This is the third in a series of articles, over the course of several months, that focuses upon the repair, maintenance and troubleshooting of the braking system of Series I, II and III Land Rovers. August's focus was upon squealing brakes and binding brakes. September's focus was upon brake pedal travel being excessive or spongy. October's focus was upon excessive brake pedal pressure and the Land Rover pulling to one side. We look at the transmission brake this month and what problems may be encountered.
Hand-brake lever slips off the ratchet
Over time, the teeth on the transmission-brake catch pawl (part No. 50235 - 'A' on the photo below) become rounded and can slip over the ratchet teeth that are supposed to hold onto them. At such times the catch pawl needs replacing. By contrast, the teeth on the ratchet itself are made from toughened steel and tend not to wear so easily. The small catch pawl can be replaced from underneath the Land Rover but much easier access is obtained by removing the center seat or driver's seat, as appropriate.
When setting the transmission brake lever, adjust to allow two clicks on the upward movement of the lever before the transmission brake engages.
Hand-brake lever movement problems
If movement of the lever is restricted, then first check to see if it is due to the transmission-brake rubber boot being either incorrectly fitted, damaged or perished. If the boot is OK, then probably the lever mechanism requires adjustment. This adjustment can be carried out using the nuts on the upright threaded rod that is connected to the transmission brake lever ( 'B' on the photo below). Access can be obtained underneath the vehicle but is best accomplished by removing the center seat on SWB Land Rovers or removing the driver's seat on LWB models. The Land Rover should have its wheels chocked before work is carried out on the transmission brake mechanism.
After the adjustment is made, it is usually possible to check if the transmission brake drum is free to move
normally by turning the drum a little by hand; there is often enough free-play in the rear prop-shaft to allow this check to take place. If however, this test is inconclusive, then you will need to raise one rear wheel off the ground and try again.
Transmission brake ineffective
The problem may just be that the brake linings have worn down and need adjusting outwards. This is actually rarely the case as, unlike the wheel brake linings, the transmission brake linings are not used to slow the Land Rover down so wear is negligible over time. But to adjust them, look for the squared spindle on the transmission brake backplate and turn this a quarter turn clockwise at a time (one click) until the brake drum cannot be rotated. Then back off the spindle 2 turns and test the drum movement again. Apply the transmission brake to center the brake shoes and then test again.
If adjusting the brake shoes does not solve the problem, then the linings need to be inspected. You can remove the transmission brake drum without disconnecting the rear propshaft. When inspecting the linings look for glazing on the surface; this can be removed by abrasive paper (wear a face mask for dust - especially if you are working below the vehicle). Also look for oil contamination of the linings; if this is present then the output shaft oil seal will be responsible (part FRC1780). To replace the oil seal the rear propshaft needs to be removed, along with the transmission brake assembly. You will need to fit new brake shoes also; some brake shoes have pre-drilled holes in them and the linings are riveted in place onto the shoe; replacement linings and matching rivets are available as a kit (part No. 219007 for 1948-64: part No. RTC2960 for 1964-84).
Series Land Rover transmission brake
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