Rod Wobble or Wiggle

[G/F DAVE]

Richard, I think you may need to start again if you are not happy ,I,d find a good engineer who can measure crank journals and determine if they need to be reground, then fit new shell bearings ( dont buy italian made ones as they are junk) buy yourself a secondhand set of rods,I bought a set stateside for $60.00 that came with a good set of pistons these are now in my motor.There seems to be a lot of good condition used parts for old bikes in the states, compared with the worn out stuff here in uk, so you should be able to source good ones easily. The shell bearings you need are made by glacier if you have large journal crank you can fit bsa a65 ones as they are the same. If crank needs to be re-ground tell your engineer not to grind the radius as this will cause crank to snap at the journals (I know from experience as it happened to a old A10 I had once ) . Looks like your in for the long haul but will be worth it in the end. This is where a lot of owners go wrong on these machines as bottom end of these motors need to be 100%. Spend your money on a good reliable motor then make it shiney as you can afford it while using it. Dave........

[RichardL]

Dave,

This is really great advice and I may well go this route if the rods prove oval or the crank proves too far under or non-parallel. (I just ordered a 1"-2" micrometer, so I will know in a day or so.) I think I should find out how much SRM wants for reconditioning the rods. I believe that their work must be as good as it gets. I think they will tell me if I must toss my existing rods, either because they (the rods, not SRM) can't be saved or are not economical to save. As for regrinding the crank, I guess that's a possibility, since I see I can get 0.040"-under shells. I just looked at ebay and there are a lot of A65 rods out there at reasonable price (but they're not shiney).

Richard

[G/F DAVE]

Richard,  Don,t buy A65 rods as they are different to A10 .however they both use the same size shell bearings.Glad ebay didnt have a pair of shiney ones as they would be of no use to you. Regards Dave

[G/F DAVE]

Richard,  Look at ebay item no 290222617583 these should be shiny enough for you.I have bought A10 parts from this seller before all been good stuff and he will post worldwide.. regards Dave

[RichardL]

Dave,

Funny you should mention those, they were already on my watch list and very well might end up in my bike. And, yes, they are nice and shiney. Regardless, thanks for thinking of me.

Now that I know that I need new rods (given your advice, SRM's advice and my own measurements with my newly acquired micrometer), it frees me up to try to fix the ones I have. I don't have much hope for that but, at this point, I have nothing to lose but a little time. As it turns out, to get the diameter across the parting line down to 1.844" (the right figure), I will need to remove 0.035" from each landing. That's quit a bit, but, I think, not enough to weaken the rods significantly. I may not bother, but I am thinking about it just to have an idea, for the future, of what can be done.

Thanks again,

Richard 

[RichardL]

Update on the rods.

I asked the machinist to replace the rods and told him that used pieces would be OK, as long as they were not out of tolerance. I believe he just wants me to quietly go away, without publicizing the problems. He decided to send me brand-new forged-billet M.A.P. racing rods. I told him that that was above and beyond my needs and I wasn't fishing for over-the-top accommodation (though, by now, maybe I deserve it). Anyway, I've received the rods and was surprised by two things: 1) It appears that they do not use small-end bushes as the gudgeon-pin bearing surface. Rather, the aluminum seems to serve as the bearing. I tried to call M.A.P., today, to confirm this, but they're closed; 2) They take 50 ft. lb.s torque at the torx-head bolts. This sent me to the garage (i.e., "shed") with a bucket of water to calibrate my torque wrench.

The set of rods that was on eBay went for 82 GBP. Quite high, I thought.

Richard

[G/F DAVE]

Sounds like your luck has changed. These must be a better option than 40 plus year secondhand rods.Triumph changed there rods to all alloy ie; no small end bush on the T140 models with no problems. Also a lot of racing rods use no bushes. If you dont want them I.ll have them... Dave

[RichardL]

AI YAI YAI! (My best shot at phonetic spelling of how I feel about what I just realized). The brand-new billet rods do not have the little oil hole in the left-side rod. Now I wonder if good-ol'-"machinist" forgot to differentiate, or if M.A.P. does not include the hole for some reason I don't understand. I will be calling M.A.P. on Monday to discuss. The purpose of the hole has come up before on this forum. Some say it is to squirt oil on the left cylinder wall (or, maybe, both). If it is just left, then how does the right get wet? Otherwise, is it needed just to assure oil flows into the crankshaft rather than be kept out by back pressure?

Richard

[bsa-bill]

My understanding is that the hole was added ( should that be taken away) due to the drive side cylinder overheating.
Anyway I have read several post from people who have drilled the hole in the rod themselves, I imagine lining it up with the hole in the shell is the thing.

All the best - Bill

[RichardL]

Bill,

I suppose my discussion with M.A.P. will be revealing. I was thinking about drilling the hole, trying to replicate the exit angle, and all. Do you (or, others) have any idea why the drive-side cyclinder should get hotter that the timing side? Have we discussed this before?

Richard

[a10 gf]

Richard, I admire your perseverance and quest for a good working engine, and this is a valuable thread.

Excerpts from Bacon's twins and triples:
"..modification..of importance..1951 engines..drilling of hole..lh conrod. A drilled big end shell to match. ..if not fitted correctly, the left big end will be inadequately lubricated."

So he refers to helping the flow of oil reaching the lh rod, not the extra oil to the lh cylinder wall. If I get this right, the drilled hole should help equalize the factual oil fed to both big ends (and as a biproduct, the lh cyl wall gets a dose in the process).

[RichardL]

Erling,

Thanks for the info and encouragement. I will be dirilling the hole and will show the fixturing when I get to it. As close as I can tell it takes a #56 or 3/64" drill. The drills themselves are sealed in packets at the hardware store, so I can't really test for the exact one. I was probing with different wires from push-pins and paper clips to see if I could get the best fit, but if anyone knows exactly, please jump in.

M.A.P. says they do not provide the holes because they haven't seen any need for them over the years. SRM says, maybe not for a racing engine, but a good idea for a road machine. I have, yet another, unsubstantiated idea of why the hole is a good thing. First, I think you are correct about equalizing the oil pressure across the width of the crank, thus sending equal oil to both journals. My new thought has to do with bubbles in the oil that would tend to compress inside the crank rather than increasing the oil pressure at the holes to the journals. Like I said, I don't know that this is true, and maybe the science is not correct, but I think it is enough of an interesting angle to cause some controversy (uh, I mean, interesting discussion).

Richard

[groily]

Have to say I really never did, nor do I yet, understand the hole in the rod thing.
The oil gets to the journal the same whether there's an escape route or not after its arrival, and most other engines seem to do quite well without such an arrangement. If SRM reckon 'maybe not' to the hole for a race engine, then it can't be because there won't be adequate pressure at the journal (or supply to the cylinder wall on that side) if there's no 'ole.
My own thoughts, when told as a youth it was critical to have this here hole and to make sure the shell lined up etc, used to be two-fold and similar to Erling's: 1) an extra squirt up the lh cylinder was a good thing, sure; but more importantly, 2) had there perhaps been problems with FLOW in engines that were still at as-new tolerances because the oil couldn't escape at the lh journal fast enough? So the oil backed up on the pressure-side and possibly got too hot and very thin at the end of the line - ie the lh big end? To ensure a copious cool flow and still maintain reasonable (and equal) pressure, the hole was added?
I also believed the improved flow allowed more oil back to the scavenge pipe faster, keeping bubbles in the whole oil system to a minimum and keeping temperatures down. Which would be to the benefit of the delivery side in its turn, as pumping over-heated aerated oil in again would be a bad thing.
 
Some of that is logical, but it still doesn't explain how an undrilled rod could be better for racing, where life is a lot harder. Or is it just that a race engine will have slightly greater journal-to-shell clearances to minimise risk of seizure in extreme conditions, allowing the oil to leak out faster than it could on a tight road motor? Do pre-hole early engines blow up more often?
So I still don't really know! But I would love to. And a great thread.

[RichardL]

I said I'd show pictures of the fixturing for drilling the little hole in the left-side connecting rod from M.A.P. The small adventure in this is that I tried, at first, to drill intesecting holes, only to irretrievably break off a drill bit in the angled hole. Good news, each rod has two sides. I said then, to myself and father-in-law, I have a degree in engineering, I could actually use math to determine the angle I needed to drill directly from the housing to the base of the I-beam in one operationm. Voila! It worked. 

Richard

[RichardL]

Hello Gents,

For those of you following or who will recall, the new M.A.P rods are on the crank, in the case, in the bike and with barrels over pistons. I hope to have the head and rockers on before the end of the weekend.

In case you are interested, I did a video of the new rods on the crank (I'd done two previously so I figured I might as well close the deal). Here is the link:

http://www.youtube.com/watch?v=G1FSruempm4

I know it seems I am incredibly slow (and I am) but, sometimes, even the BSA must take back seat to work and home. I only hope I can get it done to ride this season.

Richard