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Posted By: Hillbilly bike Pile of junk connecting rods. - 09/15/14 12:29 pm
I've been sorting through my pile of parts for the ongoing T120/750 build...I can't believe in this whole pile of connecting rods that every big end is out of round by .0015 to 0025. I checked them twice and even had the machine shop check them..
I have a set of Carrillo steel rods but don't want to go that path...
Anyone got a got set of good 70-9525 rods? grin
Posted By: John Healy Re: Pile of junk connecting rods. - 09/15/14 1:34 pm
Just for giggles which torque figure were you using?
The rod bolts with UNF threads should be 24 ft/lbs and the CEI should be 28 ft/lbs.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/15/14 1:43 pm
22 ft pounds...UNF
Posted By: Pete R - R.I.P. Re: Pile of junk connecting rods. - 09/15/14 4:02 pm
22 ft-lbs (dry) is right, or 0.004"-0.005" elastic extension of the bolts.
Posted By: reverb Re: Pile of junk connecting rods. - 09/15/14 5:57 pm
...somehow I torque mine (UNF)with 4kgs because that was the only way that the conrods moved perfectly free on the crank.
Posted By: kootbiker Re: Pile of junk connecting rods. - 09/15/14 6:16 pm
Why can't the machine shop true up the big end? I would think .001" would be OK.
Posted By: Old Cafe Racer Re: Pile of junk connecting rods. - 09/15/14 6:17 pm
Why not just get a pair of those rods resized in the bigend bores, common enough operation.

davy
Posted By: John Healy Re: Pile of junk connecting rods. - 09/15/14 6:40 pm
Aluminum only gives you one "tap on the shoulder" that the load has exceeded the material's modulus of elasticity. It means that the stress stretched the material past the point where it would normally spring back. While you can do this with steel and resize the rods, aluminum is a different story.

I have never bought an aftermarket rod to go racing with. I always have used stock rods, and bolts, racing. That said I measure, and record, the rod and bolt dimensions before and after I use them. Any variation and the rods are thrown away. In some 30 plus years of racing I never broke a stock rod, even running the 500s between 9,000 and 10,000 rpm. Can't say the same about stock and Nourish crankshafts, especially the 500. The 750 broke its share of Nourish crankshafts until I switch to the Nourish large journal. That was problem solved.

Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/15/14 7:45 pm
I'm aware of "one warning " before the crankcases get sawed in half by a broken rod...

So here's how the rod big ends measure, I believe the are scrap...
Holding the rod with the small end straight up and measuring straight up and down is 1.7695 . Measuring across from left to right just above and below the parting line is 1.7710 .Out of round by .0015 across the parting line, both rods measure within a few 10 thousands of each other. The rods look nice and the small end not covered in burnt oil.

I run after market aluminum rods in my race 650 for lack of good used rods and not wanting to pay 400 bucks for NOS rods.
Posted By: Denis J Re: Pile of junk connecting rods. - 09/16/14 1:41 am
Hey Hillbilly, when you say aftermarket do you mean cheap rods? I am hoping to button up a set of 500 cases with a set of rods that won't mind the occasional spin to 8k rpm on the dirt track. I thought the Carillo rods were the only way.

Jon, do you mean stock Triumph bolts or replacements. Does a company like APR get into this stuff?
Posted By: John Healy Re: Pile of junk connecting rods. - 09/16/14 9:41 am
HB: Here comes the conundrum. The Triumph specification for the big end bore dimension is 1.770". So the problem is where did this rod start out. Also it is a bit odd is that it is oval side to side rather than top to bottom.

Did you oil the threads before tightening? Did you face the threaded end of the rod bolt in a valve stem grinder so you could get an accurate reading on bolt stretch?
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/16/14 1:18 pm
The threads are dry.I thought about spot facing the bolts but from the odd measurement I think it's a bit late for that..Yes,it's strange the way the big end is stretched. I also had my retired machinist friend come over with an assortment of measuring tools so the measurements are accurate.
Posted By: John Healy Re: Pile of junk connecting rods. - 09/16/14 1:47 pm
Threads dry- good! In the future you might look at facing the rod bolts and take some notes for future reference.

But the bolt stretch of .004" to .005" is a good way to approach this especially when using lock nuts on the rod bolts. It is hard, without a bunch of experience, to get a meaningful torque reading.

Using lock nuts also precludes the multiple tightening recommended by ARP in an effort to seat the threads in the nut and bolt.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/16/14 2:29 pm
I got a deal on a new set of Harris made in UK rods...
Posted By: wilksville Re: Pile of junk connecting rods. - 09/17/14 12:54 am
So which "STD" rods and bolts does John Healy use with large journal cranks ?
Posted By: John Healy Re: Pile of junk connecting rods. - 09/17/14 8:24 am
The Nourish crank is the exception as TSS rods are like hens teeth. We have used alloy rods, and modified rod bearings, supplied by Nourish. I am not sure they still supply these rods.
Posted By: JubeePrince Re: Pile of junk connecting rods. - 09/18/14 9:41 am
This may be of interest to some:

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=563673&gonew=1#UNREAD

Cheers,

Steve
Posted By: PatrickMcG Re: Pile of junk connecting rods. - 09/29/14 3:47 pm
Denis J: I use thunder engineering rods. They are aluminium and beautifully made. Extremely strong. Personal experience I think they are superior to carillo rods but no denying they are at least equal. We had a crank bolt let go and wizz around inside, it gouged the rod and it took it in its stride. Highly recommend
Posted By: PatrickMcG Re: Pile of junk connecting rods. - 09/29/14 3:49 pm
All race use for my usage of them
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/29/14 4:45 pm
The Harris OEM type rods didn't meet my quality inspection...I had talked to Marino at MAP cycle about his forged steel lightweight rods. I also considered another set of R&R aluminum rods...
The steel rods from MAP arrived a few days ago.. On my triple beam scale they weigh 429 grams.A stock late T120 rod is 405 grams.The Carrillo rod I have weigh 505 grams....The R&R rods about 415 grams.
The MAP rods look like aircraft quality,a very impressive piece...I also bought a set of MAP 750 "Routt" pistons so the cylinders can be honed to get a proper fit. The forged MAP pistons weight 10 grams less than a standard bore Hepolite 650 piston.
I sold the Carrillos on Ebay. I have a set of nice used TRW Routt 750 6.5 inch rod forged pistons to fit a 3.012 bore if anyone is interested...
Posted By: DMiller Re: Pile of junk connecting rods. - 09/29/14 7:41 pm
I highly recommend the MAP steel rods. After searching high and low for a good set of alloy rods, I used them in my last 650 project. I returned 2 sets of stock rods and 2 sets of R&R rods for bad quality. I check them with mandrels on a CNC set up and I can tell you the MAP rods are really precision parts. I was measuring as much as .02" out of straight over 6" on some of the junk rods I sent back. The scary thing is these will probably be sold to someone else...
Also, I sent the crank to John Healy's guy for ballancing.The MAP rods are really light so he had to remove very little material from the flywheel.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/30/14 12:37 pm
I remember your problems with the R&R rods.To be honest I never checked my set of R&R's other than bearing crush but the race bike runs great so they must be fine grin
Posted By: ken sak Re: Pile of junk connecting rods. - 09/01/16 1:05 pm
Originally Posted by John Healy
HB: Here comes the conundrum. The Triumph specification for the big end bore dimension is 1.770". So the problem is where did this rod start out. Also it is a bit odd is that it is oval side to side rather than top to bottom.?


old thread, I know Chevrolet found that the rods pinch in at
the parting line and wipe oil off the crank so they had more
clearance at the parting line either on rod or bearing

when I've checked rods on engines i've built, verticle
measurement then 45 degrees each side of verticle to get
correct out of round
Posted By: John Healy Re: Pile of junk connecting rods. - 09/01/16 2:06 pm
Quote
I know Chevrolet found that the rods pinch in at
the parting line and wipe oil off the crank so they had more
clearance at the parting line either on rod or bearing


All rods are torqued and finished honed perfectly ROUND during production. Rod bearing shells are NOT manufactured perfectly round. They have more clearance designed in at the split.
Posted By: ken sak Re: Pile of junk connecting rods. - 09/02/16 12:58 am
yeah,i didn't know if the rods were being measured with out bearings
which is the norm -didn't want good rods being chucked out if they
were still allright
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/02/16 6:32 am
Originally Posted by John Healy
Quote
I know Chevrolet found that the rods pinch in at
the parting line and wipe oil off the crank so they had more
clearance at the parting line either on rod or bearing


All rods are torqued and finished honed perfectly ROUND during production. Rod bearing shells are NOT manufactured perfectly round. They have more clearance designed in at the split.


Let me clarify my statement...Many years ago Smokey Yunick was digging into what was causing spun bearing failures in stock car engines. He discovered that when the rods and mains were stressed from HP and or detonation the big end "stretched" caused the parting line of the bearing bore and insert to be drawn in..The bearing insert split acted like a squeeze wiping oil from the crank surface... Yunick claimed he had TRW/Clevite 77 bearing company taper the bearing shell at the split to eliminate the problem...
Posted By: kommando Re: Pile of junk connecting rods. - 09/02/16 6:36 am
All bearing shells have a relief area next to the parting line to offset the effect of the inbuilt crush to stop the bearing rotating in the housing. So maybe he asked this to be increased rather than added as it was already there.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/02/16 7:12 am
Originally Posted by kommando
All bearing shells have a relief area next to the parting line to offset the effect of the inbuilt crush to stop the bearing rotating in the housing. So maybe he asked this to be increased rather than added as it was already there.


He asked the bearing manufacturer to decrease the insert thickness near the parting line which gave more leeway to prevent the squeeze effect. This was a problem on US production engines modified for racing in the mid 1950's.
Posted By: kommando Re: Pile of junk connecting rods. - 09/02/16 9:04 am
When I said increase I meant increase the depth of the relief, so same as decreasing the thickness.
Posted By: John Healy Re: Pile of junk connecting rods. - 09/02/16 9:06 am
HB as Kommando said the thinned area of the shell insert, adjacent to the rod split, has always been there. As Kommando said, it is there to offset any distortion created by the inbuilt crush. With a replaceable rod shell the crush is necessary to keep it from spinning in the rod.

Those bent out tangs are not there to keep the shell from spinning, but to insure the shell is aligned with the center line of the rod. The amount the seated shell sticks up above the rod parting line is there by design. It is called the crush. The thinning of the shell, or as you said it the decrease of shell thickness, is there to compensate for the slight distortion caused by the crush.

It can, and should be checked, during any engine build. It should be checked especially if you suspect, or know the rod has been re-sized. IMHO it must be checked, or at least visually verified, if you plan to use the engine "in anger." It's presence can be checked with a feeler gauge.

Kommando is Glacier Scotland still sending rolls of shell stock to Atlantic?
Posted By: kommando Re: Pile of junk connecting rods. - 09/02/16 9:18 am
Kilmarnock is hanging on and still making Al/Sn strip and sintered Cu/Pb, Atlantic takes the Al/Sn, bearing production is close to ceasing but they currently have nowhere else to go for the Al/Sn strip until the Slovakian plant is upgraded so a few more years to go. The Cast Cu/Pb strip line factory closed some years ago, roof was taken off the building last week to stop the requirement to pay local rent tax.
Posted By: ken sak Re: Pile of junk connecting rods. - 09/02/16 9:44 am
Originally Posted by Hillbilly bike
Originally Posted by kommando
All bearing shells have a relief area next to the parting line to offset the effect of the inbuilt crush to stop the bearing rotating in the housing. So maybe he asked this to be increased rather than added as it was already there.


He asked the bearing manufacturer to decrease the insert thickness near the parting line which gave more leeway to prevent the squeeze effect. This was a problem on US production engines modified for racing in the mid 1950's.

yeah i'm aware of Smokey Yunick and David Vizard research and
development for Chevrolet
Posted By: John Healy Re: Pile of junk connecting rods. - 09/02/16 12:41 pm
Quote
when I've checked rods on engines i've built, verticle
measurement then 45 degrees each side of verticle to get
correct out of round


Inquisitive minds would like to know how you routinely machine a rod big end eye oval. That's a bit of clever engineering or you have access to a CNC machine.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/02/16 1:36 pm
Originally Posted by John Healy
HB as Kommando said the thinned area of the shell insert, adjacent to the rod split, has always been there. As Kommando said, it is there to offset any distortion created by the inbuilt crush. With a replaceable rod shell the crush is necessary to keep it from spinning in the rod.

Those bent out tangs are not there to keep the shell from spinning, but to insure the shell is aligned with the center line of the rod. The amount the seated shell sticks up above the rod parting line is there by design. It is called the crush. The thinning of the shell, or as you said it the decrease of shell thickness, is there to compensate for the slight distortion caused by the crush.


The story is in Yunick's book Power Secrets. He presents the story as if he was instrumental in having the bearing thinned more than it had been...Yunick is gone and the story was from about 1955 so ......
Posted By: kommando Re: Pile of junk connecting rods. - 09/02/16 1:58 pm
In my day the reduction in thickness of the shell to give the relief area was derived from the amount of crush which was itself derived from the diameter of the bearing and the thickness of the steel, all set down in formula. If an application needed more relief clearance then that could have been accommodated on the drawing and the angle of the taper modified so the bearing was thinner near the joint with the metal machined from the bearing material side. What would not have been allowed would be the extension of the relief area to cover more of the diameter, this would reduce the bearing surface area and cause premature bearing failure.

So the story is perfectly possible, the std relief that was fine in a production engine, in competition it was a problem and all production changed to increase the amount of relief at the joint with no effect on production engines.
Posted By: desco Re: Pile of junk connecting rods. - 09/02/16 5:04 pm
HB
Enough technology and physics, I'll take 5 of them to make a coat rack.
Posted By: Hillbilly bike Re: Pile of junk connecting rods. - 09/02/16 8:29 pm
Originally Posted by desco
HB
Enough technology and physics, I'll take 5 of them to make a coat rack.


Oh, the junk rods? They have left the building

Kommando, Yunick was arguably the most innovative American race engine and car builder. He was also a great story teller and perhaps he may have seen only his version of the facts...
Posted By: Triless Re: Pile of junk connecting rods. - 09/02/16 9:48 pm
My favourite Smokey Yunick story is the one where ( one of his Chevelles, I think ) completed a long race without a fueling stop. This being impossible if the fuel tank capacity was within the rules.
Anyway,Smokey's car won and the first thing the officials did was to check ( then, of course, bone dry!) the fuel tank capacity.This was legal !
Then Smokey got into the car, started it up and drove off.
Yes, the fuel tank was legal.......... I think the miles of large diameter fuel line coiled out of sight around the car may have been a bit borderline, though !!
Posted By: Irish Swede Re: Pile of junk connecting rods. - 09/03/16 9:24 pm
And, Smokey's reply to the judges was "If the rules don't specify it's 'illegal' to do it, I must assume IT'S LEGAL!"
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