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Shifting Issues on A65-T #712955
10/28/17 12:58 am
10/28/17 12:58 am
Joined: Sep 2014
Posts: 178
Ohio
A
Andrew Dunham Offline OP
BritBike Forum member
Andrew Dunham  Offline OP
BritBike Forum member
A
Joined: Sep 2014
Posts: 178
Ohio
Hi guys,

I just finished installing a NOS shift quadrant, but am having some shifting issues. Basically when I move the lever in either direction, it stays there. I have to force it back to "center."

I do not believe it to be the return spring. I believe the problem is something to do with the little spring loaded tabs in the quadrant mechanism that rest/slide on the open slots in the plate. Part numbers #1 and #39 in the image:

[Linked Image]

Here is an image of the "tabs" I'm speaking of: https://i.imgur.com/XJP4MJf.jpg

I lubed the springs and tabs during installation to ensure they moved easily. It seems like they are catching the slots and not letting them go.

Sorry for the lack of proper terms... any ideas?


1961 BSA Super Rocket
1968 BSA A50
1969 BSA 441 VS
1970 BSA Thunderbolt
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Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713002
10/28/17 4:02 pm
10/28/17 4:02 pm
Joined: Sep 2014
Posts: 178
Ohio
A
Andrew Dunham Offline OP
BritBike Forum member
Andrew Dunham  Offline OP
BritBike Forum member
A
Joined: Sep 2014
Posts: 178
Ohio
I think I found the issue. The plungers in the NOS quadrant stick out about .5mm further than the used piece. Shown here by the red arrow in the picture:

[Linked Image]

If I understand the mechanism correctly, the slotted sides allow the lever to return to the center position. Since they have that little extra flat area, they are sticking in the cam plate and thus requiring force to return to center.

I am going to disassemble each quadrant and try to insert the old plungers into the new quadrant.


This job turned into way more than I was expecting...


1961 BSA Super Rocket
1968 BSA A50
1969 BSA 441 VS
1970 BSA Thunderbolt
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713022
10/28/17 7:45 pm
10/28/17 7:45 pm
Joined: Aug 2001
Posts: 3,919
argyll. scotland, uk
gavin eisler Offline
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gavin eisler  Offline
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Joined: Aug 2001
Posts: 3,919
argyll. scotland, uk
The NOS part looks like a reject, the casting with the plungers protruding looks to be too short.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713027
10/28/17 8:25 pm
10/28/17 8:25 pm
Joined: Feb 2014
Posts: 1,096
Lancaster, California
C.B.S Offline

Parts Dealer
C.B.S  Offline

Parts Dealer
Joined: Feb 2014
Posts: 1,096
Lancaster, California
So was the issue fixed?

Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713030
10/28/17 8:54 pm
10/28/17 8:54 pm
Joined: Sep 2014
Posts: 178
Ohio
A
Andrew Dunham Offline OP
BritBike Forum member
Andrew Dunham  Offline OP
BritBike Forum member
A
Joined: Sep 2014
Posts: 178
Ohio
Unfortunately not, CBS.

I hadn’t even considered them being reject parts, Gavin. Perhaps that’s why I was able to find two of them...

I suppose my best option at this point is to have the splined shaft welded onto the original casting.

I will measure each casting to confirm.


1961 BSA Super Rocket
1968 BSA A50
1969 BSA 441 VS
1970 BSA Thunderbolt
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713059
10/29/17 4:55 am
10/29/17 4:55 am
Joined: Jan 2004
Posts: 3,727
ca, us
D
DMadigan Offline
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DMadigan  Offline
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D
Joined: Jan 2004
Posts: 3,727
ca, us
The centering spring in the outside of the timing case has to overcome the force it takes to push the pawls back into the quadrant. If the pawls stick out too far the sides of the camplate windows will hit the cylinder and not the angled portion of the pins.
The arms of the centering spring (17) cross each other to contact the pin (19) on the quadrant, yes? That provides the preload for centering.
Someone might have put the plate (42) that retains the pawls in the wrong way around.

Last edited by DMadigan; 10/29/17 4:56 am.
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713072
10/29/17 12:51 pm
10/29/17 12:51 pm
Joined: Sep 2014
Posts: 178
Ohio
A
Andrew Dunham Offline OP
BritBike Forum member
Andrew Dunham  Offline OP
BritBike Forum member
A
Joined: Sep 2014
Posts: 178
Ohio
You’ve nailed it, Dmadugan. That is exactly what’s happening.

Yes, the quadrant and return spring are installed and working properly. I have tried reversing the return spring as I read somewhere, but I couldn’t tell or see any appreciable difference.

Part 42 was my thought as well. I will give that a check today and measure the castings.


1961 BSA Super Rocket
1968 BSA A50
1969 BSA 441 VS
1970 BSA Thunderbolt
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713075
10/29/17 1:14 pm
10/29/17 1:14 pm
Joined: Aug 2001
Posts: 5,076
Stone Creek OH USA
R
Rich B Offline

BritBike Forum member
Rich B  Offline

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R
Joined: Aug 2001
Posts: 5,076
Stone Creek OH USA
I had a "new" shift quadrant for a unit single once that wouldn't shift the cam plate correctly. Turns out the POS was machined wrong and the plungers were at a different angle than the original quadrant.

I used the stub shat repair on the original, the "new" quadrant got trashed.....BTW, the stub shaft came from the "new" part before I tossed it.


Life is too short to drink cheap, bad beer.
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713094
10/29/17 5:09 pm
10/29/17 5:09 pm
Joined: Sep 2014
Posts: 178
Ohio
A
Andrew Dunham Offline OP
BritBike Forum member
Andrew Dunham  Offline OP
BritBike Forum member
A
Joined: Sep 2014
Posts: 178
Ohio
That's interesting, Rich. I (perhaps naively) hadn't even considered that the NOS units could be machined incorrectly as you and Gavin have pointed out. I was excited that I found some and it wasn't going to be a tedious job. Boy, was I wrong!

I think I have made a working solution, however. It took a fair bit of grinding with a Dremel and fitting over and over again. I ended up flipping the retaining plate (#42) upside down, even though I'm still not sure that's correct. It didn't fit immediately as when the raised sections were placed into the bore, they didn't quite fit. I took a bit of metal off the corners and sides so that the plate could sit flush and not interfere with the bore or the pawls. The working one is on the LEFT:

[img]https://i.imgur.com/wQUZLbo.jpg1[/img]
[Linked Image]
[Linked Image]

This took the most time. I had to do it several times to make sure I could get the bolt tight on the retaining plate while still allowing the pawls to work smoothly.

[Linked Image]

I have reassembled things temporarily to test and confirm that things are working properly and they seem to be. Fingers crossed.

Now I need to figure out if I've changed the timing in any way before reassembly.

Last edited by Andrew Dunham; 10/29/17 5:11 pm.

1961 BSA Super Rocket
1968 BSA A50
1969 BSA 441 VS
1970 BSA Thunderbolt
Re: Shifting Issues on A65-T [Re: Andrew Dunham] #713287
10/31/17 12:54 am
10/31/17 12:54 am
Joined: Mar 2006
Posts: 1,304
Magnolia, TX
htown Offline
BritBike Forum member
htown  Offline
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Joined: Mar 2006
Posts: 1,304
Magnolia, TX
Take a lot at how the shifting pawls are machined. In this picture the one on the right is aftermarket and the one on the left is an original part. Notice how the stop on aftermarket is cut on an angle. This causes the pawl to stick out further. It also doesn't snap back as easily. I have another set of oem's and they also have the 90 degree step. The gearbox on my 70 Thunderbolt is now apart because I couldn't get 3rd and 4th gear. Just noticed this. Also, I replaced a really worn camplate and plunger.
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1978 Bonneville T140E
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1971 Norton Commando
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1974 Norton Commando
2004 XL 1200R Sportster

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