What a great resource this man has taken the time to provide us all with. Having just bought my first ever BMW motorcycle, a 1981 R100RS I cannot express how please I was to find this channel. Thankyou 👍
Excellent explanations as ever Brook. I’m impressed at how thorough you are in preparation of work, I wish I had your level of patience, oh and such a well equipped workshop. Its going to be great to see the final results on this rebuild, but that said it will be a pity to see the project come to an end, the regular video’s are an inspiration!
Do you have previous experience with RaceTech emulators and their single rate springs? I would be interested to learn what you think if that is the case. Things like static sag, ready-to-ride sag and comfort compared to stock. Thank you. Eirik
Looking for any feedback after riding with the Race tech setup? Looking to do the same and curious if it’s worth it? Great videos! Thank you very much.
Shadowrayray, The low speed (small bumps) performance is much improved. I had to reduce the compression damping (lighter weight fork oil) and rebound damping (internal spring on the cartridge) to make the high speed (sharp bumps and potholes) a bit less harsh from the original RaceTech recommendation.
IT seems You need an adjustable Cap Bolt. If you ride with a full tank bag and a full tank of gas one day then no tank bag and a half a tank of gas the next you are going to need a different preload. If you are going to the trouble to change the forks would it be nice to be able to make adjustments to it. If you could make up a cam like on rear shocks then you would have something nice. How much fork travel do you loose with this kit and will it give a harder ride?
Hi Alan, The damper rod travel is the same since the cartridge emulator fits on top of the damper rod so it does not limit the damper rod and fork slider travel. As to adjustment, the original forks, preload adjustment was done the same way with a spacer on the spring, so nothing is lost in that department. However, having three damping circuits in the fork, one of which is adjustable, instead of only two circuits, not adjustable, in theory provides a better ride. It makes sense to me that a separate low speed compression damping and high speed compression damping circuit can improve fork compliance compared to a damper rod design that only has a single compression damping circuit. Damping rod compression damping it's always a compromise between smooth small bump (low velocity) compression and smooth sharp bump (high velocity) compression. Anyway, it's done now, so I'll have to wait to see how it handles and feels after I get the bike back on the road.
so you use both racetech valves? one on each leg? when I did this to my r100gs I only needed one because the other side does the rebound. when you modify these does the rebound dampening change? looking to do this to my 84 RS
Hi dsruddell, The fork design on the GS is different from the RS/RT design with only one leg having a damper rod. The RS/RT are symmetric with a damper rod in each leg.
I just drilled out my damper rod and am ready to measure for length of spacer needed for pre-load. I have a clarifying question for you. When you hold the fork tube upright and drop in the emulator spacer, emulator, two washers and fork spring to measure the depth to the spring top, the damper has to extend and slide out the bottom, correct?
@@BrooksAirheadGarage Thank you. Your how-to video is excellent. Too bad RaceTechs instructions aren’t. A couple of differences as regards my K100RS, but really due to your type of damper and fork tube cap. It applies otherwise.
Just wondering why you used the plastic spacers from the OEM fork springs? I am about to do this upgrade to my 1985 K100RS and RaceTech told me to not use them. The OEM springs need them to sit flat but the RaceTech springs are ground flat and do not need them to sit flat in the tube.
Tom, the spacers (white plastic PVC) are not from the original springs. I cut them from the piece Race Tech provided using their formula for spring pre-load for the length. A K bike suspension is not the same as an airhead suspension, so the parts and procedure provided by Race Tech differ.
@@BrooksAirheadGarage Hi. I'm not talking about the PVC we are given in the kit to cut for pre-load, but the plastic end caps that twist onto either end of the OEM springs. You've twisted them onto the RaceTech springs but they actually don't fit properly because the RaceTech springs are ground flat and sit flat naturally in the tube, unlike the OEM BMW ones. Tyler at RaceTech told me to not use them. I don't see it as an issue, necessarily, as the only thing it changes is the overall spring length and therefore the length of PVC required for preload.
I’m having some difficulty here brook I tried taking my thread piece at the end of the absorber off and completely destroyed it. Do you know a place I can get a replacement part for it?
If you mean part# 31 42 1 232 054, any BMW motorcycle dealer can sell you one. In fact, just about any parts for these bikes are available at the BMW dealer.
Brook's Airhead Garage not that exact part but that’s the piece of aluminum thread stopper I’m talking about. It has a nylon strip to seal the dampening in the fork tubes.
@@BrooksAirheadGarage you did an amazing job. It’s just ironic that it came to that length. Just curious. Do you believe the pvc pipe in forks will deteriorate over time?
Hi Sssthpok, Well I held the bottom spacer on the damping rod that way to avoid putting grooves in the spacer since it slides inside the fork tube and I didn't cut a lot of serrations in it. I caught the edge on one of the vice grip serrations so it didn't end up scoring the OD of the spacer.
What a great resource this man has taken the time to provide us all with. Having just bought my first ever BMW motorcycle, a 1981 R100RS I cannot express how please I was to find this channel. Thankyou 👍
Excellent explanations as ever Brook. I’m impressed at how thorough you are in preparation of work, I wish I had your level of patience, oh and such a well equipped workshop. Its going to be great to see the final results on this rebuild, but that said it will be a pity to see the project come to an end, the regular video’s are an inspiration!
Excellent explanation of a very “steppy” process Brook. Well done, as always.
Thanks Peter. This one took a lot of time to shoot and edit.
Run some 400 grid paper cross wise to remove those straight scratches. That would be like crosshatch on cylinders and help lube the seals.
Do you have previous experience with RaceTech emulators and their single rate springs? I would be interested to learn what you think if that is the case. Things like static sag, ready-to-ride sag and comfort compared to stock. Thank you. Eirik
Looking for any feedback after riding with the Race tech setup? Looking to do the same and curious if it’s worth it? Great videos! Thank you very much.
Shadowrayray, The low speed (small bumps) performance is much improved. I had to reduce the compression damping (lighter weight fork oil) and rebound damping (internal spring on the cartridge) to make the high speed (sharp bumps and potholes) a bit less harsh from the original RaceTech recommendation.
Hi Brook, thank you very useful!
Did you have to heat the rood to take out to bottom support?
No I did not need to heat anything. That said, I do heat the fork slider when I remove the old fork seals.
IT seems You need an adjustable Cap Bolt. If you ride with a full tank bag and a full tank of gas one day then no tank bag and a half a tank of gas the next you are going to need a different preload. If you are going to the trouble to change the forks would it be nice to be able to make adjustments to it. If you could make up a cam like on rear shocks then you would have something nice. How much fork travel do you loose with this kit and will it give a harder ride?
Hi Alan,
The damper rod travel is the same since the cartridge emulator fits on top of the damper rod so it does not limit the damper rod and fork slider travel.
As to adjustment, the original forks, preload adjustment was done the same way with a spacer on the spring, so nothing is lost in that department. However, having three damping circuits in the fork, one of which is adjustable, instead of only two circuits, not adjustable, in theory provides a better ride.
It makes sense to me that a separate low speed compression damping and high speed compression damping circuit can improve fork compliance compared to a damper rod design that only has a single compression damping circuit. Damping rod compression damping it's always a compromise between smooth small bump (low velocity) compression and smooth sharp bump (high velocity) compression.
Anyway, it's done now, so I'll have to wait to see how it handles and feels after I get the bike back on the road.
The other key thing is that these things aren’t THAT sensitive. Adding 15-20 lb to a 500 lb motorcycle and a 200 lb rider simply isn’t a big deal.
so you use both racetech valves? one on each leg? when I did this to my r100gs I only needed one because the other side does the rebound. when you modify these does the rebound dampening change? looking to do this to my 84 RS
Hi dsruddell, The fork design on the GS is different from the RS/RT design with only one leg having a damper rod. The RS/RT are symmetric with a damper rod in each leg.
I just drilled out my damper rod and am ready to measure for length of spacer needed for pre-load. I have a clarifying question for you. When you hold the fork tube upright and drop in the emulator spacer, emulator, two washers and fork spring to measure the depth to the spring top, the damper has to extend and slide out the bottom, correct?
Hi Tom. Yes.
@@BrooksAirheadGarage Thank you. Your how-to video is excellent. Too bad RaceTechs instructions aren’t. A couple of differences as regards my K100RS, but really due to your type of damper and fork tube cap. It applies otherwise.
Just wondering why you used the plastic spacers from the OEM fork springs? I am about to do this upgrade to my 1985 K100RS and RaceTech told me to not use them. The OEM springs need them to sit flat but the RaceTech springs are ground flat and do not need them to sit flat in the tube.
Tom, the spacers (white plastic PVC) are not from the original springs. I cut them from the piece Race Tech provided using their formula for spring pre-load for the length. A K bike suspension is not the same as an airhead suspension, so the parts and procedure provided by Race Tech differ.
@@BrooksAirheadGarage Hi. I'm not talking about the PVC we are given in the kit to cut for pre-load, but the plastic end caps that twist onto either end of the OEM springs. You've twisted them onto the RaceTech springs but they actually don't fit properly because the RaceTech springs are ground flat and sit flat naturally in the tube, unlike the OEM BMW ones. Tyler at RaceTech told me to not use them. I don't see it as an issue, necessarily, as the only thing it changes is the overall spring length and therefore the length of PVC required for preload.
I’m having some difficulty here brook I tried taking my thread piece at the end of the absorber off and completely destroyed it. Do you know a place I can get a replacement part for it?
If you mean part# 31 42 1 232 054, any BMW motorcycle dealer can sell you one. In fact, just about any parts for these bikes are available at the BMW dealer.
Brook's Airhead Garage not that exact part but that’s the piece of aluminum thread stopper I’m talking about. It has a nylon strip to seal the dampening in the fork tubes.
Why not just the pvc spacers until they are flush with the fork tube?
Lou, I just followed the instructions RaceTech provided for how to determine the length of PVC to get the recommended front suspension sag.
@@BrooksAirheadGarage you did an amazing job. It’s just ironic that it came to that length. Just curious. Do you believe the pvc pipe in forks will deteriorate over time?
@@louprimo6062 I've used them in other bikes to set the sag for over 30 years and no detectable damage occurred.
IIWY, I would turn the vice grips 90 degrees on the work so the jaw serrations run across the direction of rotation..... just sayin'
Hi Sssthpok, Well I held the bottom spacer on the damping rod that way to avoid putting grooves in the spacer since it slides inside the fork tube and I didn't cut a lot of serrations in it. I caught the edge on one of the vice grip serrations so it didn't end up scoring the OD of the spacer.