Note:
- The crankshaft journal clearances are measured using 'Piastigage' (Triumph part number 3880150-T0301).
- Do not turn the connecting rod and crankshaft during the clearance measurement as this will damage the 'Piastigage'.
- a) Remove the big end cap from the journal to be checked.
- b) Wipe the exposed areas of the crankshaft journal, and the bearing face inside the cap.
- d Apply a thin smear of grease to the journal and a small quantity of silicone release agent to the bearing.
- d) 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.
- e) Lubricate the threads and under-head of the bolt with molybdenum disulphide grease. Refit the bearing and cap and tighten the big end bolts (see page 5-9).
- f) Release the bolts and remove the cap being measured. Using the gauge provided with the Plastigage kit, measure the width of the compressed Plastigage.
Checking the Measured Clearance
Conrod big end bearing/crankshaft journal clearance
- Standard: 0.035 - 0.065 mm
- Service limit: 0.070 mm
Note: If the measured clearance exceeds the service limit, measure the crankshaft journal diameter.
Crankshaft Journal diameter
- Standard: 32.984 - 33.000 mm
- Service limit: 32.960 mm
Note: If any crankshaft journal has worn beyond the service limit, the crankshaft must be replaced. Due to the advanced techniques used during manufacture, the crankshaft cannot be re-ground and no oversize bearings are available.
Connecting Rod Bearing Selection
Minor differences in crankshaft dimensions are compensated for by using selective bearings. For further information on bearing part number to colour cross-references, see the latest parts information.
1. Select the correct big end bearing shell as follows:
- Measure each-crankshaft journal diameter.
- Select the correct bearings by matching the information found with the chart below.
Note: All dimensions in millimetres.
Big end bearing selection chart
Shell Colour | White | Red |
Con-rod Big End | 36.009 | 36.009 |
Bore Dia. | 36.000 | 36.000 |
Crankshaft Journal | 33.000 | 32.991 |
Dia. | 32.992 | 32.984 |
Running | 0.065 | |
Clearance | 0.035 |
For instance:
- Conrod Big End Diameter: 36.002
- Crankshaft Journal Diameter: 32.987
- Required Bearing: Red
Note:
- Repeat the measurements for all connecting rods and their respective crankshaft journals.
- lt is normal for the bearings selected to differ from one connecting rod to another.
2. Install the new bearings in the connecting rod.
1. Big end bearings
Caution: Always confirm, using the Plastigage method, that the running clearance is correct before final assembly. Severe engine damage could result from incorrect clearance.
Crankshaft main bearing/journal wear
Main Bearing Selection Chart (all dimensions in millimetres)
Shell Colour | White | Red | Red | Blue | Blue | Green |
Crankcase | 35.982 | 35.981 | 35.989 | 35.988 | 35.997 | 35.997 |
Bore | 35.973 | 35.973 | 35.981 | 35.981 | 35.989 | 35.989 |
Journal Dia. | 33.000 | 32.992 | 33.000 | 32.992 | 33.000 | 32.992 |
32.993 | 32.984 | 32.993 | 32.984 | 32.993 | 32.984 | |
Running | 0.044 | 0.044 | 0.043 | 0.043 | 0.043 | 0.044 |
Clearance | 0.020 | 0.020 | 0.021 | 0.020 | 0.020 | 0.020 |
Minor differences in crankshaft and crankcase dimensions are compensated for by using selective bearings. For further information on bearing part number to colour cross-references, see the latest parts information.
- Measure the bearing to crankshaft main journal clearance using Plastigage (Triumph part number 3880150-T0301) (see page 5-10).
Checking Crankshaft Journal Clearance using Plastigage
Crankshaft main bearing/journal clearance
- Standard: 0.020 - 0.044 mm
- Service limit: 0.07 mm
If the clearance exceeds the service limit, measure the diameter of the crankshaft main journal.
Crankshaft main journal diameter
- Standard: 32.984 - 33.000 mm
- Service limit: 32.960 mm
Note: If any journal has worn beyond the service limit, the crankshaft must be replaced. Due to the techniques used during manufacture, the crankshaft cannot be reground and no oversize bearings are available.
Select bearings as follows:
1. Measure and record the diameter of each crankshaft main bearing journal.
2. Measure and record each main bearing bore diameter in the crankcase (bearings removed).
Compare the data found with the chart above to select bearings individually by journal.
For example:
- Crankshaft Journal diameter: 32.995 mm
- Crankcase Bore: 35.997 mm
- Bearing Required: Blue
Note:
- It is normal for the bearings selected to differ from one journal to another.
- lt is also normal for there to be two options of bearing shell colour. In such cases, pick the shell size which gives the greater running clearance.
Caution: Always confirm, using the Plastigage method, that the running clearance is correct before final assembly. Severe engine damage could result from incorrect clearance.
Crankshaft End Float
- Standard: 0.15 - 0.30 mm
Note: Crankshaft end float is controlled by the tolerances in crankshaft and crankcase machining. No thrust washers are used. If the crankshaft end float is outside the specified limit, the crankshaft and/or the crankcases must be replaced.