mx5 crankshafts

Michael Donovan · Post by **Michael Donovan** » Wed Mar 28, 2001 10:20 pm

I just brought a 1990 import mx5 last weekend..its crank is still connected!

can I do anything other than live in hope, to ensure it wont snap or grind out
the keyway?

Has anyone tried a "modified" i.e. mid 1991 crank which I hear has a longer
snout, which should distribute the load on the crank better. Just brought a
book on the subject and the photos show just how bad a design the original
crank/ cam pulley was.
Any help much appreciated.
Are there any aftermarket cranks tat do the job better. Thanks

Gary Morrison · Post by **Gary Morrison** » Thu Mar 29, 2001 11:14 am

Michael,

Just live with it. If and when the timing belt is or was done, just hope or
arrange for someone who knows about the problem to deal with it. Replacing the
crankshaft is a costly job.

Gary

Post by **zorruno** » Thu Mar 29, 2001 11:56 am

the archives of this list show a couple of checks for the condition and
links for bandaid type repairs.

I don't think it is worth worrying about really, just keep an eye on it and
if it gets to be a problem, whack in a new
balanced/ported/polished/nicely-rebuilt engine. It will prob cost you the
same and take the same amount of time as worrying about aftermarket cranks.

what book did you get with this info by the way?

H.

Michael Donovan · Post by **Michael Donovan** » Fri Mar 30, 2001 10:48 pm

From:Mike
Sorry my messsge might have been confusing. I got info on cranks breaking
from many web sights mainly from U.S. + pics. I also got pictures of the
engine in different stages of stripdown from the Haynes manuel, these show
(though don't say) how poor a design the crankend is..i.e. only protruding
1/2 way through the cam pulley and such a very narrow diameter.
I read that they brought out a different crank that fitted the 1600 engine
in mid 91 as a stopgap measure until a new bigger diameter one was
introduced in maybe 92 or so. It (the stopgap unit) was same diameter as
standard original but went all the way through the cam pulley giving at
least much greater effective surface area/contact area.
I'd like to try and find one of these, though by now my hopes are slim( of
getting one from a wrecker).
Cant afford a nice new engine ported engine..it'll be sometime before I get
the car paid for.
Thanks and regards
Mike

Chic & Morven · Post by **Chic & Morven** » Sat Mar 31, 2001 8:21 am

Mike,

I doubt that a wreckers would sell a crankshaft separately. I guess as time
goes on more of the 'light weight sports cranks' will fail, but so far only
a small percentage of them have. Like zorruno said, I really wouldn't worry
about it until it happens. Second hand engines aren't that expensive anyway.
I got one for $400 with only 32,000 Km's on it.

Cheers

Chic

Michael Donovan · Post by **Michael Donovan** » Sat Mar 31, 2001 7:46 pm

Continuing on from my earlier questions about the mx5's crank, today I got a
new cam belt/ woodruff key and bolt, so I could have a look at my
pulley/crank and get some idea of the condition of them both. Can anyone
help with how to remove the 21mm A.F. crank bolt, with engine in car? the
book I have recommends putting in one of the little water pump drive pulley
bolts and using a screwdriver to jam the pulley while undoing the crank
bolt. Tried that with handbrake on/ car in gear, but it just bent the little
bolt? Thanks in advance.
Mike

Gary Morrison · Post by **Gary Morrison** » Sun Apr 01, 2001 12:08 pm

Michael,

One suggestion is to put a solid socket and bar on the bolt head, brace the
end of the bar against an appropriate part of the engine, and fire the
starter. The crank rotates clockwise, so take that into account when chosing
the point to brace the bar against. Someone on the list may have done this
and be able to comment. My 1.6 has the later nose, the same as the 1.8, and
I have a tool that bolts to the pully mount and locks against the water pump
so you can use a long bar and socket to break the bolt free.

If you undo it, and then later put it back together, be very sure you torque
it up with a torque wrench to EXACTLY the correct spec. Using the later
crank spec will risk failure of the crankshaft nose. For your crank it is
80-87 lb/ft or 108-118Nm. For the later crank it is 116-122 lb/ft or 157-165
Nm. (In both cases you should use some blue Locktite 242) And note how the
key comes out so the new one goes back in the same way.

Gary

Peter Sweetman · Post by **Peter Sweetman** » Sun Apr 01, 2001 8:51 pm

Howdy All
I have used the starter motor method myself while changing a timing belt. It
works and saves skinned knuckles and a strained back.
I used a LONG power bar (try not to use a ratchet as it is a huge force)
braced against the concrete floor in my garage, then hit the starter - once.
Because the car can climb up slightly on the shocks it relieves some of the
sudden stress on the bolt and it should undo easily.
Peter

Michael Donovan · Post by **Michael Donovan** » Mon Apr 02, 2001 6:15 pm

From: Mike Donovan

Thanks to all who replied to my request for info and advise on getting the
crank bolt off. Will leave it for Easter and try it then.Thanks.
Mike.

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