help identify whats up with my crank.. boohoo
Turbo Mini Forums

yo basically i have a standard 998 bottom end which i am freshening up with new bearings rings etc,
the problem is the crank sizes..

Haynes states Mains Dia. BigEnd Dia.
1.7505" 1.625"
My crank is 1.675" 1.550"
(measures with a micrometer, this is 75 thou under the standard size and not like anything i can find...

thrust washers say STD size.
thing is the bearing caps say 7305, as in 1.7305 which would be 20thou under what haynes says but does not relate to actual measurement even though bearings were fine with no play?!?!?!
heellpp



[edit] crank number is 12A 451 which according to somwhere on this site is ''later 998cc pre-A+ EN16T spec metal''

Edited by hario on 9th Jul, 2008.

What are the numbers on the back of tthe original bearings

all they say is 7305 nothing else apart from a brandmark i think, its like two joined triangles and what looks like a P on one side of the triange, is that VP bearings?
heellpp

I would check that the micrometer is reading correctly.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

assuming the bearing number is 7305 any chance it could mean 1.7305 because thats exactly 20thou under the 1.7505 standard size?!

As above, 75 thou under on BOTH mains and big ends is not credible.

75 thou is also exactly three divisions on an imperial micrometer - do you have the 1" "standard" that should be in the micrometer case (assuming you are using a 1-2" micrometer).
It will be either a small metal disk exactly 1" diameter or a short metal rod exactly 1" long, test the micrometer against this, it should obviously read zero.

As for the markings, see attached.
The symbol is standard for that period (Vandervell I think), the number is probably the part number and (as in this example) any undersize would be stamped next to it (010, ie, 10 thou in this case).

I have never seen these bearings without the undersize stamped so I think yours are standard and the micrometer is set all wrong.
Borrow a simple vernier caliper and measure the journals with that, they are accurate to 1 thou or better if used right.

EDIT - the photo is a 1275 big end, hence different part number.

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Edited by Rod S on 10th Jul, 2008.

Schrödinger's cat - so which one am I ???

i can pretty much guarantee that the mic is correct, whether the operator is however remains to be seen!!!

And on the 7th day........... God created turbochargers!

Schrödinger's cat - so which one am I ???

hey f-u nutterman
im thinking did i press origin when the mic wasnt would all the way in when i was trying to convert to imp.?! ..Damn iT!
yo retired man mine are the same as that but with no markings, i assumed they werent standard because they werent stamped STD but i guess they are..

added some pics of the current state of affairs..
itsa pocketed 998 so the head chambers are 15cc and the only way to get 8:1CR for forced induction is with a new 940 i got from nutterman, so the red ones going on fleabay this weekendo
i think ill start a project thread sa im pretty much ready to reassemble once i get the bearings, is it ok if its just an engine project thread thou?!

note quantity of jerrycans, blato mini owner, also MG rockercover with fins half-assedly angle-grinded by me at lunch

Edited by hario on 10th Jul, 2008.

bring it in tomorrow dude, and we'll check it over again!!!

And on the 7th day........... God created turbochargers!

Schrödinger's cat - so which one am I ???