Topic: 750 K2 twin disc concerns.

[Old Moe Toe]

I have read the excellent thread in this forum by Ben Hiles on how to set up a twin disc brake set up on a 750 and felt pretty confident about finally doing mine.
Got my wheel all set to go with a modified speedo drive, discs attached etc, etc.
Went to fit the second  pivoting caliper holder assembly today and was rather surprised how much of a gap there is in the 2 upper mounting lugs. In Bens article he says he had to file back the lower lug to get the caliper arm parrallel to the disc/rotor. Also when he had got that right it was just a matter of shimming out the upper 2 bolts with a couple of washers.
The problem I have is that I will need heaps of washers or even a solid spacer as I have a gap of about 15mm. I could file down the bottom mounting lug by 3-4mm before the caliper arm will foul on the fork slider but that still  leaves a pretty hefty gap to deal with. Hopefully the picture will be somewhere below.......
I notice the 750 Ben twin disc'd was a different model to a K2, its got a different master cylinder and caliper holder.
Would be most interested to see how anyone else has dealt with this problem on a K2 or K1. It would seem to me that simply putting in a 15mm spacer is not an ideal fix as it would put a lot more stress on the 2 upper mounting bolts.

[Nic]

The easiest way is to not file any off the bottom. See the red lines in the pics, you don't need these areas on the r/h side and I just cut them off with the hack saw, then I make round spacers out of the two bits that are cut off, use the hack saw to cut off some of the sides and then file the rest of it round. In my case I used a drill press, I used a bolt and a nut through each piece, tightened the nut then put the bolt end in the drill press and with a course file I made them round, pretty easy. This way you have perfect sized spacers. Hope you can understand??? Bolt the mount on via the bottom bolt, then insert spacer and then put bolt in the two upper mount holes. See my r/h side spacers in place. You'll need to get two longer 8mm bolts as well. The same length as the lower one. This is how I did it in the 70s n it's still the way I do it now.

[Old Moe Toe]

Thanks Nic for the advice and pics. I did see a "not so" close up picture you had put on a thread in this forum sometime ago  regarding your brakes and was rather hoping you would reply.
I agree, about not filing the bottom as the caliper arm looks pretty parallel to the disc as is.
Still a bit concerned there is lots more stress on those top bolts....have you had your set up working well with no issues for some time?.
Also in the above mentioned thread you had drilled out the small pointy thing that goes into the caliper underneath where the brake fluid line connects and made another one(on your drill press,with file) from brass so you could reverse the bleed screw and fluid line on the right hand caliper. Must say you did a tremendous job on that!......Well done. What did you start with on that? i,e a small brass rod?. Had been thinking I'd just have the input line and bleed screw on opposite sides but the way you did it looks better by a mile.
Cheers

[Nic]

I just edited the text above that says this is how I did it back in the day and still do it like that now. Never had issues, solid as a rock. As for the nipple/seat inside, mine wouldn't come out so I had to drill it out and make up the brass one, yes I used some 3/8" brass rod, you can make it out of steel as well, the most important thing is to get the hole in the centre, put the brass stock in the drill press and the drill bit exactly perpendicular in the holding vice and it will centre automatically.
To try and get the nipple out, see if you can find a screw that will bite into the nipple and try to pull it straight out, if it comes out it should be usable again if the taper on the top is good, you can tidy it up with some 320 paper. If you have the line on the r/h side at the front and the bleeder at the back you will always wish you had done it properly 

[Old Moe Toe]

Ah Ha! The side of the caliper that has the piston in it is a DSS repro....never used. So hopefully I may be able to fish that little nipple/seat out. With a screw....Hmmm, fingers crossed. Did previously try poking it out with a bit of bent wire from the inside of the piston cylinder to no avail, Will try tomorrow, when the beer has worn off! and its not so freezing out in the shed.
Thanks for the advice, just what I was after,

[Nic]

Well seeing as it's new, you might do less damage if you use a jolt head nail ( see pic )  from the inside, cut it so it's just long enough to fit sideways in the piston bore, put the cut end in first so the head of the nail pulls the seat out, if this fails try the screw method.

[Old Moe Toe]

Fantastic! Gottcha ,will try the good old "jolt head nail" method first.

[70CB750]

What Nic says, the nail method worked for me everytime.

[Rookster]

http://forums.sohc4.net/index.php?topic=91781.0

[Don R]

 You could weld the spacers on. I was hoping someone would be repoping the right side bracket by now. I guess it's not really needed.

[Old Moe Toe]

Thanks for the feedback you guys, it was an enormous help.
Nic,did as you suggested and cut those extra bits of the caliper holder and did the same as you did. Also using a nail to get that little nipple seat out worked a treat. I tried it on my brand new DSS repro caliper and the nipple just popped out. Incidentally, they use a brass one on their current units. However be WARNED if anyone else is going to use one of these DSS replica calipers for a right hand caliper! They are not the same...identical...to the original ones. The difference is on the bottom of the holes where the bleeder screw goes in and the brake fluid line goes in . The bleeder screw base has the tapered hole at the bottom to match the taper on the bleeder screw, however the hole where the brake fluid line goes in has a flat bottom and won't seal when the bleeder screw is reversed into that hole. I did try to countersink the flat bottomed hole but the drill(hand held) kind of chattered slightly and the bleeder nipple would not seal. Noticed on the stock caliper the bleeder screw will seal happily in either hole. So I reassembled the DSS one and reversed the stock one on the other side. Took blimmin ages and plenty of swearing. Callipers are now attached both sides.
Rookster, I don't have those Lester wheels but my stock hubs don't have the flats on them either. I went for grinding out little slots on the outside face of where the rotor bolts on to the hub and modifying the speedo drive to suit. Goldwing chrome plate covered up the handywork nicely. To grind out the slots I went for an "agricultural approach", firstly an angle grinder then one of those little re-inforced cut off wheels that fits on to a dremmel.
So all that is left to do for the moment is to bend the right hand side brake fluid line to the opposite shape to the left hand one. Like you Rookster I have a new stock one for the job, I don't have a brake line bender though. Reckon I will just use the Irish calculators. However that brake fluid line Nic used looks pretty smart and shiny.....where did ya get that Nic?.
Don, yes welding them on seems to make sense.

[Nic]

Argg, so you now have the bleeder at the back on both? I don't know how handy you are with stuff and how outside the box you think. I used to know a guy RIP, he could fix any problem just by thinking about it, never needed a manual, I love people like that, he was a qualified auto electrician but could do anything.
Anyway, I'd be tempted to try and fix that flat bottomed hole by reshaping the correct size drill bit on the bench grinder to the same angle as the bleeder, then in the drill press lightly drill out the bottom of the hole. Of course you need to be good at sharpening drill bits, if you are it's not biggy to change the angle. If not then forget it.
As for my brake pipe on the R/H side, I measured the left one and went to a brake joint and got them to make me one with the same fittings, it cost about $15, they put the wrong ends on though n I had to drill them out to make them cone shaped, I then bent the pipe which bends differently than the left side due to the guard being different on both sides, then I had the pipe chromed. I also made a bracket for the right side similar to the one on the left and had it chromed, I drilled a 6mm hole in the guard stay for the bracket.

[Old Moe Toe]

No "ARGGS" here Nic,! I have the bleeder on the front both sides. Cripes, maybe I didn't explain it properly.
I do consider myself to be pretty handy with the 10 bratwursts.
It's all sorted.
Just waiting to get the new twin braided lines made up to suit.
Happy as a Tasie devil in a rotten wallaby carcase!

[Nic]

So I reassembled the DSS one and reversed the stock one on the other side. Took blimmin ages and plenty of swearing. Callipers are now attached both sides.

I read this as you put the bleeders at the back?
edit, oh now I think I understand, you must've put the left one on the right side and visa versa?

[Old Moe Toe]

"So I read this as you put the bleeders at the back?
edit, oh now I think I understand, you must've put the left one on the right side and visa versa?

Yeah mate!, that's what I did.
Thankful for your advice...everything is on track.
Probably should have put a few pictures on there about the DSS repro calipers to further explain the problem. Just got caught up in the excitement of the procedure and forgot.

[Nic]

Well done mate, glad it went well. I hope you have the front wheel on, it won't go on with the two calipers bolted up. I have a 410x19 front tyre and I can only just get the wheel on n off with one caliper off