Making a MaxiDrive fit where it shouldn't

[stirlsilver]

Ok,
So I have a complete maxidrive assembly with 4.7:1 gear ratios, now the problem I have is that I am intending to fit it to a Series 3 stage 1 which has 3.5:1 ratios. Now normally this isn't a problem when you have open diffs as it all fits together, however since the MaxiDrive is a larger diff centre i've run into problems where the diff is fouling against the side of the carrier.

I'm looking to remove some material off the side of the carrier, ring gear mounting flange and the back of the ring gear itself to allow the whole thing to fit. However, before doing so, I was wondering if anyone has done anything like this, where have they removed material from and by how much? Obviously a pretty obsqure question and I am aware that it will weaken the assembly, however it should be ok as it is a single cab ute with 31" tyres.

Any advice would be greatly appreciated!!
Stirling

[isuzurover]

What is fouling on what exactly???

AFAIK MD rover carriers are ALL 3.54 type carriers. To fit a 4.7 crownwheel, you need to fit a spacer to the ring gear flange. To swap back, you just need to remove the flange spacer when refitting the 3.54 ring gear.

[rovercare]

^^^^^x2

You haven't left the spacer on have you, their really isn't enough meat to machine the flange on the maxi unit, only enough to correct runout:)

Got a pic and I'm sure myself or Ben will spot the error;)

[stirlsilver]

Thanks for the replies guys. This is one of the old maxidrives made back in 85. There was no spacer behind the 4.7 ring gear. So when i fit the 3.5 gear on it sits at the 4.7 offset which is why i'm looking into machining some parts. Will get a photo to post when i get home.

[stirlsilver]

Ok,
I took a close look at the maxidrive today and I can't see any spacer on the flange. When I go to mount it into the carrier, the conical material just behind the bearing shown in the first diagram fouls against the carrier preventing the whole thing from fitting together. There is a little bit of a shadow on the ring gear flange about half way but I just think that's from machining and not an actual flange... is it?? We took a couple of taps at it with a hammer but it didn't separate. See what you think guys. Any help or suggestions would be great!

https://www.aulro.com/afvb/images/imported/2007/07/397.jpg

https://www.aulro.com/afvb/images/imported/2007/07/398.jpg

[rovercare]

What's the thickness of the flange? and how much do you think you'll need to machine off it?, it looks like its got more meat on the flange than most of seen, although it could be the pic:o

The crown wheel, being hardened will need to be ground, not really machinable, with just a lathe...need a grinder......bench grinder:twisted:

It look as though they've left the "spacer" on the carrier when its been machined, if you get my drift;) a non-removable spacer:p

[isuzurover]

I agree with rovercare's comments on the flange. Looks like Mal made some early 4.7:1 specific hemispheres.

Whatever you do DO NOT machine the ring-gear. You will have a non-standard ring gear and you will have to machine another if you ever break your existing one.

I would give Mal a call, he is usually more than happy to help, and can tell you everything you want to know about your locker. It may be possible for you to buy half the casing from him - rather than machine what you have.

[stirlsilver]

I just measured the flange, it's 13mm so if I need to perhaps I can get enough out of that to make it fit together, however the bolts are recessed into the flange so hmm....I was comparing my original diff centre with the maxi and it seems like the flanges are offset by around 5mm or so (didn't take a measurement).

I have already called up the guys at maxi and they pretty well told me that there is nothing I can use and recommended a new kit at $2100 :o, no thanks. Mind you, I didn't speak to mal specifically about it. The bearings are also different sizes on this diff as well, the one on the locking dog side has a larger bearing which means I'm going to need to get my carrier milled to get it to fit. That will be first so I can determine how much material needs to be removed.

isuzurover, I think I could live with the ring gear being non standard, I picked up a complete banjo assembly with 3.5 gears in it for $80, mind you it is a little noisy (just fitted it today) but I could get its ring gear ground also to ensure I have a spare should I break my good one.

It's a pitty about the flange, I was pretty hopefull there was an easy way out!!

[rovercare]

So how much do you need to machine off it????????

All the maxi's I've installed have different bearings on each side of the carrier and have been milled to suit, all I've installed have been second hand, or fitting 4.1's

Shame your not close by, I would donate a few 3.54 centres for spares to get ground for a few measly beers:D

[stirlsilver]

So how much do you need to machine off it????????

Dunno... I have to sort out my bearing fitment issue first. I tried getting the guys from British Offroad to swap out the pinion from the original carrier (the one from an earlier series landrover) that the maxidrive originally came in. However it wouldn't fit back together with the 3.5 gears. So i've decided to use my original carrier that came with my car and mill the bearing holders to the right size. Who knows it might go together in my carrier?? I doubt it tho since i'm told they are all the same.


Shame your not close by, I would donate a few 3.54 centres for spares to get ground for a few measly beers

Cheers for the thought. However, I really can't imagine breaking a ring gear (touch wood!!) so one spare should do me. I hope!!! :D

[isuzurover]

It's a pitty about the flange, I was pretty hopefull there was an easy way out!!

There is - swap to 4.7's F&R, and fit 0.998:1 high range gears in the t-case!!! :D

If you don't want to do that I still wouldn't machine the ring gear. As Rovercare said, you will need to spin it up on the lathe and use a grinder - you will have a hell of a time machining it evenly, and an even worse time setting up the gear pattern.

Do you have the carrier that the hemisphere was originally fitted to?

I would call and speak to Mal himself. I spoke to him once about turning a very old HD front axle in a mate's rangie (back) into a locker. He told me all the different iterations the lockers had been through, and that parts for all of them were still available.

[isuzurover]

However it wouldn't fit back together with the 3.5 gears. So i've decided to use my original carrier that came with my car and mill the bearing holders to the right size.

Why don't you use the casing the locker came in, to save having to mill a new one? As BOR said, they are the same.

[rovercare]

Can't see why the 3.54 pinion wouldn't fit the 4.7 member, any details why not??

[rovercare]

another problem you'll face is moving the carrier to suit the mesh, as you may run out of room pushing the carrier bearings across :o

[stirlsilver]

isuzu,
going to 4.7's front and rear was suggested to me at british off road, but I don't really see that as an option since I have a salisbury rear diff. Plus tracking down another complete axle assembly is something I would rather not do. Perhaps I don't have to grind the ring gear, and simply machining the flange down by 3-4mm will get me out of the woods.

I could use the original carrier that came with the diff, however the input shaft seal holder is in pretty bad shape, and I'm told that the later carriers are much stronger and better designed then the ones mounted on the original series landies.

rovercare,
The 3.5 pinion fit in the original 4.7 carrier no problem, the bearings just needed to be swapped, however like you said with the bearings, the diff center needed to be so far across that it fouled with the side of the carrier, and there was only about 3 threads left for the bearing caps thats why some material needs to come off somewhere so that I can actually achieve a correct mesh and have the bearings closeish to where they should be.

I'll give mal a call and see what he has to say.

[stirlsilver]

spoke to mal, he told me that the maxi drive I have is a really old one, possibly pre-production and there is no parts available for it. I discussed the options with him and he said while grinding the ring gear or flange isn't good, I should be able to get away with taking off 2mm off both the ring gear and flange.

[isuzurover]

isuzu,
going to 4.7's front and rear was suggested to me at british off road, but I don't really see that as an option since I have a salisbury rear diff. Plus tracking down another complete axle assembly is something I would rather not do. Perhaps I don't have to grind the ring gear, and simply machining the flange down by 3-4mm will get me out of the woods.

I could use the original carrier that came with the diff, however the input shaft seal holder is in pretty bad shape, and I'm told that the later carriers are much stronger and better designed then the ones mounted on the original series landies.


To change the sals to 4.7:1 you just need a centre and a ring and pinion (the ring gear flange is in a different position on the sals too). Contrary to popular opinion, you just need a couple of tyre levers to change centres. But it is probably just as easy to get a complete sals since they are so cheap. I bought one recently drum-drum for $200 in good nick.

Isn't the pinion seal retainer bolt-on? I have never had a problem with the strength of early casings.

[rovercare]

To change the sals to 4.7:1 you just need a centre and a ring and pinion (the ring gear flange is in a different position on the sals too). Contrary to popular opinion, you just need a couple of tyre levers to change centres. But it is probably just as easy to get a complete sals since they are so cheap. I bought one recently drum-drum for $200 in good nick.

Isn't the pinion seal retainer bolt-on? I have never had a problem with the strength of early casings.

Agggh, yea to change the gears, what about setting up the pinion height correctly???? need a little more than a set of levers ;)

[isuzurover]

Agggh, yea to change the gears, what about setting up the pinion height correctly???? need a little more than a set of levers ;)

Yeah, but nothing more than you need to set up a rover ring and pinion diff properly - which will have to be done on the front. Admittedly, the sals is a bit more annoying to set up, as you need to dismantle, add/remove shims, then reassemble every time you don't get it right.

[stirlsilver]

Admittedly, the sals is a bit more annoying to set up, as you need to dismantle, add/remove shims, then reassemble every time you don't get it right.

yuck heh heh :p I'll go with the machining/grinding. See how it goes

[mark2]

Using the 4.7 gears will give you a 68:1 crawl ratio :)

[rovercare]

http://www.mcnamaradiffs.com.au/sixgear1.html

3/16" is your measurement:)

[stirlsilver]

Hi again,
I just thought I would post up the conclusion to all the dramas I had with the MaxiDrive.

I got both the flange and ring gear machined down by 2mm. All fitted together beautifully :). I installed it into the front yesterday and tried it out today. My comments are, yep I can definitely get up much crazier stuff now :D and I NEED POWER STEERING WHEN IT IS ENGAGED!!! My arms are so sore!

[stirlsilver]

Hi again everyone.
Just need an opinion on one thing relating to the maxidrive. It is housed in a series 2A housing which on a 2A has a drive shaft with a universal joint on either end (single cardac).

I have fitted this to my stage one forgetting that the stage one has three universals in the drive shaft (double cardac), so the diff input shaft should actually the same angle as the drive shaft. So i'm now getting some pretty wicked vibration because of the incorrect angles.

What I want to ask is:

Should I shim the diff housing to bring the input shaft from horizontal to match the angle of the drive shaft or fit a RR front drive shaft which I've bought for $30 (See Diagram)?
https://www.aulro.com/afvb/images/imported/2007/11/208.jpg
Thanks all

[rovercare]

If you shim it, you'll lose castor and it'll drive like poo;)

[DaveS3]

I have a single uni shaft on the front of my Stage 1 without any problems

Just replace the uni's with new ones on the new shaft and keep an eye on it.

Cheers
Dave.

[stirlsilver]

If you shim it, you'll lose castor and it'll drive like poo;)
Castor angles are wrong as they are at the moment... That's why the steering is SOOO heavy... The housing had slotted holes for the swivel balls. Gonna have to readjust that.