Inspection And Identification - Triumph SPEED TWIN 1945 Workshop Instruction Manual

C r a n k s h a f t a n d C o n n e c t i n g R o d Assembly.
The dismantling, bverhauf and
assembly of this unit i s a job that
i s
normally undertaken by the dealer,
or
at the works.
If t h e owner wishes t o carry o u t t h e work, he must have
a
certain amount of
mechanical a b i l ~ t y and a good workshop.
D i s m a n t l i n g . G r i p the bottom end o f the flywheel i n the vice and carefully mark
each r o d so that they can be replaced i n exactly the same position relative t o t h e
cranks and t h e connecting rod cap t o the rod itself. Unscrew t h e t w o nuts recurin,
each r o d and remove the rods from t h e cranks. Replace the cap t o the rods f o r
the t i m e being.
Identify the cranks t o the flywheel and then remove the six bolts
and nuts when the assembly can be parted.
I n s p e c t i o n a n d Identification. Wash all parts thoroughly and examine the
bearing surfaces.
New.
Crank big-end journal size
:
Earlier pattern 1.4360" (3.6484 cms.)
1.4365" (3.6497 cms.)
Currsnt models 7.6235" (4.1237 cms.)
1.6240" (4.1 250 cms.)
Connecting rod big-end size : Earlier pattern 1.4370" (3.6510 cms.)
1.4375" (3.6522 cms.)
, ,
,
Current models 1.6250" (4.1 275 cms.)
1.6255" (4.1 289 cms.)
Connecting rod sma!l end (All)
...
...
0.6885" (1.7488 cms.)
0.6890" (1.7501 cms.)
. . . . . .
Gudgeon pin size (All)
... ...
0.6882" (1.7480 cms.)
0.6885" (1.7488 cms.)
Connecting rod end float (All)
...
...
0.0290" (0.737 mm.)
0.0320" (0.81 3 rnm.)
Light score marks on the crank big-end journals can be carefully eased down w i t h
smooth emery but after this operation the parts must be carefully washed again.
If the cranks are scored, rhe connecting rod big-ends w i l l also show similar signs,
these should be carefully removed by using
a
scraper and i f necessary
a
minute amount
of metal can be removed from the mating surfaces of the cap and rod t o enable the
r o d
to
be refitted t o
i t s
original clearances. If any metal i s removed from the mating
surfaces, the bearing will have t o be re-bedded by remov'qg all high spots (use
engineers' marking blue on the journal bearing t o detect higri ipots) w i t h a scraper.
Remember, the maximum amount of white metal i n the connecting rod cap
is
0.025"
(0.635 mrn.). This operation should only be done by a mechanic who
is
fully con-
versant w i t h this type o f engineering procedure.
If the damage
i s
beyond repair, service re.ground cranks and connecting rods t o fit
can be obtained from
a
dealer i n the following UNDERSIZES :-
Cranks
...
. , .
...
...
...
...
. . . .
0.010"-0.020''
Connecting rods
...
...
...
...
...
...
0.01 0"-0.020''
The small end bush wear can be detected by inserting the gudgeon pin into the bush.
If i n good condition the pin should be
a
smooth working fit i n the buih, no rock
being i n evidence. To replace the bush, press out the old one and
a t
the same t i m e