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Twinpot Brake upgrade on 78 Skunk

Just a quick note to let everyone know that I don't have many of these left. I'm down to about the last set of bolts, a couple of sets of brackets etc.

IF I do this again it may be:

a. A while in coming as I have a baby on the way & won't be travelling for a while (in order to pick them up).
b. A bulk buy with money up front

Dan :)
 
If anyone does want to do this, I have a set of '92 ZX7 calipers I think are the correct ones for this.
I'll let them go for a fair offer...as I decided not to do this mod at this time.

Dan...the zx7 ones will work, correct?
 
Not sure Bob... Show me a picture & I'll let you know.

Dan :)
 
Not sure Bob... Show me a picture & I'll let you know.

Dan :)

Here ya go Dan...

zx7_calipers.jpg
 
Nope... sorry. Those are the wrong ones. If it had been an 89 or older they would be the right ones on that model bike.
 
Nope... sorry. Those are the wrong ones. If it had been an 89 or older they would be the right ones on that model bike.

OK...off to ebay they go...

Sorry if I got anyone's hopes up...

Thanks Dan....:)
 
Salty--I have done twin-pot upgrade on my 81 GS1100e and got them to work very well :eek:. I may still have some pad alignment issues later. Do you still have any of those brackets left?
PICT0748.jpg
 
Salty--I have done twin-pot upgrade on my 81 GS1100e and got them to work very well :eek:. I may still have some pad alignment issues later. Do you still have any of those brackets left?

Just interested , what type of discs/rotors are you using on the 1100E?
Thanks.
 
I used cbr900rr rotors and Ninja 600zx calipers--I believe 88-97 vintage(the calipers). Also the master cylinder from an 89 Ninja 600.
The master cylinder and stainless brake lines by themselves will work the original calipers quite well--you're pushing quite a bit more fluid thru the system--the feel in the brake handle is somewhat stiff. And you might need longer fingers(!)
 
I used cbr900rr rotors and Ninja 600zx calipers--I believe 88-97 vintage(the calipers). Also the master cylinder from an 89 Ninja 600.
The master cylinder and stainless brake lines by themselves will work the original calipers quite well--you're pushing quite a bit more fluid thru the system--the feel in the brake handle is somewhat stiff. And you might need longer fingers(!)

Yes I thought so. The same as I have on my 550.

Thanks


m_S3010004.jpg


m_S3010010.jpg
 
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Don--Did you have to drill out your mounting holes on your rotors-if so, how much? Mine I had to go up to 7/16 in. and the bolts touch just the very outside of the new holes. The original lock/tab washers cover up the offset discrepancy.
 
Don--Did you have to drill out your mounting holes on your rotors-if so, how much? Mine I had to go up to 7/16 in. and the bolts touch just the very outside of the new holes. The original lock/tab washers cover up the offset discrepancy.

There is no offset with the Fireblade discs. The holes are 6mm and have to be drilled out to 8mm and it all bolts straight up. The hole centres on the discs and the Suzuki hub are in identical positions. hope this makes sense, if not let me know.
 
I suspect Don is using the 98 900RR rotors. They are 310mm & the bolt pattern is correct the holes just need enlarging.

I suspect Windcrow is using the 600CBR F3 Rotors (They look the same). They are 296mm. These are the ones I used but the bolt pattern is different to Suzuki.

Instead of enlarging the hole which in my opinion is the wrong way to do it as you build in potential for the rotor to slip back & forwards & the holes becoming elongated over time (It's only Aluminium) I used a jig to drill new holes at the correct size & pattern in between the original bolt holes.

Yes I do have a couple of sets of brackets & spacers left but to use them with that rotor you'll also need some hub spacers. This brings everything into alignment so the calipers are placed centrally over the rotor & you use the full width & depth of the pad.

If you have pad alignment issues then you need to be careful about caliper clearance on the rotor (basically as the pad wears you could reach the limit of movement of the rotor & the caliper half will drag on the rotor).

Be careful of caliper to wheel clearances too, it's quite tight the way you have it fitted with the caliper bracket on the inside. Out of interest what thickness of material are you using for that Tag you have going to the bottom bolt hole?

Cheers,


Dan :)
 
Hi Dan,
I am using the Fireblade 296mm rotors from '94 to '97. Drill out and bolt up. Of course I drilled undersize and then reamed the holes for a perfect fit, no movement when brakes are applied. No elongation.
 
Hmm, not sure then... I just thought this guy might be using the same rotors I have. If you simply drill those out to size they won't fit as the PCD is wrong.

The PCD is right on that rotor I sent you but that was a 310. There are obviously some smaller ones with that PCD over there too, I haven't seen any over here but that isn't to say there aren't some!! :D
 
Dan the Fireblade obviously use the same wheel, hub, I would think, no matter which disc they are using. So whether Honda are using the 296mm or 310mm on the Fireblade the spacing would be the same. So the 296mm CBR900RR discs that I have used have the same PCB (whatever that means) spacing as the 310mm disc that you sent me.

BTW I purchased the 296mm discs from the US. And they are quite distinctive from the other Honda discs in the pattern the holes are drilled in the discs for ventilation. Which can be seen in the pic I included at the bottom of this page.

These CBR900RR discs also have 10 rivets holding the outer braking surface to the inner as opposed to the eight on the CBR600 discs.

I guess in the end people are going to use the discs that are more available and easily obtainable even if it is a bit more work to make them fit. And it would seem there are more CBR600 discs around than the CBR900 discs. I guess I was just lucky as I bought them on EBAY from the States and you dont get to ask too many questions in that arena. So I took a risk not really knowing if they would be a perfect fit or not -- and as luck would have it they did fit perfectly with minimal work.

BTW Dan thanks for all your help in those early days of these modifications and even though I ended up not using your brackets your help and advice was very much appreciated. GS owners are very few on the ground over here and it was great to have someone to bounce ideas off. Both you , Jeff and Mark Mattock were a great help to me.


m_S3010014.jpg
 
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That makes sense Don. I guess the 900RR ones are the ones to go for over the 600 if you don't want to re-drill just enlarge then :)
 
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