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Just trying to see if it would be easy for a manufacturer to make a 42T rear sprocket/hub fit a QD A65 rear wheel.

This looks similar except for saying 5 holes and showing 6? Allan said the bearing is a mm or so different.

https://www.ebay.com.au/itm/NEW-BSA-A7-A10-B31-B33-B33-B34-QD-REAR-WHEEL-DRUM-SPROCKET-42T-42-TEETH/143416030644?hash=item216442f5b4:g:~noAAOSwxEldqwBd&frcectupt=true

If the later A65 bearing can be fitted and centre bolted in, it's just the brake plate. Could the alloy brake plate or drum be machined/filed to fit?

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

Using a 42T rear sprocket gives lots of options depending on what front sprocket is used.

21t-47t- 4.63-1 - 78mph @ 4,100rpm but vibes are there by then.
19-42 - 4.58-1 but not much different.
22-47 - 4.423-1 4100-82mph 75mph @ 3,756rpm which isn't too bad, making using 42T at the back less necessary.
20-42 - 4.35-1 @4100 83mph Not much different to above.
21-42 - 4.142-1 @ 4100 87mph, 62mph @ 2940rpm. 3,756rpm -80mph. My brother's 750 has this gearing and you would not want it lower. Though he does have a front disc. The Firebird front drum isn't great, though apparently can be improved quite a bit, if I knew exactly how to profile the cams.


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The 1964/65 Lightning was fitted with a 42T sprocket as standard, the part number is 67-6149. Burton Bike Bits normally have them in stock. Their version is finned but the original was not.. If you want to use the big bearing you will need to machine the housing. If you use this drum, you will need to use the steel brake plate 42-6030 as used on Gold Stars.


VicCyclone

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Originally Posted by VicCyclone
The 1964/65 Lightning was fitted with a 42T sprocket as standard, the part number is 67-6149. Burton Bike Bits normally have them in stock. Their version is finned but the original was not.. If you want to use the big bearing you will need to machine the housing. If you use this drum, you will need to use the steel brake plate 42-6030 as used on Gold Stars.

I think you’ll find the aluminium brake plate fouls the chain. You’ll want to use the steel plate as vic says but you may also need to machine that to take the fatter stub axle from the later bike. Alternately you might be able to machine the stub axel to fit the correct bearing and brake plate.

I know it’s a pain but I went through the same thought process when I did mine and in the end said sod it and bought all the correct bits.

Out of curiosity Mark, have you fitted a 22t front sprocket to any of your tamed beasts? I’ve just fitted one to mine and find the lower chain is close to the lower run of the case, I’m thinking of making a chain guide (either nylon or Delrin) to improve that clearance.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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I have not used a 22 and I have wondered about the clearance. People use them though. Raining here so I replaced rear brake shoes and took photos. Made another fitting to hold a second magnet on the front wheel to see if I can get the speedo correct. The fitting is pretty easy to make, and to think I was contemplating spending $3.80 for one and waiting.


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As noted above you can get the parts to make it work. My turbo bike has the 42. It was a bit of work but no machining. Pretty sure I just swapped the later hub to the 42 sprocket/drum. The details are fuzzy now but the bike uses a one piece axle. So far trouble free. With the 22/42 she has been to 166 mph with a bit more gearing left. Sounds like you are turning your 360 Beezer into a Harley to try and avoid the vibes. No doubt they buzz a fair amount. PRT
PS Great looking bike!!

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Originally Posted by VicCyclone
The 1964/65 Lightning was fitted with a 42T sprocket as standard, the part number is 67-6149. Burton Bike Bits normally have them in stock. Their version is finned but the original was not.. If you want to use the big bearing you will need to machine the housing. If you use this drum, you will need to use the steel brake plate 42-6030 as used on Gold Stars.
I actually bought a plain one from them. Not advertised, you have to request unfinned one.


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I chose the 22/47 route as 'everything' was available off the shelf, for exactly the reasons you outlined - the vibes start at around 4k rpm.

I am trying to gear my 72 A65 + A10 Crank + big bore kit, so it can cruise at between 70 to 85 before the vibes really set in. I didn't want to change out the back hub in order to keep it all looking 'stock'.

However, I share Allan's concern about how close the chain and lower case are. I was eyeballing using an old Delrin kitchen 'chopping board' as the basis for a chain guide.

However, that's not the issue you are talking about.

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I used Delrin as a chain guide on the H-D XR750 tracker here.


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Originally Posted by S-NJ-W
I chose the 22/47 route as 'everything' was available off the shelf, for exactly the reasons you outlined - the vibes start at around 4k rpm.

I am trying to gear my 72 A65 + A10 Crank + big bore kit, so it can cruise at between 70 to 85 before the vibes really set in. I didn't want to change out the back hub in order to keep it all looking 'stock'.

However, I share Allan's concern about how close the chain and lower case are. I was eyeballing using an old Delrin kitchen 'chopping board' as the basis for a chain guide.

However, that's not the issue you are talking about.

I run the equivalent ratio on my lightning And it pulls better than it does with 1 tooth less at the gearbox. There’s a lot of torque from a standard small port head (albeit less than a modified small port head) the 823 is more like 23:47 by virtue of the fact the belt primary gears it up equal to a tooth more at the gearbox. With the 104 (soft cam compared to the spitfire) should make it a nice tourer.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Originally Posted by Allan G
I run the equivalent ratio on my lightning And it pulls better than it does with 1 tooth less at the gearbox.

That's interesting. You are running the 22/47 ratio on the 650. No issues in traffic or pulling away ?
My only concern (other the the physical size of the sprocket and proximity of the chain to the cases)
was that the 1st gear might be too high to be comfortable in slow traffic. I don't get much of that here,
but it has been known.

Remember this magazine article, where the owner is running an A10 crank + a SRM big bore kit, plus
a 23 tooth rear sprocket, plus belt primary, plus a close ratio box ? Now, that's gotta be a PIG in traffic.

Mark, not trying to hijack. I think this would be of use to your OP.

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My 883 runs 21-36 final drive. It's C/r 5speed. The wheel's 17"

[Linked Image from i.postimg.cc]


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Why don't you just fit a 32 tooth engine sprocket and add another link to the primary chain.
That way you speed up the box and take a little torque loading off of it.
I ran a 33 but you have to use pre-stretched chains with that.
Anything to help the gearbox is a good thing on an a65 sidecar.............keeping it's speed up
helped a lot.

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ok not on topic really but see the nuts in Marks 2nd pic

those have got to be one of the most idiotic pieces of "engineering" ever to leave the factory !

they are a pretty critical component so what do they do ? fit a ridiculous 1/2 nut so close to the hub that the tip of the hex nearly touches , no way you can even get a thin box spanner on it , you cant get it really tight with a open ender either cause the spanner will sit at an angle on the hex flats ....all you can do is ruin a good spanner by bending the end or cut it off and use a hammer and a punch. I do like the lock straps though

Geniuses and Pinheads

how have others tightened these ?

33 tooth engine sprocket Mark ? surely thats a typo? 13 teeth bigger than std what am i missing?


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The standard is 28t Triumph used 29t. ENGINE sprockets.
Problem with late cases is the cast in alternator housing, i think you may get a 32 in there
with a little dremel work..... 33 may be too much. (I just machined the casting off.)
There is a standard 32 triplex on something , i can't remember where, may be a vinnie but you
have to machine the centres out and weld the outer on, not hard to do/get done.
33 raises the gearbox speed by 18%.
Easier to just get a duplex 32, they are readily available, duplex is fine on an a65 anyway.

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Hi

While not quite on topic. When I put the Commando clutch on my 845, its 57t one less than the A65. I managed to get a 29 A75 triplex front sprocket, which allowed me to go back to the 80 pitch chain. Just took the inside out of the A75 and the outside of an A65, shouldering them to get the correct alignment I wanted then welded them together. This took the primary ratio up to 1.966. As Nick said anything that will spin the box a little quicker is all good. Using the 29t was without any dremmel work, although I ended to turn the alternator round to bring the wires on the outside of the mounting lug, as on the inside they were to close to the teeth.

Stay safe

John

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Originally Posted by S-NJ-W
Originally Posted by Allan G
I run the equivalent ratio on my lightning And it pulls better than it does with 1 tooth less at the gearbox.

That's interesting. You are running the 22/47 ratio on the 650. No issues in traffic or pulling away ?
My only concern (other the the physical size of the sprocket and proximity of the chain to the cases)
was that the 1st gear might be too high to be comfortable in slow traffic. I don't get much of that here,
but it has been known.

Remember this magazine article, where the owner is running an A10 crank + a SRM big bore kit, plus
a 23 tooth rear sprocket, plus belt primary, plus a close ratio box ? Now, that's gotta be a PIG in traffic.

Mark, not trying to hijack. I think this would be of use to your OP.

The ratio is similar to 22:47 rear with a standard 28:58 primary. That would give a overall ratio of about 4.42:1

(Lightning)I have 36:70 belt drive primary and 19:42 (so no clearance issues on the 650) total ratio of 4.29:1 which is Taller still. I did run this with a close ratio box and on solo ride outs it was great fun, I started killing clutch cables though on group rides as I seldom got out of first. But I don’t have any issues with the tall gearing. The setup is quite torque’y so you don’t suffer so much with slow speed snatching.

The 823 will be 36:70 primary and 22:47, simply because I am using a conical hub. A disk rear end would give endless choices like mark has with the 880. But I’m trying to keep it looking stock. I used to ride
A thunderbolt which was 650 but had 22:47. I don’t remember if this had anything to support the chain but it never gave any issues. Total ratio for this bike is 4.15:1

To put it in the real world, my Lightning will do 70 at exactly 4000 rpm. (That’s with a rolling 80.5” rear wheel circumference as measured)

The 823 will be doing 3850 at 70mph

I did try running a 21:42 And the belt primary on the 650 Lightning at one point just too see what it could do, though the first 2 gears were fine there wasn’t enough guts to pull the bike in 4th. And barely enough in 3rd.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Originally Posted by Allan G
To put it in the real world, my Lightning will do 70 at exactly 4000 rpm. (That’s with a rolling 80.5” rear wheel circumference as measured)
The 823 will be doing 3850 at 70mph

My '69 Lightning was doing about 4200 rpm at 70, so I think it was the (standard?) 19/47 combo.
I also think that the 22/47 combo on the A65 I am building now will be similar to your 823 with 3800 at 70mph.
As I said, trying to drop the cruising speed to below the vibration band.

Mark - the downside to the 22 tooth rear is that you need to split the cases to fit it. It won't fit through the panel
behind the clutch basket. I think Allan said he knew of someone who took the ubiquitous rotary tool to the cases
to make it fit, but I don't know that for a fact.

Steve.

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Originally Posted by NickL
The standard is 28t Triumph used 29t. ENGINE sprockets.
Problem with late cases is the cast in alternator housing, i think you may get a 32 in there
with a little dremel work..... 33 may be too much. (I just machined the casting off.)
There is a standard 32 triplex on something , i can't remember where, may be a vinnie but you
have to machine the centres out and weld the outer on, not hard to do/get done.
33 raises the gearbox speed by 18%.
Easier to just get a duplex 32, they are readily available, duplex is fine on an a65 anyway.


ok Sorry /.. im loosing it a bit bro .........ive been messing wit pre unit gear boxes a bit latley and the brain was in that mode and i was thinking of the final drive sprocket behind the "trap door" on the a65 ...the one that drives the secondary chain ....thats why i couldnt visualize a 33 t on there ........motor sprocket could be bigger but yeah it would sure need a bit of reliving of the casing etc


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Originally Posted by S-NJ-W
Originally Posted by Allan G
To put it in the real world, my Lightning will do 70 at exactly 4000 rpm. (That’s with a rolling 80.5” rear wheel circumference as measured)
The 823 will be doing 3850 at 70mph

My '69 Lightning was doing about 4200 rpm at 70, so I think it was the (standard?) 19/47 combo.
I also think that the 22/47 combo on the A65 I am building now will be similar to your 823 with 3800 at 70mph.
As I said, trying to drop the cruising speed to below the vibration band.

Mark - the downside to the 22 tooth rear is that you need to split the cases to fit it. It won't fit through the panel
behind the clutch basket. I think Allan said he knew of someone who took the ubiquitous rotary tool to the cases
to make it fit, but I don't know that for a fact.

Steve.

The old thunderbolt I used to ride with the 22t was a gearbox out job. Recently I saw a post on Facebook where someone had cut the casing to accept the 22t, so I did the same with mine. Popped the sprocket in place, drew it out on the case and cut away. It looks a bit of a sows ear if I’m honest, you have the problem where some of the teeth line up with the original cut outs for the 21t, others do not and it stops looking like teeth cutouts and more like the Cork and Kerry mountains. But it works... or least it does with a dry clutch. 2 of the teeth utilise the same position as 2 of the trapdoor screw holes. So I put the other 4 back with a drop of loctite. There’s no oil in my clutch so leaving two holes exposed isn’t the end of the world.

(I did later dress the cutouts up a bit nicer than they are in the photo)

[Linked Image]

I also drilled And tapped 2 holes in the sprocket for 1/4unf. Just in case it’s a bit of a pig to slide out in the future. I can attach a simple sliding jaw puller

Also if using the 22t you will need to remove some of the hex from the plunger retaining bolt head. I bought a heavy duty DID chain for mine. I think it’s actually as aside as the vx530 chain. But the sprocket wouldn’t turn unless this had been ground away.

Last edited by Allan G; 01/27/21 5:07 pm. Reason:

Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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Yikes! I didn't realize that you lost some of the trapdoor screws. Those you can see look pretty marginal now.
I was going to fit a gearbox shaft 'outrigger' support bearing which uses that trap door. I guess I will just live with
the knowledge that it's a 'split the cases' job to pull the sprocket.

I went back and re-read that magazine article I linked to previously. The text also mentions a custom chain tension
set up. I wonder where the 23 tooth sprocket came from.

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is it possible to fit a 22 tooth sprocket if the gearbox mainshaft and sleeve gear pinion are stripped out, marginally less hassle than lifting barrels and splitting the case?


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I believe SRM will do up to 24t, god knows how that fits in. I’m surprised the 23t does to be honest. It’s one thing being able to pull the tall gearing but it is another thing having a low enough first gear ratio where your not constantly working the clutch.

You wouldn’t have to split the cases... just remove the gearbox.

There are 2 decent trap door screw holes at the top of the case, two are marginal and the ones around 6 and 9 o clock position are those that I didn’t bother with.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

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I'd sooner have an outrigger bearing than slightly taller gearing on any a65.
Cutting away all that area will make fitting an outrigger much harder.

The crap overgrown c15 box which is what the a65 has, was over it's limits
on standard engines, putting another 20%+ torque through it AND slowing
the box down without an outrigger is daft in my opinion.

Last edited by NickL; 01/27/21 11:54 pm.
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HI

Plus 1 on what Nick has just said about the outrigger Brg. Even if its the mainshaft that is running on the outrigger Brg. My five speed replaced the bush on the output gear with a lip to carry the outrigger Brg, with the mainshaft running on two needle Bags in the output gear.

regards

John

Last edited by JER.Hill; 01/28/21 7:11 am. Reason: typo
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The fact that you can push one of the chains and watch the other move shows the value of that outrigger. Something the Firebird has not got. But I need to get. I made one that was a little wide to fit but PES make them and I've just asked them about having an oil seal.



https://www.ebay.com.au/itm/223926456392

I have a bearing plate outside the alternator on both my bikes, but it would be nice if they were manufactured.


mark
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