4x2 RRC with GKN Overdrive

[Little mule]

Hi everyone . It has been a while since my last post .

I have a cpl of questions on the GKN over drive 

my truck is a RRC 1990 that I bought 10 years ago form a guy in France and shipped it to Canada .

it is a completely rust free truck and has about 250k miles . It came with the original VM 2.5 which is now a boat anchor ( long story)

it came with a rebuilt Ashcroft LT77 and the factory B/W T case.

it’s a two door left hooker and the only electronics are the electric windows and mirrors .

I love it because of there are no electronics and it’s a really beautiful truck .

my plan is to replace the VM with either a 200 or 300 with hybrid turbo turner performance head (brand new not rebuilt)

I also have the parts to fix the grinding second gear problem which in my fault trying to speed shift lol.

the Tcase will be replaced with a LT230 and a part time 4x4 kit I also have free wheel hubs for the front.

I also have a front and rear Salisbury for stronger axles .

My question is with the GKN. It is brand new still in the box but no fitting instructions .

I will be taking out the electronic box and speed sensor because they are known for problems and I want the over drive to be as simple as possible .

Is there a certain ratio of transfer box that I need to use to install the over drive into ? 

I have a Ashcroft rebuilt Tbox with the part time kit installed and is a 1.4 ratio.

I live in Canada and where I live there are a lot of hills so the GKN will come in handy .

I will be running 33 x 10.5 x 15  BFG  alterrian  tires .

my truck will not be a off road truck I have a D1 for that more of a daily driver .

is the 1.4 the correct Tbox for this over drive or do I need to change it for a different gear ratio.

if I need to change gearing I would rather do it on the axles as the T box is pretty much new with the rebuild .

I can also get the axle gears a lot cheaper here for the salisbury / dana60,s

any advice Wurl be greatly appreciated .

thank 

 

 

[FridgeFreezer]

2 hours ago, Little mule said:

the Tcase will be replaced with a LT230 and a part time 4x4 kit I also have free wheel hubs for the front.

I'm curious as to why you'd do this other than the ability to do donuts?

[landroversforever]

2 hours ago, Little mule said:

the Tcase will be replaced with a LT230 and a part time 4x4 kit I also have free wheel hubs for the front.

I also have a front and rear Salisbury for stronger axles .

My question is with the GKN. It is brand new still in the box but no fitting instructions .

I will be taking out the electronic box and speed sensor because they are known for problems and I want the over drive to be as simple as possible .

Is there a certain ratio of transfer box that I need to use to install the over drive into ? 

I have a Ashcroft rebuilt Tbox with the part time kit installed and is a 1.4 ratio.

I live in Canada and where I live there are a lot of hills so the GKN will come in handy .

I will be running 33 x 10.5 x 15  BFG  alterrian  tires .

my truck will not be a off road truck I have a D1 for that more of a daily driver .

is the 1.4 the correct Tbox for this over drive or do I need to change it for a different gear ratio.

if I need to change gearing I would rather do it on the axles as the T box is pretty much new with the rebuild .

I can also get the axle gears a lot cheaper here for the salisbury / dana60,s

Not sure why you'd want the 2wd option to be honest.... Even with freewheeling hubs you're still dragging all the weight around with you. 

Also, if you're only running a tdi and 33" tyres, the standard axles will be more than up to it. 

[western]

Install instruction book & owners handbook for GKN overdrive is in the Tech Archive look in the index under the manuals  section. It's a scan of my books. Or just click this link 

 

[reb78]

You need to use the 1.4:1 transfer box. The input gear for your overdrive wont match the number of teeth for the other variants out there. 

[FridgeFreezer]

13 hours ago, Little mule said:

my plan is to replace the VM with either a 200 or 300 with hybrid turbo turner performance head (brand new not rebuilt)

Also curious why you'd do this in the land where 200/300TDi are not common - they were good engines 20 years ago but these days they're all shagged out and 110hp is nothing to write home about, must be something locally available that is a far better solution. An LS lump would fit in lovely and make it drive like a RR should.

[Little mule]

Thanks for all the reply’s .

the main reason for the 4x2 swap is as you stated I’m dragging all the front axles drive train around . 
the is no real reason in my opinion to have the truck is 4x4 all the time and it helps a little with fuel mileage and easier steering .I have owned rovers for over 30 years and I don’t do the burn out thing or race the trucks I have . I drive them because I enjoy building and driving them . I’m a tired retired injured vet and building my trucks helps keep my mind focused .  I’m also not wearing out components that really don’t need to be used unless in off reading or in snow . I converted my 2500 ram Cummins and the fuel mileage went up to just under 25 mpg and it’s a  7000 lb truck. It steers much easier and using 2 wheel low helps backing my car trailer up much easier .

I have the Salisbury diff already rebuilt and they have less that 3500 miles on them from factory . They came out of a ex military snatch rover I had them shipped over about ten years ago and were absolutely in perfect condition . The parts on this side of the pond for a D60/ Salisbury axles are alot cheaper than standard rover axles and yes I know they are heavier than a standard rover type. it’s the cost of shipping these days To get diff parts sent over . I had also built these axles up for another project for someone and they bailed on the project . 

The engine swap 

im trying to keep the cost down and I have all the parts in stock for the 200/300 engine left over from the same build that the axles were for . I also have a cpl of old D1/D2 for parts. if I decide to go with a V8 I have a stroked 4.6 P38 engine I can throw in and everything will line up and match . 
the 4.6 was built for my off road truck and is still waiting for the old 4.0 to blow up but it is still hanging on .

I have been down the engine conversion route several times and besides cost it’s a pain trying to find ,locate or have parts made to fit the swap properly.

with my RRC I’ll probably get about 135 hp out of my engine and that’s more than enough for me to cruise around with . If I want to hit the loud peddle I use my D1 . I will also probably go done a little on the tire size . I have 235/85/16 on my off road disco and it works fine .

I love the reply’s and advise from everyone thank you . 
opinions and comments are always welcome 

Thanks very much Western for the install manual . 
 

Tony 

 

[Snagger]

Yes, you need the 1.4 LT230 for an overdrive, be it a GKN or Roverdrive.  They won’t fit the other ratios.

I agree with the others that you are making life difficult for no real benefit with the axle swap, but if you have the axles ready and it makes you happy, they will be tougher.  You will need custom prop shafts.

I also agree that the part time 4wd is a real backwards step that will hobble the car in feel, capability and safety.  Don’t do it - it may have helped the Ram steering, but will make no difference on the RR if your power steering is working correctly.

[Little mule]

Thanks for your input Snagger 

when I bought the Salisbury axles I made sure they sent me the front drive shaft with the cardinal joint in it . They also sent me the mating drive flange for the T case. I also received the front sway bar and mounting hard ware. The front sway bar is huge compared to the factory RRC one . The rear axle came with drum brakes . I found a set of disc brakes calliper mounts to convert the rear axle to discs . These calliper mounts allow you to,convert from drum to discs by using the rear stub axle bolts to mount them . These mounting brackets were Land Rovers fix util they completely converted all of the 110 rear axles with the calliper mounting brackets already installed and part of the axle housing and mount onto the axle casing tubes.

when I did a vin search on my RRC it came back and a 400D model and had all the police spec suspension the funny thing is the truck did not come with any sway bars at all front or rear . I almost drove into the ditch when I picked up my truck from the RowRow . I thought I had a flat tire or something wrong with the truck . I had a few pucker moments driving the truck util I realized there were no sway bars . 
once I was used to the way the truck handled with out them the truck was more predictable when making sharp turns and going around a round about . You just let it lean over and go lol.

the rear sway bar will most likely be a 110 rear or a P38 rear as they  are very strong and will hold the truck down in the turns .

the rear drive shaft I know will need to be replaced and have a double Cardin joint installed at one end or possibly both ends .

the front drive shaft has already been up graded to greaseable U joints at both ends and I also can grease the centre joint in the cardinal joint.

the rear shaft will be built the same as the front . The company I’m using builds drive shafts for the racing industry and know about the D2 drive shaft joints blowing up and taking out the tranny and Tcase. Ill just have them install new joints and make the centre ball joint greasable .

you may be right on the handling and possibly safety . When the truck is on the road I know if I need to,change it back to a stock LT230 with the center diff. If I need to I’ll get a Ashcroft centre diff unit and install that and take off the free wheel hubs and go back to normal drive flanges. 

plans can still change as nothing is set in stone .

the rover type diffs I have here now are out of D1/D2 and a cpl of old RRC ones. The P38 axles I have the diff is on the wrong side but I can still use the diff center .if I use these P38 diffs I’ll have to have drive shafts made anyways because they are the short bull nose diffs and are shorter than a regular rover diff. The problem here in Canada they love to put tons of salt on the roads and the axle housings are pretty rotted out . Even the axle tubes are full of heavy corrosion and would need a lot of work to redo.

the axles out of my RRC when I bought it are ok and not too badly corroded and can be saved . They were also 10 spline . I can up grade the half shafts to 24 spline out of a D1/D2 with out too much hassle .

I might use these Salisbury axles under my off road truck as it only sees off road and is not a daily driver . I’ll fix up the old RRC axles housings and use them.

the B/W Tcase has to go because of the over drive and the viscus unit is well past it’s life expectancy and keeps burning up the fluid in it .

that’s is why I’ll be changing it out to the LT230.

once I get the frame back from the galvanizes and restart the assembly I’ll have a better idea of what I will need and want .

im not even installing a winch on my RRC . I have a factory ARB front bumper made out of aluminum that doesn’t have a winch mounting plate 

it will give me a good place to mount driving lights and so on.

having the GKN over drive will help out a lot on the hills I’m my part of the country and being able to split shift gears comes in very handy so the engine isn’t screaming or lugging along on the long up hill drives we have here in NB Canada.

I have been using Ashcrofts ratio calculator and running some numbers to see what the best combo will be .

im glad they added the different over drive makes so you can see what RPM you will be running with different gears and tires and so on.

I want my RPM to be around 2200 to 2600 when cruising on the highways .

tony 

 

 

 

[Snagger]

I think you should be braced for some disappointment.  A 1.4 transfer box with overdrive isn’t much taller geared than a 1.2 and is less reliable, more maintenance and noisier.

The Salisbury axles are going to take a fair bit of cash to fit, and a disc conversion of the drum braked rear axle takes more than just the brackets - I’ve done that myself.  For a Range Rover, especially a daily driver, you just don’t need the enormous weight of the Salisbury axles.  Their antiroll bars would be way too stiff for the RR, given they are designed for a taller aromoured vehicle.

The part-time 4wd conversion is the biggest concern.  That is going to make driving in Canadian winter quite sketchy - the vehicle dynamic stability will be severely reduced with rear wheel drive, especially with the oversized tyres, massively increased unsprung weight and modified suspension.  I completely understand why you are replacing the Borg Warner unit with an LT230, as good as they are, but crippling it with that 2wd conversion is a big mistake.  If anything, most would be looking at replacing its centre diff with an ATB if they weren’t content with a standard unit.

It’s your prerogative, but when you get it on the road, for god’s sake take it very easy, especially in slippery conditions, for the benefit of other road users as much as yourself.  I honestly don’t think you’ll be happy with the results, though.

[Little mule]

Thank for your input I appreciate another point of view.

my RRC is not going to see snow lol it’s in way to nice of shape to do that to it . This is what I have the D1 I drive it in the winter as my daily and yes it handles very well with the factory set up. 
this 2nd conversion was a I’ll try it and see how it works . It was a option for the 110 in its early days when the 110 was running the 2.25 and 2.5 petrol. They then had to install the 1.6 T box . 
I have already had to install tire chains this winter because of the amount of snow we had be received .

one thing I love about these trucks are the ability to change things up if needed .

[Bowie69]

The only reason the 2WD was available on the 110 was because it had the stronger back axle, the Rover type won't like it long term,  by running 4WD you reduce the stress on things significantly. 

 

 

[Snagger]

2 hours ago, Bowie69 said:

The only reason the 2WD was available on the 110 was because it had the stronger back axle, the Rover type won't like it long term,  by running 4WD you reduce the stress on things significantly. 

 

 

The plan to fit a pair of Salisbury axles more than allows for the stress in the transmission, but for most RR users, the standard Rover axles are adequate even for significant off-roading and heavy towing.  Salisbury axles are way over the top and their extra weight, complication in fitting and the combination of 2wd and weight will make the car drive unpleasantly, to put it mildly.

For a bit more food for though, Little Mule, the disc brake conversion can retain the existing stub axles, but you will need the hubs from a 200Tdi or earlier 90/110 front axle, the 300Tdi rear calliper brackets, metric RR rear callipers and pads, RR front solid discs and some spacers to pad the bracket from the axle flange, aligning the calliper with the disc.  The result will be hubs on both axles that don’t fit alloy or Rostyle wheels without spacers.  The spacers will be illegal in some nations, though I believe they are fine in Canada, but will have a far worse effect on steering feel than any concerns you have over permanent 4wd, and also induce reactive pulling on any uneven stir face or if ever the tyre pressure or brake performance is uneven.  It’ll look peculiar, too, having such big tyres and protrusion wheels on a Range Rover.

So long as you have the facts and have carefully considered the pros and many cons, then good luck in whatever choice you make.

[hurbie]

i see this ending in a very expensive undrivable classis range rover 😉 

 

but if you like tinkering , have a go at it ...

[Little mule]

I tried to use early 110 front. Callipers on my d1 and that was a huge mistake and failed badly . I only got down my street and had no brakes at all on the first pump . On the second pump I had full hard brakes but bairly stopped at the stop sign. The truck went back to the shop and I reinstalled the factory disco 1 calibres.

when I installed the bigger calliper I didn’t take into account the amount of volume of brake fluid I would need for the bigger pistons.

the master cylinder was to small to give enough push on the first peddle push . For a second I was having flash backs of driving a old series truck lol.

the front brake master provides much more fluid to move the bigger pistons. 
you can just change out the master either because the mounting flange in mounted on a 45 degree compared to the 110 which it sits level .

im sure once I install the huge vacuum booster from another RRC it will be more than enough to stop the truck .

I have some factory turbine wheels I bought a few years ago and I hope they will fit the bigger. Callipers with no problems I like the look of them .

[Bowie69]

1 hour ago, Snagger said:

The plan to fit a pair of Salisbury axles more than allows for the stress in the transmission

I thought this idea had been discarded.

[Little mule]

Bowie69 

I believe they used the Salisbury in series trucks as well as 110 and 130 as well as the 1 ton.

the splines are 24. And yes the axle,is heavier but I can’t see how it will cause more stress on the transmission.

In the series trucks and stage 1 v8 had Salisbury axles front and rear and used a LT95 out of a RRC 

they also installed the Salisbury into series trucks and those transmissions worked out ok .

we now move to the 90/110/130 and it’s used very well when bolted up to a R380 and a LT77 and LT77S.

I don’t. Drive my truck hard and I’m not out doing donuts so I’m pretty sure the tranny will hold up to what ever engine I use as long as the tranny is shifted properly and maintained properly.

all I can say is I’ll  try it out and if it doesn’t work I’ll swap it back the the factory setting and axles .

before I take any truck out on the road way I always make sure I drive it around my property and make sure things are working they way they are supposed to,work .

I’ll know right away weather or not the braking systems is going to stop and work properly . Once I do that I move up to the next phase of driving it up and down my country road and slowly increase speed and make sure the steering and shifting works well as well as the brakes and sway bars .

you get the picture lol 

our trucks and cars here have to have a yearly MOT as you call it and I’ll have the inspection shop check to make sure everything is correct and steering alignment is done so it drives down the road straight and doesn’t wander all over the place . 

one other inspection we have is a engineers report if the truck have been rebuilt . They go through and make sure the truck meets all the safety guide lines in order to be able to drive it on the road . This inspection also needs to be done if the chassis has been swapped or altered in anyway like galvanizing . I’m sure it will pass with flying colours and. Safe to drive .I may also have to put historic plates on it and will have driving restrictions placed on when and where I can drive it (going to,a car show or meet and so on) .

im pretty sure I’ll be happy with it and it not change it u til it’s correct 

Tony 

[FridgeFreezer]

I think you're expecting the 4x2 conversion to be better than it is - most other 4x4's use a straight "locked" transfer case for 4x4 or some sort of viscous coupling which will affect the mileage, whereas the LT230 having an open diff in the centre is a relatively unique thing (and very useful for traction).

Unless you remove all the axle internals as well, switching to 4x2 is not actually saving anything from spinning so although the engine is putting no power through the front axle, it is still having to rotate & accelerate all the contents of the axle just as much as it ever did.

[reb78]

Wonder if this thread should be split... its well off of the thread title now...

[western]

Split from GKN Overdrive thread.