QuestionQUESTION: Howard
I have a '77 stock MGB. 4 speed. It engages 1st,2nd, 3rd and 4th without problem going up the box. Coming down, 3rd to 2nd is aweful - unless I double clutch, or slow down, the gear crunches. I believe the 77 has all-gear synchro. Why may this be happeneing and any remedies I could try??
ANSWER: Hi Steve,
Down shifting is a lost art due to the better synchronizers in newer transmissions. However, there are things that can go wrong to give you gear clash as you down shift.
Most common is worn syncro rings.
Usually caused by speed shifting on up shifts and the lack of reving the engine just as you down shift.
(commonly called double clutching but different than truckers double clutching)
Other causes are,
Dragging clutch. Usually noted by gear clash when setting still and going from neutral to reverse.
Driver not depressing clutch pedal all the way to the floor on a down shift.
If the gear clash is noted to be excessive cold oil more than after driving for a while it could be the use of gear oil in the transmission. The older MGBs used engine oil and when BLM took over MG they recommended gear oil and we at the dealership were then covered up with gear clash complaints so we switched back to engine oil. You should read my tech tip on prolonging the life of a standard trans. http://mg-tri-jag.net/tech4.htm
Howard
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QUESTION: Howard
Thanks! I read the hyperlinked tech report. Helpful. What 'grade' of motor oil would you suggest go into an MG's transmission system?
ANSWER: Any engine oil, 20w 40 works well.
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QUESTION: last question on this - when making the switch from transmission oil to motor oil should I flush the system or can I just drain out the old transmission oil and replace with the motor oil?
AnswerIn the dealership, we just drained the gear oil out and put the engine oil in but it did take a few miles of driving with the engine oil to clean out and dilute what little gear oil was left for the syncros to start working again.
Keep in mind this only extended the life of a syncro, it is not going to make it new again. It is still important to practice proper downshifting. Besides making the gearbox last longer there is a side benefit of the professional appearance of a driving habit and thus bragging rights to friends who don't know how to "drive" a car and who just aim their car. Not to mention impressing the ladies with that macho "sports car driver" appearance as opposed to just a car operator. (that's how I got my wife)
Let me know how it does.
Howard
