DeviousLandyGod
Active Member
Hi… hope someone can help!
S3 SWB 2.25petrol.
Third time of trying to get my gearbox working well, and it’s still not good.
Most previous issues have been sorted, but I am left with gears crunching the warmer the gearbox gets.
This is mostly from 4 to 3, but also 4 or 3 to 2.
When cold and for first 10 minutes say, it’s perfect. Then progressively gets worse. A lot better going up the gears.
My thoughts are;
1. It seems the oil is losing viscosity when hot to the point that the synchros don’t work properly…? Using EP90. Maybe there’s an alternative?
2. The 3/4 selector hub is a new Bearmach unit… maybe that’s a bad one? But it works ok when cold. I did think the unit was quite easy to slide on assembly… presumably the strength of the springs provides pressure for the synchro to do its job, before engaging the gear. If too weak, crunch time? Maybe the oil being thicker when cool allows the appropriate pressure.
3. Maybe, the clutch isn’t disengaging properly? Maybe it’s enough when the oil is thick, but not enough when hot… or the clutch when hot closes reduces clearance?
I have rebuilt it twice now. This time with a new main shaft. In fact, everything is new. Most NOS. The bearmach unit is probably the only non gen item…
Bit ****ed off tbh. I am tempted to try a more viscous oil… there’s an EP 100, and upwards… not sure that’s a good idea though.
Am I missing anything obvious?
I also have a fuel starvation issue… so, electric pump might be on the list. Also, I’m not entirely convinced the SimonBBC electronic ignition is great, seems odd as it advances up the revs.
Apart from that, it’s perfect!
S3 SWB 2.25petrol.
Third time of trying to get my gearbox working well, and it’s still not good.
Most previous issues have been sorted, but I am left with gears crunching the warmer the gearbox gets.
This is mostly from 4 to 3, but also 4 or 3 to 2.
When cold and for first 10 minutes say, it’s perfect. Then progressively gets worse. A lot better going up the gears.
My thoughts are;
1. It seems the oil is losing viscosity when hot to the point that the synchros don’t work properly…? Using EP90. Maybe there’s an alternative?
2. The 3/4 selector hub is a new Bearmach unit… maybe that’s a bad one? But it works ok when cold. I did think the unit was quite easy to slide on assembly… presumably the strength of the springs provides pressure for the synchro to do its job, before engaging the gear. If too weak, crunch time? Maybe the oil being thicker when cool allows the appropriate pressure.
3. Maybe, the clutch isn’t disengaging properly? Maybe it’s enough when the oil is thick, but not enough when hot… or the clutch when hot closes reduces clearance?
I have rebuilt it twice now. This time with a new main shaft. In fact, everything is new. Most NOS. The bearmach unit is probably the only non gen item…
Bit ****ed off tbh. I am tempted to try a more viscous oil… there’s an EP 100, and upwards… not sure that’s a good idea though.
Am I missing anything obvious?
I also have a fuel starvation issue… so, electric pump might be on the list. Also, I’m not entirely convinced the SimonBBC electronic ignition is great, seems odd as it advances up the revs.
Apart from that, it’s perfect!