gearbox dilema

[guystrungout]

Not sure if you've covered this before because I'm a new member and haven't ever owned a minor as old as the one I have just bought. Its a split screen 1955 2 door saloon and its been fitted with a 1098 engine which I know is definitely not standard for the year. My problem is that it revs really high and will go up a hill in 4th but only has a top speed of roughly 60 mph. The gearbox looks like an original, so is it the gearbox that is geared high for an 803cc engine or is it the differential that needs changing? If I wanted to put a later gearbox in, would it be possible without having to change the floor pan, as the gear lever is in a different place on the earlier box. Can anybody give me any advice please?

[minor_hickup]

What does the gear box look like, is it smoth or ribbed, is it cast iron or ally? I think an 803cc should have a cast iron 'box. It is possible to use the 1098 ribbed box and lose the remote change, someone on here has done this recently. Or the box can be used as is with a later transmission tunnel.

The low gearing however will be due to the differential ratio. A 1098 should have a 4.22:1 ratio earlier axles came with lower ratios, about 4.5:1 I think.

[guystrungout]

Thanks for your prompt reply, its an ally box for sure. What do you mean by losing the remote change? Do you mean its possible to use a later box and remove the gear lever attachment? If so, where do you put the gear lever? Sorry for my ignorance on this matter...I did think this might be a possibility but looking at the diagrams in the workshop manual I came to the conclusion that it wasn't. I'd be very happy to find out that it was possible!

[DAVIDMCCULLOUGH]

Try this guy, hes advertises in the club magazine. John Evans, 02392 465256 or mobile 07776381520. He does an 803-1098 conversion and is based in Hayling Island

[Matt]

It will be the diff. AFAIK all the gearboxs have a 1:1 ratio on 4th

[guystrungout]

Ok thats really helpful, thanks for the info everyone. So I'm now in the market for a good secondhand 4.22:1 differential...anyone got a spare??

[Stig]

So I'm now in the market for a good secondhand 4.22:1 differential...anyone got a spare??

Yep. Well, I don't know about 'good', but useable anyway. Whereabouts are you? It's worth putting your location in your profile.

[Willie]

You will have to be careful. The early diff casings had the oil filler hole
on the DIFF casing itself rearwards of the pinion flange. The later diffs do not have this filler hole as it is actually on the Back axle half way up the diff housing facing the rear of the car. If you fit the wrong diff unit
you can finish up with NO filler hole! Hopefully you have the ribbed gearbox casing(1098) but your diff could be either 5.375-1 or 4.55-1.
The 5.375-1 diff ratio was fitted from 1954 and, if your diff unit fits into the rear axle casing at the front with a ring of nuts then it is the later
'three quarter floating type' which is good news.

[guystrungout]

Thanks Willie, thats good advice. Mine has got a ring of bolts on the front and looks very similar to later models I have owned previously, so hopefully I should be ok.

[bmcecosse]

But the difference between 4.55 and 4.22 diffs is not all that great. Your top speed of 60 mph suggests a very much higher diff ratio may be in that car. Maybe it has the early axle from the 803cc car ? In which case you may need to change the complete axle to get a better ratio.

[Willie]

As I have already said the diff on a 1955 is 5.375-1. They changed it from 4.55-1 in order to increase the acceleration!

[bmcecosse]

That's it - I didn't see that - it was v late last night! So - a 4.22 will make a big improvement. These 5.375 diffs used to be in demand for competition cars where acceleration was the priority rather than top speed -ie Hill Climb cars.

[mike.perry]

A quick summary of rear axle ratios:-
Morris axle with 4.55 ratio used on Series MM
Morris axle with 5.375 ratio used on early Series II
A Series axle with 5.375 ratio used on later Series II
A Series axle with 4.55 ratio used on 948 Minor 1000 and 1098 commercials
A Series axle with 4.22 ratio used on 1098 Minor 1000
A Series axle with 3.9 ratio suitable for use on 1275 conversions.
Bolting a 1098 engine onto an 803 gearbox will give an unsuitable set of gear ratios for the more powerful engine and the gearbox may self destruct as it is not strong enough for the 1098 engine. John Evans' conversion uses the 1098 box but keeps the long gear lever of the 803 box.

[minor_hickup]

Thanks for your prompt reply, its an ally box for sure. What do you mean by losing the remote change? Do you mean its possible to use a later box and remove the gear lever attachment? If so, where do you put the gear lever?

Exactly, or I think that's how it's done, to keep the interior looking original the gear lever acts directly on the gearbox rather than on the later boxes that have a remote unit moving the gearstick further back and utilising a shorter gear stick. I'm sure there was a chap on here who very recently did this on a black split screen.[/b]

[alex_holden]

I'm sure there was a chap on here who very recently did this on a black split screen.[/b]

That was Callyspoy.

[Willie]

I think you have that slightly wrong? You can have the later 1098 gearbox internals fitted into the series 2 box so keeping the interior as original. You could speak to John Evans on 02392 465256

[bmcecosse]

Yes - Callum fitted the older gear lever to a later box. He detailed how on a thread at the time - think it involved a Dremel and loads of time !

[alex_holden]

I think you have that slightly wrong? You can have the later 1098 gearbox internals fitted into the series 2 box so keeping the interior as original.

I'm pretty sure what he did was fitted a Series 2 tail casting (the type that doesn't have a remote control unit) onto a 1098 box.

[Willie]

That would be even better because it would use the stronger 1098 casing,
so, there are two ways of sorting the problem if you wish to retain the original gearstick.

[callyspoy]

hello, im here! yes...it was in fact a midget 1275 box i'll have you know! hehe!
yeah, if you are going with 1098 engine, i would think a 948 'box would be fine, am i right? as long as you are not thrashing it around like a loon...
if so, then the tail casing can be swapped very easily from 803 box to 948 box. literally just a case of swapping over the tail shaft.
but...if you want a 1098 box...it is a bit of a nightmare if you dont have the right tools, like me! i would explain, but i ran a 1098 with a 948 box no problem, so i would just go with that!! unless you are thinking 1275 power...