Author Topic: gl1000 front on cb (Read 11026 times)

robe0531 · « **on:** March 21, 2009, 04:47:05 PM »

does anyone know if a gl1000 front end fit on a 1978 cb750k i heard it does but i am not 100% sure if the info i was given
was correct
thanks for any help

Ecosse · « **Reply #1 on:** March 21, 2009, 05:04:40 PM »

I'm curious too. The tubes are 35mm I think but wonder about the triple clamp offset and bearing concerns.

Brakes I think are better designed. Good luck with the project.

MCRider · « **Reply #2 on:** March 21, 2009, 05:38:09 PM »

Quote from: Ecosse on March 21, 2009, 05:04:40 PM

I'm curious too. The tubes are 35mm I think but wonder about the triple clamp offset and bearing concerns.

Brakes I think are better designed. Good luck with the project.

I'm curious too. There are many threads here on the subject, but sometimes hard to find.

I know a little I've gathered. I'm pretty sure two of the advantages are the tubes are 37mm making for a stouter fork, but still eligible for Vintage Racing classes. But that means you have to use the GL triple trees, top and bottom, which means you have to do something about your instruments.

The second advantage is the dual disc setup. Ready to go and better pieces than a homemade CB750 conversion. But something has to be done about the wheel. I think you can use the trees/forks and the CB750 wheel, with CB750 brakes, (that can't be right?), or, the full GL swap.

Fianlly i think there is something about the first 2 maybe 3 years of the GL model is the setup to use. 75/76 i think. Later than that there are issues.

Hoipefully this will bring someone who knows into the discussion. With a link to prior threads maybe.

here's a short thread: http://forums.sohc4.net/index.php?topic=45405.0

Here's a longer thread, unfortunately pictures are missing. Page 2 confirms the tubes are 37, not 35mm. http://forums.sohc4.net/index.php?topic=16903.15

Ecosse · « **Reply #3 on:** March 21, 2009, 06:10:09 PM »

Thanks MC. Here I thought the GL forks were 35mm. The greater (assuming) spring rate must be good for spirited riding but would the ride height have to be adjusted?

Aren't the calipers improved over ours? Sorry to barge in robe0531.

MCRider · « **Reply #4 on:** March 21, 2009, 06:19:19 PM »

Quote from: Ecosse on March 21, 2009, 06:10:09 PM

Thanks MC. Here I thought the GL forks were 35mm. The greater (assuming) spring rate must be good for spirited riding but would the ride height have to be adjusted?

Aren't the calipers improved over ours? Sorry to barge in robe0531.

Skimming the longer of the threads, I noticed comments on slipping the tubes up the clamps, which is common racer practice anyway, to tune the ride. That implies the overall tube/leg length may be longer than the CB750s, but its such a popular modification, must not be a problem.

And different fork springs can be had from RaceTech, Progressive etc, if the stockers prove too stiff. Or not stiff enough. The stouter GL fork, with racetech gold valve emulators and some tuning is said to be a fine competition piece. For Vintage type racing. Seems it would be a big improvement on our streetbikes.

I have heard that the GL brakes are superior to the CBs.

robe0531 · « **Reply #5 on:** March 21, 2009, 06:37:02 PM »

i would like to do it for the bigger tubes and dual brake setup with out having to mod to much
i do think you need to slide the tubes up above the top tree alittle which is how i have mine now

eurban · « **Reply #6 on:** March 21, 2009, 07:22:20 PM »

Here's a couple of pics of my 78 with the GL front

I actually have the tubes flush with the GL triple but it does give the bike a bit more of a rake out. Brakes work very well, better than my buddies dual stocker front brake setup. They are heavy but the home grown lightening holes help a bit. Obviously you must use the GL tree's as the tubes are 37mm. Rotors are different than the 750s but the wheel and hub is interchangeable. The stock GL front rim is a nice alloy DID rim but is identical in size to the 750 piece. The GL hub and 750 hub are essentially identical. Speedo drive and rotor hardware must be GL pieces. You will also need to fashion a steering stop and modify the 750's gauge mount if you want to use your stock gauges. Racetech now lists a cartridge emulator kit for the GL forks which I really want to get my hands on. . . Overall the GL swap gives you dual discs, with spoke wheels and for the most part Honda factory engineering . . .

MCRider · « **Reply #7 on:** March 21, 2009, 07:29:23 PM »

Very Nice!

robe0531 · « **Reply #8 on:** March 21, 2009, 07:36:45 PM »

that is really nice looking cant wait to get all the parts for this upgrade

how well does it turn

robe0531 · « **Reply #9 on:** March 21, 2009, 07:50:54 PM »

how do you think it would be with some clip ons or some clubmans

Ecosse · « **Reply #10 on:** March 21, 2009, 08:29:26 PM »

me barging in again. eurban, build thread by any chance? nice motorsickle ya got.

mc, i read through that thread (long one) you provided and there's some really helpful stuff therein. it is worth going to the home page, punching differently worded searches on this and cruising older threads. the member (name?) who did a 500/gl swap had good info too.

assuming a correction for the 3" longer tubes i'm still not 100% if the gl clamps increase trail for the 750 or 500/550. i look forward to your swap robe' even if i do have a 550.

lastly, another bonus seems to be lighter rims of the gl.

robe0531 · « **Reply #11 on:** March 21, 2009, 08:33:34 PM »

going to be some time to gather every thing but i am looking now for them

Ecosse · « **Reply #12 on:** March 21, 2009, 08:42:46 PM »

do you have a specific idea of an end result for your bike? resto-mod, cafe, etc...

robe0531 · « **Reply #13 on:** March 21, 2009, 08:48:10 PM »

i am building a cafe racer got a seat and tank from carpy put a 836 big bore kit in it and got a cam from cycle x
i am ordering an exhaust from carpy also soon
i wanted dual disc front brake and all the conversions i seen on here looked a little to hard for me so i thought i would just switch out front ends

MikeB · « **Reply #14 on:** March 21, 2009, 08:48:55 PM »

Quote from: eurban on March 21, 2009, 07:22:20 PM

Obviously you must use the GL tree's as the tubes are 37mm. Rotors are different than the 750s but the wheel and hub is interchangeable.

This is great guys I have been looking for 37mm uppers to replace the ones that are bent on my
82 cb650 Nighthawk ,seem they are also 37mm and alittle longer than other CBs
did not think to look at the goldwings front

Very nice job eurban
and thanks MCRider for the links

Mike

cxtecs · « **Reply #15 on:** March 21, 2009, 10:01:50 PM »

here's link to some info I found that was helpful on this:
http://forums.sohc4.net/index.php?topic=1355.0

Geeto did a big write up on this conversion, but I think it was on caferacer.net.

Here's my K8 with the conversion and clip-ons, although the bike is not finished in these pics.

I did bolt everything together last fall so I could ride it before it got too cold. All went well. Everything on the front end is GL1000 except for the speedo/tach and upper steering bearing. I was able to mount those on the GL bracket using one of the mounting posts on each gauge and one of the acorn nut studs. I just wired the GL idiot light cluster to the CB harness (same wire colors). I even trimmed up the GL front fender to look more sport and less cruiser (sorry no pic...it's getting stripped for paint). It's plastic which makes it lighter than the stock CB chrome fender.

I laced up a GL rear rim to my CB rear hub, but the shortcut would be to find a CB750A rear wheel (17 inch aluminum DID). I did this to match the front and rear wheels up.

robe0531 · « **Reply #16 on:** March 21, 2009, 10:15:34 PM »

your bike looks awsome i am also building a 78 750 k
what type of rear sets are those i been looking found of on omars site but didnt know how they would look
and i see you cut off the rear fram section where the passenger pegs would have been

cxtecs · « **Reply #17 on:** March 21, 2009, 10:57:01 PM »

The rearsets on my bike are Omar's, but they do ride a little high (probably very race specific). I think Carpy mentioned he used to put these on his bikes, and even sold them at some point, but he also commented on them being a little too high up and maybe too far back. On the same page, he mentioned sourcing out some new sets that he felt were more comfortable, but I didn't see a pic of those.

I have another cafe bike with clubmans but no rearsets. I think without the rearsets, the ride gets uncomfortable on my hands/wrists pretty quick. With the rearsets on my CB, it feels like I get more weight on my legs/hips which makes longer rides much more comfortable.

If you do plan on getting the Omar's, make sure you get them specific to the 78 (if available). I bought mine on ebay advertised to fit all years of cb750, but the brake arm collar was too wide in diameter for my 78 spline (where the stock brake pedal mounts to). I had to chop up the original brake pedal to accomodate the Omar linkage. I'll be welding up something nicer as the project gets closer to completion.

cxtecs · « **Reply #18 on:** March 21, 2009, 11:10:48 PM »

Something else I thought about regarding the GL conversion which you might want to consider since you're going cafe....

Here's a pic of the gl top tree on the CB:

The height of the clamps are higher than the stock CB tree. I'm not sure about clearance issues if you run clubmans in those.

It seems most people running clip-ons on their CB's like to shave the top tree. Not a problem with the stock CB tree, but the GL tree has hollow handlebar clamps. I don't think these can be shaved flat without compromising strength and leaving big holes in the top of your tree. Here's a pic of the hollow area of the GL tree and a pic of what I ended up doing:

eurban · « **Reply #19 on:** March 22, 2009, 06:04:02 AM »

Quote from: MikeB on March 21, 2009, 08:48:55 PM

Quote from: eurban on March 21, 2009, 07:22:20 PM

Obviously you must use the GL tree's as the tubes are 37mm. Rotors are different than the 750s but the wheel and hub is interchangeable.

This is great guys I have been looking for 37mm uppers to replace the ones that are bent on my
82 cb650 Nighthawk ,seem they are also 37mm and alittle longer than other CBs
did not think to look at the goldwings front

Very nice job eurban

and thanks MCRider for the links

Mike

Are you sure that your 82 nighthawk has 37mm tubes?? I was under the impression that forks didn't change size until they went to the DOHC in 83? Anyways, you need to consider the spacing between the fork tubes and their distance (front to back) from the steering stem as well. I would guess that the spacing on GL pieces is different from the 37mm DOHC ones but I don't know for sure. . . .

eurban · « **Reply #20 on:** March 22, 2009, 06:15:56 AM »

Quote from: cxtecs on March 21, 2009, 10:01:50 PM

I even trimmed up the GL front fender to look more sport and less cruiser (sorry no pic...it's getting stripped for paint). It's plastic which makes it lighter than the stock CB chrome fender.

I laced up a GL rear rim to my CB rear hub, but the shortcut would be to find a CB750A rear wheel (17 inch aluminum DID). I did this to match the front and rear wheels up.

For the 75 and 76 Gls, the stock front fender is the chrome steel "Whale Tail" that can be seen on my bike. Never thought that there was any way in Hell that I would use that piece on my bike but after I put it together it kind of went with the "muscle bike" look. What year is your plastic one from? Finding a 750A rear wheel assembly is indeed the easiest way to get a complete assembly with the alloy rim but they are a bit rare. The GL pieces are a bit more plentiful and the 17" rim is identical in size to the 77/78K rear rim. You would of course have to lace it to your 750s hub as the GLs have a shaft drive rear hub. Earlier 750s (w 18" rears) can use the spokes from the 77/78Ks to lace the 17" rim to their hub.

fishhead · « **Reply #21 on:** March 22, 2009, 07:08:14 AM »

I used clubmans on my 1975 GL front end and the stock gauges were used with the stock gauge mounting bracket. I had to cut off the mounting tabs from the CB 750 K gauge bracket, swap them from side to side and weld them back on to fit the GL gauge mounting points on the top tree.
The stock CB 750 idiot light cluster bolted right on to the GL top tree also.

robe0531 · « **Reply #22 on:** March 22, 2009, 11:12:10 AM »

man i am glad i posted the question here
you guys have been very helpful and i will post pics once i start the conversion

cxtecs · « **Reply #23 on:** March 22, 2009, 01:25:55 PM »

I also tried to use the early style idiot light cluster/handlebar clamp on my project like Fishhead has done, but the ignition switch is up on the tree on our 78's and gets in the way.

Regarding the fender, I'm not sure what year it was. On ebay, I just searched for "gl1000 front fender" and looked for pics of plastic ones. They are not in high demand, and if you're going cafe, you want to chop it up from it's original shape. Mine was pretty rough from the PO with two coats of chipped spray paint, but I was able to get it for $12 shipped.

I'm also running a Markland forkbrace. These are plentiful for the old Goldwings, so with the large supply/low demand, can also be had for cheap. I think I got mine for $35-$45 shipped.

fishhead · « **Reply #24 on:** March 22, 2009, 02:09:24 PM »

+1 on the fork brace. I like steering dampers also for the GL forks on the CB.
You'll also have to make new fork stops for the GL forks (to keep the forks from slamming into the tank).
Another option for the plastic front fenders is Yamaha. This fender on this GL fork is off a Yamaha XJ Turbo. I had to get rid of the "fender brace" that originally mounted it to the Yamaha forks and make a new mount to bolt it to the GL forks.

cxtecs · « **Reply #25 on:** March 22, 2009, 03:22:13 PM »

Quote from: fishhead on March 22, 2009, 02:09:24 PM

You'll also have to make new fork stops for the GL forks (to keep the forks from slamming into the tank).

Are you talking about the crescent shaped plate that is welded to the headtube?

I agree, at least on my bike, the GL front end needed to travel on a limited arc. I just drilled and tapped some holes on the the two posts sticking up from the bottom tree and screwed in some allen head screws which eventually hit the plate. That way I could finely adjust were the forks stop.

robe0531 · « **Reply #26 on:** March 22, 2009, 05:52:34 PM »

very nice idea this tapping the stop so you fine tune the turning to your needs

Jim F · « **Reply #27 on:** March 22, 2009, 07:38:30 PM »

I replaced the entire front end from a 75 GL1000
I had to take the inner race for my tapered steering head bearings
and use that on the GL1000 but that's all.
Your dash assembly wont bolt up but you can make brackets for that
or in my case I am going to use a small tech and that's all.

MikeB · « **Reply #28 on:** March 22, 2009, 08:51:48 PM »

Quote from: eurban on March 22, 2009, 06:04:02 AM

Quote from: MikeB on March 21, 2009, 08:48:55 PM
Quote from: eurban on March 21, 2009, 07:22:20 PM

Obviously you must use the GL tree's as the tubes are 37mm. Rotors are different than the 750s but the wheel and hub is interchangeable.

This is great guys I have been looking for 37mm uppers to replace the ones that are bent on my
82 cb650 Nighthawk ,seem they are also 37mm and alittle longer than other CBs
did not think to look at the goldwings front

Very nice job eurban

and thanks MCRider for the links

Mike

Are you sure that your 82 nighthawk has 37mm tubes?? I was under the impression that forks didn't change size until they went to the DOHC in 83? Anyways, you need to consider the spacing between the fork tubes and their distance (front to back) from the steering stem as well. I would guess that the spacing on GL pieces is different from the 37mm DOHC ones but I don't know for sure. . . .

yea they are, checked 4 times, 1.457"

and the research continues

again nice job on these front ends guys
and thanks for all the info

Mike

robe0531 · « **Reply #29 on:** March 23, 2009, 12:22:37 PM »

i am a litte confused here can i use the cb750 races or do i need to use the gl1000 races for the bearings

Jim F · « **Reply #30 on:** March 23, 2009, 05:05:35 PM »

I had to use the lower inner race from the 750 steering head to the GL1000 steering head
and everything bolted up

robe0531 · « **Reply #31 on:** March 23, 2009, 08:09:03 PM »

ok
thanks

Hinz · « **Reply #32 on:** May 04, 2009, 07:40:26 AM »

Quote from: big-jim on March 23, 2009, 05:05:35 PM

I had to use the lower inner race from the 750 steering head to the GL1000 steering head
and everything bolted up

I'm having a little problem visualizing this. Can you explain better? Maybe include a pic or drawing? What do you mean by "steering head"?

fishhead · « **Reply #33 on:** May 04, 2009, 07:56:31 AM »

Probably the steering stem.

Heres 2 links

http://forums.sohc4.net/index.php?topic=46084.msg484557#msg484557
And
http://forums.sohc4.net/index.php?topic=46362.msg486489#msg486489

Hinz · « **Reply #34 on:** May 04, 2009, 11:43:23 AM »

awesome. Thanks Fishhead, those links help explain much better. There's no replacement for specific dimensions and pictures.

I call the cylindrical part of the frame where the steering assembly get bolted to, as the "Head" since it is at the head of the frame.
The threadded rod that connects the 2 triple trees, I've allways called the "Neck". No explanation why thou.

I'm not sure if this is "industry standard" but some sort of standardized lingo would help to avoid confusion in situations like this.

Hinz · « **Reply #35 on:** May 04, 2009, 11:59:56 AM »

Quote from: fishhead on May 04, 2009, 07:56:31 AM

Kinda..
The steering stems are the same. The 75-77 GL uses K&L kit number 31-5830 that has an upper bearing of 26 X 48.5 X 15.2 and a lower bearing 30 X 50 X 14.4.
The 78-79 GL uses K&L kit number 31-2260 and it consist of an upper bearing 26 X 47 X 17.3 and a lower bearing 30 X 55 X 17.
The first digit of the bearing size is the inside diameter of the bearing and is where it would sit on the stem. The only differnce between the 75-77 and 78-79 GL is the frame was changed where the bearings sit and the changes in outer dimension of the bearings show this change.

Now back to the Kinda..
The only difference between the lower triple tree is the fork stops are wider apart(about 10mm) on the 78-79 than they are on the 75-77. This is because of the larger bearings used in the later GL. Other than that, they are identical.

What usually happens next is some one will chime in with an online list that was compiled with many hours of work stating that I am wrong.
The online list is wrong. I have both of the GL front ends and I have measured them many times.

The steering stem bearing kit for the CB 750 is the same one for the 75-77 GL 1000. It will also work when you put the 78-79 GL steering stem on your CB 750 K. (SOHC as the DOHC uses a different kit)

so since i'm putting a 75 GL1000 assembly on a 76 750K frame, I "shouldn't" have to mix and match the bearings? I have the All Ballz kit for the 750K and just wanted to make sure I have the right parts before I try and install them.

Bruiser · « **Reply #36 on:** July 27, 2009, 12:57:30 AM »

Hey...new member here...sorry for intrusion but there is something I don't know about:

It's been made obvious, from here and other research, that the most logical and easy swap for a duel brake spoke rim is to us a 75-77 GL1000.

However there are two things I need to know before I pursue a path. I have a 74 that was tried to be duped as a harley/chopper so the forks are 6+ inches longer which makes it look & ride like crap. I have a pair of 77f forks but I think that becomes a bigger issue than using the GL (correct me if i'm wrong ie: spacers and schtuff)

Q1. Am I absolutely able to use my current 74 rim & tire?
Q2. Without sounding too much like an idiot, what is and how difficult is it to install fork stops?

I guess the least expensive route is just to get original forks but I like the look and the idea of better braking power.

Super Thanks

!!!RANDOM THOUGHT!!!
can i just get a second rotor caliper and mount it to a pair of 76 forks that i found on ebay??

News:

Author Topic: gl1000 front on cb (Read 11026 times)

Bruiser