Morris Minor Forum

Hello All,

It was suggested that I post in the main forum about this topic instead of in the modified. I am new to this world, loving the car and finding the community to be very helpful.

I have a 59 Tourer with a 1098 cc that was rebuilt but still running stock 4.55 gears. I'd like to get some highway speed out of it without replacing the engine as it seems to be running quite well. The body is just okay so it'll only ever be a driver and can't justify swapping the whole drivetrain.

What do you think about getting some donor 3.9 gears or 4.22 gears to run with it?

Does anyone have some to sell or a full axle?

Tony

Have you thought about installing taller tires? What size rear tires are on it now? This would most likely be cheaper than changing the rear diff ratio. Also. it would be easy to go back to what you have now if you don't like the difference in performance.

---

Bob Marcum

1959 Bugeye
1960 Morris Minor Tourer
Ex vintage Mini racer

I use 3.9 with a1275 in Florida. No mountains to climb. On flat land I still just feather the clutch in second to take off from traffic lights etc. 70mph cruising is comfortable. I see no reason to use anything else unless you are always carrying 5 passengers, towing a trailer and have really steep mountains to climb. Car was designed to run a family around in 30mph city driving in England.

A 4.22 diff will bring you up to later Minor spec. The 1098 is a longer stroke engine so it's more on torque that rpm so it needs to be changed. Does the engine have a serial number under the number one spark plug? The first four numbers/letters will tell what the engine came from. What gear box you have will also have some affect because there were different ratios in Minors than Midgets. 4.22 are less expensive and should still be plentiful since Midgets used them through 66 or 67. The only caveat is the oil fill plug, but there are options there. Once you have the 4.22 installed (a quick process) and you'll get an idea how the acceleration changed and how the cruising changed. Then project those changes farther as to estimate what a 3.9 will give you. A lot will depend on your typical trips.

I have a ‘54 Minor with a 1098 fitted.
I switched from a 5.33 cwp to a 4.22 cwp.
This just transformed the car. No noticeable change in acceleration but way better cruising.
It runs at 65 mph easily & this is enough for all except Interstates.
I live in a hilly area & would not want to drop to a 3.90 cwp as on many inclines,
my Minor looses speed too quickly & this can be a problem in traffic.

Hello Tony,

I'm also interested to read the advice from those with practical experience, based on that, I'd agree with Ian the 4.22 is good first step, unless the terrain is relatively flat. A 3.9 would definitely not be a good choice in Pittsburgh for example.

I might be able to help with your quest for a 4.22, I have acquired two over the last several years off Ebay (one of them I think was about $75), with the thought of eventual replacement of the drivetrain on my car (its a very early S2 803 with a 5.375). One I thought was a 4.55, but turned out to be the 4.22. Either seem in good condition and have the drain plug, but having never had first hand experience of them in service, or had a chance to check some of the specifications like backlash etc., I can't guarantee them 100% as is. Might need an expert to check over and make any needed adjustments/replacements (new pinion seal would be a definite). Fortunately these are one of the better designed parts of the Minor. Let me know, in the end I'd be happy to see one of these put to use, rather sitting in the garage.

- Scott

Hey Scott,

Thank you for the offer and I will gladly accept to buy one of the 4.22 gears from you and share in the quest to learn about/swap the existing gears out. Perhaps my quest will be short with a successful conclusion! A few different people that I have reached out to have offered up some helpful advice (including in the forums here) on the options and the consensus is with you in that 4.22 is the way to go unless you have a 1275 cc. The 3.9 will likely struggle without some engine performance tweaks.

I actually talked to a friend tonight who has a transmission shop and I think he could be a good resource for us to figure out next steps. Do you know what vehicles they came off?

Tony

Hi Tony,

send me a PM and we can figure out which one. Unfortunately the Ebay information has aged out, one is pretty much original, and the other (which I think I paid more for) has been cleaned up and the pinion seal replaced. With the drain plug in the casing, I think they are both Morris Minor, but could be other I am not aware of (anyone know?). I have a Midget 3.9 for a possible future project which is good apart from the Carrier/spider gears that disintegrated for some reason. That one has no oil fill plug, definitely better to have one for a straight swap. I'm also glad you have a contact in a transmission shop to check it all over.

- Scott

A taller diff wont necessarily give you more speed.. but it will make the car less 'fussy' at freeway speeds.. factory used the 4.2 diff with the 1098cc engine.. in practice a good running 1098cc engine will pull a 3.9 diff easily.. but you'll have more top speed with a 4.22 and reach optimal velocity (quoted as 78 mph with 1098cc and 4.22 diff) faster too.. Brits tended to undergear their cars..wheras the French overgeared em.. you'd need about 70 bhp to get the most out of a 3.9 diff.. stock 'amw' 1098 has 48 bhp..Sprite/midget 1098 has aprox 60 bhp.. and 65 for the 1275.. the Riley 1.5 ( 3.7 diff) is faster in 3rd gear than it is in 4th.. the BHP output is the limiting factor... a Riley 1.5 with an MGB engine will pull close to 100 mph V +/-80mph with a stock 68 bhp 1500..

Hey Scott - sent you a PM

Tim - I suppose the goal would be to avoid redlining (if there was a tach) whichever engine is in place so less fussy at higher speeds is key. Good notes on horsepower and diff options. I'd like to try the 4.2 and 3.9 but it does seem like the 3.9 will struggle under anything less that optimal 1098 performance

Tony, each engine option has differences .. the 948 will never redline on a standard 4.55 diff.. and overall its much sweeter running engine than the 1098, which is known for its harshness, due to being the longest stroke A series combined with poor balance .. they are much better when internals are properly balanced.. but the small main bearings wear before anything else regardless ( the unique to spite /midget '10CC' engine being the exception) the upside of the 1098cc engine is it produces more torque than most of the others due to its long stroke..and that is what gets you up the hills with less fuss.. the 1275 is known to be the most robust of all of them.. and it matches a 3.9 diff perfectly in a minor..For optimal driving and longevity, a 5 speed conversion is the solution..

Tony, for some reason it did not go through, I will try sending one,- Scott

The 1098 has done quite well on hills in third gear but a bit of a dog in 4th on inclines. Great input. I hope this thread ends up with the simplest and cost effective solution to enough speed to handle some US highway driving.

I have an extra set of 4.55 gears because I also swapped to 3.91 , It's a good choice, car will still perform nicely with the 1098. The 4.22's would be a waste of time and money.

---

Of all the things I've lost - I miss my mind the most.