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Adjusting Crankshaft End Play | Performance Engine Building [HPA Q&A]

November 14, 2019


– Aurelio has asked, can you touch on
crankshaft end play and how this can be adjusted? OK so yep absolutely crankshaft end play,
also called thrust movement, basically what we’re talking about is the
crankshaft moving backwards and forwards in the engine block. Now this is supported and controlled by
the thrust bearings in the engine block. And while they’re not as critical as the
rest of the bearings in the engine, the clearances aren’t quite so critical,
we still need to check and make sure everything is within specification there. So generally this comes into being important
in a manual transmission car when we’re engaging and disengaging the clutch because
obviously that applies and end force or end loading on the crankshaft trying to
force the crankshaft forward and backwards in the engine block and that’s supported
by those thrust bearings. So the important aspect there is checking
during a dummy assembly. Generally the easiest way of doing this is
by fitting a dial gauge onto the snout of the crankshaft and then we can use a
couple of pry bars and basically we’ll pry the crankshaft backwards and forwards in
the engine block and we can measure thrust clearance. If it is outside of the manufacturer’s
specification, then there are a couple of options there, often there are oversized
thrust bearings that are available in the aftermarket or from the OE manufacturer,
so these can be incorporated but will require the thrust surfaces of the crankshaft
to be machined as well so that’s generally how we go about doing that. Basically in my own experience, unless the
crankshaft is damaged on the thrust surfaces, and is showing excessive wear,
it’s very very rare that we’ll have a problem with the thrust or end flow in the crankshaft
because partly the tolerance is quite a lot wider than what we have for our
main bearings or for our connecting rod bearings. That question was taken from one of
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6 Comments

  • Reply MrR31power April 7, 2019 at 9:02 am

    What happened to the l98 LS build ? i haven't seen anything for months

  • Reply The potato Party pooper April 7, 2019 at 10:14 am

    what about crankshaft bearing clearance? how do you adjust them?

  • Reply hondatrix April 7, 2019 at 12:08 pm

    Bought a brand new L200 2.0 Mitsubishi Ute several years ago…on the 1st drive from the dealer…the very 1st time I was a little harsh with the clutch shifting to 2nd, the v-belt fell off…put it back, same thing next day..took it back, they replaced the v-belt…gave it back to me..as I drove out of their yard, it fell off again…then i knew instantly the play was too much…turns out there was NO bearing inn at all and the block had already shown marks..32km..only 32km..they replaced the engine with a 2,4L by mistake…then wanted to fix their mistake after Mitsubishi refused to pay the warranty…lol….I just laughed and walked out.

  • Reply Monkey mania April 8, 2019 at 12:43 am

    I've built engines with to much thrust clearance and no oversized thust washer option and had to have my machinist build up the thrust wasers and machine to spec

  • Reply Realtime1501 April 8, 2019 at 5:02 pm

    Would it be alright to either shim a crankshaft thrust bearing or surface grind it ?

  • Reply Mikael Gaiason April 24, 2019 at 11:54 pm

    I work on bikes mainly, and I always wondered why that's completely ignored when car guys do the rest of the bearings in a race engine. Well, mostly I wonder why you guys don't destroke the shit out of those things and get the ratios closer to square, if not over. But I digress. Honestly, that's the clearance we spend a lot of time on. Rods and mains are almost never run on the loose end of the spec for us. I'll chamfer passages and all that, but otherwise it's oem bearings and tight tight. End play though? I've seen 10hp differences from one end of the spec to the other. Our cases are vertically split though, so none of that two-piece-shim crap.

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