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Rear Brake Stop Plate on D1
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Postie
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September 12, 2020 - 3:14 pm
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Afternoon folks,

     I hope everybody is well and coping with these difficult times.

     For some time now I have been using my GPO Bantam with the rear brake pedal sticking up at an unacceptably high level , it has got worse. in truth it is quite dangerous so I have decided to take the engine out and get to the root cause of the problem.

     I have found, as expected, that the bosses holding the stop plate have become loose from the bottom frame tube and will need brazing. At the moment  the nearside boss is very loose and the offside one not quite as bad. The stop plate has become twisted.

     I suspect when in the correct position the stop plate should sit at right angles to the bottom frame tube and the two bosses should be in the same horizontal plane as the bottom frame tube. ( I hope this makes sense).

     I would be grateful for any advise with any measurements if any body deems them to be crucial.

     I presume the parts should be brazed as it is unsuitable for welding.

     Many thanks, keep well and ride safe.

     Cheers Mick

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GlenAnderson
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September 12, 2020 - 5:21 pm
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Yes, the plate should be straight. The bit of the pedal arm that hits the plate also wears away (as does the plate), making the pedal sit too high too. 

The frame, and this bit of it in particular, is a pretty marginal piece of design that’s prone to damage in even a minor accident. The factory made a big thing about the frame being of “all welded construction”, gas welding in this case. Brazing would definitely not be a suitable way to repair it, even if you could get it clean enough to do so. 

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Postie
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September 13, 2020 - 2:53 pm
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Many thanks Glen,

Yes I have had two stop plates in the past 25 years and , as you say, they are subject to wear which alters the brake angle.

I was told I should braze the damage but I will now gas weld ( or get someone with a gas welder to do it) in view of what you say.

Keep safe and keep the bike wheels turning.

All the best Mick

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GlenAnderson
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September 13, 2020 - 9:00 pm
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No problem Mick. Hope you get it sorted. 

If you click on my profile, and search my threads, I have had to carry out some fairly extensive repairs in the same area on my D3. 

All the best, Glen. 

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Postie
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September 15, 2020 - 8:31 pm
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Thanks Glen I will look at your profile etc as you suggest.

Another "welding" issue. The nearside rear hub mounting lug is, I presume of cast iron and can be very difficult to weld. The lug onto which the rear hub cover plate slides is worn causing a distinct knocking noise when I brake as it is not a snug sliding fit. Is it possible to put some weld on this protruding lug then file it down until the cover plate fits over it? The amount of metal which would be left on the lug after filing would be miniscule.

Thanks again, keep well and ride safe.

Cheers Mick

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Postie
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September 15, 2020 - 8:48 pm
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Thanks Glen,

I found the pictures in your thread - nice neat bit of gas welding to the lugs on the frame.

 

Cheers Mick

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GlenAnderson
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September 15, 2020 - 10:02 pm
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Hi Mick. 

Is your bike a plunger or a rigid? The rigid frame bikes’ lugs are steel, the same as the rest of the frame, and can be easily built up with weld and reprofiled. I’m not sure about plunger ones, but I’d doubt that they’d be cast iron; more likely to be cast steel, and you should be able to weld that too. 

It might be easier to build up the brake steady plate than the frame. Indeed, the wear is likely to be in both items, so maybe a measure/comparison of the unworn part of both pieces will show where best to focus your efforts. 

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Number6
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September 16, 2020 - 4:27 pm
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On the plunger it's part of the LHS clamp on the suspension slider tube that holds the wheel spindle, I very much doubt that all that is mere "cast iron".  Or I hope not!

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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Postie
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September 19, 2020 - 1:45 pm
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Many thanks folks,

Mine is a plunger.

My mistake I meant to say "cast steel" not "cast iron".

Surprisingly the wear is mainly on the rear hub mounting lug not the rear hub cover plate. I will put a spot of weld on the lug and file it back to fit.

Keep well, ride safe.

Cheers Mick

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Ringting
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September 25, 2020 - 4:58 pm
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Hi Mick. I had the beginnings of this problem with my D1 plunger when I bought it. I did what I'd like to call a "quality" bodge as I didn't want to take the engine out at that stage. Thing is, 10 years later I've still had no reason to so it's still there. My mounting lugs had just twisted backwards but were still secure on the frame. To stop them bending any further I made a new plate to bolt across the 2 mounting lugs that was wide enough to re-position the brake lever and centre stand and added another plate, welded on, to extend it backwards to sit on top of the frame tube under the gearbox. This has a short piece welded across it with a hole drilled each side and then a "U" bolt from an exhaust clamp going around under the frame tube. A piece of ally stops the "U" bolt digging into the frame. 

This is too late to fix your problem but it might be worth doing something similar to stop it happening again and it may help someone else. The cause of the problem is that every time the bike is put on it's stand, that plate gets whacked by the stand stops. Add to that, if someone sits on the bike while its on it's stand, those lugs are simply not strong enough to take the strain. My bike sits nicely on the stand and I've adjusted the brake lever to where I want it.

A picture paint a thousand words.  Cheers, Alan.Img_2359.2.jpgImg_2362.2.jpgImg_2369.2.jpg

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D1, D14/4, Guzzi LeMans, Triumph Trident 900, Maserati 160 t4. Mk1 Mini Traveller, Berkeley T60.

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GlenAnderson
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September 25, 2020 - 7:32 pm
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That’s a good solution. I intend doing something similar. 

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