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Thomas, with thanks for measurements already offered may I trouble you to take a read of the margin width on the flange periphery? Those of us with material already lost on the wear side would find that info helpful. 

Cheers

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A good way of saving this sort of area is by metal plasma spraying.  This can build up the surface without introducing the heat levels that cause distortion..  It is quite common to see this used on c

Ok, off to the garage attic to measure the spare "cracked" crank. This from a 1985 910, history unknown, presumed original to the car. The flange in question is tapered and has a fillet on both s

Having just installed a crank, I reckon 30lb could be in the ballpark. A quick calc, and shipping could be around £100 - £150 depending on ultimate weight/size.

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Gavin et al, just downloaded Engine Service 1874938432_SecEA-Enginepg50B-9XXModtoMainBrgPanel-1980-87910-912note.jpg.09042cfcb2096d9d9dfff6a2ef118673.jpgNotes courtesy of Tim Engel, will attach here.

Take care to review the pertinent notes in the full PDF also attached as this mod is not appropriate for all engines. Do read carefully! 

Sec EA - Engine - Modify #5 Rear Bearing Web, Pg 50a, 50B & 51.pdf

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Steve,  I believe my issue is the result of the circlip failing on the Citroen transmission input shaft and the subsequent load being placed on the crank. The crank being then pushed forwarded resulted in milling the MBP and the rear thrust washer. Once there was enough float the front thrust washer got spat out and ended in the sump. I have have owned the car for 2 1/2 years and driven it maybe 200 miles in it during that period. The PO had paid $6000 for work that included a new input shaft as a result of a ‘grinding noise’ . The car had paper on the repairs so I figured all was good. Test drive before purchase revealed no concerns. I didn’t push it because the timing belt was 10 years old. The car did have a fuel leak. So it needed a belt service and the leak addressed. No biggie. On getting the car home I discovered that both tanks were shot. So the work began to replace them. New tanks in and belt service completed. I drove it and again no issues. Then one day I stated to get first gear selection problems but it was intermittent. It then quickly became more often than not. So I pulled the tranny thinking clutch or throw out bearing but those were good. For some reason I decided to grab the flywheel and give it a pull and a push. It moved about a 1/5 of an inch. So that was it, engine out and start the disassemble process. That revealed a damaged MBP, totally milled and chewed rear thrust washer and milling of the crank thrust flange.

I was more upset over having to pull everything apart again after putting it all back together following the tank replacements. The miles I did drive were really good and underlined how much I could enjoy the car.

I hate dead cars so seeing it the garage disabled just p***es me off.

Cheers, Gavin

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The input shaft could never exert enough pressure to do that.

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Sympathy for your misfortune, Gavin, typical Lotus tragedy of indifferent, or crooked, or ignorant maintenance which have brought many a fine car to a premature end. No quarrel with either your or Sparky's latest posts, circlip fail is problematic though it would have been clutch loading providing the force needed to wreak such damage. I'll be out for a consult with a veteran machinist in the week ahead, will share anything concluded back here for sure. BTW, QED shows steel cranks at 1470 Pounds Sterling on their website, FWIW. I'm pleased you are determined to repair your car, suggest you take in as much info as you can find through venues like TLF. Wisdom is gold when it comes to owning a Lotus.

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@gtookey The crank moved 1/5 of an inch with a thrust washer missing? Correct?

Please post a photo of your crank flange. And your block where the thrust washers go as well!

It may actually be usable with thicker thrust washers, not much strength is needed in that area.

I would suggest you measure the gaps between crank and block in that area, and see if a set of thicker washers would correct the end float.

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Travis, yes... front thrust washer was bent over in the sump...

 

B64ED4C2-3F33-49C6-8B82-62259647010A.jpeg

82070CF4-B859-4005-8DA3-7B7FDB3EC619.jpeg

 

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9A5B9E9C-A7DD-4203-90B9-0F882B4A10A5.jpeg

Cheers, Gavin

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To me it looks like the block is fine. The crank is s little worn, could be machined smooth if there are shims thick enough to make the end float correct. The flange does not need to be that strong. The MBP needs to be repaired so that the shims are held and can't spin again.

I think someone installed the thrust washers backwards...

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Boggles the mind that someone so ignorant as to reverse the TW's could be at work on one of these! Gavin's thrust flange looks less grim than did mine IIRC, though I have yet to haul the crank out of its stash for a refresher examination. I did throw my block and MBP up onto the bench last evening, finding havoc most apparent inside the aft end of the block where the forward TW had been caught up by #4 counterweight and mauled that area of the crankcase including substantial reduction across a significant arc of the TW register. That was sobering, to say the least, and begs the question whether better to weld up and machine an OEM spec register, cut the existing one deeper into the #5 saddle, or just mate the dry sump MBP with my original 907 block.

Must wonder why the undue wear on the clutch loaded thrust interface? Once gone sufficiently that leads to forward walk of the crank allowing the other TW to depart its register location altogether.  

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