Topic: Recommended Fork Tube Length and Mods to GL1000 fork swapped onto CB750

[SOHC4 Cafe Racer Fan]

Since so many members have swapped a GL1000 front onto their CB750 projects, I wanted some advice on replacing/upgrading parts:

(1) My GL1000 fork tubes are pitted.  What size replacement tubes are recommended (-2")?  [And Sources]

(2) Any particular internal upgrades (specific model progressive springs and/or Racetech valve cartridge emulators versus others)? 

[Pecantree]

Source Franks Forks
http://www.frankmain.qpg.com/

[SOHC4 Cafe Racer Fan]

I'm figuring there are plenty of sources for fork tubes between Frank's, Cycle X, Racetech, etc. I'm more curious about recommendations on the length of the replacement tubes since the GL tubes are longer than the CB tubes.

[MJL]

Franks will make them to any length you want.

[azuredesign]

I wonder how many folks have done this mod.

I am still getting my front end set up, so can only say that I built my forks with Racetech emulators and springs. I have one billet upper tree and one modified stock GL upper tree, and the stock lower one. Not sure which one will work out yet. Although I do not know for sure, it looks like the gl inner tubes are ~1.5 inches longer than the cb ones.

I am modifying the lip on the head tube so that the steering stops on the lower GL tree will actually contact the lip.

Using stock calipers, stainless lines, and a 2005 GSXR front brake master and lever. This allows me to use the brake light switch in the master, run 2 almost same length lines from the master and not have to use a junction for the in-line switch.

[SOHC4 Cafe Racer Fan]

I wonder how many folks have done this mod.

I am still getting my front end set up, so can only say that I built my forks with Racetech emulators and springs. I have one billet upper tree and one modified stock GL upper tree, and the stock lower one. Not sure which one will work out yet. Although I do not know for sure, it looks like the gl inner tubes are ~1.5 inches longer than the cb ones.

I am modifying the lip on the head tube so that the steering stops on the lower GL tree will actually contact the lip.

Using stock calipers, stainless lines, and a 2005 GSXR front brake master and lever. This allows me to use the brake light switch in the master, run 2 almost same length lines from the master and not have to use a junction for the in-line switch.

Thanks, Azuredesign.

Is the billet top triple clamp from DCC or someone else?

[KRONUS0100]

running a 76 gl1000 front end with used valve springs as spring spacers.  using aftermarket ebay master with braided lines to each caliper.  brake switch is in master itself.  running the stock 78 cb750f front brakes fitted to an 82 KZ750 enkei wheel.
i dropped the triples down 3/4 inch on the top tubes to level the bike out a bit
all balls tapered bearing kit for the headstock.

[azuredesign]

Thanks, Azuredesign.

Is the billet top triple clamp from DCC or someone else?

Hi, yes from DCC. I also purchased fork ears from them. Very nice folks they turned aluminum spacers for the ears for me gratis.

[azuredesign]

Here is a photo of my 73 cb with the GL 1000 front end. I think the front end length is about right as far as attitude between front and rear end, although maybe it could come down a small bit? I am using  18 ” front and rear wheels. With the stock tree in place I have 33 mm of clearance above the top tree. Using the Dime City slab tree there is about 8mm because the stock tree fork clamps are about 25mm lower than the head tube clamp height.

Hope this helps!

[SOHC4 Cafe Racer Fan]

Thanks Azure.  I sprung for the DCC top triple clamp (with gauge mounts and key mount).  Should arrive tomorrow or so.  I'm also switching from Tommaselli adjustable clubman bars to Tarozzi high-rise clip-ons. 

[azuredesign]

I also purchased the Tarozzi bars, but in low rise.

I will make a decision concerning which bars/ tree to use when I mount the bars, but may use the Dime city tree with some handlebar mounts, perhaps Betors, and conventional bars.

[SOHC4 Cafe Racer Fan]

My original fixed position clubmans were at a pretty severe angle that would have been slightly painful for any extended ride.  I like the Tarozzi clip-ons because you can adjust the downward angle to even a flat position.  The high-rise will give me a little more room to play with angle and to help clear the tank.

[azuredesign]

  I like the Tarozzi clip-ons because you can adjust the downward angle to even a flat position.  The high-rise will give me a little more room to play with angle and to help clear the tank.

I am thinking I might even rotate them so that the riser is on the inside of the fork legs or closer to me. They do offer a lot of flexibility, the trade off is whether a single bolt is enough.
What are you doing for steering stops?

[SOHC4 Cafe Racer Fan]

I will likely need to weld on an extension to the stock stop.

[azuredesign]

I will likely need to weld on an extension to the stock stop.

The trick is that one cannot determine where the stops should be without installing bearings and bars, along with at least inner fork legs to keep the trees parallel. Once the lower bearing is installed, I would be concerned about adding material to the lower tree stops as the heat may deform the bearing, as well as melt the lower rubber seal under the bearing. I have decided to modify the headtube flange mechanically by adding a 5mm thick piece of aluminum to the existing flange. I have made the extension, but need to wait for my bars before I will know if it is adequate before installing. I will post a photo once finished.

[Pecantree]

I'm figuring there are plenty of sources for fork tubes between Frank's, Cycle X, Racetech, etc. I'm more curious about recommendations on the length of the replacement tubes since the GL tubes are longer than the CB tubes.

Bringing this thread back up.
Curious what you decided to use for fork tubes and springs.
Did you spring for shorter tubes?

[SOHC4 Cafe Racer Fan]

I ended up doing 1.125" shorter than stock tubes from Forking by Frank, and the Dime City Cylces billet triple tree on top.

[SOHC4 Cafe Racer Fan]

I'm figuring there are plenty of sources for fork tubes between Frank's, Cycle X, Racetech, etc. I'm more curious about recommendations on the length of the replacement tubes since the GL tubes are longer than the CB tubes.

Bringing this thread back up.
Curious what you decided to use for fork tubes and springs.
Did you spring for shorter tubes?

In addition, I have Race Tech gold valve emulators and springs.  I have asked Rob aka Voxonda for a pair of his preload adjusters to replace the stock fork caps.