Outer Limits 4x4 Board

i was wondering if there is a way to make a maxi locker more bullet proof , i stuffed mine on the weekend and was wondering if anyone has tips . The carrier is still ok but the pinion is stuffed missing 5 teeth crown wheel much the same . Someone told me about screwing a brass bolt through the housing locked off like a 1mm off the crown wheel to stop the flex has anyone heard of this or done this ?

Unfortunatley this is thew weak point in the Maxi-Drives. I know Mal sells a stronger 4.1:1 CW and pinion, but he wants quite a bit of brass for it. I knew a bloke who had done this to his and it cost about $2K including fitting!!

You must of being giving it a flogging to break it!!

Have fun,

Aquarangie

If in ain't broke, leave the bastard alone!!

i can get the 4.1's at a good price but i am told they can break too .. i am yet to have them so i have no idea on how strong they are . believe it or not i was doing around 5 to 7 kph in second low when it when bang just going over a wash out ... i think it might have been past treatment ...

G'day,

I bought 4.1's from mal, haven't used them yet but plan to soon (project's not finished yet) They are stronger but like anything there will always be a week link. When you have the Maxi-drive locker and axles and flanges the weakest link becomes the CW & P. I think fitting the 4.1's should do the trick for you, how long did it take for the CW & P you had to go with the maxi - drive fitted?

The problem is inherent in the RR design centre bevel as against a hypoid setup.

If you start to break the R&P then start looking at other diffs or diff centres.

Michael.

Please excuse my ignorance, but what is the difference between a bevel and hypoid R&P? I know what a hypoid setup looks like but not the bevel style.

Easier to copy it from Jac mac site.

The advantages of using this hypoid differential in Rover 4 Wheel Drives is the much stronger crown wheel & pinion gear sets, that are used, the Hypoid 3.54 Ratio Gear Set has a 21mm Larger Pinion Head and the 4.71 Ratio Gear Set is 14mm Larger at the Pinion Head compared to what the Standard Rover is. The Hypoid Off Set is 1 1/4" which creates a greater Tooth Load surface area compared to the Centreline driven Spiral Bevel Gear Set. Also the Carrier (Hemisphere) uses 4 Pinion Gears to drive the 2 Axle Gears, being able to use either 24 or 30 Splined Axles with the Hypoid Differential makes this Rover Replacement Differential extremely strong and reliable.

much better than I could do.

Michael.

And Michael, is that easy to do? Any machining? For both fronts and rear? what Axle ratios are available? (Are those enough questions )

A few ways to do it.

Jacmac uses Toyota centres in his hypoid diff centre.

Options:
1: Jac mac new casting to take the toy carrier and R&P.
2: Fit toy centre to RR housing requires drilling RR to Toy bolt patern
3: Fit Jacmac hypoid locking centre complete.

All options give you 30 spline axles, lot stronger than RR ones.

Dissadvantages:
the rear is a low pinion.

Advantages.
Strength, the availability of fitting a hi pinion reverse cut centre to front lifting pinion by about 70mm no need to fit D/cardan shafts (reduces angle that the front shaft has to operate at.

The jack mac and the toy centre give you the options of fitting ARB, tractec and jacmac locking centres.

Ratios are many, 3.42,3.54, 3.72, 3.9, 4.1, 4.3, 4.375, 4.56, 4.71, 4.875, 5.28 & 5.71.

Costs are varied.
Complete jacmac set up $2800.00 each end.
Toy cntres aprox $2000.00 inc new axles.
Jac make casting to take toy carrier and R&P $ 400.00 + toy bits and axles.

Front axles about $550.00
Rear axles about $650.00


you can also fit toy cvs to the RR swivell housinng.

Next move is to fit a complete housing from something else.

I believe this to be the strongest set up to fit into a rr housing with out cutting and changing diff centre to something like ford 9 inch.

Michael.

There is another option which is probably best for people who already have a Maxi-drive locker... Which keeps all the maxi-drive components

You can apparently, get a toyota centre, keep the casing and the CW&P, but instead fit the maxi-drive (rover) centre to the toyota casing, just by redrilling the flange on the centre (that the CW&P bolts to) and getting some differently sized bearings. This keeps the entire maxi-drive and keeps the locker working as before, just gives you a toyota CW&P (and diff centre casing).

This sounds like a great option for maxi users.

More info would be good if possible.
Has it been done.

what bearings are required.

Michael.

it doesn't sound to hard to do either which is good .. strange how with mine it is all on the pinion maybe it was heat related in some way .. we were climbing a long steep hill at the time oil ran to back of diff and if it was low on oil no lube ... just a thought .

I was under the impression that the rover diffs break because when u bounce it there is a slight flex in the crown wheel is this true does anyone know for sure why they break CW&P ?

they break because the pinion head diameter is so small.
Michael.

ok pinion head is so small out of the 3 diffs i have shattered ( this one had the least pieces when removed) first two spider gears this one only 5 teeth off the pinon . is it because the teeth don't have enough meat in them ?

The teeth dont have enough meat in them - yes.

But it basically comes down to pinion diameter. The rover dif is a normal spiral bevel and the pinion points at the centre line of the axle.

Now at the other end of the spectrum is a worm drive where the pinion sits underneith the crown wheel. In this instance the "pinion" can be very large while still maintaining the desired ratio because is just the pitch of the worm drive that gives the reduction as opposed to the "pinion size"

Now in between these two extremes are the hypoid differentials. Now the lower the pinion is in the differential the more worm drive effect you get and thus the bigger the pinion is. The ford 9in diff has a very low pinion and thus has a very large pinion (which makes it strong). The toy diff isnt as low as the 9in but still gets siginificant strength increases over a spiral bevel setup (rover diff)

Just for comparison a rover diff has 8.5in crown and the crown and pinion is weak in all diff ratios compared to the 24 spline axles. Even at 3.54:1 the crown and pinion strength are a bit marginal

A toy diff is only 8in crown diameter but is reasonably stonge with 30 spline allow axles up to about 4.88:1. The 5.3:1 (or something) are a bit marginal for strength but nothing like the strength decrease we see with the 4.7:1 rover stuff. A toy 4.3:1 ratio is known as being fairly well bullet proof.

A d44 has a 8.5in crown wheel (same dia as rover) and these things are still strong into the 5.38s with 30 and 33 spline axles.

Imagine how weak a rover diff would be if it had a 5.38:1 ratio. This just shows the advantage of a hypoid diff over the bevel drive of the rover.

Sam

I had Maxi Drive with MacNamara Hypoid conversion in 4.7. Good apart from 3 CWP in 60,000km. None broke but got real noisy.

HSV Rangie wrote:This sounds like a great option for maxi users.

More info would be good if possible.
Has it been done.

what bearings are required.

Michael.

There has been a post about this on here (or pirate) before - the bearings required are the ones on either side of the centre which locate it in the housing - the bearings are different sizes between toy and rover, so you need to get bearings with toy outer size and rover inner size.

Further to what Sam and others have said.

Torque is a measure of force times radius. For the same torque at the pinion, the smaller pinion must have a greater load imposed on the teeth.