Nick Jones Posted June 16, 2012 Share Posted June 16, 2012 Getting close to finishing the PI bottom end.Just fitting the flywheel and checked the torque specs. Getting a large degree of conflict from different sources.Mk1 factory manual says 42 - 46lb ft (I thought this seemed a bit light so checked elsewhere)Haynes 2000/2500 manual says 50 lb/ftHaynes Vitesse/GT6 manual says 42- 46 for 1600, 2000 mk1 & 2, but 50 - 75 lb/ft for GT6 Mk3Unipart 2000 manual says 90 - 95 lb/ft. (this seems like rather alot)So what the hell should it really be?!ThanksNick Quote Link to comment Share on other sites More sharing options...
CRAJ Posted June 16, 2012 Share Posted June 16, 2012 Factory blue book says for mk2 '7/16 UNF Flywheel to Crankshaft 90-95 lb/ft'so the Haynes manual is correct this time Nick.Colin. Quote Link to comment Share on other sites More sharing options...
Richard B Posted June 16, 2012 Share Posted June 16, 2012 Sounds about right. You don't want them working loose! ??) Quote Link to comment Share on other sites More sharing options...
DJB_Harvey Posted June 16, 2012 Share Posted June 16, 2012 I use a dab of Loctite as well . The lower torque figures are for early engines running 3/8 UNF bolts . Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted June 16, 2012 Author Share Posted June 16, 2012 Thanks :)Indeed I do not want them working loose........ or snapping off either. They're 55 lb/ft now so I'll nip them up a bit more.It's not the Haynes that is right Colin - the nearest Haynes is the GT6 Mk 3 @ 50 - 75 lb/ft - which is such a wide margin it sounds like a blind guess anyway!CheersNick Quote Link to comment Share on other sites More sharing options...
CRAJ Posted June 16, 2012 Share Posted June 16, 2012 Nick_Jones wrote:Thanks :)Indeed I do not want them working loose........ or snapping off either. They're 55 lb/ft now so I'll nip them up a bit more.It's not the Haynes that is right Colin - the nearest Haynes is the GT6 Mk 3 @ 50 - 75 lb/ft - which is such a wide margin it sounds like a blind guess anyway!CheersNickYeah I missread your original post, I knew the correct figure was there somewhere :B Quote Link to comment Share on other sites More sharing options...
esxefi Posted June 17, 2012 Share Posted June 17, 2012 well timed thread nick,i was just going to ask the same info........ :) Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted June 17, 2012 Author Share Posted June 17, 2012 Well, I'm a bit wary of that 90 - 95lb/ft figure. I think it's too high and wonder if it's a misprint and should be Nm :-/Having now tried for a 90 lb/ft setting on one bolt, it was seeming to want to go alot further (normally just a relatively few degrees is all it takes, especially on short bolts like these with limited stretch), so I stopped and looked up general bolt info.This site http://www.leytonfasteners.co.uk/pdfs/TorqueValueGuide.pdf seems to be showing max torque for 7/16" grade S @ 50 lb/ft and even T grade would only be 55ish. Don't know what grade these bolts are - main bearing bolts are marked S.Even ARP have a maximum specified torque for their very strongest grade material of 90 lb/ft....... and that will be alot stronger than the OE bolt.Nick Quote Link to comment Share on other sites More sharing options...
GT6 M Posted June 17, 2012 Share Posted June 17, 2012 Nick, im maybe a little too pikkee, but the bolts in my mind are just plain wrong.the shank does no go into the crank, just the thread part.on a few Ive took to bits, the holes in the flywheel have been elongated, and the bolt sides shiney.On my engine,I drilled out the crank 1/4 inch and fitted longer bolts,so the bolt shank,also acts as a spigotBeen OK for last 20 odd yearsM Quote Link to comment Share on other sites More sharing options...
esxefi Posted June 17, 2012 Share Posted June 17, 2012 bit late now,i've torqued to 90lbs :-/.marcus what you said i thought too and ended up double doweling the flywheel when i originally built my engine,the bolts should just clamp the flywheel on and the dowels transmit the torque. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted June 17, 2012 Author Share Posted June 17, 2012 Surprised they went to 90lbs - felt like something was going to give way when I tried earlier...... I've got a bust crank and some stray bolts of the same type so perhaps I'll try an experiment with those and measure bolt length before and after.The bolts I have (standard ones) do have short shanks on them - probably 1/2 - 2/3 the depth of the flywheel. The torque should be transmitted by the friction between the two tightly clamped surfaces in any case - elongated holes/damaged bolts indicates bolts not tight enough.Twin dowels is a nice idea.Nick Quote Link to comment Share on other sites More sharing options...
andy thompson Posted June 18, 2012 Share Posted June 18, 2012 I use 75lb/ft on a standard boltARP 200-2802 (Extra Strong) with lube says 85lb/ft http://www.summitracing.com/parts/ARP-200-2802/http://arpinstructions.com/instructions/200-2802.pdf Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted June 18, 2012 Author Share Posted June 18, 2012 Thanks Andy. I settled on 65 lb/ft in the end. May yet get some ARP ones though.......Looking forward to the next installment of the 2.1 screamer..... but seems like you have several projects all at exciting stages!CheersNick Quote Link to comment Share on other sites More sharing options...
esxefi Posted June 18, 2012 Share Posted June 18, 2012 think i'll take mine out and redo them or get new ones,i won't take the chance. :o Quote Link to comment Share on other sites More sharing options...
esxefi Posted June 21, 2012 Share Posted June 21, 2012 well just got my arp 2802 bolts and i'm not conviced that 9mm thread engagement is enough,considering research on the net suggests arps' info of 1.5 times diam is recommended.slightly peed off as i now may have to return them and see if there is a slightly longer bolt in the listings. >:(and they are 2mm shorter than the original bolts so who's right? Quote Link to comment Share on other sites More sharing options...
esxefi Posted June 27, 2012 Share Posted June 27, 2012 i have now got and decided to use some 12.9 allen head bolts which i have modified to make maximum use of the threads in the crank.their blurb states they are good for 190,000psi tensile strength and max 100ftlbs torque(won't be going that high though,75-80 should be ok)one and a half english pounds each ::).as tough as or exceeds the standard bolts but maybe not up to the arp spec.i know how tough allen bolts can be ,i used to use them in 20mm flavour on big presses with high tonnage so have seen their performance.any way some arp bolts going for what i paid,should be ok for a 1500 i would have thought(thinner flywheel?). Quote Link to comment Share on other sites More sharing options...
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