Identification of 5sp gearbox in 1972 Dunstall and part search

A blown gearbox is probably the worst thing which can happen with a race bike. It would be on the ground before you could pull in the clutch - and pulling-in the clutch would not save you anyway. I am always very careful with gearbox internals.
 
I hope I'm not having another senior moment here, but the gear looks to me like a Quaife 5-speed layshaft fourth gear, not a second gear. This is a drawing I made of the early '70s Quaife 5-speed that came with my PR. I did it as I took the box apart, so I could manage to re-assemble it. You'll notice that the order of gears on the layshaft, starting from the right side, is 1st gear, 4th gear, 3rd gear, 2nd gear, and 5th gear. The later part number for it is A 1H1 17, and it is 19T. If I've got this wrong, ignore it, but it seemed worth mentioning.

I' also attaching some assembly instructions, just in case they are useful.

Ken

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Assembly Instructions P1 1200.jpg


Assembly Instructions P2 1200.jpg


Assembly View 1200.jpg
 
It’s a long shot, but I heard that Patrick Walker, of Works Racing, took over all the Quaife stock from Hemmimgs. Might be worth a call.

www.works-racing.co.uk

Works Racing

Home of Works Racing Ltd. Precision Engineering for the Motorsport & similar industries
www.works-racing.co.uk www.works-racing.co.uk
 
lcrken said:
I hope I'm not having another senior moment here, but the gear looks to me like a Quaife 5-speed layshaft fourth gear, not a second gear. This is a drawing I made of the early '70s Quaife 5-speed that came with my PR. I did it as I took the box apart, so I could manage to re-assemble it. You'll notice that the order of gears on the layshaft, starting from the right side, is 1st gear, 4th gear, 3rd gear, 2nd gear, and 5th gear. The later part number for it is A 1H1 17, and it is 19T. If I've got this wrong, ignore it, but it seemed worth mentioning.

I' also attaching some assembly instructions, just in case they are useful.

Ken

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So I am confused now. I am certainly no expert but had based it be second gear on this.
 
Gorio said:
So I am confused now. I am certainly no expert but had based it be second gear on this.
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lcrken said:
I hope I'm not having another senior moment here, but the gear looks to me like a Quaife 5-speed layshaft fourth gear, not a second gear. This is a drawing I made of the early '70s Quaife 5-speed that came with my PR. I did it as I took the box apart, so I could manage to re-assemble it. You'll notice that the order of gears on the layshaft, starting from the right side, is 1st gear, 4th gear, 3rd gear, 2nd gear, and 5th gear. The later part number for it is A 1H1 17, and it is 19T. If I've got this wrong, ignore it, but it seemed worth mentioning.

I' also attaching some assembly instructions, just in case they are useful.

Ken

View attachment 120876

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I went through all of the gear ratios and you are right Ken it is forth gear. I do feel a bit stupid having not noticed it before.
I guess once I have a gear box in stead of a box full of gears I will learn a few things. Thanks again for the info.
 
I am glad you have sorted that out. 5 speeds close ratio is all that is needed to help a Commando motor be very good. One of my friends said 'if you have a torquey motor, you do not need a close ratio gearbox'. That is total ignorance. It is the one thing which should be changed when using the Commando motor. With wide ratios, the drop in revs on up-changes exacerbates the throttle response problem, which is due to the heavy crankshaft.
 
lcrken said:
I hope I'm not having another senior moment here, but the gear looks to me like a Quaife 5-speed layshaft fourth gear, not a second gear. This is a drawing I made of the early '70s Quaife 5-speed that came with my PR. I did it as I took the box apart, so I could manage to re-assemble it. You'll notice that the order of gears on the layshaft, starting from the right side, is 1st gear, 4th gear, 3rd gear, 2nd gear, and 5th gear. The later part number for it is A 1H1 17, and it is 19T. If I've got this wrong, ignore it, but it seemed worth mentioning.

I' also attaching some assembly instructions, just in case they are useful.

Ken

View attachment 120876

View attachment 120877

View attachment 120878

View attachment 120879
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Gorio said:
I went through all of the gear ratios and you are right Ken it is forth gear. I do feel a bit stupid having not noticed it before.
I guess once I have a gear box in stead of a box full of gears I will learn a few things. Thanks again for the info.
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Pay attention to Ken's page about the outer cover areas marked A. Your gearbox may or may not have had the shaded areas relived. If not, it's recommended to prevent shifting failures into 1st and 5th gears.
Both of my 5 speed boxes needed a firm push to engage 5th while underway, so the modification was necessary.
 
Gorio said:
Hi. I am trying to find a replacement lay- shaft 2nd gear. It is in a 5sp box in a AMC case that came in a Dunstall 810 in 1972. The only markings on the gear are "H" and "19".
Wondering if you can help me out with any information as to who may have manufactured this box and if there maybe a source of spares?
I can send photos to anyone who would like to have a look.
Thanks
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I have some Quaife A1H117 gears used and new. PM me if you are interested.
 


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