OzVMX Forum

Clubroom => Tech Talk => Topic started by: mx250 on November 04, 2011, 03:30:52 pm

Title: Alloy Con Rods.......
Post by: mx250 on November 04, 2011, 03:30:52 pm
.........who's heard of such a widget ???.

(http://i323.photobucket.com/albums/nn458/mx250syd/OzVMX/15497226-6903-large.jpg)
Title: Re: Alloy Con Rods.......
Post by: pancho on November 04, 2011, 04:35:53 pm
 Mark 5 Jaguar. they used to stretch and hit the head ,Speedway Jap, they used to break, 500 excelsior Manxman, I think they were reliable. Various 4/ stationary engines, probably lots more. Not seen one in a tooee.
 pancho.
Title: Re: Alloy Con Rods.......
Post by: Colin Jay on November 04, 2011, 05:02:32 pm
The 1969 Triumph 650 Trophy that I once owned had alloy conrods, and I think the majority of other British twins also used them. I have alway thought them to be reasonably common.

CJ
Title: Re: Alloy Con Rods.......
Post by: John Orchard on November 04, 2011, 05:04:07 pm
I've only seen them top-fuel drag cars; but then they're replaced every 5 seconds  :-)
Title: Re: Alloy Con Rods.......
Post by: LWC82PE on November 04, 2011, 05:16:37 pm
A lot of Triumphs and Nortons use them.
Title: Re: Alloy Con Rods.......
Post by: pancho on November 04, 2011, 05:20:44 pm
  ??? fancy me forgetting Triumphs, AJAYs Matchos Norton twins!
Title: Re: Alloy Con Rods.......
Post by: tony27 on November 04, 2011, 05:50:23 pm
First time I've seen 1 in a 2 stroke, what is it?
Title: Re: Alloy Con Rods.......
Post by: JC on November 07, 2011, 01:45:58 pm
Sachs?
Title: Re: Alloy Con Rods.......
Post by: Nathan S on November 07, 2011, 01:53:08 pm
As others have said, alloy conrods are generally pooh because they have a short fatigue life.

There's a reason you don't see them often.
Title: Re: Alloy Con Rods.......
Post by: mx250 on November 07, 2011, 02:05:16 pm
 ;) ;D
Sachs?
Title: Re: Alloy Con Rods.......
Post by: firko on November 07, 2011, 03:17:59 pm
I'm replacing the alloy con rods in my Triumph with steel Carillo's just to be on the safe side. I don't know how much action the engine's seen so it's better to spend a quid up front than cry over the big hole in the front of my engine later on. ;)  That engine's a Sachs.

*back in the seventies we bought a Chevy bottom end that'd seen action speedway sprint car for our drag racing altered. It had Howards alloy rods which we thought was a cool mod but my mate worked for the Water Board in the pipe testing section so we got the rods magnafluxed (crack tested) at his work. Lucky we did as three of the rods had hairline cracks and would have only lasted a run or two before letting go bigtime.
Title: Re: Alloy Con Rods.......
Post by: Brian Watson on November 08, 2011, 12:10:28 am
When I first rode in Juniors.."14-16 years"..I raced the first KTM (Penton) in OZ..see my avatar...It had a 5 speed Sach engine in it , along with an alloy rod....as in the picture.....then one day at Manjimup after the second turn and heading towards rock & roll hill...over the first jump ..and bang......!@#%$&...there goes the alloy rod...still have what is left of the rod at home in the workshop bench draw...
Title: Re: Alloy Con Rods.......
Post by: Marc.com on November 08, 2011, 02:10:29 pm
British twins of the days used them, there are a couple of reasons to use alloy rods, lighter reciprocating mass so especially when you have British twin with both pistons traveling top dead center at the same time like a big single, then there is a lot of vibration and lighter rods are one step to reducing reciprocating mass.

The other issue is that the alloy rods offer some dampening effect between the pistons explosive force and the crankshaft and bearings, that you can use steel rods but on engines with white metal bearings they hammer them. Both reasons are probably why the drag racers use them.
Title: Re: Alloy Con Rods.......
Post by: VMX247 on November 08, 2011, 02:58:39 pm
 :'(

http://ozvmx.com/community/index.php?topic=14519.msg144891#msg144891
Title: Re: Alloy Con Rods.......
Post by: Tossa on November 08, 2011, 04:23:15 pm
When I first rode in Juniors.."14-16 years"..I raced the first KTM (Penton) in OZ..see my avatar...It had a 5 speed Sach engine in it , along with an alloy rod....as in the picture.....then one day at Manjimup after the second turn and heading towards rock & roll hill...over the first jump ..and bang......!@#%$&...there goes the alloy rod...still have what is left of the rod at home in the workshop bench draw...

you keeping just in case!!!!
Title: Re: Alloy Con Rods.......
Post by: Rossvickicampbell on November 08, 2011, 07:49:54 pm
it was a bloody long time ago  :o
Title: Re: Alloy Con Rods.......
Post by: Tossa on November 08, 2011, 08:34:15 pm
classic Watto hoarding, just like the huskies!!lol