4.22 Differential

jimberlake

jimberlake

0
Been waiting to test it and now have done and have a 4.22 differential that slots straight into a Commer back axel, simple upgrade. Should allow people to reach a good top end without breaking your ears or drop the van down on 14” wheels and slimmer tyres without compromising current top end. With my OD, 14” alloys and slimmer tyres I’m confident of doing 70mph now at about 3200 revs which is right near the top torque.
There’s a lot of confusion about what they come from between the supersnipes and Hawks but this is a Hawk one with a smaller crown wheel, I think fitted to the later models.
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Nothing just the correct Hawk diff, goes straight in, same casing and everything. The trouble is that some Hawks appear to have a larger crown that doesn’t go through the Commer case. I might contact the place I got this from to see if they the year of car
 
Yes it would be great if you could find out more about which one would fit as it sounds like a very good option to make them more usable
 
Hi do you think the standard Commer engine fitted with a Weber carb have enough grunt to pull a 4.22 diff on standard 185R/15 tyres??
 
I too think you would struggle. Hills can be a problem even with the standard final drive so I think you would be down shifting a lot more, would be great on the down hill sections though :)
As an example I fitted a few go faster goodies to my Morris Traveller and it improved performance and acceleration considerably, I then replaced the 4.22:1 standard diff with a 3.7:1 from a Riley 1.5. The acceleration seemed to be dampened down to about where it was with the standard engine set up but the gearing was noticeably taller and cruising at high(er) speeds more relaxing. I think if I had simply put the taller diff in with the standard engine set up I would have really struggled to get anywhere.
A better solution with your set up would be an overdrive box, you would then have normal gearing to cope with windy stuff and hills with the option of the extra higher gears when you need them on the straight.
Our Jennings Roadranger is a heavy old bus but with an SU conversion to give a bit more pep to the standard engine and an overdrive box can cruise on the motorway at 60 quite easily when the roads allow, it takes a while to get there and still struggles on those hills a bit though. Our Auto-Sleeper with the mildly tuned Rapier engine and ODrive laughs at those motorway climbs and laps up any hill you can throw at it:cool:
 
Thanks for the advice guys, an overdrive gearbox does sound the best option or what if I was to put the 4.22 diff in and put onto 14 inch wheels which would drop the overall height a bit which won't be a bad thing either, would it manage that better?
 
4.22 drops 12% from the 4.77 Dodge diff (I think), most are 5.22 ratio though...so you can balance that with a similar wheel diameter reduction. I’m running 14”s with low walled tyres so it fits in the garage, I have a 4.77 diff and OD and 60mph is around 3200-300 rpm, I’m fitting the 4.22 diff over winter which should bring 70 at a similar rpm.
For warning 4.22 diffs that fit are pretty much impossible to find as they came off a very rare car indeed
 
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