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Early or late A65 con rods? #786004 10/01/19 7:10 pm
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Jan Hellinge Offline OP
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I’ve read that there is some difference between early and late A65 con rods and the late is best. How can I identify late rods? I think I read that they are heavier but what should they weigh in that case?

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Re: Early or late A65 con rods? [Re: Jan Hellinge] #786008 10/01/19 7:24 pm
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gunner Offline
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I don't know what the weight difference is but the later rods introduced for the 1970 onward models should have a casting mark of 71-1112, 71-1105 or 71-1106. They certainly look a bit stronger than the earlier rods and might need the crank re-balancing.

If you can afford it might even be worth getting some after market rods such as MAP or Carillo.

The MAP website has some info on their conrod weights Here

Last edited by gunner; 10/01/19 7:29 pm.

1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: Early or late A65 con rods? [Re: Jan Hellinge] #786012 10/01/19 7:34 pm
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MarcB Offline
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Oil holes were added to the left-side rod in '65, I think.

See this post by Rich B: http://www.britbike.com/forums/ubbthreads.php/topics/269507/re-a65-con-rod-oil-holes#Post269507

The entire thread is good to understand whether this is necessary, and how to make best use of this feature.

Re: Early or late A65 con rods? [Re: Jan Hellinge] #786015 10/01/19 7:53 pm
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Ignoramus Offline
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the very last of the rods 71/72 ? had been shot blasted to "harden up/smooth out/consolidate " the surface ........worth getting those if you can , but might not be that easy.


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Early or late A65 con rods? [Re: Jan Hellinge] #786016 10/01/19 8:04 pm
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Andy Higham Offline
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71/72 rods are over 47 years old, how many times have they been over revved or otherwise abused? Do you really want to put those in a newly rebuilt engine? If a rod breaks it will trash the cases, barrels, pistons and possibly gearbox and head.
Rods should be treated as consumable items like bearings, clutch plates and chains


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Re: Early or late A65 con rods? [Re: Jan Hellinge] #786021 10/01/19 8:27 pm
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Ignoramus Offline
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well Andy I suppose I really should have said NOS .......but I kind of thought i implied that when i said ".worth getting those if you can , but might not be that easy."

and sure i would use some 2nd hand ones if i had them X rayed and checked for ovality of the big end

the poster asked what were the differences, i answered him

Last edited by Ignoramus; 10/01/19 8:29 pm.

"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Early or late A65 con rods? [Re: Andy Higham] #786023 10/01/19 8:35 pm
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Shane in Oz Online Content
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Originally Posted by Andy Higham
71/72 rods are over 47 years old, how many times have they been over revved or otherwise abused? Do you really want to put those in a newly rebuilt engine? If a rod breaks it will trash the cases, barrels, pistons and possibly gearbox and head.
Rods should be treated as consumable items like bearings, clutch plates and chains
Yep, and if you're going to fit NOS rods it's best to go with the later type. A70 rods have a steel cap and were also fitted to some 1971 A65 engines.

Alternatively, there are a number of aftermarket high performance rods available.
MAP or Carrillo as gunner pointed out
SRM
Thunder Engineering. Allan Gill put me onto these a while back, and they appear to be excellent quality at a reasonable price.

Re: Early or late A65 con rods? [Re: Jan Hellinge] #786024 10/01/19 8:50 pm
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gavin eisler Offline
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Ive weighed a bunch of A65 rods, later are heavier and have a thicker "I" section near the small end.
Weights were all over the place, out of 6 I had one close pair , some with an ounce or more difference, I think the grew more than once from 63 to 71.

I am still waiting for my 1970 rods to break.
A65 rods usually break when the timing side bush fails, I have an end feed. New rods are probably a good bet. I have lost at least an ounce worrying about my old ones.


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Re: Early or late A65 con rods? [Re: Jan Hellinge] #786029 10/01/19 10:29 pm
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NickL Online Content
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The late steel capped rods are the best, as an option
you can use T140 rods and have them bored to suit.
Although now it's cheaper and easier to just fit a pair
of those MAP steel ones. The later alloy beezer rods
were shot peened, a good move.
It's all the rage to have your crank dynamically balanced
now so the small weight difference of using steel rods
can be balanced out.

Like Gavin i'm also waiting for my 1972 ones to break.
Despite the last of the a65's supposedly having steel
capped rods, my '72 doesn't. They fitted what was in
the stores, must have been all alloy that day.
Following the advice that they should be renewed due
to age, i suppose you'd better look for a new set of cases
and a crank and cam too eh? They may have 'metal worm' too.

Re: Early or late A65 con rods? [Re: NickL] #786042 10/02/19 12:18 am
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Shane in Oz Online Content
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Originally Posted by NickL
Despite the last of the a65's supposedly having steel capped rods, my '72 doesn't. They fitted what was in the stores, must have been all alloy that day.
Yep. Apparently some of the OIF A65s had steel-capped rods. As you say, it would have depended on what came out from the stores. With any sort of luck they came as pairs and not 1 of each smile

Originally Posted by NickL
Following the advice that they should be renewed due
to age, i suppose you'd better look for a new set of cases
and a crank and cam too eh? They may have 'metal worm' too.
It's more to do with the number of duty cycles rather than age. Connecting rods alternate between compression and tension.
Crankshafts are drop-forged steel, and I think camshafts are as well. Steel can handles at least an order of magnitude more duty cycles than Aluminium alloys can. Having said that, the last 3 A10 crankshafts I sent off to be reground had cracks, 2 of them through big end journals.

Just for luck, I had a Golden Flash con rod break at the little end eye on the way to last year's All British, but that appears to have been the result of a DPO fitting an oversize little end bush.

Re: Early or late A65 con rods? [Re: Jan Hellinge] #786059 10/02/19 5:13 am
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The rods I'm using on my .050" under Norton crank are forged alloy drag race type, I had them made by Ridgecrest in Melbourne in the late '90s. They are heavier that MAP steel rods and have bigger bolts. The bolts torque to 50-55ftlb into the alloy cap because of limited clearance in the crankcases. The MAP A65 rod is only slightly heavier than a stock rod, a bit heavier on the L/End. Though a stock 9-1 piston probably varies in weight more compared to a +.040" or +.060" piston.


mark
Re: Early or late A65 con rods? [Re: Shane in Oz] #786102 10/02/19 10:17 pm
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NickL Online Content
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Originally Posted by Shane in Oz
Originally Posted by NickL
Despite the last of the a65's supposedly having steel capped rods, my '72 doesn't. They fitted what was in the stores, must have been all alloy that day.
Yep. Apparently some of the OIF A65s had steel-capped rods. As you say, it would have depended on what came out from the stores. With any sort of luck they came as pairs and not 1 of each smile

Originally Posted by NickL
Following the advice that they should be renewed due
to age, i suppose you'd better look for a new set of cases
and a crank and cam too eh? They may have 'metal worm' too.
It's more to do with the number of duty cycles rather than age. Connecting rods alternate between compression and tension.
Crankshafts are drop-forged steel, and I think camshafts are as well. Steel can handles at least an order of magnitude more duty cycles than Aluminium alloys can. Having said that, the last 3 A10 crankshafts I sent off to be reground had cracks, 2 of them through big end journals.

Just for luck, I had a Golden Flash con rod break at the little end eye on the way to last year's All British, but that appears to have been the result of a DPO fitting an oversize little end bush.



I know what you're saying but if the rods measure up OK, and aren't bent etc
they'll normally be ok for the road if the little end doesn't show any signs of being cooked.
Different story for the track but keeping things in the realms of reality as far as cost goes,
keeps more old bikes out there.

Re: Early or late A65 con rods? [Re: NickL] #786107 10/02/19 11:07 pm
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Shane in Oz Online Content
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Originally Posted by NickL

I know what you're saying but if the rods measure up OK, and aren't bent etc
they'll normally be ok for the road if the little end doesn't show any signs of being cooked.
Different story for the track but keeping things in the realms of reality as far as cost goes,
keeps more old bikes out there.
It's worth crack testing them as well, and cleaning up any little nicks.
I don't mind rebuilding an engine with the rods that were in it if the general condition looks good, in fact I'm doing that with a 1964 LR at the moment. Used rods bought at a swap meet tend to be a different matter, and really aren't all that much cheaper than some of the new replacements by the time you replace the big end bolts and nuts.
I was lucky with the Golden Flash motor and Mike Reilly had some NOS small journal con rods available.

Re: Early or late A65 con rods? [Re: Jan Hellinge] #786111 10/03/19 12:01 am
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Mark Parker Online Content
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I swapped a good '70 Lightning tank with good chrome plus some $ for a pair of s/h Commando rods that were all nicely polished, one took out the R/h crankcase punched into the G/box etc. I used them for about 7-8years before that happened. It didn't break at high rpm either. So the idea of riding gently and keeping the revs down is a bit flawed. This one broke a bit down from the L/end. I've also pulled a Lightning down with the stock left rod split through the little oil drilling right up to the L/end which was only holding by the other half of the rod. Steel capped rods I got from Devimead had no oil drillings.

Having said that, the '70 Firebird I'm hoping to get going soon had hardly any miles on it and the rods looked good so I re-used them.


mark
Re: Early or late A65 con rods? [Re: Jan Hellinge] #786112 10/03/19 12:37 am
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NickL Online Content
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The devimead rods were modified/bored t140 ones, they don't have drillings.
Polishing rods is a good way to cover up cooked small ends etc.
A65 rods will crack as you witnessed when ridden with the motor pinging continually
or if the t/s bush is worn and too little oil is getting there.
I liked special corrillos in my race bike, liked the 6 inch centres. Norton ones are a bit short
although i used them for a while.

Last edited by NickL; 10/03/19 12:40 am.
Re: Early or late A65 con rods? [Re: Jan Hellinge] #786153 10/03/19 2:58 pm
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BSA rods are just like Triumph rods,if the big end is still round and the rod looks good, it's ok....Otherwise it's scrap....I don't think it worth the risk in an engine planned to be used hard considering the aftermaket rods availalbe.


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..

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