Four speed gearbox

Sam Christie · Post by **Sam Christie** » Sun Dec 30, 2007 10:22 pm

When did a four speed gearbox become an option on a Morris Minor ? Was the same four speed already available for Wolseleys and/or MG's or did they all gain the option at the same time ?

Post by **Ian Grace** » Mon Dec 31, 2007 12:15 am

Hi Sam,

The 4-speed box was first fitted to the SV Minor in the 1933 season, so from chassis SV20301 (engine 20713) - around July 1932, to engine 34262, when the synchro box came in (on all except the '33 Hundred Pound 2-seaters). I can't prove it, but I'd be willing to state that the MGs and Wolseleys would have had the box available from that date, and not before. I'm sure that Kimber used whatever he got from Cowley to build his M Types.

Paul Rogers is looking at making a batch of 3-speed gear clusters from an original unused set I let him have a while back. These gears should be correct for all OHC and SV 3-speed boxes. However, the OHC gearbox and gear part numbers changed from engine U35392, from which the box part number was 36958. Previously it had been part number 35102. On the SV cars, from engine SV101 to SV20712 (i.e. to the beginning of the '33 season) the box part number was 36722, and this reverted to 35102 for the '33 season 3-speed Hundred Pound cars!

The question is - were the gear ratios different between the 35102 and 36958 boxes, as the parts list suggests.

I have the gearbox ratios as:

Top 1:1, second 1.833:1, first 3.5 to 1 and reverse 2.833 to 1 for all 3-speed boxes, but this may be a simplification.

I do have a 3-speed box in the garage which is considerably different to all the OHC 3-speed boxes I have seen:

It has a taller top than the OHC boxes and so the lever is longer between the ball and selector. What Minor is this from? And would the gears be a differnet ratio to the OHC 3-speed boxes?

I have heard a rumour in the past that VSCC trials types have been searching out SV 3-speed boxes because they offer a lower first gear ratio for trials work, and SV 3-speed boxes wouldn't be spotted by the scroots like a 4-speed box would be - or might be.

Who can say more?

DF9053 · Post by **DF9053** » Mon Dec 31, 2007 6:48 am

I have a box for Y407 which is the same as your picture Ian. I assumed the difference to be the change in the handbrake from transmission type to using the brake cross shaft, which resulted in a different top cover and rear casting. I would have said the top cover was the same as that in DF in terms of height.

I'll check the gear ratios today and see what they are.

Cheers
Jeremy

Sam Christie · Post by **Sam Christie** » Mon Dec 31, 2007 12:04 pm

I think this is probably an M-type MG gearbox. My own M-type came with a 4-speed box (not original ) and I found a Minor 3-speed to take its place. But of course I have not the correct M-type top. I believe that the ratios are the same.

Ian I have to confess that I had not taken a good look at a gearbox like the one in your picture till quite recently and it was fitted to an M-type (ripe for restoration) .

I believe the top of this gearbox is distinctive simply because the starter switch on the M-type is mounted on the dash. I think the box itself is almost the same as a Minor but it does look as though the casting has lost the redundant transmission brake detail. Were later Minor 3-speed gearbox casings also like this ?

DF9053 · Post by **DF9053** » Tue Jan 01, 2008 7:03 am

The ratios in my box are as Ian quoted.

The starter switch bracket still fits on the top, but instead of the bracket fixing to the extened top cover, it is folded back and bolts through the bolt you can see on the back of the top cover in the picture.

Cheers
Jeremy

Sam Christie · Post by **Sam Christie** » Tue Jan 01, 2008 12:12 pm

I have just found a copy of an article written by Barry Foster for the MG Triple-M Yearbook ( no date ) and a three speed box like Ian's is pictured and described as a "late M and D-type gearbox" - though the one pictured in Barry's article has no top.

Post by **Ian Grace** » Tue Jan 01, 2008 4:36 pm

Jeremy,

I know what you mean - this was a mod to the starter button bracket for later box tops which didn't have the extension over the transmission handbrake. But on my box, the top is too tall for even a folded bracket to reach, so it might make sense that it is M Type.

I think the 4-speed boxes had a rightangle starter button bracket bolted to the back of the box. What I'd like to know is how the starter button on a SV 3-speed box is mounted, because I always thought this was a SV Minor box. But then this would have been the box fitted to M's as well, as I don't think they had their own unique box, but just fitted whatever came to them from Cowley.

Sam Christie · Post by **Sam Christie** » Tue Jan 01, 2008 5:05 pm

Ian I have sent some pictures. Have they come through OK ?

Post by **Ian Grace** » Tue Jan 01, 2008 5:23 pm

Sam,

Yes they did. Here's the M you looked at recently. Certainly looks like the box I have.

And here is the factory photo showing the gearbox and cranked lever:

DF9053 · Post by **DF9053** » Tue Jan 01, 2008 5:29 pm

Looking at mine again the top cover is slightly different, there is an extra lug. Ian I have just emailed some pictures

Post by **Ian Grace** » Tue Jan 01, 2008 5:58 pm

Here's your pic - shows the extra bolt on the back for the starter bracket.

So I think this is a SV 3-speed box, as the OHC Minor boxes, even after the deleting of the transmission handbrake still had the overhanging box top fitted.

DF9053 · Post by **DF9053** » Wed Jan 02, 2008 6:32 am

Thanks Ian, I can confirm that the main box casting is the same as on DF and the gear ratios the same as you quoted. Interesting that the M type cover also has that rear lug removed. This gearbox is intended for Y407 so will ultimately end up with an ohc engine.

Cheers
Jeremy