Outer Limits 4x4 Board

Hi Guys,

thought you might be interested to see our new range of rover ring and pinions :

http://www.ashcroft-transmissions.co.uk ... t&catId=12

Dave,
Should be a good step up in strength over stock rover R&P.

I noticed your online ordering doesn't allow a choice between normal rear directional cut and reverse cut for the front.

What is your opinion of using the new 3.50:1 reverse cut front R&P with a stock 3.5385:1 Salisbury rear (front wheels would turn 1.1% faster)?

Bush65 wrote:Dave,
Should be a good step up in strength over stock rover R&P.

I noticed your online ordering doesn't allow a choice between normal rear directional cut and reverse cut for the front.

What is your opinion of using the new 3.50:1 reverse cut front R&P with a stock 3.5385:1 Salisbury rear (front wheels would turn 1.1% faster)?

Just the question I wanted to ask!

Also - any idea what would the lifespan of a 3.5 be like compared to a 3.54 - for a vehicle used mainly for road/touring (what you usually call an "expedition" vehicle).

Bush65 wrote:Dave,
Should be a good step up in strength over stock rover R&P.

I noticed your online ordering doesn't allow a choice between normal rear directional cut and reverse cut for the front.

What is your opinion of using the new 3.50:1 reverse cut front R&P with a stock 3.5385:1 Salisbury rear (front wheels would turn 1.1% faster)?

would not the center diff take care of this? is it possible to get perfect speeds between the left and right wheel/tyre on a front or rear axle??? so would not this be the same? at only 1.1% not a hell of alot

Serg

Hi John,

you are right there is no separate item for front and rear but there is a 'notes' field where this can be speced,

as long as you don't have the centre diff locked for along time when on a high traction surface, ie tarmac then I can't see this being a big problem for the centre diff to take up this difference when unlocked, as mentioned it's only similar to uneven tyre wear, I once worked out the difference between 4.10 rear and a 4.11 front to be 0.75 mm difference in tyre diameter, this would be alittle more but I don't think it would be enough to cause premature wear to the centre diff,

too early to tell on the lifespan but I can't forsee much of a difference, we had the same concerns when the HD CV's came out but they are lasting OK,

in theory the teeth may wear quicker as there are less but again I doubt if this will be significant, I have seen rover diffs do 400K if you keep oil in them, maybe these will only do 350K ? don't know yet but obviously most customers will be buying these foir low milage off roading trucks,

I will know soon if they are any good, we have one customer that would blow 3.54 diffs regularly on the start line with a 4.2 Jag supercharged racer, we pegged the 3.54's and they lasted 2 races before they failed, they are now pegged with new 3.75's and new quaifes, I told him they should be good for 3 races now !

ashtrans wrote:I once worked out the difference between 4.10 rear and a 4.11 front to be 0.75 mm difference in tyre diameter

Hmm,

3.50:1 compared to 3.5385:1 is 1.1% (350/3.5385) ~ 11m on 1km.

I dont think it is a very good idea after driving a hilux of a friend with 4.1 back and 4.3 front. That is a big different from 4.1 to 4.3 but it shows what happend. It was very very hard to steer - nearly not possible with 4wd engaged.

Maybe it will work nice in 4wd with only 1.1% difference but it will give your steering a harder time, the tyres wear quicker and your drive train will bind up more.

There was a topic about it on here. Somebody had issus with a Nissan/Toyota mix. Front 4.11 and back 4.1. He could not life with it.

Hope that helps.


Thanks
Chris

Hi Chris,

does the hilux have a centre diff ?

I would not suggest running the LT230 on the road with the centre diff locked,

My opinion is that it wouldn't matter enough (I am tempted to try exactly what I spoke of when I have some more $$ to spare), but I wanted to get Dave's thoughts as he may have considered that situation.

On most turns, the front wheels travel around larger radius arcs than the rears. And as the difference in the ratios in this case makes the fronts turn more the problem is reduced.

The other 2 cases Chris mentioned involved the fronts turning less than the rears.

HI

I have run 4.75 reversecut in the front and 4.7 std rover in the back now for more than a year without any issues.

The truck is a series two LWT, so we have no center diff, but on the other hand we only run 4wd away from tarmac concrete and other high traction surfaces.


Kind regards

Ole

Bush65 wrote:...(I am tempted to try exactly what I spoke of when I have some more $$ to spare),....

Me too - I just wish these had come out before I had built my front diff!

Hi just an update on our HD ring and pinions, 3.5 (Top) compared with the stock 3.54. You will easily see the tooth profile change but we also upgraded the steel, changed the helix angle (for more tooth contact) and supply a reverse cut gear set for the front.
OOps tried to post a photo but not yet had the required 5 postings. Photo on AULRO for those who are interested. Regards Ian Ashcroft

Hi,

Will this fit a 1997 300tdi discovery? what do I have to order
aside from the R&P? I am looking at replacing my stock R&P
with 4.75 and increase tires to 33" . tia

ps. how much is shipping to the philippines and do you accept payment
via paypal? again thank you in advance.

this is the photo Ian was trying to post :



this photo compares the stock 3.54 with our new 3.5 (28/8)ratio,

monmendoza, 4.75 may be too low with 33's, maybe 4.12 or 4.37 would be better,

next week we will have a ratio calculator on our web site, so you can put in the gearbox type, transfer case, tyre size and diff to give you the different engine RPM at any given speed for each gear in high and low ratio, should be very useful.

you can order online with our new website, we can accept visa or mastercard, we will have a neat carriage calclator on there soon but in the mean time if you would like a carriage quote just email us and I wil get a quote,