Further to 5 speed Gearbox Noise

[simonriley11]

I am readying my Plus 2 to take the engine and gearbox out to get the gearbox rebuilt and upon removing the proshaft flange to diff flange bolts I could hardly seperate the two flanges. The propshaft did not want to move forward at all as if the spline at the gearbox end of the propshaft is stuck/siezed. This might explain the loud noise (previous post) I had a little while ago. Has anyone had this problem before and does anyone know how much I should expect the propshaft to move forward on the spline?

[1964 S1]

Hello, what was your loud noise. What is wrong with the gearbox? Eric

[simonriley11]

Eric
The main gearbox fault was that the synchro had gone on third gear so it was going to need a rebuild anyway at some time. The loud noise happened a few weeks ago at circa 80mph cruising in fifth. It came from the gearbox area and was loud enough to make me brake hard and aim for the hard shoulder. However after about 5 seconds it stopped and as it was dark and very wet I carried on at reduced speed (initially) and could not make it reoccur as I neared home in any gear at any (legalish) speed. It sounded like something seizing, it wasn't the wiper motor as I thought of that at the time and switched them on and off. It definitley sounded like the gearbox area. So not wanting to risk major mechanical failure I decided to get the gearbox rebuilt.
I would normally expect a propshaft to have at least 1/4 to 1/2 inch of movement forward when undoing it from the diff flange but it's a real struggle to even get it to slide across the diff flange face. It just doesn't want to move froward in the tunnel. I know I'll find out when I get the box out but it would be nice to know if this is a known problem and what can be done to fix it. Any thoughts anyone?

[rgh0]

The spline has enough movement to side the shaft forward about 40mm in my plus 2. In normal use there is almost no movement in the spline once it is installed. If not removed for a long time rust and dirt on the external exposed section of the spline shaft will build up and make sliding it forward extremely difficult. I suspect this is why you could not easily separate the diff flange. If the spline is not properly lubricated internally when assembled or its leaked out over time then you could also get rust build up inside the spline joint causing the same symptoms. Damage to te spline and a forced assembly by a DPO could also cause the same result.

Given that the spline does not move once installed then this siezing up should not produce the noise you experienced.

Rohan

[1964 S1]

Now I remember your previous posts, couldn't find it last night... Did the seizing noise continure as you stopped at the side of the road, or as you were pulling off? Have you tried to pry the shaft off the flange and remove it? My S1 has the same problem, I've got a rear end whine.. (no jokes) and will find out if the shaft is stuck on the splines, it's this winter's project. I agree with Rohan's assessment, so the noise remains a mystery...what made it stop?

[simonriley11]

Rohan, many thanks for the feedback I'll post what I find when I can find a hoist long enough to clear the Plus 2's nose and get the gearbox and propshaft out.
Eric, I didn't actually stop when the noise occurred because it stopped before I had time to stop (about 5 seconds) and I was on busy dual carriageway so I carried on at reduced speed. As far as splitting the two flanges is concerned I can only just slide them a few millimetres across the flange face, I have tried and failed to pry them apart as the propshaft appears to be absolutely solid and will not move forward. Unfortunately I have no idea what made the noise stop, so as the gearbox needed a rebuild anyway I thought that was a good place to start. If it's of any help, over the years I have had a whine from the back end of my Sprint and my Climax Elite which in both cases proved to be a worn differential.

[john.p.clegg]

Maybe as you have no clearance on the prop. this could be putting pressure on some part of the gearbox,hence the noise/problem?
John