CB750 Barn find project - First Timer

[Chris400F]

I had a problem removing my seals a while ago so I posed the question on here, and got the suggestion:
"Heating the fork legs in the area of the seals with a heat gun and gently prying the seals with a metal bicycle tyre lever has worked for me in the past".
So I tried it, and my seals then came out pretty easily.

[Underdog1]

I had a problem removing my seals a while ago so I posed the question on here, and got the suggestion:
"Heating the fork legs in the area of the seals with a heat gun and gently prying the seals with a metal bicycle tyre lever has worked for me in the past".
So I tried it, and my seals then came out pretty easily.

I tried a hair dryer and then screwdrivers/pliers/all sorts to try and get them out but they didn't budge. Do the seals have a metal ring through them or have I literally been cutting into the fork leg?

[Chris400F]

They do have a metal core. which from your picture it looks as if you have been cutting in to.
I don't know if a hairdryer puts out enough heat. You couldn't use one to strip paint, which you would do with a heat gun.
I think you may need to go hotter to get the metal of the fork leg to expand enough to loosen the seals. Maybe someone else will confirm this theory.

[Underdog1]

They do have a metal core. which from your picture it looks as if you have been cutting in to.
I don't know if a hairdryer puts out enough heat. You couldn't use one to strip paint, which you would do with a heat gun.
I think you may need to go hotter to get the metal of the fork leg to expand enough to loosen the seals. Maybe someone else will confirm this theory.

I'll see if I can get my ancient blowtorch fired up then and just use it at a distance that doesn't melt everything

[Jontyp]

I feel your pain on this one but the solution is more heat. There's nothing else to damage with heat except the seals and you're losing them anyway so have at it with a blow torch. I used a larger motorcycle tyre lever (has a perfectly designed hooked end just right for the job). Take your time, apply plenty of heat and they will come out (always assuming you've taken the wire retaining ring out first which it looks like you have).
Don't be afraid of using heat when stripping down old stuff (with the obvious proviso that you're not melting something important. It works great with steel parts stuck in aluminium (the seal inner ring will be steel) but even with the same materials it can be the best way to break a bond caused by years of corrosion.

[Underdog1]

I feel you pain on this one but the solution is more heat. There's nothing else to damage with heat except the seals and you're losing them anyway so have at it with a blow torch. I used a larger motorcycle tyre lever (has a perfectly designed hooked end just right for the job). Take your time, apply plenty of heat and they will come out (always assuming you've taken the wire retaining ring out first which it looks like you have).
Don't be afraid of using heat when stripping down old stuff (with the obvious proviso that you're not melting something important. It works great with steel parts stuck in aluminium (the seal inner ring will be steel) but even with the same materials it can be the best way to break a bond caused by years of corrosion.

Cheers mate!

Just received a front brake caliper i bought yesterday from DK. Got it for £60 which is cheaper than they usually go for on the bay but its negative piston and pad seat.

The pad seat is number 17 here, just before i order one can someone confirm whether this would come with a new brake pad set or is it actually part of the caliper?

[Underdog1]

Managed to get both fork seals out, went medieval with a dremel and then managed to hammer a flat head screwdriver behind it. As soon as they shifted slightly i could pull them out with pliers.

My fork tubes were rusty as hell so i ground off as much as i could. They're badly pitted but not on the actual part which slide in the lowers. Do you guys reckon i can get away with leaving them like this or should i at least paint them to stop them rusting again?

One done


two done



Could probably do with a bit of a sand as they're a bit rough, but currently all i can find is 240 grit wet and dry


Now the latest challenge is the DK special front brake caliper has a seized piston. Im not able to attach the front brake lever as the master cylinder is tits.. I have an air compressor but i can't screw it into the caliper as it just has a rounded nozzle. wrapped some insulation tape around some pliers and tried to pull it out but it doesn't budge. Any ideas? if i could fill it with something that wold dissolve the old crusty brake fluid that would be ideal!

[Trigger]

They look normal for a early 750 fork. You will have to heat the caliper and you can use a grease gun to push the piston out.

[Underdog1]

They look normal for a early 750 fork. You will have to heat the caliper and you can use a grease gun to push the piston out.

Ok cool so something like this yeah?

http://www.screwfix.com/p/hilka-pro-craft-manual-grease-gun-500cc/19235#product_additional_details_container

Might be a daft question but how do you actually attach a grease gun to the brake line hole?

secondly whats a good grease to get that I can use on the bearings and swing arm etc? Might as well get something i can use for other stuff

[Trigger]

You need to find out if the fitting on the grease gun will fit the caliper at the pipe.

[Bryanj]

Multi purpose grease for everything and if you remove the end fitting from the grease gun pipe the thread will screw in about 1 1/2 turns into the pipe fitting hole as it is a different thread and that is enough  DO NOT FORCE IT or you wreck the caliper

[Underdog1]

You need to find out if the fitting on the grease gun will fit the caliper at the pipe.

Multi purpose grease for everything and if you remove the end fitting from the grease gun pipe the thread will screw in about 1 1/2 turns into the pipe fitting hole as it is a different thread and that is enough  DO NOT FORCE IT or you wreck the caliper

Got myself a grease gun earlier and it worked like a charm, thanks for the advice.



Onwards to the next challenge, the front axle it stuck tight in the wheel, put a screwdriver through the end with a hole in and clamped it in a vice then heated the nut on the other side with a blow torch until it was so hot i was worried the aluminium bits would start to melt. got a spanner on it and hit it with a hammer for about 15 minutes and it didn't budge. I don't have a deep socket that size (17mm i think), looks like ill have to get one so i can get a breaker bar on it.

On another note I'm off rock climbing in switzerland! Peace out 

[Underdog1]

Well I'm back and able to work on the bike for a few days before i head off again and the project gets put on ice until late october   

Sprayed the upper  (previously rusty) parts of my fork stanchions today, look a lot better. Hammerite smooth rattle can stuff is actually pretty good.

Half on the lookout for a replacement right hand switch gear, some seem to have a headlight on/off switch below the kill switch and some don't, whats that all about? The listings were for the same year as well 

[Bryanj]

UK has on/off US doesn't

[Underdog1]

UK has on/off US doesn't

Interesting, Is it/was it legislation in the US for bikes to always have lights on?