Tr4Tony Posted February 24, 2003 Report Share Posted February 24, 2003 bad news on the TR4 rallycar front - my flywheel has come off. On inspection it appears that all four of the bolts have sheared off, taking the dowel between crank and flywheel with them. Damage limited due to quick shift to neutral and switching off. Firstly any thoughts on why this might have happened ? I have a few myself ? Secondly any thoughts on how to stop it happening again - barring a 6 or 8 bolts fixing to the crank ?? Thanks (gloomilly) Tony Quote Link to post Share on other sites
jonlar Posted February 24, 2003 Report Share Posted February 24, 2003 Hi Tony, Just a thought, probably wrong, is there any chance the flywheel fixing bolts have been replaced with ordinary steel bolts instead of high tensile? The dowel is just ordinary steel designed for location only. Quote Link to post Share on other sites
Tr4Tony Posted February 25, 2003 Report Share Posted February 25, 2003 I think youre right, either that or old stretched bolts. Thankd Jon Quote Link to post Share on other sites
Guest harry dent Posted February 25, 2003 Report Share Posted February 25, 2003 Just a guess,the flywheel bolts could be the stretch type and only used once.Maybe they have been used again and worked loose resulting in the flywheel chattering against the bolts. Regards Harry. Quote Link to post Share on other sites
Guest Ady Posted February 25, 2003 Report Share Posted February 25, 2003 loose bolts would indeed lead to them all shearing at the same time. when fitting the new flywheel the correct grade of bolt tightened to the correct torque should prevent this happening again use thread lock for extra security Quote Link to post Share on other sites
Guest thurlands Posted March 13, 2003 Report Share Posted March 13, 2003 Not sure if this TR uses tab washers but if it does throw them away and use loctite. What happens is that the tabs being soft, fret and then the bolts come loose. Incidentally it's the dowel(s) that takes the torque together with the friction on the faces, the bolts only locate the flywheel. If you uprate to the point where the flywheel falls off then you need either bigger or more dowels. Jim ------ Quote Link to post Share on other sites
jonlar Posted March 14, 2003 Report Share Posted March 14, 2003 Incidentally it's the dowel(s) that takes the torque together with the friction on the faces, the bolts only locate the flywheel. If you uprate to the point where the flywheel falls off then you need either bigger or more dowels. Jim ------ I'm interested to see your posting Jim, as I've always understood the opposite as I posted above. The dowel is only mild steel and for location only, and shouldered high tensile bolts clamp the flywheel to the crankshaft and transmit the torque. Can anyone confirm which is correct please. Quote Link to post Share on other sites
Guest thurlands Posted March 22, 2003 Report Share Posted March 22, 2003 Right now I've got five minutes I'll answer this. I was always taught that the bolts hold the flywheel in contact with the crank and should be in tension at all times and NEVER take any of the turning loads which put them in shear. The dowels are their to take any of the turning loads hence when uprating engines (early Fords being a common one) then you drill the flywheel & crank and add extra dowels. So the main things ensuring that flywheel goes round with crank is the dowels and the friction of the flywheel to crank. Years ago I built a cooking 2litre Alfa twin cam for a stock car, I got called away before the final assembly was complete. At the first meeting the throttle jammed and because of the noise etc, the driver didn't realise so we estimate the engine sat at valve bounce for a minimum of 1-2 minutes or so. On recovering the car and trying to start it it made a good impression of having a broken crank. On pulling engine fully expecting a rebuild, we noticed the flywheel was hanging off. Then I noticed that the guy who bolted it on had used the tab washers on the bolts. What had happened was they had fretted and loosened the bolts. Retightened new bolts with o tabs and some loctite reassembled engine was fine! Quote Link to post Share on other sites
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