Topic: CB750 to GL1000 front end conversion *UPDATED* pics.

[mrbreeze]

Nice looking front end Eurban. I'm in the market for front tubes at the moment. What would it take to go Goldwing at this point? Do I need the whole enchalada +wheel or are there pieces of the 750 (K5) that will be used?

[xtalon]

Jinx or Eurban,

Either or you guys (or anyone else) know how much fork oil goes into the GL1000 forks?  Mine are off a 1976 GL.
I'm draining mine as I speak so I can replace the springs with progressive springs and install new seals.

Also, what type of oil?

Thanks!

--xTalon

[xtalon]

Nice looking front end Eurban. I'm in the market for front tubes at the moment. What would it take to go Goldwing at this point? Do I need the whole enchalada +wheel or are there pieces of the 750 (K5) that will be used?

MrB, I'm currently in the middle of this conversion, so mines not all together yet, but as far as I know, you will need the forks, the triple tree, the two calibers, the two brake disks and at least the hub.  The GL rim is aluminum, but the GL hub will mate with a CB750 steel rim (on your K5).  Also need the axle and spacers, so yep, pretty much the whole enchalada, but other than than, should be a pretty straight forward swap.

--xTalon

[eurban]

Jinx or Eurban,

Either or you guys (or anyone else) know how much fork oil goes into the GL1000 forks?  Mine are off a 1976 GL.
I'm draining mine as I speak so I can replace the springs with progressive springs and install new seals.

Also, what type of oil?

Thanks!

--xTalon

Clymer manual for the GL (75&76) says 170-180ccs ATF for the front fork.  Forget the ATF tho and use 10w fork oil.  With the 10w oil and Progressive Suspension front springs my 78 K rides great.

[xtalon]

Jinx or Eurban,

Either or you guys (or anyone else) know how much fork oil goes into the GL1000 forks?  Mine are off a 1976 GL.
I'm draining mine as I speak so I can replace the springs with progressive springs and install new seals.

Also, what type of oil?

Thanks!

--xTalon

Clymer manual for the GL (75&76) says 170-180ccs ATF for the front fork.  Forget the ATF tho and use 10w fork oil.  With the 10w oil and Progressive Suspension front springs my 78 K rides great.

Thanks Eurban.  Exactly what I needed!  Now just need to figure out how to measure cc's. 

--xTalon

[mrbreeze]

Nice looking front end Eurban. I'm in the market for front tubes at the moment. What would it take to go Goldwing at this point? Do I need the whole enchalada +wheel or are there pieces of the 750 (K5) that will be used?

MrB, I'm currently in the middle of this conversion, so mines not all together yet, but as far as I know, you will need the forks, the triple tree, the two calibers, the two brake disks and at least the hub.  The GL rim is aluminum, but the GL hub will mate with a CB750 steel rim (on your K5).  Also need the axle and spacers, so yep, pretty much the whole enchalada, but other than than, should be a pretty straight forward swap.

--xTalon

I guess I will just stay with what I got for now but good info......If/when I start a project ride,I will keep the GW front end in mind. Thanks Talon.

[78 k550]

170cc = 5.748 ounce
180cc = 6.08 ounce

Paul

[xtalon]

170cc = 5.748 ounce
180cc = 6.08 ounce

Paul

Thanks Paul.

MrB, watch ebay and you can source everything you need fairly cheap.

--xTalon

[mkramer1121]

FYI, Honda part numbers for the CB750 hub and GL1000 hub are the same.  What is required for the stock complete 750 wheel to work on GL1000 forks are all the GL1000 wheel parts, like the speedo drive, etc.  Then the spacing is correct and the wheel will align properly.

[dusterdude]

just for informational purposes,the 750 spoked wheel is the same as the 75-76 gw wheel.

Dusterdude,

I thought CB750K had a 3.25 x 19 front rim and the GL1000 had a 3.5 x 19 front rim.   

--xTalon

since im late coming to the party again,let me rephrase this,the hubs are the same,you just need the longer bolts to use with both rotors.

[xtalon]

just for informational purposes,the 750 spoked wheel is the same as the 75-76 gw wheel.

Dusterdude,

I thought CB750K had a 3.25 x 19 front rim and the GL1000 had a 3.5 x 19 front rim.   

--xTalon

since im late coming to the party again,let me rephrase this,the hubs are the same,you just need the longer bolts to use with both rotors.

Gotcha!     Thanks for the correction and the input! 

--xTalon

[eurban]

Mr Loco-  I'm no 500/550 expert but I believe that the steering stem on the GL tree will not fit 500/550s head stock.  This would make it a considerably more difficult swap.  The GLs forks are wider apart and longer than the 750s so they would definitely give a 500 a raked out appearance unless you slid the forks up.  All in all this swap makes pretty good sense for the 750 because the headstock is essentially the same as the GLs. For the 500/550s its a bit more of a project. . .  .

[Jinxracing]

Loco,

Noel here on the forum put together a very comprehensive topic on converting his CB500 over to a GL1000 front end. I don't have a link for you, but if you do a search it should come up. I've seen the bike in person, and you'd never know it didn't come that way from the factory.

On the other hand, his license plate bracket is a different story...

Jinx

[jsaab2748]

170cc = 5.748 ounce
180cc = 6.08 ounce

Paul

Also   1c.c. = 1 ml.  if your particular measuring container is divided into ml. this might help.

[Noel]

You only wish your license plate bracket was as cool as mine.

The main trouble with the 500/550 to GL1000 swap is indeed the steering stem. You will have to grind off the welds at the bottom of each yoke and have a shop press out the stems, and then press the 550 stem into the 1000 yoke and weld it back up. Or something like that; I'm drunk at the moment. Find my thread for the real deal. And yeah, the improvement in braking is worth the effort.

[Noel]

Thanks mate, I appreciate that.

I didn't know how bad the brakes were until I fixed them. I guess there are front drums that do the job, but the 500/550 bit isn't one of them.

[eurban]

Here's a few observations on the GL conversion. . . .Probably the biggest plus of this conversion is that it gives you much improved  braking performance while still maintaining the classic good looks of spoked wheels.  The larger diameter forks and the light weight aluminum wheel rim also are a nice plus.  On the 750 it also is essentially a bolt on project requiring only minor mods to the steering stops and guage brackets.  Basically you are bolting on a factory engineered dual disc setup and don't really need the knowledge and machinery to custom fit an "alien" front end.  From my personal experience on my 750K8 the changes in fork length, fork diameter, fork width spacing etc do not cause any handling problems.  Steering radius is poorer due to the need to pad out the steering stops and if you don't slide the forks up in the trees steering response is a bit slower (but stability is improved) and most importantly, braking performance in excellent.  It is definitely much better than the dual stock 750 style caliper/disc setups that I have ridden. . . .All said however, there are certainly other options for front end swaps that would provide potentially better braking and fork performance.  Certainly for 750 owners who don't mind having a Comstar front wheel the installation of the 77/78f2/f3 dual disc front end with the 35mm forks (triple trees don't need to be swapped but using the F2/f3 trees might improve handling performance on the earlier 750s) is a relatively easy option that provides good braking.  If the fork width spacing is the same on the 500/550s then this would be an obvious and relatively simple option. . . .If you are going to have to change steering stems inorder to make the Gl swap work on a 500/550 then you ought to at least consider other options that provide better more modern braking, lighter weight, and much superior fork performance.   Basically I have trouble seeing the logic in going to the trouble and expense to install a "dinosaur " GL front end on a bike that its steering stem is not compatible with.  There are probably a plentiful supply of modern front ends available that could be adapted with a similar amount of work.  If spoked wheels are a must (as they were for my tastes) then the GL option might make a bit more sense but still with a bit of ingenuity you could probably find a donor bike (or combination) that would give you modern forks and brakes with spoked wheels. You are aleady heading over to the machine shop anyway!

[Noel]

There are probably a plentiful supply of modern front ends available that could be adapted with a similar amount of work.  If spoked wheels are a must (as they were for my tastes) then the GL option might make a bit more sense but still with a bit of ingenuity you could probably find a donor bike (or combination) that would give you modern forks and brakes with spoked wheels.

"Probably" sounds pretty good when you're not the one doing the work. 

Someday, someone will probably go to the effort of tracking down a dozen likely contenders, going through all the gruntwork, expense and heartbreak of trying and failing over and over again, and after having spent thousand or tens of thousands of dollars over months or years of trying, finally come up with a good workable solution. He will then condense it all into a few paragraphs which will earn the eternal gratitude of a whole bunch of us SOHC motorheads.

I nominate Eurban.

[Noel]

But here's the deal: the GL swap has been done and documented. Give me a stock 500/550 and a budget of $350 or so, and I can go from the barely functional -- and mildly dorky -- front drum to a cool looking and very functional double disk/spoke wheel setup. Maybe two weeks including Ebay time.  Yeah, it's "old tech" -- I can hardly believe I'm hearing those words as a complaint on this website, fer cryin' out loud -- but it works and works well.

Having to figure it out on my own (plenty of help from yous guys, of course) was 9/10ths of the trouble. Now that the "unkown" is out of the way, it seems like a very appropriate and relatively straightforward mod.

[eurban]

Someone on this site bought the GL front end for the 500/550 (don't they have stock single disc not a drum up front??) thinking it was an easy swap only to find that the GL trees didn't fit the 500/550's stem. They were kind of upset about it . . .Wasn't that you Noel??.  An important thing to "document" here is that the GLs trees are not compatible with the 500/550s.  Anyways once you have the parts on hand by all means make them work.    I would have done exactly what you did and stuck with the plan.  Keep in mind I have an old GL front end on my bike and love it but if I was going to alot of machine work to fit it I might consider other options. Especially if I haven't already plunked down the money.  The monster sized single piston calipers and the thick and large diameter rotors have considerable weight and certainly don't stop as well as modern brakes that weigh half as much.  GLs are touring bikes that often time see very high miles. The caliper pistons are almost always badly rusted (I disassembled 3 pairs before I decided to have a stainle$$ set made).  These parts are also 30 years old.  This means that if your actually want improved fork and brake performance that you will be rebuilding the calipers, master cylinder and forks, and also perhaps replacing caliper pistons and even fork tubes.  You also might want to plunk down the $ for progressive fork springs  This is going to cost a good bit of $ and time. . . .There have been a number of threads here discussing the adaptation of sport bike (CBR600 for instance) front ends which are indeed  avaliable on places like Ebay.  These parts would have a good chance (if they are not from a badly wrecked bike) of being in almost new condition. As I also mentioned the use of the F2/F3 35mm forked front is also a viable option. These routes didn't appeal to me because I had a very particular classic look in mind for my project but for the cafe racer types here it may appeal. . . . .  I don't need to spend anymore time on front end mods or research. I have already spent huge amounts of time on my project bike and when I was gathering and assembling parts 4 years ago for my Gl conversion I had very little "documented" info to draw upon. I have tried to add to the documentation including the pluses and the potential pitfalls. . . . . Oh and fer cyrin' out loud, no ones complaining about old tech stuff. But isn't replacing that "dorky" stock front brake with something less dorky the whole point? The less dorky the better!

[xtalon]

Eurban, do you have a picture of your bike anywhere?  Gallery?  I looked for your user name and didn't see.

Thanks mate!

--xTalon

[eurban]

Well until recently I have been in the photo sharing stone age and frustrated with the image sizes that I could send to this site.  Just got a photobucket account so perhaps these two shots might come out nice . . . . .



Many more shots here if you are interested:
http://s168.photobucket.com/albums/u182/eurban_photos/78Honda750K%20project/

Getting there but still needs a professional paint job on the tank and side covers

[Jinxracing]

Here are some more pics of the progress on the GL1000 front end swap...I've included photos of the process of making the parts, in case anyone else goes all goofy for machining like I do. 



I bought the headlight mounts on eBay and the included plastic shims weren't fitting the 37mm GL1000 fork tubes, so I made a set of reducer sleeves out of aluminum.



I also cut down a stock GL1000 "whaletail" front fender.


The fork tube caps were really tricky. They have a 1.5mm thread pitch, but my lathe is imperial (16TPI leadscrew). So, I found a geartrain that would give me a 1.5009mm thread pitch and hoped for the best. Lo and behold, it worked! They thread into the fork tubes really nicely. I got a little fancy on the top surfaces with some circumfrential holes. This of course meant I needed some way to tighten and loosen them. I came up with what our friends across the pond would probably call a, "pin spanner" or possibly a, "Featherington Bottomsly Device".    I decided to call it a "wrench".

[bill440cars]

        Gotta tell ya eurban, that's a very nice ride you've got there. Enjoy! BTW, I'm liking that frontend.


                                                        Later on, Bill

[bill440cars]

     Hey jinx,
             I'm sure liking the direction you're going with yours! I'm really liking those fork caps too!
     I'm not going with spoke wheels myself but, I've got a VT750C (83" I think, that I got from Terry
     also known as CB650) that I'm looking to put on my 77' CB550K (it's got 39mm fork tubes, dual disc
     setup w/ calipers behind the fork legs, air assist and a built in factory fork brace. Gotta swap out the
     tripletree stem to make it work though. No pictures posted yet. Keep up the good work.

                                                         Later on, Bill