Dual Leading Shoe upgrade for 82-84 PE175?

[Chuck78]

I was searching for the elusive RM dual leading shoe (or twin leading shoe) front brake plate assembly with no luck, all that turns up are the ones that have no cable housing stop on the brake plate - they had a cable housing stop on the fork, with a long length of exposed cable that will apply the brake the moment it snags a stick or branch or bush or brush... Not ideal for a motocrosser, DEFINITELY not ideal for an enduro/woods bike, and requiring modification of the plate for a cable housing stop, or the appropriate 1983 forks with the cable housing stop on the fork:

I came across a ThumperTalk topic of "Drum brake question, Dual vs Single Actuator" and noticed a photo of a DLS setup with a slightly different Dual Leading Shoe lever arrangement than the Suzuki RM's had.  I read further, and the owner said he retrofit his (Honda) CR with a (Yamaha) YZ Dual Leading Shoe brake setup, housed in a Suzuki RM250 hub:

So of course I had to dig up the EBC catalog and flip back and forth for 25 minutes, taking notes on bike models, pad numbers, dimensions, and bike models between PE's, RM's. IT's, & YZ's

So the 82-84 PE175 with the bigger 38mm forks uses a 130x22 front drum, same as the RM's of that era that used the dual leading shoe setup!  The earlier 80-81 PE175 uses the wider 130x28 drum/shoes, FYI.  The PE250 & 400, all years, use a much larger 150x28. 

Well it turns out that EBC shoe #508 used on all the Yamaha IT and YZ dual leading shoe brakes is a 130x22 same as the 82-84 PE175 and RM models!

So in the photo above, I'm going to assume that guy is running the same bearing sizes as stock in the RM hub, and the brake plate is not drilled out for a larger size axle etc... Does this mean that a Yamaha brake plate is compatible with the PE/RM hubs? And also very importantly - is the brake plate to fork leg interface slot the same between the two makes of DLS brake setups???

EBC  brake shoes # 508, 130x22 DLS, fit:

84 YZ125L

83 IT250K

82-84 YZ250J/K/L

81-82 IT465H/J

80-81 YZ465G/H

83-84 IT490K/L

82-84 YZ490J/K/L

Since the Suzuki dual leading shoe brake plate assembly with the integrated cable housing stop is so difficult to find, I was hoping that perhaps these very prevalent Yamaha examples would be a direct fit.  The notch/groove in the brake plate raised portion for the interface with the fork leg is the critical part here.  Can anyone verify if this in fact is a direct fit for the 38mm and 43mm Suzuki PE and RM forks?

[ESR80PE]

You can put a cable stop on the plate. machine one u out of steel with a male thread. Drill and thread hole in plate and add a lock nut on inside. Possibly with a stiffening piece on inside of plate to add thickness too. If you can find someone who's good at welding magnesium you could have one welded onto it as well but the stock ones were always known for breaking anyway so a bolt on steel part would be better in long run i reckon.

I think you need the matching 43mm RM forks to run this RM plate though. I am pretty sure the lug angle is different on the PE forks.

I am interested with that schrader valve coming out the bottom of that fork. Thats strange.

Yamaha has 15mm front axle. If you come across mis match of 12 v 15mm sizes that's an easy fix. That would be least of my worries if i was doing this swap.

If you go the yamaha plate route the one you want is the one with the plate slotted at 45deg. That one will fit PE forks.

Possibly you may strike a minor issue of the lug thickness on yamaha forks vs suzuki forks being 1 or 2mm different and if thats the case that is easy fixed by milling down the fork leg lug a little or milling out the slot in the plate. What ever is needed. From memory Suzuki and Yamaha all uses 17mm thickness lugs on the forks though but dont quote me. I am only 99% sure on this from the stuff i have investigated when i was trying to ID some mystery aftermarket KYB forks i have. I found that all the Yam and Suz forks had same luck thickness. So in the end i gave up trying to find the right brake plate for it and i am just getting the lug milled down 1mm so then i can use any suzuki brake plate i want.

From memory the yamaha TLS plate will work with 130mm suzuki hub. I am pretty sure  a friend did this mod and i bought a yamaha plate with plans to do the same mod.

[Chuck78]

Some info borrowed from the Oz VMX forum, with some PE info added:

The RM125 X,Z,D & use a EBC 602 @ 130x28 mm

The RM250 & 465 X,Z use a EBC 621 @ 150x22 mm

The RM125E & RM250/500 D,E use a EBC 622 130x22 mm

The PE250/400, all years, use EBC 605 150x28mm

The PE175 T/X 80-81 use EBC 602, 130x28mm

The PE175 Z/D/E/ 82-84 use EBC 618 130x22mm

(sorry, didn't look up the 78-79 PE175)

Suzuki brake panel assembly part numbers:

1985 (F)
RM125, 250, Disc Brake

1984 (E)
RM125, 250, 500 Twin Leading 54400-14840

1983 (D)
RM125 Leading/Trailing - 64400-40810
RM250, 500 Twin Leading - 54400-14840

1982 (Z)
RM125 Leading/Trailing - 64400-40810
RM250, 465 Leading/Trailing - 54400-14860

1981 (X)
RM125, 250, 465 Leading/Trailing - 64400-40810

[Chuck78]

Dec 16, 2019 6:51:01 GMT ESR80PE said:

You can put a cable stop on the plate. machine one u out of steel with a male thread. Drill and thread hole in plate and add a lock nut on inside. Possibly with a stiffening piece on inside of plate to add thickness too. If you can find someone who's good at welding magnesium you could have one welded onto it as well but the stock ones were always known for breaking anyway so a bolt on steel part would be better in long run i reckon.

I think you need the matching 43mm RM forks to run this RM plate though. I am pretty sure the lug angle is different on the PE forks.

Yamaha has 15mm front axle.

If you go the yamaha plate route the one you want is the one with the plate slotted at 45deg. That one will fit PE forks.

So the RM DLS brakes aren't compatible with the PE fork interface lug? I'll have to look at the 82-84 PE175 brake plate to compare to the RM and YZ/IT brake plates on ebay. That was one thing that I did not think of, I figured PE and RM would be the same in those Full Floater years/versions. Thanks for chiming in, Leith!

[Chuck78]

From what I'm seeing, the RM and PE fork lug / brake plate lug interface are the same between the DLS RM brakes and the PE175 82-84:

 

EDIT - now I see what Leith is mentioning about the 45 degree lug... the  lug on the fork is still straight out radially from the axle, but it is angled down more in relation to the fork tube, which positions the levers in a slightly different arrangement.  So running the RM brake on the PE fork may work, but the lever will be angled down significantly more, and in harm's way of branches, brush, etc. & The cable will be looped a bit more extreme to the front, & lower. Hopefully the length would be okay.

82 PE175 plate vs 84 RM DLS plate:

I believe 83-84 were the only yellow PE175 forks, correct? 82 was silver, and the 36mm 78-79 and 80-81 were silver? So this is an 83-84 if I'm thinking correctly:

Yes the brake plate lug is at an angle to the fork leg, but it is radially straight out from the axle center, as it is on both of the brake plates in question. 

If it were vertical on the fork, then the brake plate would have the lug interface slot offset to the right of the axle hole center. 

So I'm thinking that it is likely a direct fit-up on the RM at least, perhaps the IT/YZ plate if the interface slot/lugs are the same widths. 

Now I am questioning the axle sizes... I will have to compare the RM vs PE, vs IT. I believe Partzilla etc gives bearing dimensions for their wheel bearings.  

[Chuck78]

Dec 16, 2019 6:51:01 GMT ESR80PE said:

You can put a cable stop on the plate. machine one u out of steel with a male thread. Drill and thread hole in plate and add a lock nut on inside. Possibly with a stiffening piece on inside of plate to add thickness too. If you can find someone who's good at welding magnesium you could have one welded onto it as well but the stock ones were always known for breaking anyway so a bolt on steel part would be better in long run i reckon.

I was thinking of how to add a cable stop lug to the plate, but I am not sure if the location of the OEM stop on the 84 plates were going to pose a clearance problem with the shoes on the inside, where it would have to be nutted/bolted on.

And yes, my '77 PE250 rear brake plate actually was broken off here where the cable housing stop lug attached. I bought a used one to replace, but then ended up getting a 78 RM400 floating rear brake plate anyways...

I am uncertain of the strength of bolting something onto the casting, without having the casting and a pair of shoes here in front of me. 

I was thinking that if i did get one with the cable stop built in, that perhaps I would clean it up, sand around the lug, and then use some JB Weld to form a reinforcing area built up around the cable stops.  Then perhaps it would stiffen it enough that I wouldn't have to worry about it breaking in the future. 

[Chuck78]

One last concern - with dual leading shoes, how much hill holding ability do you really lose?
In my experience even with disc front brakes, the strength of the brake doesn't really matter, as the steep hills prove the front brake almost useless, as the wheel will lock up, but all the weight will be off the front and onto the rear, and the front tire will just skid backwards without rotating... I suppose on a less steep hill, this lack of traction would actually be able to test the brake a bit more, and in those scenarios, the Dual Leading Shoe setup may be not so great. But on the not so steep hills, I don't see if being too much of a problem.
Most of my experiences on the disc front KDX, trying to hill-hold, were on failed hill climb attempts, and all were very steep hills that would not allow any backsliding front wheel traction anyways.

Any additional feedback on the lack of backwards braking power for hill holding on a Dual Leader?

[Chuck78]

As far as the brake cable housing stop lug on the brake plate, location vs the back side of the earlier more prevalent 1983 RM250/500 brake plates, it looks like perhaps it would be possible, but I'd want to make a longer lug with 2 bolt-on points perhaps slightly offset from the path of the cable, and I'd make an aluminum backing piece that fit into the reinforcing ribs on the inside of the casting areas.  Then, I don't know why this keeps coming into my head, but it seems a viable solution to the magnesium issue, fill in the hollow casting area between the webs in this vicinity with JB Weld, to stiffen it and permanently attach the threaded backing plate section of the added cable stop.

Photos:

vs:

[Chuck78]

Well, it looks as if the YZ465/IT465 Twin/Dual Leading Shoe brake plate is the #1 choice, as most of the other Yamaha plates have the fork interface lug / slot positioned at the wrong angle, which would rotate it further down than the 84 RM plate which was already at or beyond the acceptable limit of a lever angle hanging down into oncoming brush/trail hazards. The only question left is whether or not it will be easily fit or easily slightly modified to fit the 38mm 82-84 PE fork.
Thanks to Leith for pointing out this info that there are 2 distinct versions of the Yamaha.

also, Leith pointed out that the second half of the Suzuki part numbers for bearings, the four digits after the hyphen, generally are the industry standard bearing number, so if dimensions are not listed on the parts page, you can just look up the industry standard number. Although one of them was an obsolete and superseded industry number, they changed the format, the size was not obsolete, just the industry-standard number that was used in the Suzuki part number changed to a 22__ instead of a 15__.

So... This led me to discover that the 38mm fork '82+ PE175 wheels used a 15mm i.d. 6202 bearing, same as the '84 RM dual leading shoe brake/wheel, & the Yamaha IT/YZ dual leading shoe brake/wheel. I will have to do a little bit more checking just to verify 100% of that the early IT465 / YZ465 still used the 15 mm i.d., but I believe Leith confirmed from memory that they do.

[Chuck78]

I just picked up an IT465 brake plate for test fitting on my Full Floater PE fork... Awaiting it in the mail. I'll re-poston how that looks to work out 👍

[ESR80PE]

I have a Yamaha TL plate too that i considered fitting to a 130mm suzuki hub. I did not try it on a 82-84 PE hub but i think with some fiddling it could work on 78-81 type. i don't think it will be bolt on an go, It needs machining work to set up so the brake shoes contact the drum at the right depth, stuff like that.