Twinpot Brake Upgrade on GS550E - GS750C - GS1000C

[salty_monk]

So... bought some parts with this in mind a year or so back & when TKent approached me with a suitable test bike I sent them to him to bolt up...

This uses a 310mm Honda Blackbird Rotor along with a single bracket & spacer kit.

The holes in the rotor are the correct PCD (bolt circle) so only need enlarging to 8mm.

Caveat - The rotors are quite rare - I paid $150 for a good set (obviously you only need one).

I have 1 rotor here on the shelf - first come first served at $75 plus shipping.

This mod will fit any of the single rotor brake models that come stock with a 290mm rotor I believe (apart from L, GL, or T variants).

For the GS450 Twins - This same mod can be done but with the CBR F3/F4 295mm rotor (these are more common).

This mod uses the same Kawasaki Twinpot caliper as used in the other upgrades & the same brackets (but only one side obviously!).

Price on the brackets - $47 shipped.

As usual - Stock bolts with blue loctite.
You'll need to source 1 x M10 bolt & nut for the third hole (fine thread preferred but not essential).
Stock line will work.
Stock Master will work.
Speedo Drive dust shield may need trimming by 4mm.

 

[posplayr]

Clean looking mod

 

[tkent02]

After riding a week, a few hundred miles…

Much much better than the original single front brake, but not quite as good as the twinpot Kaw setup on dual brake bikes. I would say it's about the same as the best dual brake bike with stock Suzuki brakes, and better than most of them. One or two fingers except for the absolute max effort braking riding two up takes three. I would prefer to have it a little stronger, so two fingers is all I would ever need, like the newer bikes. It does seem to be getting stronger as the pads bed in more, but it's not quite there.
I may try a smaller diameter master cylinder, could try better pads too. These are GG pads, but inexpensive ones. Not sure yet. Maybe just need stronger fingers.

On a 1000 I'd want to go dual brakes, on a 750 maybe, but on a 550 it seems fine to me, or just almost fine. If it were just a hair stronger it would be fine.

Overall I like it, it's a lot lighter than the dual brakes, or the original single brake. Don't have to buy different forks, just one disc, one caliper, one set of pads, one line.
It's that much easier and quicker to install.

 

[Guest]

I bet you're spoiled, now!

 

[tkent02]

I noticed the calipers are not located exactly right, a few mm of the pad is hanging off the side of the disc. A slightly larger disc would work better, I think 320mm instead of 310 would be perfect, but it might be a hair too big, might need to be turned down a tad. I don't know what discs are available in the correct offset.
I moved the master cylinder in on the bars about an inch, so now my finger hits the lever farther out from the fulcrum. Increased the braking for a given finger pressure quite a bit.
It's also getting stronger as the pads bed in.
I think a better design MC or even just a smaller bore MC would have it working very well.

Yeah, I'm spoiled.

 

[hotrodalex]

I've finally collected all the parts to do this upgrade and finished other more pressing projects, so hopefully next weekend I'll knock it out!

 

[hotrodalex]

I did indeed get it done that weekend, just haven't gotten around to posting about it.

- CBR1100XX Blackbird rotor from ebay
- front left caliper from a 2000 Kawasaki Concours ZG1000A from ebay, practically new pads included
- SS lines from Slingshot Cycles (http://www.slingshotcycles.com/GS550_c_95.html)
- Speed bleeder from Slingshot (SB7100)
- Stock master cylinder

And while I was at it, I replaced the wheel bearings too. Bike stops much better, although the MC seems to be on the small side. Lever travel is fairly long, but easy effort.

 

[salty_monk]

Just sent another single bracket set out yesterday... Looks like this variant is working well with the back corner of pad chamfered (to stop it building an edge).

 

[Guest]

I'm interest in doing this upgrade on my '80 550E, but have a few questions.

Is there a consensus on whether a 310 mm or 320 mm rotor is a better fit?

I know this information is somewhere on the forum, but would someone kindly post here what other calipers would work, besides the 2000 Kawasaki Concours calipers that hotrodalex used?

Is anyone happy with their master cylinder after doing this? Tkent02 says he would try a smaller one, while hotrodalex says stock might be too small.

Thanks for any help you can provide!

 

[salty_monk]

That is a Blackbird rotor. So far I am yet to find a 320mm that would work but it would be better as with this you need to file a chamfer onto the top corner of the pad so it doesn't wear to an edge (slight overhang).

You can get the brackets from me.

Yes that is the only caliper that works with the brackets.

 

[salty_monk]

From member Jabcb's research this should work:

I found MetalGear’s eBay store: https://www.ebay.com.au/sch/mgear2003/m.html

The 88-97 Honda NTV650 rotor: http://www.ebay.com.au/itm/MetalGear...-/162121183600
OD: 320mm
ID: 62mm
bolt circle: 78mm with 6 holes
bolt hole: 8.5mm
offset: 22mm

Doesn't look like it will need the rear hub spacer. The rotor won't be quite central in the caliper because the offset is slightly off but not enough that it will cause a problem (you get a similar mismatch when using the GS550 rotor on GS1000E GS1100E etc forks & plenty have run that for many miles).

 

[Guest]

Thank you!

So it sounds like the best fitment would be the 320 mm rotor from the 88-97 Honda NTV650 and the caliper from a 2000 Kawasaki Convours ZG1000A.

Maybe the rotor could even be modified with light grinding or a small spacer to get it perfectly centered in the calipers?

 

[limeex2]

Are there different calipers that will fit GS wheels? Calipers that squeeze from both sides would be superior. Probably would have reconfigure everything I suppose. Who makes a smaller 1/2 bore master cylinder? Most have 5/8 bores. I believe EX500's use them

 

[Guest]

I?m not a Honda expert. Honda?s designations for the NT650 & NTV650 are confusing.


EBC lists disc for:
Honda NT 650 J/K/L (Bros) 1988-1992 as MD1124LS which is 320mm
Honda NT 650 V2/V3/V4/V5 Deauville as MD1008 which is 296mm
Honda NT 650 VW/VX/VY/V1 as MD1008 which is 296mm
Honda NTV 650 J/K/L/M/P/S/T/V 1988-1997 as MD1021LS which is 316mm


https://ebcbrakesdirect.com/motorcycle/honda/nt-650-j-k-l-bros/1988-1992/36837

https://ebcbrakesdirect.com/motorcy...-all-three-sets-at-pad-change/2002-2005/36839

https://ebcbrakesdirect.com/motorcycle/honda/nt-650-vw-vx-vy-v1-deauville/1998-2001/36838

https://ebcbrakesdirect.com/motorcycle/honda/ntv-650-j-k-l-m-p-s-t-v/1988-1997/36840



I have an EBC catalog spreadsheet from 2008.
It lists the MD1124LS for models:
NT 400 Bros (NC25)
NT 650 J/K/L (Bros)


Also have an EBC catalog pdf from 2009.
It lists the Honda part numbers corresponding to the MD1124 as:
45120-MN8-000
45120-MN8-910


My local Honda dealer?s online parts manual does not list these two #s as valid.


cmsnl.com lists the two #s as valid.
The NT400 Bros 1988-1990 Japan uses 45120-MN8-000 or 45120-MN8-910
The NT650 Bros 1988-1990 Japan uses 45120-MN8-000 or 45120-MN8-910


From what I?ve found so far.
The Honda NT650 Hawk sold in the US uses a different disc.
I didn?t find any used NT400 Bros or NT650 Bros front discs on worldwide eBay.
Looks like the MetalGear 21-079-GL & EBC MD1124LS will both work.

 

[salty_monk]

Not much room for opposed piston Calipers... Twinpot sliding pin is about as good as it gets with any kind of safety margin

 

[Chuck78]

FYI I thought I recalled when mocking up twin pot calipers to custom fab a weld-on adapter bracket, that the 310mm rotors worked out perfectly IF the location of the relocated lower/rear mounting hole was altered slightly from where it needs to be for the dual disc 296mm location. I may recall the pad being right at the very edge of the rotor, but from what I recalled, a 320mm rotor would most definitely have close to 4mm excess rotor hanging off of the edge beyond the pads.

That has me very curious about this 316mm diameter rotor, although it seems to be only a non-USA model, as that NTV650 searched on eBay USA brings up solid rotors with a significantly larger center bore and bolt pattern. So unless one could cross reference the metalgear specs over to EBC, having one shipped from Australia is the best bet. It would be nice to find out if any US models used that particular rotor... So that we could source them used!

 

[Guest]

Thanks for sharing

Thanks for sharing

I did indeed get it done that weekend, just haven't gotten around to posting about it.

- CBR1100XX Blackbird rotor from ebay
- front left caliper from a 2000 Kawasaki Concours ZG1000A from ebay, practically new pads included
- SS lines from Slingshot Cycles (http://www.slingshotcycles.com/GS550_c_95.html)
- Speed bleeder from Slingshot (SB7100)
- Stock master cylinder

And while I was at it, I replaced the wheel bearings too. Bike stops much better, although the MC seems to be on the small side. Lever travel is fairly long, but easy effort.

I am in the process of buying a '83 GR650. Been thinking about rebuilding an older suzuki for sometime. As I start down this process will make sure to post my progress and share. Besides the carb rebuild, the brakes were going to be my second item to rebuild. Appreciate the info

 

[salty_monk]

There are a few guys running this setup now. You have to chamfer one corner of the pads to stop it wearing an edge where they don't touch the rotor but reports are good...

 

[salty_monk]

Bumping this for the guy looking for his 550. I do have brackets available.

 

[Rogerlinder]

Successfully converted my 1977 GS550. I did things a little different than standard went with a W800 master (12mm bore), MD1124LS 320mm Rotor and an EX500 caliper. The brake master was a bust, but the rotor worked out rather nicely. It’s the No drill original fork option that has been asked after many a time in this thread.

As some of you know salty_monks bracket has been successfully used on single disc GS550 or GS750’s to fit a 310mm 1998-99 CBR900RR rotor. The issue with using this rotor is pad overhang and you must drill it. BCD is correct, but holes are for 6mm hardware and The brake pad needs to be chamfered. The pads will touch each other as they wear. A potential alternative noted during the initial development was a Honda NT 650 or 400 bros rotor is 320mm, has the same BCD, offset, and was intended for M8 hardware like the GS. Not only does it solve the pad overhang issue (https://imgur.com/U91id2G) you don’t have to drill it. The rotor bolts right on and you can even use Hondas bolts (90105-KV0-700); they are same thread as the GS hubs. The only issue is that early speedo shields are too short to use without a rotor spacer, the Hondas rotor bolts felt too short to use with a spacer I reused the bolts I already had. But if you have a later model with a deeper speedo shield you likely won’t have to run the spacer and could use shorter bolts. With spacer, https://imgur.com/nKuejZY, and without https://imgur.com/1Q7RWtm

There are a couple of issues with this rotor, mainly price and availability. As far as I can tell very few NT BROS are in North America, saw one in Vancouver BC classified, couldn’t tell if it was an import or not. It’s very unlikely to find a used rotor. EBC and Metal gear (model number 21-079-A-GL) do make new rotors; I only saw them in Australia or Europe. When I asked an EBC distributor in the states, they said the EBC MD1124LS was discontinued but I neglected to check if that was just for the US, seem to be plenty on eBay at present. Price is going to be the other limiting factor the rotors are $200-300 shipped vs $130 for a single Arashi CBR900RR rotors. You end up spending around $70 to avoid drilling and chamfering pads, if you’re buying new.

Master cylinder was a bit of a bust. I was unable to find a rebuild kit for my master so I wanted something I could get parts for. The W800 and W650 both use a 12mm master, that looks the part, but it just doesn’t push enough fluid for 2 finger braking, pinky and ring finger got in the way. worked ok with 4 fingers but I switched back to the 14mm the bike came with for now. Another annoying feature of this master is a 34mm bolt spacing handlebar clamp, $34 clamp from Kawasaki. Most clamps have 32mm bolt spacing, I ran out of patience trying to find one and jury rigged it with a triple tree handlebar clamp from my bin of spares. Worked well enough to know it wasn’t usable.

Brake caliper came off a EX500, not much of note. If you’re redoing pistons and seals with OEM part look for a Suzuki rebuild set (59100-01831). It’s $75 for both pistons and all the seals vs $190 piecemeal from Kawasaki. The pin and piston seals are about the same price Kawasaki or Suzuki if your pistons aren’t corroded or you’re switching to stainless pistons, it’s not as big of a difference.

As for pads, I just went with a cheap NOS OEM pair I think for a concourse

The new rotor is 3lbs lighter than the original. 6.6lbs vs 3.6lbs

Calipers were both 3lbs.

This is an album of the previous photos:

https://imgur.com/a/gs550-twin-pot-mod-YSguVLJ
​

The brackets work with a nt bros rotor. (Honda equivalent P/N is 45120MN8000)

Edit:

took a 1982 GS650​ speedo shield (suppose any of the later models should work) cleaned and re-painted it. fits nicely,​ ended up shaving another 1/2 lb off the front end once I removed monks disc spacer
https://imgur.com/W9nZoHg​
​