Dragging cluch

[Tom Coates]

I find it impossible to get into 1st gear on my three speed box with grating the gears. Its ok when cold but troublesome once everything has warmed up. Any thoughts? There's no problem once its on the move.

I relined the clutch last year and thought I'd got everything set up right. I tend to run with a bare minimum of oil in the box having had problems with it getting on the clutch.

Also, what is the recommendation for oiling the thrust race? The consequences of over or under oiling seem to be pretty dramatic!

Thanks

Tom

[bob46320]

Fortunately the release bearing is outside of the clutch, oil the bearing spareingly. I oil mine when it gets noisy !!

My first exhibits the same problem, OK when cold and a quick "Grunch" to engage either 1st or reverse on a 3 speed box. However, just engage gear positively.

[GK5268]

I had a similar problem on a 4-speed box, 1st & reverse would not engage without crunching the gears, after a lot of yanking the gearbox in and out (was getting quick at it!), I found that a rivet (may have been two) that holds the splines to the clutch disc was making contact with the gearbox boss/shaft that the release bearing fits onto, effectively preventing full disengagement. I overcame this by a dodge that someone else suggested and that was to fit thin spacers (washers with a slot cut) between the gearbox & crankcase, worked a treat. Cutting the washers allows them to be slid in position with just the gearbox nuts slightly undone, slightly fiddly as the odd one will fall out until they are all tightened.

[Ruairidh Dunford]

There are several lengths of spline on centre plates and corresponding depths inside the gearbox spline. If you mix them incorrectly the clutch won't disengage fully and causes the symptoms you describe,

[dickie65]

Hi,
Could it be worn clutch toggle heels, or wear in the flywheel. Its a common problem for our cars.
My Fathers Box saloon was put into a garage in the 1960s for a clutch reline. the clutch would not disengage afer the new linings were installed.
The Owner left it in the garage where it got covered in old tyres till my Father found out about it in 1973. Father liberated it took it home took the clutch apart and drilled the grooves and tapped them to install high tensile screws which were set to the correct height then the excess ground off from the back of the cover plate then the screws were staked to hold them in place.
Nowadays you can buy new fingers toggles and pins. ( No such luck in the 1970s not much new stuff being made back then )
Any wear in toggles pins and fingers will result in lost motion as well as the wear in the pressure plate where the toggle heel contacts.

[Robert Leigh]

The fact that the problem only exists when hot suggests that the clutch is not totally disengaging, and my experience is that there is usually some very slight 'drag'; it can be caused by dirty splines not allowing the driven plate to float free in the disengaged position. When the gearbox oil is cold there is no crunch because the gears do not turn very easily; when things are hot the free turning gears can crunch. Positive gear lever movement reduces the crunch to a minimum.
Robert Leigh

[David.H]

For what it is worth.....the AC owners Club recommend using an 80/90 Hypoy in the Bristol engine's gearbox rather than the recommended SAE 30 and apparently it "cushions " the clearances between the gears....?

[Nick Turley]

Hi Tom

What ever the problem is it will not just disappear sadly.

Mr Dunford may have hit the nail on the head, or as is very common with Austin Sevens the levers may not be correctly adjusted.
There are many different ways of adjusting these.
My chosen method is to heat the centre part of the lever <cherry red> and bend, letting it cool fully naturally. You really need acetylene/oxygen for this.
How ever you choose to do it, the tips of the levers need to be 1/4 inch from a straight edge across the bell housing and need to be within a 64th of each other to have a nice clutch.
Even with new levers and repaired slots, they usually need pulling out a bit.
A lot of the reference books have a different measurement but in my personal experience they are wrong.
Hope this is helpful.

[Hedd_Jones]

I would echo Nicks comments. Ive been using a 6mm drill as a setting gauge for years!