GT550/GT750 4LS brake

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jabcb
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GT550/GT750 4LS brake

Post by jabcb »

There are no aftermarket brake shoes for the 4LS that are currently available.
But the ST400 Temper did use the 4LS front brake & Vesrah made the VB-331 brake shoes for it.

The VB-331 shows up on eBay from time to time, so I bought a few. They look correct.
Pic of shoes from my GT550 cafe project & VB-331:
Image

Interesting; a PO made grooves in the stock shoes. Not sure why.

Also if you are interested, there currently are more Vesrah shoes listed on eBay.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
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GT550 72 & 75
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jabcb
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Re: GT550/GT750 4LS brake

Post by jabcb »

The printed parts manual for the GT550 4LS brake:
Image

It shows an axle spacer adjacent to the axle nut.
Part #50 in the diagram, part # 09180-15019.
The online parts diagrams show the part but do not list it.

Also, the manual lists the part count as 2, but the pic doesn't show the second one.

Its NLA. Anyone know how thick this the spacer should be?
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
GTandcbr
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Re: GT550/GT750 4LS brake

Post by GTandcbr »

I have a 550 J drum brake. I dont have and never have had item #50. I had my OEM brakes relined with modern improved material(dont know what though just took them to a specialist in UK) The grooves in the shoes was a common practice by racers in an attempt to improve performance by cooling them down quicker.
EDIT just checked my parts book which is original and there is no trace of the part you mention
98 carb Blackbird and GT550j
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jabcb
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Re: GT550/GT750 4LS brake

Post by jabcb »

Thanks for the info.

Took a look at the manuals on OldJapaneseBikes.com
Ian, thanks for listing all this good info.

The GT550 shop manual has a parts diagram of the 4LS front wheel — part #50 of my diagram is not shown.
The GT550 parts manual shows one spacer listed as part #52 with the same info (part # & count of 2).

The GT750 parts manual (1974 edition) shows two spacers listed as part #20 with the same info (part # & count of 2).
The second spacer is on the other end of the axle.
The manual lists the spacer dimensions as 15.1x30x5

No doubt that the modern brake material will provide the best brakes.

There might be some interesting history behind my 4LS brake.
Some PO had used a center punch to mark the cam lever positions on the brake cams.

The second part #50 spacer seems unnecessary in that it just impacts the number of turns to tighten the axle nut.
The other part #50 spacer changes the wheel lateral location because it positions the hub further from the axle nut.

My GT550 is in bits, so I can’t check mine.
GTandcbr, is there enough lateral room so that your front end can be assembled with the part#50 spacers?
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
GTandcbr
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Re: GT550/GT750 4LS brake

Post by GTandcbr »

Hi, i think the answer is yes but it would mean the axle nut would sit more proud of the fork clamp. Like you i think the washer is not necessary. This is my hub rebuilt https://youtu.be/oOHbhaJwrc0" onclick="window.open(this.href);return false;
98 carb Blackbird and GT550j
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jabcb
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Re: GT550/GT750 4LS brake

Post by jabcb »

GTandcbr wrote:Hi, i think the answer is yes but it would mean the axle nut would sit more proud of the fork clamp. Like you i think the washer is not necessary. This is my hub rebuilt https://youtu.be/oOHbhaJwrc0" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Good video.

On your bike, is there a gap between either of the brake panels & the fork tubes?
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
GTandcbr
Yeah Man, the Interstate
Posts: 590
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Country: WALES
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Re: GT550/GT750 4LS brake

Post by GTandcbr »

Just took this photo does it help? As you can see there is a gap
Image
98 carb Blackbird and GT550j
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jabcb
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Re: GT550/GT750 4LS brake

Post by jabcb »

Thanks. This is an interesting little quirk from the way things were done back in the 70s.

I think my GT550 had a spacer on the left side. Vaguely remember thinking “what’s this doing here” when I took the front end apart. I tossed the part in a box of other stuff. Looked today & there is a 3mm thick “washer” with the correct OD & a slightly larger ID. Maybe 5mm in the GT750 parts manual was a typo, or a PO used a substitute part.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
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Re: GT550/GT750 4LS brake

Post by garyr »

OE brakes are sold here.. http://www.cmsnl.com/suzuki-gt550-1972- ... ml#results" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

The groves in those shoes were to stop squeaks and supposedly stop better. I would grind them into shoes back in the day.
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