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+--- Thread: 4 speed g/box (/showthread.php?tid=359)
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4 speed g/box - jonmilne7@yahoo.com - 20-10-2017
Gear leaver jumps out of gear when under pressure, any suggestions please.
RE: 4 speed g/box - Hugh Barnes - 20-10-2017
http://www.austin7.org/Technical%20Articles/Jumps%20out%20of%20gear/ will reveal all....
RE: 4 speed g/box - Dave Mann - 20-10-2017
Does it jump out of all gears? Or is it just one gear and if so which one?
RE: 4 speed g/box - jonmilne7@yahoo.com - 21-10-2017
First gear only, Dave
Jon
RE: 4 speed g/box - Hugh Barnes - 21-10-2017
I refer the Honorable Member to my earlier answer...
RE: 4 speed g/box - Peter Naulls - 22-10-2017
Jon,
Be cautious if you replace the balls and springs - I bought some recently and they were 5 thou too big. They would push into the slots in the selector rods, just, but were far too tight. I needed pliers to remove them. Maybe they varied from year to year, I'm not sure.
I had a 4-speed box rebuilt some years ago and it jams in gear, I suspect it's the same cause.
Peter.
RE: 4 speed g/box - Dave Mann - 24-10-2017
I recently experienced the gear lever returning to neutral under it's own weight after engaging bottom and before engaging the clutch on a 2 SYN 4 speed box. If I held the lever in bottom until the clutch was engaged it stayed in gear whilst under load but promptly dropped into neutral as soon as the clutch disengaged. This was caused by failure of the first gear selector spring, it's replacement is covered in the Cornwall club website.
Forty odd years ago I had a 4 speed 3 SYN gearbox lock up after descending a very steep hill, the transmission was locked and the gearlever firmly stuck in bottom. I've heard of a couple of other cases of this happening. Removal of the gearbox top allowed the gearbox to be put into neutral with a crow bar accompanied with the 2 gear synchro balls flying everywhere. The box was drained and the balls collected and we proceeded on our way. The only way back was up the steep hill and I soon learnt to balance the power versus the effort required to keep it in bottom.
RE: 4 speed g/box - Reckless Rat - 24-10-2017
My RP still has the original 4 speed crash box, which suffered a similar problem with 3rd gear. On any hill I had to hold it in gear. Replacing the detent balls & springs sorted it. However, in all the years I have owned the car I can probably count on the fingers of one hand the number of times I have had to use first gear. I always set off in second, and if it's slightly downhill I can do it in 3rd. The ratios in the later synchro gearboxes are slightly different but even so first is so low that it's not worth the trouble.
Standard Gear ratios are: Crash 1st, 1:4.44 2nd 1:2.74 3rd 1: 1.73 Top 1:1 Reverse 1: 5.69
2/3 SYN 1st, 1:4.37 2nd 1:2.64 3rd 1: 1.66 Top 1:1 Reverse 1:5.61
RE: 4 speed g/box - Chris KC - 25-10-2017
(24-10-2017, 09:24 AM)Dave Mann Wrote: I recently experienced the gear lever returning to neutral under it's own weight after engaging bottom and before engaging the clutch on a 2 SYN 4 speed box. If I held the lever in bottom until the clutch was engaged it stayed in gear whilst under load but promptly dropped into neutral as soon as the clutch disengaged. This was caused by failure of the first gear selector spring, it's replacement is covered in the Cornwall club website.That happened to me up a Swiss alp once - 1st gear cog effectively fell off the end of the shaft & jammed against the casing. Combo of weak selector springs and too much end float. The crash boxes are more robust I think.
Forty odd years ago I had a 4 speed 3 SYN gearbox lock up after descending a very steep hill, the transmission was locked and the gearlever firmly stuck in bottom. I've heard of a couple of other cases of this happening. Removal of the gearbox top allowed the gearbox to be put into neutral with a crow bar accompanied with the 2 gear synchro balls flying everywhere. The box was drained and the balls collected and we proceeded on our way. The only way back was up the steep hill and I soon learnt to balance the power versus the effort required to keep it in bottom.
RE: 4 speed g/box - Dave Mann - 25-10-2017
Ah so you were the owner that suffered this problem, I'd heard of the failure in Switzerland but forgotten who it was.. The other owner was the late Peter Fearn going to Woolaton Park many years ago. It doesn't seem to happen to 2 SYN boxes. I also suspect that incorrect setting of the selector bars had something to do with the cause.