Author Topic: GL1000 front end swap (Read 5645 times)

oldfett · « **on:** October 14, 2009, 08:44:38 AM »

hey all,

I've been researching the gl1000 front end swap for awhile now but have a quick question. Do the gl1000 and CB750k share the same front hub? I assume not but if they do its one less piece I have to purchase and fix up.

Thanks!

JS550 · « **Reply #1 on:** October 14, 2009, 08:54:01 AM »

I just did the steering bearings for this swap. I dont think they are the same. The 750 is a narrower axle so I would think the hub is too. Double check that though. ( might check to see if "narrower" is a real word also?)

fishhead · « **Reply #2 on:** October 14, 2009, 08:58:31 AM »

The 75-77 GL share the same hub as the CB 750 K (6 bolt brake discs). The wheel can be swapped from one to the other. Axle, axle spacers, discs, speedo drive and drive plate are specific to the 75-77 GL and would be needed.

The 78-79 GL use the Comstars and 5 bolt brake discs and different calipers. The 78-79 speedo drive is also moved the the left hand side.

The steering bearings for the CB 750 are the same ones you would use for the GL swap.

754 · « **Reply #3 on:** October 14, 2009, 09:22:17 AM »

When you say the discs are different, how so?
I have a dual disc wheel here with a DiD rim, and I have noticed that the discs look like 750 discs, same size (I think) but the middles are different the shpe of the metal on the spokes of the aluminum carrier are different than on a 750..

HMMMM, maybe it is a GL wheel, not a 750 dual disc converted.. rim is runnable but rough on the edges..

fishhead · « **Reply #4 on:** October 14, 2009, 09:31:11 AM »

Quote from: 754 on October 14, 2009, 09:22:17 AM

When you say the discs are different, how so?
I have a dual disc wheel here with a DiD rim, and I have noticed that the discs look like 750 discs, same size (I think) but the middles are different the shpe of the metal on the spokes of the aluminum carrier are different than on a 750..

HMMMM, maybe it is a GL wheel, not a 750 dual disc converted.. rim is runnable but rough on the edges..

The 750 K has larger diameter discs and the 75-77 GL has smaller discs with more offset than the K.

754 · « **Reply #5 on:** October 14, 2009, 09:37:31 AM »

Ah, I will go check and measure today..

MJL · « **Reply #6 on:** October 14, 2009, 11:24:22 AM »

When I did my swap I used the 750 wheel (hub rim spokes) with the GL discs and speedo drive. In other words, everything GL swapped onto the 750 wheel and bolted right up, no special parts.

greasy j · « **Reply #7 on:** October 14, 2009, 12:25:34 PM »

the GL wheel is aluminum, so if you have both it seems like that would be the better bet. why would you use the 750 wheel? unless your GW wheel isn't spoked.

just wondering cuz I'm dealin with the same issues.

oldfett · « **Reply #8 on:** October 14, 2009, 04:01:41 PM »

Quote from: greasy j on October 14, 2009, 12:25:34 PM

the GL wheel is aluminum, so if you have both it seems like that would be the better bet. why would you use the 750 wheel? unless your GW wheel isn't spoked.

just wondering cuz I'm dealin with the same issues.

I was wondering about the hub not the wheel. Heck yes the wheel is worth buying! But if I was Honda I would have tried to use the same parts across a few bikes to save on the bottom line. I was just wondering if the hubs were identical or not.

Thanks for the help everyone! That should shave a little money off of my purchase as well as many hours of polishing!

fishhead · « **Reply #9 on:** October 14, 2009, 04:35:35 PM »

Quote from: JS550 on October 14, 2009, 08:54:01 AM

might check to see if "narrower" is a real word also?

I think "more narrow" might be appropriate-er

JS550 · « **Reply #10 on:** October 14, 2009, 04:49:19 PM »

Got my front end on! Glad to hear about the wheel. I just swapped the GL rotors & axle onto the 750 stuff for fitment. Now I can rebuild the aluminum GL wheel over the winter. Thanks again Fishhead.

754 · « **Reply #11 on:** October 14, 2009, 06:53:12 PM »

Looks like I may have GL rotors FOR SALE.. I am thinking speedo drive , should be good for cb750 dual disc conversion.

Discs are smaller and have more offset .. 138mm or 5 .44 across the Outside of the discs on the wheel.

MJL · « **Reply #12 on:** October 14, 2009, 06:55:18 PM »

Quote from: greasy j on October 14, 2009, 12:25:34 PM

the GL wheel is aluminum, so if you have both it seems like that would be the better bet. why would you use the 750 wheel? unless your GW wheel isn't spoked.

just wondering cuz I'm dealin with the same issues.

It matched my rear wheel, and it had a new tire and tube on it.

GoatBaSS · « **Reply #13 on:** October 14, 2009, 07:55:10 PM »

Quote from: 754 on October 14, 2009, 06:53:12 PM

Looks like I may have GL rotors FOR SALE.. I am thinking speedo drive , should be good for cb750 dual disc conversion.

Discs are smaller and have more offset .. 138mm or 5 .44 across the Outside of the discs on the wheel.

What I was going to point out.....

It was the off set bear that came out of the woods......

fishhead · « **Reply #14 on:** October 15, 2009, 04:41:22 AM »

Quote from: 754 on October 14, 2009, 06:53:12 PM

Looks like I may have GL rotors FOR SALE.. I am thinking speedo drive , should be good for cb750 dual disc conversion.

Discs are smaller and have more offset .. 138mm or 5 .44 across the Outside of the discs on the wheel.

No, The GL speedo drive wont fit the SOHC forks. The GL speedo drive is about 3mm(ish) wider than the CB speedo drive.

JS550 · « **Reply #15 on:** October 15, 2009, 04:57:34 AM »

After reading this, I happened to be doing a GL front on my 750 on the same day, I swapped the discs,axle & speedo drive from my 77 GL rim to my 75 750 rim. It went onto the GL fork with out a hitch. So I would say yes they are identical hubs. Now for the relace on the GL wheel!

754 · « **Reply #16 on:** October 15, 2009, 07:55:36 AM »

Sorry about being unclear, what I meant was the speedo drive plate and cover looks like it may already be modded to fit the the 750 speedo drive and the 2nd disc.
I think them GL rotors are thinner than the 750 ones by a mm or so..

fishhead · « **Reply #17 on:** October 15, 2009, 08:35:12 AM »

Quote from: 754 on October 15, 2009, 07:55:36 AM

Sorry about being unclear, what I meant was the speedo drive plate and cover looks like it may already be modded to fit the the 750 speedo drive and the 2nd disc.
I think them GL rotors are thinner than the 750 ones by a mm or so..

Oh, OK, Just to clarify matters, Heres a pic of the different speedo drives and plates. I've posted it before, but I can't find it now.

Left to right
1st row = CB speedo and drives (single disc)
2nd row = CB 750 Sandcast drive plates
3rd row = 75-77 GL speedo drives and plates
4th row = converted single drive plates to dual (like the sandcast style)

The CB speedo drive has a square end to it and the 75-77 GL has the round end to it.

The chrome covers are shown for the drives and plates they are used on (1st row top shows a modified single cover for the dual disc).

IIRC, the CB 550 discs are close to the same outer diameter as the 75-77 GL discs, but have less off set than the GL discs. I dont know why you would have GL discs with a CB speedo drive on the same wheel (unless the speedo drive has been shimmed to fit the GL forks).

754 · « **Reply #18 on:** October 18, 2009, 11:04:06 AM »

Checked the discs and they are about 3/4 mm THINNER on the GL brakes plus added offset..
Might be worth using if you want to put a rear disc on a 6 bolt wheel.

greasy j · « **Reply #19 on:** October 18, 2009, 11:26:50 AM »

Quote from: 754 on October 18, 2009, 11:04:06 AM

Checked the discs and they are about 3/4 mm THINNER on the GL brakes plus added offset..
Might be worth using if you want to put a rear disc on a 6 bolt wheel.

would that work? are you talking about
homemade rear disc brakes?

fishhead · « **Reply #20 on:** October 18, 2009, 12:12:10 PM »

Quote from: greasy j on October 18, 2009, 11:26:50 AM

Quote from: 754 on October 18, 2009, 11:04:06 AM
Checked the discs and they are about 3/4 mm THINNER on the GL brakes plus added offset..
Might be worth using if you want to put a rear disc on a 6 bolt wheel.

would that work? are you talking about
homemade rear disc brakes?

Not easily. The CB rear disc wheel uses a larger disc (specifically, the mounting hole in the middle and the bolt mounting pattern). I have converted a front hub to rear use (click here for a few pics) -

http://fishheadbigbrakes.com/Otherbrakes.html

and I have converted a GL 1000 rear disc brake to a "Fishhead" by using a newer disc, disc adaptor and caliper,etc. (The GL rear disc is very simular to the CB rear disc - I think they might even be the same)

Fishhead

greasy j · « **Reply #21 on:** October 18, 2009, 12:24:26 PM »

the front hub used as a rear wheel with disc on the 74 cb is super slick!

nice work.

I feel like I don't use the rear brake enough to justify the expense of converting to disc. I figure if I'm going to have the dual disc big brake set up in front I should have all the braking I need. will still have the drum rear for mild braking.

754 · « **Reply #22 on:** October 18, 2009, 12:39:19 PM »

The 750 front hub will work but needs spacers on at least one side.

Way back, C&G I think made a hub that looked like the 750 front but longer on the sprocket side.. would be pretty quick to make out of billet , but I think I would widen the flanges (ie spokes firther apart at the hub)

Another wheel we needed discs for was a Morris wheel as it came with the 6 hole pattern. I think if you are building a rear disc, the smaller diameter looks better, see how small, new bike run!
Anyway just threw it out there if someone is trying to convert to disc using honda front, morris, or Yamaha mags.. I suppose Ducati wheels would work , but are probably pricey..

MJL · « **Reply #23 on:** October 18, 2009, 04:16:07 PM »

Quote from: fishhead on October 15, 2009, 08:35:12 AM

Quote from: 754 on October 15, 2009, 07:55:36 AM
Sorry about being unclear, what I meant was the speedo drive plate and cover looks like it may already be modded to fit the the 750 speedo drive and the 2nd disc.
I think them GL rotors are thinner than the 750 ones by a mm or so..

Oh, OK, Just to clarify matters, Heres a pic of the different speedo drives and plates. I've posted it before, but I can't find it now.

Left to right
1st row = CB speedo and drives (single disc)
2nd row = CB 750 Sandcast drive plates
3rd row = 75-77 GL speedo drives and plates
4th row = converted single drive plates to dual (like the sandcast style)

The CB speedo drive has a square end to it and the 75-77 GL has the round end to it.

The chrome covers are shown for the drives and plates they are used on (1st row top shows a modified single cover for the dual disc).

IIRC, the CB 550 discs are close to the same outer diameter as the 75-77 GL discs, but have less off set than the GL discs. I dont know why you would have GL discs with a CB speedo drive on the same wheel (unless the speedo drive has been shimmed to fit the GL forks).

What is hard to see in this picture and not mentioned is that the GL speedo drive is angled outward to clear the 2nd disk, and the 750 speedo drive is not. Once you have the two in front of you it is apparent that the 750 unit will rub on the disk.

754 · « **Reply #24 on:** October 18, 2009, 09:52:30 PM »

I was actually meaning to use theGL speedo drive plate, and chome cover on a CB 750 stock fork leg dual conversion. (to save modding one). I checked, looks like it fits although the part that fits into the Speedodrive housing, is designed differently.. That is to say it is THINNER between the end of the driveplate and the portion where the drive housing seal area sits on it.. now I looked at the750 drive plates and it appears they run on the dry side as the seals seem to eat into the steel portion. It seems to me that the relieved portion of the GL drive, promotes grease flow to the seal area.... worth looking at..

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Author Topic: GL1000 front end swap (Read 5645 times)