for those who know lots about Commers/Humbers

[LowStandards]

The diff is very noisy on my '69 commer PB, now i know these use the same axle as the humber Hawk and i've been offered a complete Hawk axle, but its from an overdrive model.

Couple of questions:

Will the ratios be the same?

If not, if i bought the gearbox and overdrive unit, is it a simple fix or would it be a nightmare? propshaft length, wiring etc

Help cause the noise is driving me mad!

[arthurbrown]

I think the ratios should be OK?

The O/D units used by rootes were the Laycock type which doesn't affect the ratio's of anything else..... but don't take this as gospel necessarily...

If you do need to change the box, be aware that the box is essentially the same as used in loads of other hillman/humber/singer 1725 type cars... but the commer has a unique tail-housing. The propshaft is also unique to the vehicle.

Hope this is of some help?

[LowStandards]

Yup, as long as the ratio of the diff is the same or very similar it should be fine??? Though i do fancy overdrive, its something i can do without!

Just looking round t'web and all i seem to find is a ratio of 4.22 whichever vehicle i stick in, so it seems there all the same...

Oh, one more question, an autobox? How feasable is this? I'm reegt lazy ya see

[arthurbrown]

Quite a few Commer's came with auto-boxes.

I haven't seen one 'in real life' but I assume they use the BW35, as this was used again in the 'superminx' type cars with the same engine.
Again, you'll have issues with that tail-housing, but it is perfectly feasable.

Really don't know how the shfter works though....
Musta had a column shift, as otherwise you'd have the world's oddest shaped floor shifter.

Also, those autoboxes eat all your power. that's bad enough in a sleek, lightweight superminx... in a Commer brick on wheels it must be really grim!!

[LowStandards]

Was thinking in the long run a nice chunky diesel or maybe a subtle Merc V8 FTW. I mean mpg aint really an issuie as its pretty bad already and she don't come out to often, should be able to keep up with traffic then!

Still its a pipe dream and something that wont happen for many years i guess!

Cheers, for your help mind!

[Mr_Bo11ox]

get a lovely montego diesel in there! great engines those. Bosh one in and set off to N. Africa, fantastic.

[arthurbrown]

A modern-ish TD in a commer would indeed be A Very Good Thing. Must be enough space... it's really only height which is a significant issue.

Weren't some of them fitted with the Perkins P3? Officially the worst engine evAr....

[LowStandards]

They did a diesel version, and i think it was a perkins! My Dad tells me everytime he see's the Commer how he spent his youth sat upon the engine lid of a diesel one, smoke filling the cab and how awful it was!

I reckon a nice 2.5TD with a 5speed would go a treat, even better an auto, do they do auto transits?

[Blue850]

Some of the Transit Tourneo minibuses came with an autobox for the hire-drive market

[Paul H]

2002gimp said:

Will the ratios be the same?

If not, if i bought the gearbox and overdrive unit, is it a simple fix or would it be a nightmare? propshaft length, wiring etc

I know sweet FA about the technical side of Rootes Group vehicles but the following generally applies to most '60s cars....

The overdrive axle will probably be lower geared - ie 4th with the non o/d axle will give greater mph / 1000rpm than 4th with the o/d axle (but obviously, o/d 4th will be tallest). If you can, I'd fit the o/d too, as the complete setup will give a closer range of ratios (as well as a taller top gear once up to crusing speed), that will be more suited to the heavier weight / drag of the van.

[jizzy gillespie]

for deisal auto,s check out a motorhome breakers, although the mojority will be fwd

[Seth]

I agree with Paul H's generalisation. Certainly GT6's came with different ratio rear ends depending on wether they had OD or not.

From a Roots point of view I can give you the folowing info which may or may not be helpful - from my Sunbeam Rapier/Alpine Singer Gazelle/Vogue manual.

Gazelle 2a,3 & 3a 4.78:1
Gazelle 3b & 3c 4.44:1
Gazele 5 3.89:1
Vogue 1 & early 2 4.22:1
Vogue 1 with O/D 4.44:1
Vogue 2 late & 3 3.89:1
Rapier 1 5.22 :1
Rapier 2 4.55:1
Alpine 1 & 2 3.89:1
Rapier 3 early 4.55:1
Rapeir 3 late & 3A 4.22:1
Rapier 4, Alpine 3 & 4 3.89:1

OK, so I realise this might not be directly relevant as I'm not sure the axle is the same (Hawk/Commer might be bigger for bgger car/commercial use?) but hopefully it suggests the ratios they were playing with.

[LowStandards]

Cheers, it seems only a slight difference in ratio with an overdrive fitted.

I was reading up the specs from my Manual last night, but it confused me a little, all this mention of final drive was up there at like 5.33 and things like that, does this include the gearbox in the calcuation? Prob best if i post the page up here really, though you'll just have to wait till tomorrow!

Unless anyone can recommend a good diff rebuilder? all the bearings and pinions are fine, the only prob is when i took it apart some chewed up shims fell out so the pinion is not close enough to the CROWN wheel. And i don't have a clue about doing it myself...

[LowStandards]

K, here's the page from the Commer manual, I've highlighted my axle and i'm running 15inch wheels

The only diffs i can find are 4.22 ratio, will these work, i cant decide wether the ratios quoted in the manual include the wheels etc, is there a way of working it out???