Large Journal Conrod Big-end EYE size please

[duTch]

 Hi all,
         As the title suggests I need the measurement for-Large Journal Conrod Big-end EYE diameter without bearing shells  size please.
 Am sure I've seen the info somewhere but now can't find(found centre-centre= 6.469"), Haynes have the Small journal spec, but no mention otherwise that I can see!
  Thanks in advance, duTch

[KiwiGF]

Service Sheet 207 has this. I'll tried to post this but pdf are not allowed. Let me know if you need it and I will make a jpg file of it.

As well as the size you may need to know the clearance with shells, as an engineering firm will grind the crank to suit anyway. I asked for 001 clearance when it came to my crank regrind. LJ BE diameters are shown as:

1.687 std (not actually on the service sheet but I've calculated this from the first regrind dia)
1.677 first regrind (-010)
1.667 second regrind (-020)
1.657 third regrind (-030)
1.647 4th regrind (-040, BSA do not show this size on the sheet, but -040 BE shells are available)

More inf. The BSA technical litarature states the correct big end clearance as "effectively nil" and 002 is the wear/replacement limit, but the Haynes manual gives the dimensions for the standard size journal (1.460 nominal) and rod eyes as:

Rod Eye ID                    Journal OD
min        max                 min       max
1.4610   1.4615             1.4595   1.4600       

         

[duTch]

Thanks Kiwi,
                 I have all that info,odd that there's data for the S/J rod-eye but not L/J,  and have just been reading the thread that you started last december(?), with your saga and all the discussion re; bearing materials.
  I dropped my crank and rods into an engineering place yesterday, now waiting for a call. I measured the journal with a digital vernier,smooth and seems round, @1.675~ a bit rough-0.0015~, but see what they reckon.
  I replaced the shells as a matter-of-course(-0.010), as the crank has only done a couple thou miles since ground, it may have been done wrong,or;-
  I think I may need new rods, be easier as the little end bushes are out of whack as I suspected as per post a few weeks ago, and am not too sure the integrity of the B/E eyes as.
  I've seen your rods post re Thunderlightning, and also looking at MAP rods, and Ridgecrest.
    Cheers for now duTch

BTW, SRM have the journal sizes-
http://www.srmclassicbikes.com/technical/bsa-a7-a10-big-end-journal-sizes,
 But not the rod size, as per 'size rods to fit shells/crank'

[KiwiGF]

Hi, Dutch, oops, you asked for con rod eye dia! On that topic, and using old rods, you probably know, but in case not the eng. shop can "resize" the rods to suit the shells, they shave a bit of the mating face then make them round again. It's the end caps that distort over time (the main part of the rod is stronger and doesn't - generally!) and this causes the shells to not get clamped correctly. The eng. shop will probably be able to work out what the size should be from the thickness of the shells and target journal size.

I'd measure my rods for you but they are SJ.

I was quoted about $200 to resize and shot peen my old rods, I spent the extra $300 odd to get new ones from Thunder instead.

[duTch]

 this is what I was looking at-found as a goole search, not a bad read from all concerned(it's a rainy day).
Title: Big end clearance and indium coating
Post by: KiwiGF on 08.12. 2011 08:47

 Thanks again, but I'm fairly sure I had them re-sized first time 'round(I know I had some done), but now that it's possible to get new rods-yay-, like you, could be best, don't want to stuff around any more, just want to ride it.
 Without the shells in each eye measures within a thou, but with the shells in about 3 or 4 thou ovality, and the new shells(again with verniers) measure almost 2 thou thinner(~0.079) than the old ones(~0.081)??

 Thanks for your time, cheers duTch
   

[KiwiGF]

The new shells being thinner is a showstopper if you were not intending to regrind the crank, any chance of finding some thicker ones? But I guess you had thought of that. If the journals are round it would be a shame to regrind them.

Maybe someone can provide some specs on the shells available? There are glacier and vandervell brands maybe others. The specs will probably include the rod I.D. Which I think are accurate to much less than a thou, when resizing I think they in "10ths"  Eg 0.0001

[duTch]

AH yea,
         hooboy, yes it's curious and a bit rough measuring, but using same method. I think I'll go buy some proper micrometer tomorrow(replace what went walkabout), that way I can compare to the workshop measuring, and see. I been trying to find bearing info on the net, but only got square eyes.
      Also had a yarn with Steve at ThunderEng. was about to finish of a batch of rods an hour ago.
Cheers mate kick back 'n relax, duTch

[muskrat]

 G'day Dutch.
                  There should be a crush on the shells of about 5 thou. So if you put the shells in the rod and do the nuts up finger tight. With one side of the rod and cap meeting there will be a gap of about 5 thou between rod and cap on the other side.
Just came up from shed so will try to dig one out tomorrow to measure.
Cheers

[duTch]

Thanks Musky,
                     I guess that's with the shells butting together at both joints (diametrically)? I think I had a bit of that when I put them together the other.um month(?) I remember looking at against the setting sun, because my young fella turned up and was looking at me kind of funny-till I explained-he nodded. Will have a better look when I get them back tomorrow.
 Also anyone know about MCA slippers??
                   cheers duTch

ps Just reread the "Big end clearance and indium coating' thread yet again, seems the consensus on MCA is they're ok for general road use?? Just cos I can get those locally . cheers again

[duTch]

Little update here,
          The engineering shop, measured up and crank is 1.6752( close to what I got with my verniers),about 0.001-0.0015 under spec.
Measurement on 'rod-eyes'-1.8920/1.8930 (+/-0.0004/)..?
 I got 1.841~, about 0.050" difference...? is that ~1.25mm or not??

When I dropped it off he said 'so you want us to supply bearings and grind to size..? '......no,grind nothing, just measure please'.
Also I found variation in the new shells, they're ~ 0.081 thick, and the old ones are ~0.0825  (+0.0015)!!
 I'm buying replacement micrometer.

Point is, be very careful what you're told by those who 'know', and double check.
 Please anybody tell me if my maths is wrong!!
 cheers duTch
   

[kommando]

I got 1.841~, about 0.050" difference...? is that ~1.25mm or not??

Yep 1.27mm, Internal diameters are notoriously more difficult to measure than OD's but 1.27mm is a lot.

Where did you measure the thickness of the bearing, it needs to be measured in the central area using a micrometer with ball points, on the edges there is a relief so that when the crush is squeesed by the con-rod the deformation of the bearing in this area does not cause this are to contact the journal, any measurement here is not representative of the bearing thickness.

[duTch]

Thanks Kommando,
                   
Yes I agree that I should use 'ball-points', but don't have them. It's a very arbitrary measurement with sliding verniers, but using the same method on different shell sets produces different results, measured with the 'pointy ends' of calipers at various points round, and across the semi-shell, enough for me to question why should I not just use the older thicker ones(under duress)??
  Just tried to take some pics but too much flash, will try again in the morning in daylight.
Also,1.27mm(difference) just isn't in the ballpark. Kind of hard to be that far out and not notice! The shells'd have to be 0.108" thick, not much less than 1/8".
 I'll take the rods back and get them to do it again,if for no other reason than to point out they're wrong, and why trust them with an item that's getting close to irreplaceable. Fairly confident I'll just get new rods and shells,and get on with it.
 cheers, duTch

[Rocket Racer]

Thought I would hi jack this thread as rods always interest me and had just got an interesting email.

I have been considering options for some new rods for my race bike and had never seriously considered steel rods as I had assumed they would cause vibration due to their greater weight. However a mixture of seeing a utube clip of some heavy duty modern alloy rods and also seeing a reference to Carillo's being lighter than many OEM rods set me thinking.

My existing std BSA rods weigh (according to my scale) 370 grams being 150g reciprocating weight (stops-and changes direction each stroke so implicates inertia) and 220g rotating weight (affects balance but primarily just spins).
I sent out inquiries to several supplier and both Thunder Engineering and BritCycle kindly got back to me with corresponding weights for their Alloy and Steel rods.
The weights make interesting reading:
Std Rod         370g, 150/220 split
Thunder Eng   440g  125/312 split
Carillo            479g  130/349 split
So there is little difference in reciprocating weight between a replacement alloy or steel rod .
I havent done any maths on the implication of the additional rotating weight of both rods but am assuming it will simply move the vibration up or down the rev range slightly or the crank could be rebalanced if necessary.
My current thinking is that with no effective weight disadvantage, a steel rod will retain oil pressure better due to lower expansion rates, so be superior in a performance engine.
Now just need to save up enough money...
Tim

[KiwiGF]

Thanks for that rocket racer, thats good info. I assume the weights include nuts bolts etc?

[duTch]

Hiya Tim,
          Hi-Jack away. better than being 'you-jacked', figures Steve at Thunder'nLightning gave me was 126/314(440g overall)- close enough, as I was wondering also how different weight rods will affect the show, even though mine's just a 'run around'(currently a 'carry bits around'!), don't really want more vibes than necessary, and so thought maybe I may need to look at balance adjustment.
 Like you I'm not sure how to analyse it, as if there's a difference in either of reciprocating or rotating, creates different dynamics, and in my case if it's not much different won't matter too much. I guess it's another case of suck and see??
 Cheers for now, duTch