Connecting Rod Big End Bearing Selection/Crankpin Wear Check - Triumph Thunderbird Service Manual

Connecting Rod Big End Bearing Selectionl
Crankpin Wear Check
1. Measure the bearing and crankpin clearance as
follows.
Note:
• The crankpin clearances are measured using
'Plastigage' <Triumph part number
3880150-T0301>. Do not turn the connecting
rod and crankshaft during the clearance
measurement as this will damage the
'Plastigage'.
2. Remove the big end cap from the journal to be
checked.
3. Wipe the exposed areas of the crankpin, and the
bearing face inside the cap.
4. Apply a thin smear of grease to the journal and a
small quantity of silicone release agent to the
bearing.
5. Trim a length of the Plastigage to fit across the
journal. Fit the strip to the journal using the grease to
hold the Plastigage in place.
6. Lubricate the threads of the bolt and under-head
area with undiluted molybdenum disulphide grease.
Refit the bearing and cap and tighten the big end
bolts as described earlier.
Z Release the bolts and remove the cap being
measured. Using the gauge provided with the
Plastigage kit, measure the width of the compressed
Plastigage.
~---~----'>d
Checking Connecting Rod Clearance using
Plastigage
Con rod big end bearing/crankpin clearance
Standard 0.035 - 0.066 mm
Service Limit 0.100 mm
Note:
• If the measured clearance exceeds the selVice
limit, measure the crankpin diameter.
Crankpin diameter
Standard 52.476 - 52.490 mm
Service limit
52.452 mm
Note:
• If any crankpin has worn beyond the selVice
limit, the crankshaft must be replaced. Due to
the advanced techniques used during
manufacture, the crankshaft cannot be
re-ground and oversize bearings are not
available.
5.12 SelVice Manual - Thunderbird