- 12,195
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- Location
- gainesville, ga.
A current thread got me to post this, I have intended to do this for a while,
I hope it becomes a sticky so 5 tonners who are going to do trans or clutch work will see this.
Those of you that have the Cummins motor (do not know what the MF or the Mack have) note that the bell housing is ALUMINUM, over tightening the connecting that holds the transmission adaptor to the bell housing WILL pull the threads, also not using anti-seize WILL tend to gull the threads which in turn WILL tend to help pull the threads. The torque called IS 25-31lbs, DO NOT GO OVER, a rather light torque for a 3/8, grade 8 bolt. If you do pull the threads in a hole, you can use a bottoming tap to tap to the back of the hole and then use a longer bolt, IF this does not work, you WILL have to DROP the trans again and go though the repair thread hassle using a thread repair insert.
REMEMBER that all the weight of the trans is hanging from these 12 bolts as well as ALL the clutch release force is transferred to these bolts.
Because of the light torque, you can over tighten just using a 3/8 ratchet. A TORQUE WENCH IS A MUST, this is NOT a job for bubba who only knows one thing, either tightening as tight as you can get, or if this torque is fine the trice as much just to be safe.
Also one more thing, DO NOT use a screw driver or anything else in the bell housing bolt holes to rotate the trans to align the holes, you WILL screw up the threads. If you use anything to align, use a threaded long dowel, I use long GMC starter bolts with the heads cut off and then with a chamfered cut end.
I hope it becomes a sticky so 5 tonners who are going to do trans or clutch work will see this.
Those of you that have the Cummins motor (do not know what the MF or the Mack have) note that the bell housing is ALUMINUM, over tightening the connecting that holds the transmission adaptor to the bell housing WILL pull the threads, also not using anti-seize WILL tend to gull the threads which in turn WILL tend to help pull the threads. The torque called IS 25-31lbs, DO NOT GO OVER, a rather light torque for a 3/8, grade 8 bolt. If you do pull the threads in a hole, you can use a bottoming tap to tap to the back of the hole and then use a longer bolt, IF this does not work, you WILL have to DROP the trans again and go though the repair thread hassle using a thread repair insert.
REMEMBER that all the weight of the trans is hanging from these 12 bolts as well as ALL the clutch release force is transferred to these bolts.
Because of the light torque, you can over tighten just using a 3/8 ratchet. A TORQUE WENCH IS A MUST, this is NOT a job for bubba who only knows one thing, either tightening as tight as you can get, or if this torque is fine the trice as much just to be safe.
Also one more thing, DO NOT use a screw driver or anything else in the bell housing bolt holes to rotate the trans to align the holes, you WILL screw up the threads. If you use anything to align, use a threaded long dowel, I use long GMC starter bolts with the heads cut off and then with a chamfered cut end.
