Triumph 1300 FWD won't change down through gears unless stationary

[steve369]

Good afternoon, I have a 1969 Triumph 1300 that will change up through the 4 speed gearbox but will not change down, even with matching revs/ double de clutching. I have checked the clutch and seems ok even though on last adjustment, I added a longer clutch slave cylinder pistion to make sure but still won't change down. When going up through the gears, I wouldn't say it was brilliant with gear selection but does select ok. Any thoughts would be much appreciated.

[soe8m]

Are the engine axial bearings ok? A not fully releasing clutch can have a gearbox change up reasonable ok as the revs do drop and changing down a bit harder. Static the clutch seems fine because of the cranckshaft is being pushed forward at maximum but while driving the clutch adjustment is variable. It's easy to check by pushing and pulling at the cranckshaft at the front of the engine or at a fwd also at the rear. Maybe you need a screwdriver to move and check for play but most can be moved by hand.

Otherwise it can be synchro's but that would make all four of them worn.

Jeroen

[steve369]

Thanks for the reply, no I hadn't thought of that, but have now checked the crankshaft as you mentioned, however there seems to be no back and forth play within the block. I'm going to try and adjust the clutch further to see if that helps at all and will report back. Thanks again.

[ian.stewart]

what about engine/gearbox mounts

[steve369]

Thanks Ian, I haven't thought of that either, I will check tomorrow and report back

[Carledo]

The engine mounts won't make a great deal of difference here as the slave is bolted to the engine.

On my 1500FWD I found the slave retaining plate had been padded out with a few layers of insulating tape to remove extra play.

But my suspicion is that you may have a distorted or damaged pressure plate.

Steve

[steve369]

Thanks for the replies, yes the engine and gearbox mounts look ok. Maybe I should just go for a new clutch then? Yesterday I tried to drive the car again and change down gear, I have found it will change down if you don't use the clutch and push the gearstick and wait, it will then drop into gear.

[TrustNo1]

what about engine/gearbox mounts

that won't make any difference to gear change.

On the side of the gearbox there is an adjustable bracket that adjusts the distance of the thrust bearing onto plate , if this is loose or not correctly adjusted then it can cause issues with the gear changing.