wiley of Race Tech on installing GVE's in the 1970-1980 BMW's, along with some info on the next generation 1981-1984's , may also be useful on the 1995 on Aircooled Twin Types.
Installed GVE's in several 77-78 RS's about 2 years ago, some worked better than others, depending on spring rate, bleed holes, etc. Holds the road better over rough surface, does not dive in corners when runnig a bit fast, or during quick stops, however, did not give me as plush a ride as I was hoping for. Will use this new info that Matt Wiley has just provided me to remedy what I did on those installs for hopefully a better result. Will be months before I get a chance to do that.
I find it worth the effort and expense though it is a slow process to go through the experimenting phase.
Safe Riding To You All.....................................George
http://www.racetech.com/page/title/Damping Rod Gallery
http://racetech.com/page/title/DRod 2-3 BMW
http://www.racetech.com/page/title/Emulators-How They Work
http://www.racetech.com/page/title/Emulator Tuning Guide
With a GVE (Gold Valve Emulator) install there can be too few holes limiting oil flow however there is no such thing as too many compression holes for GVE. As long as they are in the lower half of the damping rod there could be 6 or there could be 12. 6 is typically what we call for I run 8 on the BMW as there are 8 stock compression holes ranging between 4 & 5mm OD each. I simply drill out the existing 8 holes to 6mm (1/4?) for simplicity sake.
It is critical to remove the spring & check ball at the bottom of the rod as well as to cut off the top outlet of the rod to ensure proper oil flow to the GVE. I have found that anyone who is having harsh damping as skipped one of the 4 critical steps: #1 remove spring & check ball #2 drill out all existing compression holes to 6mm (minimum of 6 holes, I like to drill all 8) #3 cut off top rod. #4 fabricate 30-40mm adapter spacer to fit between GVE & rod top. Failure to do any one of these steps will limit oil flow & result in harshness, failure to do several of these step forks will feel terrible.
I appreciate your posting for me, the BMW airhead is a very popular model for use but does generate a lot of tech calls as the mods while not difficult are a little unique & f the installer is not experienced with fork & GVE operation they get confused. Another useful link is this one about fork & GVE operation: http://www.racetech.com/page/title/Emulators-How They Work
Here is a link to the GVE setup & tuning: http://www.racetech.com/page/title/Emulator Tuning Guide
Typically the Blue# 40 GVE spring set @ 2-4 turns is what most riders like, those looking for a really plush supple ride may prefer the Silver# 26 spring @ 3-4 turns. All Airhead riders I have worked with prefer 4 low speed bleed holes in the GVE valve plate (under colored spring). The valve plate comes with 2 holes drilled & dimples to drill out if 4 are desired (don?t bother with 3, run 2 or 4 bleeds). Running 4 bleeds makes the fork more responsive to small bumps, ripples, etc. Most small (34-38mm) forks work better with 4 bleeds.
Also note that Race Tech Fork Springs MUST be used in conjunction with GVE on BMW Air Head. Stock springs are too long & too soft, Progressive Brand springs are too long & may interfere with the GVE operation due to ID being too tight.
All the best & thank you for choosing Race Tech!
Matthew Wiley
Race Tech Suspension
1501 Pomona Road
Corona, CA 92880 USA
909-273-4985 cell#
951-279-6655 RT ext# 108
951-279-7171 Fax/Race Tech
928-532-3499 Fax/MW direct
Installed GVE's in several 77-78 RS's about 2 years ago, some worked better than others, depending on spring rate, bleed holes, etc. Holds the road better over rough surface, does not dive in corners when runnig a bit fast, or during quick stops, however, did not give me as plush a ride as I was hoping for. Will use this new info that Matt Wiley has just provided me to remedy what I did on those installs for hopefully a better result. Will be months before I get a chance to do that.
I find it worth the effort and expense though it is a slow process to go through the experimenting phase.
Safe Riding To You All.....................................George
http://www.racetech.com/page/title/Damping Rod Gallery
http://racetech.com/page/title/DRod 2-3 BMW
http://www.racetech.com/page/title/Emulators-How They Work
http://www.racetech.com/page/title/Emulator Tuning Guide
With a GVE (Gold Valve Emulator) install there can be too few holes limiting oil flow however there is no such thing as too many compression holes for GVE. As long as they are in the lower half of the damping rod there could be 6 or there could be 12. 6 is typically what we call for I run 8 on the BMW as there are 8 stock compression holes ranging between 4 & 5mm OD each. I simply drill out the existing 8 holes to 6mm (1/4?) for simplicity sake.
It is critical to remove the spring & check ball at the bottom of the rod as well as to cut off the top outlet of the rod to ensure proper oil flow to the GVE. I have found that anyone who is having harsh damping as skipped one of the 4 critical steps: #1 remove spring & check ball #2 drill out all existing compression holes to 6mm (minimum of 6 holes, I like to drill all 8) #3 cut off top rod. #4 fabricate 30-40mm adapter spacer to fit between GVE & rod top. Failure to do any one of these steps will limit oil flow & result in harshness, failure to do several of these step forks will feel terrible.
I appreciate your posting for me, the BMW airhead is a very popular model for use but does generate a lot of tech calls as the mods while not difficult are a little unique & f the installer is not experienced with fork & GVE operation they get confused. Another useful link is this one about fork & GVE operation: http://www.racetech.com/page/title/Emulators-How They Work
Here is a link to the GVE setup & tuning: http://www.racetech.com/page/title/Emulator Tuning Guide
Typically the Blue# 40 GVE spring set @ 2-4 turns is what most riders like, those looking for a really plush supple ride may prefer the Silver# 26 spring @ 3-4 turns. All Airhead riders I have worked with prefer 4 low speed bleed holes in the GVE valve plate (under colored spring). The valve plate comes with 2 holes drilled & dimples to drill out if 4 are desired (don?t bother with 3, run 2 or 4 bleeds). Running 4 bleeds makes the fork more responsive to small bumps, ripples, etc. Most small (34-38mm) forks work better with 4 bleeds.
Also note that Race Tech Fork Springs MUST be used in conjunction with GVE on BMW Air Head. Stock springs are too long & too soft, Progressive Brand springs are too long & may interfere with the GVE operation due to ID being too tight.
All the best & thank you for choosing Race Tech!
Matthew Wiley
Race Tech Suspension
1501 Pomona Road
Corona, CA 92880 USA
909-273-4985 cell#
951-279-6655 RT ext# 108
951-279-7171 Fax/Race Tech
928-532-3499 Fax/MW direct
I added a couple those links to the Resources and Links thread under Suspension.
