Lotus Elan

Catastrophe on Elan ownership day one!

PostPost by: Steve G » Tue Apr 20, 2010 8:55 am

There won't be any heat related damage to the engine as it was running normally and only over revved for a period of about 2 seconds. I have to say it sound rather good in that short time, like a historic grand prix car!
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PostPost by: Steve G » Thu Apr 22, 2010 11:28 am

And the winner is...

neilsjuke and elansprint71 for guessing correctly that I had sheared the flywheel bolts!

I got the engine out last night, it was very easy, the flywheel and clutch stayed in the bell housing. Here are some pictures.

http://picasaweb.google.co.uk/stevegunn ... directlink

As you can see in the picture of the flywheel, the boltholes have elongated by a couple of millimetres! It must take some considerable force to push a space into half an inch of cast iron! I will definitely need a new flywheel. The clutch appears to be in good condition, it's not very worn and didn't seem to suffer from the flywheel separation.

I turned the crankshaft over and everything seems to be turning easily, there were a couple of bits of swarfy metal in the sump but there doesn't appear to be any damage to the crankshaft. I'm going to get it and the conrods crack tested to be sure and replace all of the main, big and small end bearings.

Thanks for all your help and advice so far guys.
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PostPost by: rgh0 » Thu Apr 22, 2010 11:53 am

I would replace the big end and main bolts also - as well as the flywheel bolts of course :P

cheers
Rohan
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PostPost by: Steve G » Thu Apr 22, 2010 12:02 pm

rgh0 wrote:I would replace the big end and main bolts also - as well as the flywheel bolts of course :P

cheers
Rohan


But are you sure I couldn't reuse them? :lol:
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PostPost by: rgh0 » Thu Apr 22, 2010 12:05 pm

mmmm -I would have to check my loctite catalogue --- maybe they have something to help you out with fixing those fylwheel bolts :lol:

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PostPost by: smo17003 » Thu Apr 22, 2010 12:35 pm

I am also after a flywheel to go onto a 711 engine that I am building for my Elan. Do I have to use the TC flywheel, or can I use one from e.g. the 1600GT, and use an uprated or heavy duty clutch to suit?

Cheers

Mike
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PostPost by: Steve G » Thu Apr 22, 2010 12:40 pm

I'm not sure whether to get this one (6 bolt, double doweled);

http://qedmotorsport.co.uk/qed-shop/lot ... d/6bdd/12b

Or this one;

http://qedmotorsport.co.uk/qed-shop/lot ... t-12b/6bdd

As it's only ?10 more. I know of the benefits and downsides of a lightened flywheel and the benefits seem to suit me.
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PostPost by: bcmc33 » Thu Apr 22, 2010 1:14 pm

smo17003 wrote:I am also after a flywheel to go onto a 711 engine that I am building for my Elan. Do I have to use the TC flywheel, or can I use one from e.g. the 1600GT, and use an uprated or heavy duty clutch to suit?

Cheers

Mike

The Twink flywheel is unique to the engine for 8" or 8.5" clutch plates - I seem to remember the 711 flywheel was to suit a 7.5" plate.
I've just bought a Twink flywheel to as part of a tall block project from Bob Yarwood (www.yarwoodeng.co.uk) for ?40 and he said he had plenty. Try him for other bits as well.
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PostPost by: bcmc33 » Thu Apr 22, 2010 1:21 pm

Steve G wrote:I'm not sure whether to get this one (6 bolt, double doweled);

http://qedmotorsport.co.uk/qed-shop/lot ... d/6bdd/12b

Or this one;

http://qedmotorsport.co.uk/qed-shop/lot ... t-12b/6bdd

As it's only ?10 more. I know of the benefits and downsides of a lightened flywheel and the benefits seem to suit me.


I've just bought a Twink flywheel as part of a tall block project from Bob Yarwood (www.yarwoodeng.co.uk) for ?40 and he said he had plenty. Try him for other bits as well.

A dowelled flywheel is not necessary, but always use ARP bolts - not just for the flywheel but also the conrods and main bearings. A touch more expensive than standard, but well worth it for peace of mind.
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PostPost by: Steve G » Thu Apr 22, 2010 1:57 pm

bcmc33 wrote:
Steve G wrote:I'm not sure whether to get this one (6 bolt, double doweled);

http://qedmotorsport.co.uk/qed-shop/lot ... d/6bdd/12b

Or this one;

http://qedmotorsport.co.uk/qed-shop/lot ... t-12b/6bdd

As it's only ?10 more. I know of the benefits and downsides of a lightened flywheel and the benefits seem to suit me.


I've just bought a Twink flywheel as part of a tall block project from Bob Yarwood (http://www.yarwoodeng.co.uk) for ?40 and he said he had plenty. Try him for other bits as well.

A dowelled flywheel is not necessary, but always use ARP bolts - not just for the flywheel but also the conrods and main bearings. A touch more expensive than standard, but well worth it for peace of mind.


Thanks Brian, I have sent Bob an email.

I was wondering about the dowels, as you can see there were none in my flywheel and only one hole for one on the engine side (back cover?). If I can get an OE flywheel for ?40 I might just go for that instead of a steel one. I still don't know whether to rebuild the water pump or go for an electric one.

Do I need ARP bolts for everything? Head bolts for instance? If the flywheel bolts hadn't sheared there could have been more damage to the engine, they acted as a rather expensive rev limiter!
Last edited by Steve G on Fri Apr 23, 2010 8:49 am, edited 1 time in total.
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PostPost by: alaric » Fri Apr 23, 2010 2:42 am

Gorgeous looking car Steve. Bet you can't wait to get it running now. Shouldn't take too long by the looks of it. Amazing to see all the bolts sheared like that.

Sean.
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PostPost by: rgh0 » Fri Apr 23, 2010 7:19 am

For the bolts to fail like shown in the photo it implies the flywheel was not properly clamped to the end of the crank. This in turn implies the bolts were not originally torqued correctly or came loose in service or were to long and bottomed out in the crank thread before properly clamping the flywheel ( seen that one a couple of times). I have never seen a properly torqued flywheel bolt come loose. The fact that the cast iron flywheel shows signs of extended hammering around the bolt holes also says the flywheel was loose for some time and the over rev was just the last straw that broke the already loose flywheel free.

Regardless of the cause of the failure - get good bolts and genuine ARP ones are guarranteed quality. Lots of problems with counterfeit bolts on the market so you need to be careful where you buy stardard high tensile bolts from to be sure they are truely up to specification. The you need to make sure all the threads are clean and check the bolt length to ensure it does not bottom out in the crank. Apply high strength loctite just to be sure and torque the bolts to the required specification in a criss cross patter nad over a few steps of increasing toque with a calibrated good quality torque wrench ensuring the flywheel is fitted snug on the flywheel and clamping correctly . You need to clamp the crank or flywheel some how to stop it turning when tightening the bolts, this is why the bolts do not get tightened correctly often as you cant easily hold the flywheel by hand when tightening the bolts

cheers
Rohan
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PostPost by: qedmotorsport » Fri Apr 23, 2010 8:13 am

Steve G wrote:I have had no reply from QED from my email a few weeks ago [...]


Hello Steve,

You emailed us on the late afternoon of the 6th April, we replied on the early morning of the 8th April. Please check your junk/spam folder...
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PostPost by: Steve G » Fri Apr 23, 2010 8:35 am

rgh0 wrote:For the bolts to fail like shown in the photo it implies the flywheel was not properly clamped to the end of the crank. This in turn implies the bolts were not originally torqued correctly or came loose in service or were to long and bottomed out in the crank thread before properly clamping the flywheel ( seen that one a couple of times). I have never seen a properly torqued flywheel bolt come loose. The fact that the cast iron flywheel shows signs of extended hammering around the bolt holes also says the flywheel was loose for some time and the over rev was just the last straw that broke the already loose flywheel free.

Regardless of the cause of the failure - get good bolts and genuine ARP ones are guarranteed quality. Lots of problems with counterfeit bolts on the market so you need to be careful where you buy stardard high tensile bolts from to be sure they are truely up to specification. The you need to make sure all the threads are clean and check the bolt length to ensure it does not bottom out in the crank. Apply high strength loctite just to be sure and torque the bolts to the required specification in a criss cross patter nad over a few steps of increasing toque with a calibrated good quality torque wrench ensuring the flywheel is fitted snug on the flywheel and clamping correctly . You need to clamp the crank or flywheel some how to stop it turning when tightening the bolts, this is why the bolts do not get tightened correctly often as you cant easily hold the flywheel by hand when tightening the bolts

cheers
Rohan


That's very interesting to know Rohan, thanks. I probably will be doing all jobs like this myself so I can't get enough advice like that. I'm getting a guy called Trevor Addison (Some of you GRRC members might know his name, he mostly rebuilds vintage motorcycle engines) to fit new valves and springs to my head and he's also going to look at the block this weekend. I could do everything myself but I don't have all the tools, knowledge and the confidence yet to do the important/more difficult tasks. I got a very good Teng torque wrench for my last birthday which will get some serious use soon. I'm going to stick a copy of the torque settings page from the Lotus workshop manual inside my toolbox lid as someone on here very cleverly suggested. Once the head comes back and I get the bottom end rebuilt with the crack tested (or new!) crankshaft and con rods, I'm going to refit the engine myself. There are lots of other jobs which need doing before/during refitting the engine. I'm planning to;

Clean up and, in part, respray the engine bay in matt black.
Replace all hoses that are looking slightly tired with Samco classic black ones.
Fit new choke cable (the last one was only connected to one Weber!)
Fit rev limiting rotor arm to optical distributor
Fit blanking plate to mechanical fuel pump mount (The pump was left on even though it has electric fuel pump in boot now)
Fit new Tudor washer bottle and tubing (I think the one in there was original by the looks of it, dark brown!)
Remount ignition coil to sensible place, not directly under intake trumpets of Webers. :roll:
Repaint Anti-Roll Bar in Red Hammerite
Repaint Block and head in correct Battleship Grey
Respray Cam Cover in Crackle Black
Grind millimetre or so from bottom of accelerator pedal so it's not touching the Spyder footwell anti-intrusion bar. :roll: :roll:

There's lots of other bits to do but that'll keep me busy.
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PostPost by: bcmc33 » Fri Apr 23, 2010 8:43 am

Steve,

Rohan's assessment of the failure seems correct to me. His advice on criss-crossing the tightening of the bolts should be standard practice - just like the cylinder head clamping. I've recently fixed my flywheel with ARP bolts and started at 25 lbs ft torque then 30, 40 & 45 in the same criss-cross pattern.

To understand fixings better download the ARP catalogue - it makes good reading.
http://www.arp-bolts.com/
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