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Triumph Repair/transmission fluid


The gearbox in my '73 TR-6 is locking up and I am having difficulty in shifting gears and it may be a faulty slave cylinder.  I would like to check the transmission fluid first but I can't find the location of the dipstick.  Help.


Hi Jim,

There is no dipstick for the gearbox. It is a square headed plug in the side of the transmission. It is the filler and level plug. You fill it to that filler hole.

To check the shifting being caused by a clutch slave cylinder or a clutch problem do this.

Put the car on level ground and with the engine off put the car in first gear with the brakes off and depress the clutch pedal all the way to the floor and start the engine and let it idle for a few seconds and note if the car tries to "Creep" forward. If it does you could have a clutch or clutch hydraulic problem. If it does not try to "Creep" then you do not have a clutch hydraulic problem. A quick "feel" test of the clutch is to have the engine off and just depress the clutch pedal with your hand. It should move about an inch free play then get hard to push and if you push it all the way to the floor it should feel about the same resistance all the way. If it is easy to push about half way or more and only gets hard to push close to the floor it has a hydraulic problem. Then you should look for signs of leakage either at the master cylinder and the slave cylinder. If you find evidence of leakage you MUST either rebuild both the master and slave or replace both. Never do just one of them. (Always use DOT 4 fluid)

Next test is to shut the engine off and just see if you can shift into all the gears. You should be able to. If not there may be something wrong with the gearbox or the shift linkage on top of the gear box.

Even though your book tells you to use gear oil in the transmission we found that engine oil works better (if you don't have too many leaks)

let me know what you find,


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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