Joined: Aug 2017 Posts: 1,533 Threads: 60
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Unless you're very lucky any second hand cast iron gear will probably have 50K+ miles on it.
I've never been convinced that in the 21st century matching gears up makes much difference
Charles
Joined: Aug 2017 Posts: 620 Threads: 7
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Location: queensland
Thanks Geoff and Chris, How much backlash taken at the perimeter of the cam gear would you deem as acceptable, between some and noisy? I have previously avoided/discarded on the basis of chipped and thin teeth.
Joined: Nov 2017 Posts: 562 Threads: 56
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Location: West Yorkshire
Car type: Type 65 1934 + RP 1932
"Oop North" doesn't pin you down too accurately, but I know Ian Bancroft at Grantham had a bucket load a wee while ago. Google "ian r bancroft restorations".
Joined: May 2018 Posts: 130 Threads: 12
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Location: Oxfordshire
07-10-2020, 02:53 PM
(This post was last modified: 07-10-2020, 02:57 PM by Geoff101.)
Edit: A check in the garage confirms that it seems to be both gears that are sized. I have a +1 and a -1 crank gear, as well as a +1.5 and a 'S' (whatever that is) cam gear.
Joined: May 2018 Posts: 2,105 Threads: 110
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Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Hi All
A few thou backlash due to mismatched gears may not make too much difference BUT if the gears are tight it can ruin your engine by seizing when it gets hot.
Do check that you do have some backlash right through the 360 degrees.
Cheers
Howard
Joined: Aug 2017 Posts: 1,462 Threads: 26
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Location: North Yorkshire
The only way to selectively fit original gears that will, inevitably, have a degree of wear is to fit them and look for any tightness or excessive backlash. Any + or - markings on the gears and/or the crankcase are more than likely to have lost their relevance by now. Any tightness is an absolute no no as they'll destroy themselves in quick time once running.
I wish I could help you, Mark, but I'm down to my last, spare, crankshaft gear.
Steve
Joined: Sep 2018 Posts: 134 Threads: 17
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Location: Oop North
Thanks for all the help & advice. I'll have another look this evening & see what we come up with.
Oop North is more specifically in the York area.
Thanks again, Mark F
Joined: Aug 2017 Posts: 984 Threads: 6
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Location: Scottish Borders
I think the size marking is only on the crankshaft gear. It should match the value stamped on the crankcase.
However after many years the numbers often no longer mean very much and it's best to select measuring the clearance.
Just replacing a damaged one check the size stamped on the gear and look for one close.
Jim
Joined: Aug 2017 Posts: 952 Threads: 38
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I have not seen a marked crank gear, I have loads of cam gears which are marked + or - or 0