Results 1 to 6 of 6

Thread: Installing RaceTech cartridge emulators on an Airhead with Brembo forks

  1. #1
    Registered User Anyname's Avatar
    Join Date
    Jun 2007
    Location
    Portsmouth, NH
    Posts
    1,015

    Installing RaceTech cartridge emulators on an Airhead with Brembo forks

    Despite my initial concerns, this installation turned out to be a straight foreward. Once the bike was secured with the front wheel off of the ground, 95% of the work was standard BMW assembly/disassembly as per the Clymer manual. As anyone who has had the pleasure knows, BMW decided to hide the handlebar clamps under the top triple clamps, nicely located between the fork tubes and the steering head. A 13mm combination wrench with a ratcheting head was very helpful.

    The critical tools were:

    1) An E10-Torx (external) wrench for the fork brace. I was so surprised to see E-Torx on a 1986 bike I doubled checked thinking they might be bolts make for 12 point sockets. I already had a set of E-Tork sockets from when I owned an early R1200GS. Generally speaking, E-Torx sockets are a bit of a pain to source, especially in local stores.

    2) A 36MM wrench for the fork caps. My bike has the early Brembo forks with the somewhat simpler fork caps. I had a 36mm socket in hand but if I had my choice, I would have preferred a combination wrench. The hexagonal section of the caps is quite shallow and I had a lot of trouble keeping the socked on the cap while wrestling a handlebar less bike. The socket marked up the caps pretty badly. Fortunately they are still available and Max was able to get them for me overnight. Had I know they were going to be a pain, I would have gone straight to the air wrench with popped them off easy-peasy.

    3) A siphon tube so your gas tank won't weigh 50lbs when you remove it. It doesn't have to be removed, but your brake master cylinder doesn't have to be leak proof either.

    4) A couple of feet of twine to secure the brake calipers after they have been unbolted.

    5) A 6 MM impact 1/2" drive socket for removing the damper rods. I worried a lot about getting the allen screws/plugs out and it turned out to be pretty straight forward. I used an air impact wrench and my fancy new 1/2" drive socket on the first tube (as suggested by a couple of sources). It stripped the screw head almost instantly. I drilled the head off (it's fairly soft as allen screws go) and slipped the slider off. Surprisingly, once it was apart, I could easily remove the shank of the screw with my fingers. I expected it to be seized as it sure had been tight.

    6) A 6mm, 1/4" external drive bit. I don't know where I got this or why I had it, but finding these guys without knowing what they are called makes E-Torx look like a common item. When I finally figured out what they are called, I saw that they were available online. At any rate, I had one and used it in my carpentry style 18 volt Makita impact driver. The second fork tube's allen screw came out in a second, with no damage. If I had been desperate, I could probably ground down a 1/4 allen head bit to 6mm. There's only a few thou difference.

    Destroying the first plug wasn't a concern as I had bought a full set of plugs, washers, seals and dust covers the same day as I ordered the RaceTech parts. I bough a fancy RaceTech tool to secure the damper rod from the top of the for, but I never even unpacked it. On Racetech's advice I put the caps back on the fork tubes and let the force of the spring keep the rod from spinning.

    7) Something to seat the fork seals. Removing the seals was easy, just pad the lip of the slider so you don't ding it up with your screw driver (Note - even the BMW factory manual says to use a wide blade screw driver. Thanks to Rusty at Max for letting me read his copy) . The Clymer manual suggested a properly sized socket for installing the seals. While I was visiting Max NH, the ever helpful Rusty grabbed the factory tool, a metric digital caliper and let me measure the factory tool. I bought a piece of 2" diameter aluminum rod from Amazon ($11.00) and duplicated the factory tool on my lathe. The factory tool has an extension that slips into the fork slider so that the seal has to go in straight. It's probably overkill, but it was probably cheaper than a large socket.

    8) Drilling the damper rods (to disable the factory damping) was straightforward. The three rows of holes are 10mm apart as measured from the center of the holes. The edge of factory damper hole (8mm in diameter) is flush with step on the damper rod so it was easy to measure up 14mm for the second row (1/2 of 8mm plus 10mm) and 24mm for the third row (1/2 of 8mm plus 20mm). I strongly recommend getting a center drill for making the new holes. They are much stiffer than normal twist drills and don't tend to wander around. This is one source for center drills:

    https://littlemachineshop.com/produc...ProductID=4867

    9) A countersink to deburr the holes in the damper rod. I strongly recommend you avoid the multi-fluted counterbores you'll find in hardware stores. They chatter and make a mess. A zero flute counterbore seems to work best for metal:

    https://littlemachineshop.com/produc...ry=-1200482820

    10) Something to measure 150mm from the top of the fork tube to the top of the oil in the fork (without whatever you are using taking a dive into the fork tube, that could easily happen). It's worth noting that Racetech's documentation for the install and tuning is scattered over three documents and the fact that you measure the oil with the springs out and the forks fully compressed took some finding. I ending up talking to the very helpful Matt Wiley at RaceTech. He is the vintage bike guy and he is very willing to help.

    11) Something to cut the plastic tubing used to set the fork preload. Racetech recommends a tubing cutter or a lathe. I tried both and then settled on using a carpentry power mitre box. It was more accurate and gave a cleaner cut.

    Everything else is basic assembly/disassembly of the forks.

    I could not find a written reference to the how the emulators are set when they are shipped, but a conversation with RaceTech support indicated that they come with 40lb springs installed and the emulators set to three turns in. This appears to be their recommended default setting for most situations. The emulators do come with two other sets of springs as well.

    I should note that all of the BMW parts for a rebuild like screws/plugs, washer, seal and dust covers cost about $100 bucks in addition to the cost of the emulators ($139), springs ($119) and Oil ($20). The emulators/springs are definitely an improvement over the factory components. The ride over both small and large bumps is noticeably better. I have been gratified to notice that the behavior of the forks now appears to match the springing and damping of the fancy remote reservoir Ohlins shock on the back. I would do this installation again of I bought another airhead.
    Last edited by Anyname; 08-11-2018 at 04:45 PM.
    BMW R bike rider, horizontally opposed to everything...

  2. #2
    Good job! Let us know how it works.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '14 Street Triple R, '17 1290 GT (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

  3. #3
    Registered User Anyname's Avatar
    Join Date
    Jun 2007
    Location
    Portsmouth, NH
    Posts
    1,015
    Generally I am very pleased with the emulators and springs. My instrument cluster no longer shakes like it was trying to jump off of the bike and the ride over small bumps is very smooth. Larger bumps are also well damped. Between the emulators and the Ohlins shock on the back, the bike's suspension is better than most new bikes i have ridden.

    I used RaceTechs recommendations for the emulator settings, fork spring preload, oil viscosity and oil level. They recommendations were based on my weight and the weight of the bike. You can fiddle with the emulator settings (compression damping), fork preload and for oil viscosity and level (the amount of air left above the oil determines the fork behavior as it nears full compression). Unfortunately all of these adjustments do require pulling the caps off of the fork. Due to the design of the handle bar clamps, that's kind of a pain, so I am quite happy that the default recommendations are working well. RaceTech has a tuning guide for this emulators on their website.
    BMW R bike rider, horizontally opposed to everything...

  4. #4
    I have the RaceTech emulators and srings on my 92 RS and they are quite good. I also found their tuning advice to be spot on. Save it well because when it is time to change the fluid you are going to want to know the brand, weight, and volume per leg. Don't substitute fork oil brands from what works. One company's 10W is not necessarily the next company's 10W. Kinematic viscosity is what is important. The volume of the fill will not necessarily be the one in the BMW manual either. It is a tuning parameter. Also, the emulators take up space one taken by oil.

    https://www.peterverdone.com/wiki/in...spension_Fluid
    Lee A. Dickinson - Danielsville, GA USA
    Airheads #3480 | Iron Butt Assn. #8914
    1976 R75/6 - 1992 R100RS - 1993 K1100RS - 2013 R1200GS

  5. #5
    Registered User PAS's Avatar
    Join Date
    Jun 2011
    Location
    N.E. Ohio
    Posts
    718
    Anyname, What bike did you install them on?

  6. #6
    Registered User Anyname's Avatar
    Join Date
    Jun 2007
    Location
    Portsmouth, NH
    Posts
    1,015
    An 86 R80 monoshock with Brembo forks.
    BMW R bike rider, horizontally opposed to everything...

Similar Threads

  1. Replies: 4
    Last Post: 07-24-2018, 09:57 PM
  2. 2004K12GT high beam cartridge/holder
    By whm1226 in forum Flying Brick K-bikes
    Replies: 6
    Last Post: 08-03-2013, 09:17 PM
  3. '85 K100RT- RaceTech front springs?
    By oldnslow in forum Flying Brick K-bikes
    Replies: 4
    Last Post: 10-29-2011, 07:21 PM
  4. Race Tech Gold Valve Emulators
    By ghlubik in forum Airheads
    Replies: 6
    Last Post: 10-29-2010, 04:07 PM
  5. Brembo rebuild kit - where to buy?
    By kentuvman in forum Airheads
    Replies: 6
    Last Post: 12-14-2009, 03:11 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •