Author Topic: Rigid 1948 A7 clutch  (Read 5882 times)

Offline Jim Griff

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Rigid 1948 A7 clutch
« on: June 16, 2009, 08:47:10 PM »
Hi all,

I'm after a bit of help regarding the clutch on my 1948 Rigid A7 longstroke. It has the original type of clutch fitted (the one with the pressed steel dome cover over the pressure plate). Can anyone suggest if a later type A7 or Triumph type will fit? The original Clutch  is a known weak area, so I want to improve it as best as possible.Any feedback will be gratefully received.

Also I'm looking for a replacement Front mudguard , non valanced, with a centre rib for this bike, as well as a bolt on side stand. Can anyone help?

Jim

Offline LJ.

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Re: Rigid 1948 A7 clutch
« Reply #1 on: June 17, 2009, 10:57:56 AM »
Hi Jim...

What you have is an early six spring dry clutch and should be a very good clutch for your bike! It is the later six spring clutch that usually gives trouble being of a cheaper nastier construction. I have the same clutch on my 1949 A7 long stroke and performs beautifully! I also have the late six spring in my 1960 A10 and is a constant pain!

Take a look at the clutch again and ensure that no oil can get into the dome, be sure that you have one of those nice teflon, nylon clutch cables, they really make a difference to the operation of clutch. Be sure your push rod is the correct length and the ends are well hardened. Setting up the plates to make them square takes a little time as with any sort of clutch.

I have also bolted on a side stand under my primary chaincase, take care as there is not a lot of room under there and damage could occur to the primary chain adjuster if the stand should ground while riding, but a sidestand is much better than pulling up the bike on that horrible swiveling centre stand.
Ride safely Lads! LJ.
*********
1961 BSA Golden Flash, 650cc A10 Blue
1961 BSA Golden Flash, 650cc A10 Red
1948 BSA Girder/Rigid, 600cc M21 Green
1949 BSA Star Twin,   500cc A7 Black
1940 BSA Girder/Rigid, 500cc M20 Bask

Offline Jim Griff

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Re: Rigid 1948 A7 clutch
« Reply #2 on: June 17, 2009, 09:36:57 PM »
Hi and thanks for the info. It's done 1500 miles since I rebuilt it a few years back, so maybe It's time I checked the adjustment. It did have some cheap, poor quality foreign friction plates in when I first bought it which came with the bike, which lasted about 400 miles before being chewed up. I've since fitted Proper Surflex ones, and had no problems.

I agree on your statement regarding the centre stand, horrible thing to operate. I've just refitted one to my T120 Bonnie after years without one and cannot believe the difference / ease of operation, the Bonnies is compared to the A7's. I guess it was BSA's first attempt at designing one, and didn't quite get it right!


Offline LJ.

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Re: Rigid 1948 A7 clutch
« Reply #3 on: June 18, 2009, 07:50:30 PM »
Quote
I guess it was BSA's first attempt at designing one, and didn't quite get it right!

Up until a day or two I would have agreed with you, but it seems that the very first centre stand on the A7 was of a ratchet hand lever design! Now what the heck that looks like I have no idea and would be grateful if anyone could point to any photos on the Internet or post some if anyone owns such a bike with stand. I cant imagine the first effort being any worse than what is on now.

Surflex plates are the way to go every time... they are expensive but... you get what you pay for.

Cheers!
Ride safely Lads! LJ.
*********
1961 BSA Golden Flash, 650cc A10 Blue
1961 BSA Golden Flash, 650cc A10 Red
1948 BSA Girder/Rigid, 600cc M21 Green
1949 BSA Star Twin,   500cc A7 Black
1940 BSA Girder/Rigid, 500cc M20 Bask

Offline L.A.B.

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Re: Rigid 1948 A7 clutch
« Reply #4 on: June 18, 2009, 09:00:54 PM »
Quote
Quote
I guess it was BSA's first attempt at designing one, and didn't quite get it right!

Up until a day or two I would have agreed with you, but it seems that the very first centre stand on the A7 was of a ratchet hand lever design! Now what the heck that looks like I have no idea and would be grateful if anyone could point to any photos on the Internet or post some if anyone owns such a bike with stand. I cant imagine the first effort being any worse than what is on now.

The very first A7s had a stand consisting of a spring-loaded telescopic tube contained within the frame seat tube.

The rider pressed down on the foot part of the stand in order to extend it to the ground, and a built-in ratchet mechanism held it in the down position.
A coil spring (also contained in the tube) retracted the stand into the seat tube when the ratchet mechanism below the seat was released by a lever on the seat tube.
 
While the design looked very good on paper, it didn't actually work well in practice, so was quickly replaced by a more conventional type centre stand.


There is a drawing of this early stand mechanism in Roy Bacons "BSA Twins and Triples" book. (pub. by Osprey)

« Last Edit: June 18, 2009, 09:07:33 PM by L.A.B. »
L.A.B.

Offline LJ.

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Re: Rigid 1948 A7 clutch
« Reply #5 on: June 20, 2009, 08:25:21 PM »
Thanks for that info Les...

I've also been told elsewhere that the ratchet mechanism got worn quite quickly enabling the stand to literally fall while riding, probably when hitting a bump or pot hole, so was withdrawn possibly because of those dangers involved.  :o
Ride safely Lads! LJ.
*********
1961 BSA Golden Flash, 650cc A10 Blue
1961 BSA Golden Flash, 650cc A10 Red
1948 BSA Girder/Rigid, 600cc M21 Green
1949 BSA Star Twin,   500cc A7 Black
1940 BSA Girder/Rigid, 500cc M20 Bask