Sam Posted June 1, 2011 Share Posted June 1, 2011 Dammit.. My rods were out of balance.. the big end caps differed in weight by up to 9 grams I set about lightening & balancing them using a variety of grinding and carbide burrs (finally sanding them down to smooth). I shaved about 5 grams off the area where the bigend cap bolts to the rod..there was plenty of 'surplus' metal there. However, i slipped with the carbide burr and scored the face of one of the surfaces where they mate together. Not terribly, but enough to make me think about binning it. Did i just ruin a rod? Even after lightening one of the caps is still 5grams heavier than the rest. Should I remove more weight? The easy option is to remove it from the bottom area (between heads of the bolts)..is that okay? btw, this is for a road car; not racing it (if i do , ill get new steel rods!) Link to comment Share on other sites More sharing options...
spitNL Posted June 1, 2011 Share Posted June 1, 2011 Did you only measure the big end caps? You should really weigh the whole thing assembled. Who's to say all the conrods have the same balance. Here's a nice video showing the process. http://www.youtube.com/watch?v=QLpiF0E0EJU How deep is the burr? I'd say if you can catch your fingernail on one bin it. Cheers, Frederick Link to comment Share on other sites More sharing options...
Sam Posted June 1, 2011 Author Share Posted June 1, 2011 Thanks Frederick, Looks like now shopping for a new rod! I did try to make a balanced jig, but just used a solid bar instead of the floating part. It didnt work, so i separated the end cap from the rod and balanced each part separately... Not ideal, but thought it was better than putting them back in as-is. Either way, the score seems large enough to worry me too much. it's about 2mm wide (width of the burr) but fairly round/smooth, and it's near the corner of the cap. Link to comment Share on other sites More sharing options...
JohnD Posted June 1, 2011 Share Posted June 1, 2011 Sam, How did you do the balancing? Costa Mesa have pro kit, a set of big end dummy centres and a chain stand to hold them. I tried by making a centre as shown in the pic, like a crown cap to fit the big ends. It was held by a knife edge on a stand, while the small end rested on the table of some scales. Plastic bag to mollify 'er indoors whose scales they were. Accurate to one gram. I levelled each rod, as my suspension device wasn't a chain like the pro kit. It seemed a reasonable compromise between proper kit and what I could make. It was hopeless! I could not get a consistent measurement of the small end weights! The measurements wavered up and down, with no trend and wider variataion than was acceptable. So, How Did You Do It? JOhn Link to comment Share on other sites More sharing options...
GT6Steve Posted June 2, 2011 Share Posted June 2, 2011 Sam, I really don't think you ruined a rod if I understand you correctly. You sanded the flank, the bit at the side of the rod at right angles to the bearing centerline? Unless you were insane there it should be OK. Old school builders will tell you that the rod side clearance is critical to maintain the oil wedge beneath the bearings. Then builders go out and totally ignore that with piston guided rods where there is a mile of clearance at the sides of the big ends. The immediate caveat is that the builders have adequate oil flow to throw away that bit. Can't argue that as the Triumph is always oil challenged. So, don't build a piston guided rod piston and don't sweat slight damage to the sides of the rods. Just be sure it has no effect on the bearing seating surface-no burrs! OOoh, just reread your post. You scored the clamping face> How badly? Anticipated revs? Any machine shop can shave the face and rebore the rods bigend. If it's not a huge bit of damage I'd run it after a check of the clearances with Plastigauge, a careful eye to squareness..... Link to comment Share on other sites More sharing options...
Sam Posted June 2, 2011 Author Share Posted June 2, 2011 John; I had exactly the same trouble but I used a socket bar (with socket) in a vice to hang the rod onto..the scales wouldn't stablise. Steve..thanks.. I thought i was safe there for a minute... Yep, i've scored the face. I'm now faced with the option of salvaging my existing rods, or getting some cheap replacements. The price to fix mine, and balance, resize, realign, shotpeen and check is about NZ$500 with cosworth bolts. That's roughly the same price as the cheap forged ones from Maxspeeding (dodgy chinese firm) which come with ARP bolts. Nobody seems to be selling the stock rods any more. Link to comment Share on other sites More sharing options...
spitNL Posted June 2, 2011 Share Posted June 2, 2011 (edited) Better hold your money, someone(spitfire6?) on here bought those rods and had to do a lot of modifications to make them fit. I'll see if I can find the thread. Frederick Edited June 2, 2011 by spitNL Link to comment Share on other sites More sharing options...
spitNL Posted June 2, 2011 Share Posted June 2, 2011 Found it! Here it is: http://www.sideways-technologies.co.uk/forum/Blah.pl?m-1301590868/s-all/ Cheers, Frederick Link to comment Share on other sites More sharing options...
Sam Posted June 7, 2011 Author Share Posted June 7, 2011 If maxspeeding rods are no good at all, then I'm kind of stuck for options. Can't afford carillo, etc. I haven't been able to source any OEM rods locally. Even if I did, they'll probably have 300,000kms on them, and require loads of machining! I can't find the specific info about what needed modifcation on the maxspeeding rods (some posts were deleted it seems). Other car forums report good results from them, so it seems odd that the triumph rods would be faulty. There's the recent thread: http://sideways-technologies.co.uk/forum/Blah.pl?v-print/m-1301590868/ And the original thread: http://sideways-technologies.co.uk/forums/index.php/topic/4640-h-beam-con-rods-forged-seen-these/page__st__100 Link to comment Share on other sites More sharing options...
spitNL Posted June 8, 2011 Share Posted June 8, 2011 (edited) Try sending spitfire6 an email. It's always difficult to advise over the internet, you could show the rod to a local machinist and ask him his opinion. If that's not possible could you take a picture? Edited June 8, 2011 by spitNL Link to comment Share on other sites More sharing options...
elsieolly Posted June 8, 2011 Share Posted June 8, 2011 i am betting we all have a few old rods floating around, i know i have a couple of sets of odd ones (ie different weights not matched) so could look at sending you one to match if weight was close. So what weight are you looking for? Laurence Link to comment Share on other sites More sharing options...
Sam Posted June 14, 2011 Author Share Posted June 14, 2011 Hey Laurence that's a generous offer, thanks very much. Whereabouts are you located? Shipping several KGs of metal to New Zealand might be prohibitively expensive...! but I'm importing some parts soon, so may be able to combine shipping. Will be in touch if i can't get any locally. On second look, the cap is well scored, definitely not useable. Link to comment Share on other sites More sharing options...
GT6Steve Posted June 14, 2011 Share Posted June 14, 2011 Sam, I think you're being silly about these rods. You do NOT have to buy a new set!! Even if you scored the clamping face a good machine shop will face that off and rebore the bigend just as if you'd asked them to index all the rods. You've not posted any pictures nor yet apparently spoken to a competent engine machinist yet we're talking about a "Save The Rods" marathon?? I've got a pile of six Carrillos laying in the corner of the garage because I'm too disgusted with them to sort out the machining required. Wanna trade for your ruined rods?? Link to comment Share on other sites More sharing options...
elsieolly Posted June 14, 2011 Share Posted June 14, 2011 I am in grantham Uk But steves suggestion sounds good to me Link to comment Share on other sites More sharing options...
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