Freightrain Posted January 11, 2016 Share Posted January 11, 2016 Anyone have some that I could get a picture of next to a tape measure? I'd just like to compare to the ones from the 237. Are they identical? Probably, but I'd like to know before I start searching for the 3/4" versions I need. I don't want to wait to pull the motor to compare.How about a flywheel? Just so I can get a visual on that. I hate flying blind and waiting to pull mine apart. Thanks. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/ Share on other sites More sharing options...
theakerstwo Posted January 11, 2016 Share Posted January 11, 2016 Here is a bolt pattern from a E7 which is same as E6 and same meauagement as 673.But if I remeneb right the early 673 had cap screws pressed thru the crank and using castellated nuts.The measurement is 5"across from center to center and from one bolt to the next is center to center 1.500" The back of this engine uses a wet flywheel housing Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319518 Share on other sites More sharing options...
theakerstwo Posted January 11, 2016 Share Posted January 11, 2016 And I don't have a push type flywheel.But i have forgotten some on the old engines but I think there was two flywheels.One for a single disc and one for a twin disc clutch.That is something you need to look at.The trans bell housing is also different from a single to a twin disc. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319519 Share on other sites More sharing options...
Freightrain Posted January 11, 2016 Author Share Posted January 11, 2016 How about the actual bolts? Should I assume the 237 bolts I have will be the same(length) as the ones in my 673? My cover plate is off the top of my bell. Maybe I can look in and see what I have for clutch.Thanks Glenn. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319522 Share on other sites More sharing options...
theakerstwo Posted January 12, 2016 Share Posted January 12, 2016 I don't know what the length will be cause the flywheel will be different thickness on the ones I have. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319538 Share on other sites More sharing options...
Freightrain Posted January 12, 2016 Author Share Posted January 12, 2016 And that is why I asked. I don't want to assume it is the same as the 237 bolts I have.The 237 bolts have a relief cut behind where the washer is and the threads. Likely where the bolt will stretch when torqued. I'm kinda wondering if I just get a std grade grade 8 case hardened bolt and torque it will it be okay? I surely don't want them to fail. Just another "what if" scenario I've had running through my head for awhile.Typical car flywheel bolts aren't anything special, persay. Just case hardened bolts, usually with a thin head to give clearance for the clutch disc. These 237 bolts area actually a thicker head then normal. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319570 Share on other sites More sharing options...
mrsmackpaul Posted January 12, 2016 Share Posted January 12, 2016 well I can measure some old ones if I can find some give me a little bit of time I have always put new bolts in if I have had to have the flywheel off and when I buy them they come with loctite already on them PIA I seem to remember let me have a look and I will see what I can find Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319584 Share on other sites More sharing options...
mrsmackpaul Posted January 12, 2016 Share Posted January 12, 2016 Well had a gander in the shed couldnt find any old bolts still in the box but I found what I reckon were the bolts out of my E6 5/8 x 3 UNF grade 8 sorry not much help Paul Quote Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319669 Share on other sites More sharing options...
theakerstwo Posted January 13, 2016 Share Posted January 13, 2016 Larry I went out and looked at my B model this evening and I think I would look at another ideal.The trans will still be in same position as it is now so play with the ideal of using a cable like later macks.They are 1/2" and you can have them made how long you want it and with what ends and what kind of attachment.If you use the flywheel you have and a pull type clutch then the clutch pedal has to move the clutch shaft opposite of what it is now.Then you will have a clutch brake and a double disc clutch. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319712 Share on other sites More sharing options...
ranchhopper Posted January 13, 2016 Share Posted January 13, 2016 Larry that flywheel had a double plate clutch set up when I took it off. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319779 Share on other sites More sharing options...
Freightrain Posted January 13, 2016 Author Share Posted January 13, 2016 All I'm trying to do is confirm what bolts a 673 uses to hold the flywheel. I'm going to get a larger(3/4") in the same design. "IF" the bolts are the same as the bolts from the 237, then I'm good. I have the sample I need. If they are in some manner different, then I was just looking to find out now instead of after I pull the motor(whenever that time comes). Glenn, I don't really what to deal with putting a cable clutch in and all that. Just don't want to deal with it right now. It is doable, I have the technology, but I have too many other things on my plate right now to tear into that project too. I understand I'll have a better clutch, but I don't have the driveline to put up with too much abuse anyway so I'm good with the current clutch. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319781 Share on other sites More sharing options...
41chevy Posted January 13, 2016 Share Posted January 13, 2016 Why not measure the flange thickness on the crank, the flywheel thickness add the lock washer and compare the dimensions to the bolts you have? Paul Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319788 Share on other sites More sharing options...
Freightrain Posted January 13, 2016 Author Share Posted January 13, 2016 I think my question got a bit off track.I'm trying to figure out what bolts are in my truck now(673 motor). It is not apart. I want to know if it is the same as the 237 motor I have in the garage. I am trying to figure it out before I tear it apart, that is all. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319801 Share on other sites More sharing options...
fxfymn Posted January 13, 2016 Share Posted January 13, 2016 You probably know this, but just in case. If you use grade 8 bolts make sure you check the torque spec for them. They are torqued much higher than a lower grade bolt and may strip the threads if that is not what the factory used. Quote Money, sex, and fire; everybody thinks everyone else is getting more than they are! Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319807 Share on other sites More sharing options...
Freightrain Posted January 13, 2016 Author Share Posted January 13, 2016 The 237 bolt is grade 8 (denoted by the 5 hash marks on the top) and I'm assuming it is case hardened also? Or it is just black anodized? I'm betting it is case hardened so the holes in the flywheel don't beat through it. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319816 Share on other sites More sharing options...
41chevy Posted January 13, 2016 Share Posted January 13, 2016 They are heat treated, the black anodizing is used because it doen't affect torque values or so ARP says in their bolt kits for boosted systems like my Mustang running 55 + lbs of boost. Paul Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/43468-673-flywheel-bolts/#findComment-319827 Share on other sites More sharing options...
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