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The mkiv Supra Owners Club

broken bolt on crankshaft


jza800

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That is alright, but will let the machine shop to the rest as they probely have the more right Tool than i have, but is it a easy fix for the machineshop?? and can they do it with the crank in the engine, as i dont feel like taking it out, as thet will result in new bearings :(

 

Why don't you ask your machine shop ? should be easy enough to make the piece i

suggest if they have a lathe and milling machine.

 

The method i suggested is to attempt to drill the bolt out with the crank still in

the engine, i don't see how you'll get swarf/metal shavings in the engine doing it

this way as you don't have to remove the sump.

 

No guarantee this will work but i'd certainly try it as i could make the ring and

have the correct drill bits.

 

You could try using a small mounted point grinding tool in a die grinder to remove the broken

torx bit and if your really careful the bolt itself, the tricky part of this job is not damaging the

threads in the crank by wandering off centre hence making the ring i suggested

Edited by Dnk (see edit history)
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Dunk has the correct ideas, you MUST use a jig to start a hole dead centre in the broken stub. Use inserts in the say 17mm hole opposite the broken stub, to allow incrementally bigger drills to be used. Open up to about 8mm initially. Tap in a suitably sized Torq bit enough to grip. Don't tap in something with such force it swells the bolt stub in the hole, it takes experience to have a feel for this unfortunately. If it doesn't undo easily apply heat to kill any Loctite. The other holes in the crank flange should show witness of any Loctite having been used. That mess is fast approaching the uneconomically salvageable state, if proper methods are not used from now on it'll end up as scrap. It is eminently salvageable if you do take the right steps though.

 

 

I have saved many Nissan GTS-t heads with broken turbo manifold studs, flush with the head face, by using a proper jig and inserts to allow incremental drill size increases. If you break a drill you are probably defeated, it would then take spark erosion to get it out, and that would be crank out and more than a good used replacement shaft.

 

Mr. Bodge might put it together as is with 7 new ARP bolts and try and forget their misdeed ;) If Mr. Bodge does involve himself make sure there are burrs stopping the flywheel sitting flush... The pitch circle diameter of the flywheel bolts means any imbalance from one missing will be fairly minor. Especially as some of it remains in the flange.

 

 

EDIT, I see there's a broken Torx bit in there, they are usually fairly hard, but not VERY hard like an Ezi Out. The right drill bit material will drill one, but this is fast approaching leave a bolt out, or find another crank status...

Edited by Chris Wilson (see edit history)
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I have new bolts, and there are red loctite on them... but if you look at the Pictures, how much would you say, it look like there are 5 and a half good thread from the bottom, and to where the damage thread are... i dont now the thread size.. do you now how far they do in?? all to the end or??

 

i found this on the web..

 

Factory OEM 2JZGTE flywheel bolts are M10 x 1.25 x 21.50mm

 

The factory 2JZGTE flywheel, where the bolts pass through is 12.50mm thick

 

the threads in the end of the crank are 18.50mm deep to bottoming out.

Edited by jza800 (see edit history)
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1.5 x 10 equals 15mm ideal minimum thread engagement. All I can say is get a good mechanic to torque that bolt by hand, probably not the hammer and punch guy.... I would imagine any damage he has done will be visual, it would take Popeye after six cans of spinach to do bending damage to the end of the crank with a pin punch and hammer :) Just nail it back together and don't do drag race type starts.

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ok, have done some new messument, when the bolt is gone thru the flywheel, i have 12mm off thread on the bolt.. and as there are 2mm to the thread on alle the others, i only need 5mm off thread to match the others one...

 

ok, have just thought of bearings, etc. at the bottom would be damage from the shock it gets from the hammer and punch ;D but if you say that i not posible you should now ;)

 

sorry for the maybe same quistions, but have put so many hours in this engine, and will cried my balls off if anything happen with this engine :D

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ohh thanks, it really helped a burden from my Heart, then i only have that last shit burden, and that i that bolt,I dont have any mechanic that is much better than myself, so it will be myself that i gonna span the damn bolt, so could really need some more advise on what the minium i can tighten it and it still keeps it all together as it was done to the Toyotas instruction.. as i dont want to have to be carefull with the car, it should could be used as it was provided, cruise trips, and hard runs ;)

 

i really now that i can be very difficult i am very sorry :D

Edited by jza800 (see edit history)
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Good threads 36 lbs ft Bad thread maybe 30 ft lbs and leave it be then. I would use liquid Loctite on the bad one, not the dry stuff on the new bolts. But I still would just do the bad one by feel if I was doing it and sod the torque wrench.

 

Why do some photos show the crank in the block, and some with the crank out???

Edited by Chris Wilson (see edit history)
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I've only ever gone to 36lbft.

 

Just throw the damn thing back together and stop worrying about it. As above though, on a dodgy thread, you NEED to have someone experienced tighten it, it's no good coming back on here and saying it stripped off at 26.2748573 lbft.

 

Anyone used to working on French Sh1t is a good bet.

Edited by nootysupra (see edit history)
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I've only ever gone to 36lbft.

 

Just throw the damn thing back together and stop worrying about it. As above though, on a dodgy thread, you NEED to have someone experienced tighten it, it's no good coming back on here and saying it rung off at 26.2748573 lbft.

 

Anyone used to working on French Sh1t is a good bet.

 

I am liking the way this new guy thinks :)

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Good threads 36 lbs ft Bad thread maybe 30 ft lbs and leave it be then. I would use liquid Loctite on the bad one, not the dry stuff on the new bolts. But I still would just do the bad one by feel if I was doing it and sod the torque wrench.

 

Why do some photos show the crank in the block, and some with the crank out???

 

many thanks chris, if you say that 30 ft ibs is ok and i can have no worries, i will leve it at that :D

 

as to you other quistion, all off the Picture is with the crank in the engine, have just taken the rear main seal off on those Pictures with the blue paper...

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