Mk IV 1.5L gearbox repairs

(Peter Lloyd) #1

Does anyone know where to source spares for the 1.5L gearbox internals? Are there any repair options to restore the teeth?

(Rob Reilly) #2

Bearings and seals should be standard sizes.
Can you give us some pictures showing what you need?

(Ed Nantes) #3

Yes post some pics , I have a box of old Jaggears , some double helical and some 1 1/2 litre , Unfortunately no part numbers marked

(Peter Lloyd) #4

Thanks gents. I’ll see if there are suitable photos available but the issue is with incredibly chewed gears - all of them. Exceptionally noisy in the lower gears and jumping out of 2nd. The box was re-installed without rebuilding as the owner wanted the car for a family wedding later this month and knew there would be insufficient time to source spares. I saw the condition and I must say I was quite concerned at the internal condition. In summary, the whole gear train needs replacement.

Some of the damage indicated that there was probably some bits being chucked about but nothing big came out after a flush and draining with the top off. It was not possible to get a good view of the layshaft gears but maybe one of the teeth came off some time ago and came out with previous oil changes, but who would know. Sometimes a double helical gear will lose a half tooth.

You might be the best bet so far Ed so I will give you a call to discuss. Just for reference, it is a double helical box with ‘Standard’ cast in the side. I guess they were all of Standard manufacture and are probably interchangeable with a Standard 14 or similar, but those boxes will be just as hard to find.

(Peter Scott) #5



(Peter Lloyd) #6

I have attached the only decent photo for information. If you can enlarge it you can see the amount of undercutting of all gears. There is a degree of tapering on the fourth gear synchro teeth, but this gear is holding. However, the second gear jumps out eagerly under load. I think all these rotating parts are scrap. I don’t know the condition of the bushes, but the bearings are in good shape. The seals were hard and cracked. The rear seal was easily sourced but the front seal was a problem as they had no listing on the size combination. The I.D. was ok but I had to make a choice of an over- or under-sized o.d. I chose the latter and made a bespoke ‘speedisleeve’ from a food can to take up the marginal difference.

This could be a result of the wrong, or insufficient, oil at some time. Saying that, the dipstick may be erroneous as it has been tampered with around the tip and may be non-original, even possibly a home-made replacement stem. Is it the same as, or interchangeable with, the 2.5 and 3.5? To help with checking, could someone please provide dimensions of the level marks from the base washer under the felt seal? I don’t know the principles of the correct oil level, but I suspect it should be up to the layshaft top, or centreline, but should not be much higher.

(Rob Reilly) #7

The jumping out of 2nd may be a case of worn synchro cone or ball plunger, not necessarily worn teeth, so possibly fixable.
Read this.
There were various dipsticks used, and none have the same part numbers as for 2.5 or 3.5, so it would depend on your chassis number.
A Mark V dipstick from an SH gearbox measures 5-7/8" from contact flange to FULL mark, 6-3/8" to ADD mark, and 6-7/8" to the tip.
That puts the FULL oil level at maybe an inch to inch and a half above the centerline of the countershaft, so the oil is not quite covering the lower gears.

(Ed Nantes) #8

Frankly , 1 1/2 litre gear boxes aren’t particularly rare , so if it’s badly damaged inside , I’d look for another gear box.
I wonder whether a 2 1/2 oe 3 1/2 litre Moss box would go in or [ Quelle Horror,.a 5 speed modern box.]

1 Like
(Peter Scott) #9

The 1.5 litre doesn’t appear to share the same part number used in the larger cars but I can’t understand why.

The outer casings don’t look different in depth. Apart from over filling I can’t personally see why the level is very critical, for as long as the layshaft is dipped in oil it will splash it everywhere.

Your top gear dog clutch teeth do look badly worn and I think that would tend to cause dropping out of gear.


(Torben Larsen 1946 1.5 ltr Mkiv) #10

Maybe worth checking with Vorlaufer in Johannesburg. For a 1946 1.5 litre I bought a reconditioned double-helical gearbox with a new 2nd gear from him. He also produces new gears for the double-helical gearbox.

Torben Larsen

(Peter Lloyd) #11

Thank you to all for your experience and knowledge. The first phase will be to try and source an acceptable other box. I will run enquiries with Wally too, he is often a good source for the hard-to-find bits common with the SSs.