Polished Rods

[RichardL]

Yeah, the stock castleated type have a washer-like base. I lost then. Grrrr! So, nothing weird about adding washers here? Seams to be enough bolt length.

Richard

[JulianS]

The end caps were changed when self locking nuts were introduced.

[RichardL]

The end caps were changed when self locking nuts were introduced.

Julian,

Thanks for this. Very informative. With my own equipment, I'm not capable of doing the spot refacing called for in the service sheet . Also, one website I looked at said the new number (67-1537) was only for large journal rods. Kind'a confusing.  I think I'm going to look for Grade 8 flat washers that will make up the difference for a socket fit. I also see Berger's point about squishing the casting and making the rod caps very difficult to remove (it was hard enough, even after the initial removal from the crank). Still wondering if anyone thinks flat washers under rod nuts are a no-no.

Richard L.

[Seabee]

I am prepping a set of late model rods now and can testify that with thin washers the aluminum displacement that Berger spoke of happens! I had some difficulty getting the caps off after torquing them to verify clearance with plastigauge. Unfortunately, with thick washers I don't believe I will be able to engage the nylock with the rod bolt. 

I just finished polishing the rod beams and small end. Is there really a need to polish out the big ends? I've never seen a rod break there.

I'd like to check my static balance before final assembly. Would you provide me the link to the write up done here Richard?

Thanks all!

[RichardL]

Seabee,

I've, basically,  been following the approach and service sheet posted by KiwiGF here:

https://www.a7a10.net/forum/index.php?topic=6086.0

I polished the big ends for two reasons:

1. I didn"t think about (or know to think about) breakage there.

2. I like the way they look, though, in closeup photos, remaining imperfections are exagerated.

Richard L.

[Truckedup]

 I have a collection of large journal A10 rods...Some are polished but all are scrap because the big ends are out of round

[berger]

not scrap the cap and rod can be faced off and bored round again. I had it done on one of my spare my A7 rods . someone had taken a slice off the cap to stop big end knock and when I fitted new shells it all locked up so engineers sorted it. that rod is now in my engine and makes about 10 thou difference between the height of the pistons. as for those who are fussy about the critical balance factor this engine has been thrashed many times and will be again this summer.

[groily]

+1 for that berger.
Have had several pairs of other all-alu makes sorted 'for round' (and crack-tested at same time) over the years. Pairs might / can even come back close as dammit the same stroke!

[berger]

if you don't want them re machined you can have a weapon

[Truckedup]

 Guys who race Trumphs like me with stock auminum rods learn that an out round or distorted big end is the only hint you get before the rod fails.Resizing the rod does not change the previous  stress on the rod. When alloy is stretched it's fatigue limit has been exceeded. Forged steel rods are a different story.On a sedately ridden machine  this may not be a huge problem... I do have 5 rods, some are out of round, all have rod bolts closer together at the ends by about .010 because the rod is distorted....That's why it's difficult to remove rod caps .  If anyone wants them, PM me, pay postage, they are yours...

[berger]

you didn't mention distortion to that extent just out of round. so it looks like you can make some weapons

[Triton Thrasher]

+1 for that berger.
Have had several pairs of other all-alu makes sorted 'for round' (and crack-tested at same time) over the years. Pairs might / can even come back close as dammit the same stroke!

There’s nothing you can do to a rod that changes the stroke.

[Truckedup]

Generaly speaking, out of round by less than .001 is ok to resize accoring to those with experience....This would be for a street engine not seeing a lot of redlne rpm..There should also show no signs of overheating on the small end.
 During the 1930's the UK metal industry made a big push for aluminum rods. There were industry ads suggestng use in aircraft engines. Besides some bikes, I don't believe aluminum rods were used in any other engine. The fatigue factor of alloy rods was not an issue when the bikes were produced. Just buy new ones when needed...
 when I found three sets of rods suffering from the same fault, I figured the majoriy are the same..I bought new aftermarket rods ,$450.....A lot of money but a broken rod at 6000 rpm is alot more expensive. And with my luck, the thrown rod locks the rear wheel, the bike goes down and crashes into a group of Girl Scouts..

[berger]

There’s nothing you can do to a rod that changes the stroke.
[/quote] well I may be thickish  most of the time but the rod I had put right makes one piston 10thou lower than the other. or is that nothing to do with the stroke

[Triton Thrasher]

well I may be thickish  most of the time but the rod I had put right makes one piston 10thou lower than the other. or is that nothing to do with the stroke

It will be 10 thou lower at TDC and BDC, so the stroke remains the same.