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The mkiv Supra Owners Club

big end bearing - workshop manual


awu98

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Hey guys.

 

Been years since I had to sell my supra when I was 18, promised myself one as a track car one day and am finally there :) Just about to buy a NA with a 2JZ conversion and 5 speed with a spun big end bearing.

 

Have some ACL bearings to sling in and will be rebuild the engine; just wondering if anyone's got any links to how tos/workshop manuals etc to help me muddle my way through?

 

Have been told it's an engine out job on the 2JZ, but then by someone else that it's not so am a little lost!

 

cheers!

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glad you mentioned that - possibly a silly question but what's the best way to identify a scrapped crank - is it Just a case of measuring the clearances? I've found a few companies selling balanced oem cranks for reasonable prices which I was thinking of replacing it with to be sure.

 

Rods I'm going for a forged set so that's covered. Oil pump has been purchased as a matter of course. I was thinking of purchasing a built head so could be the go there - cheers for that though had overlooked the steam clean - will be sure to get it off somewhere for that prior to rebuilding it.

 

Anything else worth looking at while I've got it open?

 

With the bearings etc done - If I'm chasing about 700 bhp ultimately - will a forged or even balanced crank be worthwhile?

Edited by jaw (see edit history)
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An engine that's spun a rod bearing needs the crank removing, visually inspecting to see if it's scored, got a bad groove where the oil pump seal runs, and to see if it has had heat into it from the spun bearing. If it passes those tests it needs checking for straightness, size and ovality. then polishing in a proper crank polishing fixture. Cut any corners and you may rebuild a load of scrap at huge cost in material and time. All of the above needs experience and / or special tools and machinery. Chances are the crank will be scrap if it's spun a rod bearing. People run perfect condition stock cranks in supposed 700 BHP engines. Personally I would prefer a billet crank, but few engines seem to have crank failures on stock cranks. A high qulaity build ewould see a full internal / external balance as a matter of course. I prefer to balance external items like damper, flywheel and clutch separately, so new items can be fitted with just the individual replacement balanced. If balanced as a full assmbly a new flywheel, for example, may throw the whole balance out.

Edited by Chris Wilson (see edit history)
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Ah awesome thanks for that. I have seen a few balanced stock cranks for sale from the states for not a lot of money so I think I'll go that route then rather than try and find a specialist to verify it - will be good for peace of mind - will scrap the crank that comes out and replace all bearings, seals and so on. That's comforting to know, if my ceiling is going to be 700 bhp seems I should be OK from that point of view then - have done a fair bit of looking at other spec sheets people have ended up with and have seen no mention of billets being used; I'll just uprate the conrods and pistons.

 

That's a good point, gives me a bit of freedom in shopping around for parts too I suppose.

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Sorry Chris just saw your message there - I'm actually in Aus now - but would be keen to find out the price on a good crank balanced and shipped over? (can arrange the shipping, have been advised 240 pounds for a bottom end so a crank shouldn't be too brutal)

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