Differentials

[Gippslander]

Thanks to all who gave advice regarding gearbox now I would like opinions on differential ratios to go with 186 Holden motor should I stick with original or opt for 3.54:1 centres for better highway use. Remembering I will be loaded with full camp gear and most times a 4.5 metre boat, it is a tinny and quite light
Looking forward to your insights. Gippy[biggrin]

[AK83]

with ratio changes, more important than whether you want highway cruising, is the question of how much low ratio are you willing to sacrifice for the highway cruising advantage.

ie. choose between changing two diffs, or look at either a high ratio change or an overdrive.

Changing the high ratio gears will leave the low ratios alone.

[goingbush]

Theres no high ratio option in the transfer case on a Series.

I'd stick with 4.7 , 3.54 will be too tall for the weight you will be pulling , 1st gear high ratio you will struggle to pull away on a slope . and the clutch will suffer.

The 186 is not as torquey down low as the original 4 banger.

Overall first gear with 4.7 is 19.2:1 2nd gear 11.98

with 3.54 first is 14.63 , so about 1/2 way between your existing 1st gear & 2nd gear.

You could install a Global Roamerdrive , about $2200 from Huttons Winches.

[AK83]

Theres no high ratio option in the transfer case on a Series.

....

Ooops! apologies .. didn't know this.
I was too young to remember my dads SII, even when I did start driving it.

[gromit]

I have a high ratio transfer box in a shorty powered by a C240 Isuzu motor.
Easily keeps up with the traffic on the freeway and the low ratio isn't compromised. I was told I'd be slipping the clutch like mad to pull away from a standstill but the naysayers were proved wrong, the only compromise is it doesn't like 4th much below 60kph.

You can get the parts from Ashcrofts in the UK and get the machining done locally or send them a transfer box casing and they will modify & return.

Ashcroft Transmissions (https://www.ashcroft-transmissions.co.uk/the-series-vehicle/high-ratio-transfer-case-kit.html)


Colin

[JDNSW]

To clarify the last coupleof posts - there is no high range option on the Series transfer case. But as Colin says, there is a high range modification. The problem is it requires the position of the intermediate shaft to be moved, meaning the casing needs modification, but there is an established procedure for this.

[rocket scientist]

Years ago I had a series 2 with a holden 186 engine. Found some diffs from an older Rover Car. Can't remember the model.
They were 3.9 ratio and worked well under all conditions.
They were a straight swap from what I remember.
Pete.

[Gippslander]

I also had an old one about forty years ago, it was a Series 1 with 245 Valiant slant 6 and Rover 90 diff centres but I don’t think they would fit the Salisbury rear diff housing maybe some one can help I appreciate all of the answers so far.
Gippy[smilebigeye]

[JDNSW]

No - Rover diffs will not fit a Salisbury axle. There were several different ratios used in Rover cars, which will swap into Series axles, but not the Salisbury.

[gromit]

A diff ratio change will alter low range.
The advantage of the high ratio transfer box is that there is an almost negligible change to low ratio.
So you need to decide whether the vehicle will be used seriously off road.

The next best thing would be an overdrive.

Colin

[mick88]

I run both 3.54 diffs and a roamerdrive in my Holden powered Series 3 shorty with no issues at all.
I have a (3.5kg) heavier flywheel, a Crow torque cam, and I have never have had any issues taking off in high first.
The vehicle does have a lower profile tire than 7.50 x 16, closer to something between a 6.50-7.00 x 16.
We regularly tow a trailer or camper trailer, and with the overdrive engaged on trips, unless in very hilly terrain.
The vehicle gives good fuel economy and is rather quiet to travel in.
As Colin says, the "naysayers" are not always right.

Cheers, Mick.

[Blknight.aus]

Theres no high ratio option in the transfer case on a Series.

I'd stick with 4.7 , 3.54 will be too tall for the weight you will be pulling , 1st gear high ratio you will struggle to pull away on a slope . and the clutch will suffer.

The 186 is not as torquey down low as the original 4 banger.

Overall first gear with 4.7 is 19.2:1 2nd gear 11.98

with 3.54 first is 14.63 , so about 1/2 way between your existing 1st gear & 2nd gear.

You could install a Global Roamerdrive , about $2200 from Huttons Winches.
4.11 is a good option.



To clarify the last coupleof posts - there is no high range option on the Series transfer case. But as Colin says, there is a high range modification. The problem is it requires the position of the intermediate shaft to be moved, meaning the casing needs modification, but there is an established procedure for this.

yes there is,

ashcroft make one
marks used to make one and they come up second hand occasionally
MR automotive still sell them.

its not just the intermediate shaft that needs to be pulled some kits (the better ones) also require removing the foot so you can change the gear on there as well.

Its not hard.

[fixes]

I had a 11A shorty ragtop (that I sorely miss) that had been converted with a 179, Salisbury diff and 11" front brakes, locking hubs Aaaand a Toro overdrive (11% I was told). The motor was unregisterably smoky, and I was given a 202 to put in it. I could sit on 70mph comfortably, surprising many following road users, and only the long Pheasants Nest Hill caused me to shift down. I still had all the original Landy workhorse gears available.
This is a great mod. and avoids all that buggerizing around with diffs and transfer cases. This was with the original Series tailpipe choking it, which didnt trouble me enough to change it. The previous owner didnt change the master cylinder to match the bigger wheel cylinders so I always had spongey brakes. I think the original brake upgrade was necessary for NSW engineering compliance. I had to get it re-ticketed for the jump from 179 to 202.
Refering to the other thread above, about conversions overheating...I never had a problem, summer or winter, in town or out, with the original 3-core radiator. It was tube-rot there, and poverty, that eventually forced it into the shed.

[mikek]

I found 3.54 made 1st gear to high and fast and found myself using low range when trying to negotiate tighter areas like carparks
I then went to 4.3 rover car diffs and a roverdrive gave about same road speed with reasonable 1st gear,I use the overdrive like 5 gear but also use it to split 1st & 2nd as we have a non syncro box and changing down quickly on a hill climb isnt pleasant.
The roverdrive has been in for 10 years and never given me any problems, it did require better oil but my little 161 powered 88 has been to both ends of NZ a number of times and used as a daily driver. Change the speedo over to SPEEDHUT GPS unit and you dont have to guess how fast you are going, 90-95 kmh cruise pleasant, 100kmh effortless and smooth, 110 ok but windnoise starting to annoy