Are there any suppliers of 3rd. and 4th. Gear Drive Dogs and Synchromesh Rings for the Synchromesh Gear Boxes in the UK. We have found very badly worn Teeth on the Drive Dogs and also cracking and breaking up ending up in the bottom of the Gear Box. The Synchromesh Rings have very little visible Ring Grooves left on the Ring diameter allowing the rings to go too deep in the Drum. We have made enquiries here in Australia to get these made and the cost and as always is dependant on numbers. They are the same as Austin A40.So is anybody doing anything on this in the UK. We are going to persist in following up on this.

Location: South Australia

e-mail sent

Location: Gard, France 30960. Used to be Languedoc-Roussillon but now it's Occitanie

Thankyou Reckless for your prompt email reply with photos re 4 Speed gear Box Parts. The photos you show are exactly the ware that is happening and also I'm not surprised one of the Dog Drives is missing as it has probably broken and ended up in the bottom of the gear box,at some time also the synchromesh ring/cone is also not in good condition. The ware in the synchromesh Ring we think is causing some of the ware on the Dog Drive Gear. There must be hundreds of 4 speed synchromesh boxes in cars that won't last much longer. We keep on ratting spare gear boxes to replace worn with not so worn. That's why I'm asking if any one in the UK is already making these replacements. We will continue to talk to Gear Makers in Australia to get these Gears made. Cheers from down under.

Location: South Australia

No worries, happy to help. Just one thing... I had to fiddle about with your e-mail address until I got it right - check your profile.

Location: Gard, France 30960. Used to be Languedoc-Roussillon but now it's Occitanie

Surprised that reasonable gearboxes so rare as probably the longest lasting item and were very common. Boxes are well made and despite extensive running in the gears less prone to clipped 1st as Morris 1000, gears thru hardening etc than many other makes. The lever with lid gets taken and the rest of the box ends up junked

Despite considerable wear of the selectors in some cases, indicating huge mileage, most boxes I have seen were reasonable inside. Input splines, and tracks of the 1st/3rd shaft bearing seem main problem wear points. However some synchro cones displaced and one had loosened to the extent that all the locating splines sheared off. Obviously the synchro did not work but the intermediate symptoms must have been curious! Despite the fine pattern gone all cones engage with about 1/16 inch travel remaining, not hugely less than cones with intact pattern so am surprised that this wear is a problem. If the synchro balls are wrong size get lost motion.

Would be interested in the observations of those who have seen many.

I am amazed that a steel dog ring would break in normal or any use. Anybody else seen this? Were the dog rings ever a tight fit or just the cones? Possibly with careful attention with a Dremel, intact dog rings could be reversed if desperate.

Often manufactured parts prove nbg in a myriad ways, esp where precision involved, and the spline fits are precise. As some splines would now be worn from cones having been loose a universal replacement could be a challenge. I dunno how fitted originally, but existing cones are very difficult to refit so if a tighter fit, I can imagine many new ones being butchered stretched and distorted on attempting assembly. Strife for suppliers, mechanics, owners. A lead chamfer necessary. Some might advocate a Loctite arrangement, which would simplify tolerances, and might work if prep meticulously followed.

The cones may have been machined after fitting? I wonder if a tight ring without splines, shrunk and pressed on over dressed splines and finish machined after would suffice With one or two pins to safeguard against rotation.This could be home made.

The more common problem seems to be cones and dogs loose on the splines; there must be stacks of gearboxes and gears rejected for this although I understand some have cured at an early stage. Methods would be of interest but may be trade secrets.

If cones not too worn, those without the patience to cut fine square grooves can recut with the edge of a fine tap.

If cones can somehow be subsequently locked, can these be prised off and refitted spaced slightly forward, and shortened?
Incidentally the A40 had a very specific and different step pattern.

Without cones, can some hub spacer be fitted, and stay useable as a constant mesh box?

One of the mysteries with this basic type of synchro is, once gear engaged, what stops the hub with female cones working its way along so that the cone of the other gear rubs? Or is this why they wear? Does it explain why early lwb cars were apparently so sprightly?

How many drivers rely entirely on the synchro for down changes? In a Seven that uphill momentum is too precious to waste waiting for synchro. The clutch travel was presumably provided for racing double declutch. However some degree of synchro is very helpful as speeds do not have to be so exactly matched.

Location: Auckland, NZ