3.54 diffs into S2a (Chat)

[65s2a]

...I once fitted a fairey to my series 2A, but such was the noise, that fairey came out the very same day.

I then fitted 3.54 diffs from a range rover and initially was pleased with the change.. 100km per hour with engine not screaming however, take off in first was a bit more of a stretch than I liked, slipping the clutch slightly was needed...second and third were fine. I tried takeoff in first HR on reasonably steep slope and was dissappointed.

Low ratio seemed fine...I did a trip around 4WD park near Beaudeseart and had no problems going every where around the trails that Disco's etc were going including some rather steep climbs...However, at the park there is a "test" place where you drive into a hole and try to climb out the other side...no one else made it but although I came very close, I didn't make it I reckon because I ran out of gearing...overall low ratio 1st gear not low enough!!!

After some research I found there was much more I could do to improve things...here is what I did and this may be useful to other 3.54 diff ratio series owners.

It turns out that between suffix B and C gearboxes and transfer cases... lots changed. C on gearboxes fortunately have lower first gear than B or A 3.6:1 vs 3:0 but C transfer case unfortunately has higher low ratio than B 2.35:1 vs 2.89:1

So I used a B transfer and a C Gearbox and now am very very happy with the result for both on and off road driving. No problems taking off in first gear HR, great performance in first LR...very happy compromise.

With 3.54 diffs, original suffix B TF&GB vs B TF&C GB
Overall low ratio first gear was 30.69:1 is now 36.83:1
Overall high ratio first gear was 12.21:1 is now 14.65:1

Comparison with original 4.7 diffs
B TF&GB Overall low ratio first gear 40.74:1 High ratio 16.21:1
C TF&GB Overall low ratio first gear 39.76:1 High Ratio 19.45:1

I am running 235-85-16 tyres on defender rims...adapted speedo gears out of a Triumph 2000 into the land rover speedo to give 1000 TPM which calibrated nicely for my setup.

I think I attached a spreadsheet showing calculations on the ratios (adapted from someone elses work). Hope this might be useful to someone.

Les

[akelly]

Perfect timing! I've just purchased RR diff centres for my IIA, this info will be very handy... Is yours Holden powered?

Cheers,

Adam

[65s2a]

Hi Adam, Hillston has original 2.25 Petrol...is reconditioned and goes well. Good luck with yours.

[series3]

Hi Les,

Thanks for this info. Does anyone know of a good list detailing GB & TC ratios throughout the suffix changes of the series 2/2a?

Sam

[NiteMare]

i've a Series3 suffix A gearbox/transfer box in my bitsa with 3.54 diffs, O/D and 7.50x16 SAG's, it is a little overgeared in top with the O/D engaged as it needs a long run to wind the speed up (potential for 90mph) but cruises easily at 65-75mph, hills don't faze it, tyre traction is my only problem off tarmac ...

but i am 200tdi powered

gearbox was already well tired when i fitted the engine so i'll be swapping it out for a S2/2a box soon that i collected the other day, only thing is i've no idea of the suffix as it's not stamped, just numbers

[Johnno1969]

Hey Les,

Very interesting post, thanks. I've battled with the whole Fairey thing for years, but have always been wary of changing diff ratios. Any information is always useful.

Cheers,


John

[akelly]

I spent this afternoon fitting the 3.54 diff to the rear of my shorty. Wow, what a difference! Much quieter and more comfortable on the open road. Much better match to the holden 186.

Front will have to wait a few weeks - got a few other things on.

Only issue now is the speedo. I'm running 31 10.5x15 tyres. Anyone got an idea of how to make the speedo read correctly? I'm going to use the GPS and make some marks on the glass as a temporary fix but would like it to be right eventually.

Cheers,

Adam

[landrover dave]

...I once fitted a fairey to my series 2A, but such was the noise, that fairey came out the very same day.

I then fitted 3.54 diffs from a range rover and initially was pleased with the change.. 100km per hour with engine not screaming however, take off in first was a bit more of a stretch than I liked, slipping the clutch slightly was needed...second and third were fine. I tried takeoff in first HR on reasonably steep slope and was dissappointed.

Low ratio seemed fine...I did a trip around 4WD park near Beaudeseart and had no problems going every where around the trails that Disco's etc were going including some rather steep climbs...However, at the park there is a "test" place where you drive into a hole and try to climb out the other side...no one else made it but although I came very close, I didn't make it I reckon because I ran out of gearing...overall low ratio 1st gear not low enough!!!

After some research I found there was much more I could do to improve things...here is what I did and this may be useful to other 3.54 diff ratio series owners.

It turns out that between suffix B and C gearboxes and transfer cases... lots changed. C on gearboxes fortunately have lower first gear than B or A 3.6:1 vs 3:0 but C transfer case unfortunately has higher low ratio than B 2.35:1 vs 2.89:1

So I used a B transfer and a C Gearbox and now am very very happy with the result for both on and off road driving. No problems taking off in first gear HR, great performance in first LR...very happy compromise.

With 3.54 diffs, original suffix B TF&GB vs B TF&C GB
Overall low ratio first gear was 30.69:1 is now 36.83:1
Overall high ratio first gear was 12.21:1 is now 14.65:1

Comparison with original 4.7 diffs
B TF&GB Overall low ratio first gear 40.74:1 High ratio 16.21:1
C TF&GB Overall low ratio first gear 39.76:1 High Ratio 19.45:1

I am running 235-85-16 tyres on defender rims...adapted speedo gears out of a Triumph 2000 into the land rover speedo to give 1000 TPM which calibrated nicely for my setup.

I think I attached a spreadsheet showing calculations on the ratios (adapted from someone elses work). Hope this might be useful to someone.

Les

My ex army swb used a suffix c mainbox with the later 2.88:1 low range t/case with the larger intermediate shaft. With 4.7 diffs this combination gave 48:1 low 1st! Awesome in the bush. In my series3 lwb I fitted a high speed t/case with a 202. It was capable of 140kmh, but 1st was a bit high in some instances. Very easy cruising at 100 or even 110kmh. 202 not good on petrol though 21mpg but I mainly used LPG.

[COFFEY76]

My ex army swb used a suffix c mainbox with the later 2.88:1 low range t/case with the larger intermediate shaft. With 4.7 diffs this combination gave 48:1 low 1st! Awesome in the bush. In my series3 lwb I fitted a high speed t/case with a 202. It was capable of 140kmh, but 1st was a bit high in some instances. Very easy cruising at 100 or even 110kmh. 202 not good on petrol though 21mpg but I mainly used LPG.

Im thinking of putting in higher ratio transfer case in my 2A, like you did with your ser3. Is the sacrifice to sit on 100-110kms worth the effect that it has on 1st gear? I also have a 202 (doesnt drink quite as much as that, close though)

[Disco44]

Is Jack McNamara still operating down in Melbourne.I once bought a 3.54 salisbury from him and fitted it to my series 3 .The front diff.was out of a RR.I used the salisbury as they are a lot tougher that the Rover.Worked a treat.