RedDevil72

New Member
Hi All,
I have just got a 1972 Series 3 SWB Safari that had a reconditioned 19j 2.5 TD dropped in 20yrs ago. I am upgrading the front hub brakes to 11 inch but also have been advised to upgrade the Diffs as its reving too high at 45mph - it has plenty of low end pulling power so would Range rover difs help ? 3.54 or 4.7 or something else ? thanks for any advice, BR Phil
 
why do you need to put bigger brakes on the front?
I needed to improve stopping power, other day had nice safe braking gap to car in front, traffic stopping, young git overtook 3 cars and put his Focus in my stopping gap, nearly rear ended him, my BMW X3 with disc brakes would have stopped no trouble - And apparently it would be my fault if I hit him, so now am also installing dashcam...
 
Standard brakes in good order should be capable of locking the wheels up. A freshen up of what you have might be cheaper and easier
 
Welcome to the group.

You cant expect a 1972 car to stop as well as a 2004 car, if you do you will be dissapointed.
The standard brakes should be capable of locking the wheels if they are all working correctly.
Also, yes, 45mph is getting to it's max speed. It probably has a 1.66 LT230 transfer box.

Here's some good info about the box and the gear ratios available.
 
Thanks both of you for the help and links, will look into the Transfer box exchange, bits from the link are £650 + 275= £925 so will have a think...
 
Front 11inch LWB brakes has been a popular upgrade for SWB trucks which are running larger tires.
Ashcroft transmissions do a higher gear kit for the series transfer box but you have to fit yourself, probably less trouble than changing two diffs and you will also have no issues with incorrect speedo readings.
LT 230 as pictured above is not what is in your series.
 
Welcome to the group.

You cant expect a 1972 car to stop as well as a 2004 car, if you do you will be dissapointed.
The standard brakes should be capable of locking the wheels if they are all working correctly.
Also, yes, 45mph is getting to it's max speed. It probably has a 1.66 LT230 transfer box.

Here's some good info about the box and the gear ratios available.
Fitting an Lt230 is a huge amount of work to a Series if the op still has the original gearbox and transfer box. Personally I'd not advise this route.
 
Hi All,
I have just got a 1972 Series 3 SWB Safari that had a reconditioned 19j 2.5 TD dropped in 20yrs ago. I am upgrading the front hub brakes to 11 inch but also have been advised to upgrade the Diffs as its reving too high at 45mph - it has plenty of low end pulling power so would Range rover difs help ? 3.54 or 4.7 or something else ? thanks for any advice, BR Phil
Ultimately there is no single answer here. It will come down to what you want to achieve, what you want to spend and where you are willing to compromise.

A brake upgrade is fine, although good order standard brakes should be fine too. A servo upgrade is probably worth considering if going for bigger drums and just a general check up that the entire braking system is working as it should be.

Gearing..... (making the assumption you still have the standard Series 4 speed gearbox and standard transfer box).

Firstly it is not revving too high. It is revving at exactly the same rpm that an original factory 2.25 petrol or diesel would be. Changing an engine doesn't alter this.

The difference is, you now have more power and torque and more easily attain higher speeds than a stock engine.

Overall the gearing is low on a Series, but this was on purpose given the power plants and intended use.

On the flip side, the 19J doesn't really like to be thrashed, that is when they tend to crack pistons and do head gaskets. Treat them gentle and they will generally run rather well. A factory 90 with the 19j in designed to run at mega high speed either and a fairly short 5th gear.

There are lots of options.

Tyre size is certainly one to think about. What size tyres are you running? Bigger tyres can certainly help reduce cruising rpm for a given speed. If you are on small 205's now, you might want to consider going up to a 7.50 or a 235/85. You could potentially even run all the way up to a 9.00 x 16 or something of similar height.

Changing the diff gears is an easy option. Although 10 spline 3.54 diffs are rarer these days, most are the latter 24 spline. So you'll have to hunt about. Also most Series diffs have the diff filler on the diff casing, not the axle like latter vehicles. So most 3.54 10 spline diffs will mean you'll need to fill the axle with oil by jacking up one wheel slightly and pouring it in through the axle tube, or modifying your axle to include a filling port.

The trouble with 3.54 diffs is. It makes 1st gear a bit tall, even more so if you are on taller 7.50s already. So you need to slip the clutch a bit more when pulling away. Not a major issue, but it will be noticeable and feel like a down grade in peppiness off the line. It is more of an issue if you ever tow or haul heavier loads and will be far more evident in these situations.

For me the bigger issue is it creates a large gap between 3rd and 4th due to the internal gearbox ratios. You'll find that 4th feels a tad too low for 30mph (esp if there are any inclines or hills), but 3rd will feel like you are revving it a bit hard at this speed.

Another issue with 3.54 diffs, it'll ruin your low range crawl speed. If you do off road you'll notice this, as you won't be able to go as slow as it does currently.


That said, a diff swap is the cheapest and easiest way to majorly address gearing and will give you the ability to sit and cruise at higher speeds.


There are two other main options:

-Fit an over drive. Not sure if the Roamerdrive is suitable for a Series or only Defenders, you'd need to check. Fairy used to make an over drive and a few others. This will be something that bolts to the transfer box and will essentially give you to sets of gears for each regular gear, both in high and low range. It'll give you another lever to control too. Many will just use it like a 5th gear and only select when cruising, but you could have it engaged all the time or use a combination of the over drive and transmission gears. Giving you in theory 8 forward and 2 reverse in high range and the same again in low range.

Downside is, OD units are a bit pricey and sometimes not the most reliable or at least prone to a bit of an oil leak.

-Higher range gear set for the transfer box. Ashcroft do (or at least did) offer a higher range gear set for high range. Thus retaining the 4 gears and spacing, but dropping rpm in each gear for a given speed. Typically I think it means 4th would be about equal gearing to having an OD fitted, so same rpm per 20mph in top.


It is possible to mix and match several options, although don't get carried away and end up massively over gearing the vehicle. I don't think an OD and higher high range are compatible though. So it would be one or the other.


I had a 200Tdi Series III 88, I fitted the 3.54 gears which was good in some ways, but it drove better with the 4.75 original diffs. One of my plans was to revert to 4.75 diffs and fit an overdrive.


There are other more extreme options, such as a complete transmission and transfer box upgrade to something like a 5 speed (or even an auto!!! o_O ) and a latter transfer box. But this is quite a custom thing to do with a lot of other potential changes.

Or even look to fitting a more rev happy petrol engine. It won't change the rpms you see now, but the right petrol engine may be more happy about maintaining such rpms.
 
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Thanks both of you for the help and links, will look into the Transfer box exchange, bits from the link are £650 + 275= £925 so will have a think...
A Zeus front disc brake conversion up front is what you need or better still a full disc brake conversion like i have fitted 👍
 
I had a 200Tdi Series III 88, I fitted the 3.54 gears which was good in some ways, but it drove better with the 4.10 original diffs. One of my plans was to revert to 4.10 diffs and fit an overdrive.
Std series diffs are 4.7, though I do believe some Rover diffs fit and they are/were 4.1 ratio.
 
Hi All,
I have just got a 1972 Series 3 SWB Safari that had a reconditioned 19j 2.5 TD dropped in 20yrs ago. I am upgrading the front hub brakes to 11 inch but also have been advised to upgrade the Diffs as its reving too high at 45mph - it has plenty of low end pulling power so would Range rover difs help ? 3.54 or 4.7 or something else ? thanks for any advice, BR Phil
88 with std 4.7 diffs and a 200 will do nearly 60mph revving its tits off, 4.7 diffs and 60 is much more relaxed.

I find first is ok, unless it is loaded then she has to grunt a bit to get going, I currently have 3/4 of a ton of ballast in the back and you certainly know it!

The problem is once you start down this road it can lead to one mod after another, and in the end it would have been easier to just buy a 90/defender.
 
Thanks, I did mean stock Series 4.75 diffs, just a typo as I've been thinking about 4.10's for a completely different vehicle.... :D
Never seen the 4.1 myself, but remember reaidng about them years ago, and thinking they would be bloody excellent in the series.
 
I have the fairy overdrive on mine and get a nice cruising 55mph without over revving and 60+ when it’s pushed and agree out of overdrive sounds noisy at 45 on 7.5 tyres

and I do like the slow speed in low when reversing into my drive or off road
 
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LT 230 as pictured above is not what is in your series.

@RedDevil72 I was wrong, my aplogies for the missleading information I gave you ref the LT230 transfer box.
I assumed your car had an LT77 gearbox and LT230 coupled to your 19j engine as my first landrover (a Series III) had.
I never knew that mine was a conversion until I saw the posts from @tottot and @300bhp/ton above.
 
Always been an issue in my head of pimping up a series with engines and chit when the bleedin things were never very safe at original speeds. Must be me getting old and miserable.
 
Instead of diffs, you'd be better off keeping the 4.7 diffs and original transfer gearing and fit an overdrive..
Roamer Drive makes a series Compatible box but a refurbished Fairey OD can also be fitted, but they hold high prices.
The Roamer drive is a stronger box than the fairey, can be used in low range and high range gives you the spread of ratios you need.. If you want higher gearing still, increase the tyre size.
 
Just popped over from the RR forum, but I have owned Series in the distant past .. 5 of 'em ;)

If fitting a OD strong enough to use in all the gears don't run away with the idea that you will end up with a multi-speed transmission designed for progressive upshifting like a commercial 'box, because some of your (final drive) ratios will be overlapping.