Author Topic: Rod Wobble or Wiggle  (Read 5962 times)

Online RichardL

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Rod Wobble or Wiggle
« on: 30.03. 2008 14:22 »
Gents,

Well, now I am must ask for more advice and opinion surrounding the work of my favorite "machinist." It seems that at every turn I must now question his work or my own knowledge before I can accept any of the results. This time, I need advice as to whether or not the rods are a proper fit to the journals. Before fitting the rods, I Plastigaged the journals, with the left indicating 0.001" and the right, 0.0015". I attached the rods using 22 ft lb torque on the nuts. (I suppose that my inexpensive torque wrench is not extremely precise, but the difference between nuts should be small.) On checking the fit, I noticed what I thought might be too much wobble. This is where my inexperience shows, having only assembled one other motorcycle engine, and it was this one. As for car engines, I haven't rebuilt one of them since the sixties.

In trying to get help from the "machinist" (I am enjoying the semi-inside joke of always putting that word in quotes), he says that some movement is normal, but there is no way I can show him how much there is because he is still using carrier pidgeons, or the pony express, or twenty-mule train, or Morse code, or smoke signals, or drums, etc. for his means of communication. In other words, no internet.

Here is a link to the video I took that tries to show the issue as best I can.

http://www.youtube.com/watch?v=5IYligiWUac

Thanks for your help and opinions.

Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline a10gf

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Re: Rod Wobble or Wiggle
« Reply #1 on: 30.03. 2008 15:36 »
Very descriptive video. Something that hopefully is positive: I seem to remember that some side to side wooble is far less of a problem than up-down play. Someone here may have the insight as to the why's and how's of acceptable tolerances.

After my machining job it ended up have some side movement, but no noticeable up-down play, just the conrods revolving freely, and seemingly have given no problems.

e

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Online groily

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Re: Rod Wobble or Wiggle
« Reply #2 on: 30.03. 2008 17:35 »
My wife wondered what on earth I was watching and seemed very suspicious when I explained . . .
The key thing is up and down and smooth rotation as A10gf says. If you grab the rods and pull/push them firmly at 90 degrees to the axis of the crank, there should be no perceptible movement; some side to side float is OK (can't have the rods kissing the flywheel/webs), and a I guess a tiny bit of rock is unavoidable. If the crank journals are truly round, parallel and to size from one side to the other, and the shells are correct, and there are no burrs on the mating faces of rods and caps, then I reckon it ought to be OK. Presume you gave the journals a goodly dose of oil before fitting the rods? Amazing how much a film of oil reduces these things. But there may be them as can quote chapter and verse on permissible limits - I haven't got anything to offer on that front I fear. Groily
Bill

Online RichardL

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Re: Rod Wobble or Wiggle
« Reply #3 on: 30.03. 2008 18:17 »
Groily,

Thanks for the comments. In reviewing the video, it did occur to me that that it might look like I was fondling the rod(s). I just went back out to the garage to check, again, the 90 degree movement and there is none perceptable. The question of parallel is a good one. When I did the Plastigage, I used a bit of Vaseline on one end to hold it in place while getting the cap on. Therefore, I was not able to take the measurement across the entire width of the journal. Live and learn, I now see that I should have used two bits of Plastigage for each journal, dabbing them with the Vaseline on opposite ends. I suppose I will retry the Plasigage if the answer is still a little ambiuous. Do you think I have shot the future usefulness of my hard-fought rod nuts if I take them off? I was going to experiment with the old ones and see if I could whack them in a way to reproduce the locking deformity (as shown in the last photo in the Rod Nuts topic).

As for the lubicant, I put everything together using Lubriplate No. 105 white motor assembly grease.  http://www.lubriplate.com/webstore/detail.aspx?ID=17

Richard

P.S. I meant to comment on the DVR2 information you posted. That was a interesting and, maybe, ultimately useful.

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online bsa-bill

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Re: Rod Wobble or Wiggle
« Reply #4 on: 30.03. 2008 18:27 »
The instructions that came with the rod bolts I used where to tighten up to torque and release twice and then take up to torque again, so I can't see anything wrong with your plan to take them off one more time, although I would be happy going by feel, if there is no perceptible up an down play and the rod spins free - the jobs a goodun.

All the best - Bill
All the best - Bill
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Offline Pollock

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Re: Rod Wobble or Wiggle
« Reply #5 on: 30.03. 2008 18:40 »
Again I learned on tractors and rebuilt a few Harl#$s. I believe you need to be concerned with the movement as they have stated UP and Down but also when you check side to side movement I have always checked at the top by the small ends.  HD on the older ones allow 1/4 inch movement side to side.  The old tractor manuals I believe even allowed up to 3/8 inch total side to side movement.  Up and down movement usually is if you can feel up and down movement at all change the big ends or go to oversize. I just looked for my Manual and can't find it anywhere ...but what ever it states the travel is at the top by the pistons. 1/4 inch movement side to side means total movement at the top not movement by the crank.  Hope I explained myself Properly. 

Pollock

Online RichardL

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Re: Rod Wobble or Wiggle
« Reply #6 on: 30.03. 2008 18:42 »
Bill,

Thanks for the comments. One interesting thing from an article I read about Roland Pike, maybe you've read it; BSA had one line assembler who was having problems with broken bolts (head or rod, I can't remember). Anyway, he was the only guy applying a little parafin to the bolts to make them easier to tighten. Appaently, it went so easy he couldn't tell when he went too far. From then on, all torquing or tightening-by-feel was to be done dry. To that end, I thoroughly cleaned the rod bolts and nuts with minearl spirits (allowed to dry) before tightening.

Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online groily

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Re: Rod Wobble or Wiggle
« Reply #7 on: 30.03. 2008 21:40 »
Can't argue with what BSA Bill says Richard. Have to say, personally, once I've done up a locking nut I prefer to leave it - but if the things are made to be done up the way Bill says, there's nothing to lose. However, as there's no up and down to speak of, and they rotate freely, and they don't rock that much, I think I'd leave them and start worrying about your oil pump and gears, your timing side bush, crankshaft spacers and all the other wonderful things that make us have sleepless nights but which have a funny habit of working pretty well in spite of our nervousness! I think it's job done - just hope that's not cavalier or pig-ignorant of me! Groily
Bill

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Re: Rod Wobble or Wiggle
« Reply #8 on: 30.03. 2008 21:47 »
RICHARD, I dont think you have a thing to worry about with side play on rods if you have no up & down play and the the rods fall slowly  with their own weight when held at 90 degrees to journals. but having looked at your video I would reccommend that you remove all nicks & gouges from rods & mirror polish them to avoid them failing due to these weak spots. I always have filed casting marks & blemishes from conrods then using fine emery & polishing mop I polish them to a very shiny mirror finish after weighing each rod for weight difference .Would be a shame to have a rod go and ruin all your work. all the best G/F DAVE.....

Online RichardL

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Re: Rod Wobble or Wiggle
« Reply #9 on: 31.03. 2008 06:11 »
Gents,

I don't know if it will change any of your fine advice, and I'm sorry if it does, but I decided to regauge the bearing clearance on the big ends (really, I've just done the right side) and found the clearance to be 0.002", not 0.0015" as I previously thought. I think this is still in tolerance, but it is a little looser. What I figured I was doing wrong was measuring under the cap instead of under the rod. When the Plastigage is under the cap, I think it is available to get further smashed by the effort it takes to separate the cap from the rod. I am yet to find this easy. A torch to the cap near the bolt holes helps, but there is still some soft mallet work at hand.

Dave, I like your idea about removing marks and polishing the rods, and wish I had done the cleanup before balancing the rods (I'm such an amatuer!) Maybe I'll be OK, given the conservative style of rider I think I am. Do you really think I will be in big trouble if they are left as they are?


Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

G/F DAVE

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Re: Rod Wobble or Wiggle
« Reply #10 on: 31.03. 2008 14:43 »
RICHARD, The choice is yours if you ride hard (I like to hear my old A10 rev hard) then you need to be sure of everything inside your cases. I have had a rod go on a A10 l/h side of course did a lot of damage most of motor was scrap. As with all my motor rebuilds I polish rods as a matter of course even with new rods as casting marks can be a weak point. But you should be ok if keep revs down. Not everyone takes time to build their engines ,But I,ll strip the thing down time & time again during rebuild stage till I,m satified that its right, My present A10 motor is a low comp, big bearing crank,with mild cam, really smooth almost vibe free. Good luck with your build & take your time. regards DAVE...

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Re: Rod Wobble or Wiggle
« Reply #11 on: 31.03. 2008 15:15 »
Dave,

Thanks for the additional comments. I am definately leaning in the direction of your advice. I think I can take the casting marks off of both rods without changing balance more than 0.5g, since both rods have about the same amount. When it comes to nicks, I'll have to make judgements as to how big they are and if removing them will affect balance. Finally, I am looking forward to seeing the rods all shiny, then not seeing them again for several years. I think you can probably see that I don't want to pay for or do my own balancing again.

Richard
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Online RichardL

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Re: Rod Wobble or Wiggle
« Reply #12 on: 07.04. 2008 05:43 »
Gents,

After noting the bearing clearance at 0.002" and just not being comfortable with the wobble as it was, I went to work to see if it could not be improved. Looking with magnification at the junctions between rod and cap, with the bearing in place, I noted that a small gap was left in the gap between bearing shells. I also noticed that the "machinist" did not actually dress the landings. I took a file to them and closed the gap between bearing shells, Unfortunately, in one case I took too much and ended up needing to shim (I now need to buy a new feeler gauge). In the other case it was a bit too loose, so I just touched the end of one bearing shell with a file. This was something of a mistake, as it then got a bit too tight. I answered that by dimpling the rod landings with a center punch to raise a little material. That seems to have worked just fine. I admit, I did feel like like was breeching the faith with all of this filing, shimming and dimpling, but I think it comes under the title of "whatever it takes."

Additionally, I took G/F Dave's advice and cleaned up the nicks and casting marks on the rods and gave them something of a polishing. I did not try to remove the largest dings and scatches, as it would have required removing too much material. Instead, I made sure that any deep scratch had its edges and ends smoothed or rounded to avoid the chance of starting a stress fracture. I think I was careful enough in removing small amounts of material from both rods that the balance was not changed.

I'll  post the results of the rod cleanup, but the Forum uploader is full, for now. If you're interested, you can see a new video of what I believe to corrected rod wobble on YouTube at 

  http://www.youtube.com/watch?v=A_t5BODxGk8

There are a few words dropped from the beginning of the video, as in, "Here is the BSA A10 rod wobble issue...", then the video starts, "...revisited."


I thought I should show the results, in consideration of the helpful advice that's been given.

Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

G/F DAVE

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Re: Rod Wobble or Wiggle
« Reply #13 on: 08.04. 2008 19:28 »
Hi, Richard just seen your youtube video looks like a better job this time, have you tried rods after pumping oil with a oil can thru oilway on timing side journal till it appears at big end journals ?. This normally takes up a lot of side play on rods. Rods also look much better after polishing, dont know if I would of filed material from caps (landings) though. Normaly this is done if rods need line reaming to remove oval wear. But if you are happy with it thats all that counts.. I also looked at several youtube videos featuring A10s most of them seem to be bad starters ( I like the superocket that kicks the guy who,s starting it & he loses his clog) seems most of the sweet runners are custom bikes or old originals ones . the over restored ones seem to rattle & run like a bag of bolts, maybe all the money went on making them look good. Me I,d rather have a reliable old nail any day. all the best G/F DAVE..

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Re: Rod Wobble or Wiggle
« Reply #14 on: 08.04. 2008 22:34 »
Dave, and all,

First, despite what I said in the video, I will be taking the rods off, again. I believe that I must assure that I haven't made the big ends oval. If I have, I will decide between my own honing or sending them out, again. The filing I did on the landings was done mostly with a jewelers file, just to lower the knicks. However, I might have gone too far. The worry, as I understand it, is exagerated wear on the bearing shells along the long line of the rod, because of the reduced contact area. Basically, I think they would probabaly be OK, but it is soooo much easier to deal with it now. This all would have been avoided if the "machinist" was worth a crap (a bit crude, but not an official cuss word in the U.S., in my opinion).

We'll have to see (really, "hear") what mine sounds like when its done. I assume you've seen it here in the forum. I'm worried that you might think that mine is made to look good but not run good. I'm hoping for both, though not in total original style, like the beauties that some here are riding.  More like, "how shiney can it look on a small budget and with a lot of time."

Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.