33 replies to this topic

[Heath]

I've swapped axles here and there, swapped centres etc but I have never rebuilt a diff before, so I've got heaps of questions to ask.

I just got my hands on a course spline LH 3.36 rear axle assembly, drum to drum to yoke.

What bearings should I replace? Should I just replace stuff without knowing what the gear in there is like? Or should I inspect them all individually or do some other sort of test? And how difficult is it to replace them? Do the axle bearings need to be pressed on and off? Will these bearings cost a fortune, is it worth replacing the pinion bearings etc.

If I want to change a centre from course spline to fine spline, are the spider gears and the splined area that drives the axles the same component? Like is that one cast piece or two seperate bits? I've never pulled a centre down lol

Any special tools I need? Other advice?

[76lxhatch]

Unless you're expecting it to last a long time (yeah right), don't bother replacing bearings unless they're obviously shot. Check for pitting/wear in the hard facing. Yes you need a press and possibly other equipment to replace them, and it can be costly.

The best way to change from coarse to fine spline is to remove the centre and swap the crownwheel from one to the other. Don't upset the spider gears if they're in good usable condition. The good thing about a Banjo is that the back lash is adjusted with a screw type piece behind each bearing shell which means no mucking around with shims - do you have a workshop manual with the procedure for setting the correct back lash and bearing preload? From memory I believe its 3 slots of preload and the backlash should be around 7 thou. Preferably match it to what the back lash was before disassembly though; if you've already pulled it to bits then perhaps check the tooth markings.

You're not planning on removing any pinions are you? Not worth the hassle if the one you want is in a good carrier.

[Heath]

I do have access to a press but if I need to machine up specific tooling to get the bearings out with the press, then that is a big hassle.

All I've done is pulled the centre out of the housing and had a little look at it.

Why does the crownwheel have to be swapped? This is the only 3.36 ratio centre I have, but I thought I could just swap the other stuff over so that it was fine spline

Yes I have a GM LH workshop manual, and I was planning on trying to get this thing to last

Edited by Heath, 26 February 2010 - 11:46 AM.

[Heath]

Ohhhhh I think I get what you mean. When you say remove the crownwheel you mean remove the whole crowheel * differential assy. and swap it over from one carrier to the other or something.

I would have named all these part differently!

[76lxhatch]

I have that hassle all the time with naming bits - yes keep the crownwheel but swap to the fine spline centre (which means removing the assembly, swapping the crownwheel and re-setting backlash and bearing preload upon reinstallation)

[Heath]

Maybe when i come up to Toranafest? Postage would kinda kill the fun in that but it may be good to grab it as a spare. Cheers

[Heath]

It did seem very perculiar to see you as the last poster in a thread where I was asking for advice, good thing I didn't expect it to be anything remotely helpful or I may have been disappointed!

lol anyway excuse my ignorance - what have I done wrong now to make you complain again?

[Heath]

Righto good thing not everyone has the same willingness to assist my learning as Darren or I may have been in strife!

I took the centre over to rodomo today and pulled it apart in-front of him, he gave me some good tips about things to look out, some analysis and things to do to make it easier to set it up when I put it back together. And now I know I'm up for a set of bearings & a seal for the pinion anyway Thanks again

[TerrA LX]

One thing you have not learned about banjo diffs yet but some things are only learned from experience.

[FastEHHolden]

The first thing i learned about banjos...is dont play with them.

The second thing is they are a good diff...if you don't shock them.

If you ask me centres for these things are too cheap...you can pick up good centres for as little as $30....but not when you have busted one and need one....thats when they all seem to be $70-80...which is still cheap when you are stranded.

[rodomo]

Bathursts were won with banjos.

[MRLXSS]

Bathursts were won with banjos.

Weren't Bathurst's and championships lost because of banjos?

Edited by MRLXSS, 01 March 2010 - 08:07 AM.

[mr5000]

if ya gonna get a new set of beaings and seals go to bearing wholesales they did me a kit for mine for like 80 bucks i think came with a real nice rubber sealthat hasnt leaked at all since i got it

[Heath]

Thanks Ryan that's what I wanted to hear mate! Any other notes? Have part numbers or anything I should know when ordering? Cheers

Edited by Heath, 01 March 2010 - 04:25 PM.

[TerrA LX]

The second thing is they are a good diff...if you don't shock them.

I second that.

I have been told by a local Torana enthusiast who has quite a record with Banjos, that they are a fairly decent diff, if you dont drop your clutch much or jerk them in any way.

But feeding the power in is perfectly acceptable. haha

Cough bs cough.

Bathursts were won with banjos.

They had detroit lockers, I would run one again if i could get one, at a price which would make a BW look expensive.

[FastEHHolden]

Sounds like you are a diff thrasher hehe

I've never broken a centre...I've worn a few out (one from oil loss, another from a bad setup) and I've snapped 1 axle. If you drive "normal" they last forever.

I know they aren't super heavy duty...but its not like they are made of glass

How many have you broken?

Edited by FastEHHolden, 02 March 2010 - 07:46 AM.

[TerrA LX]

7, broken everything at one time or another accept the crown and pinion.
Each time was with a stock 253 and stock trimatic.

[76lxhatch]

7, broken everything at one time or another accept the crown and pinion.

My best effort took several teeth off both the crownwheel and pinion, twisted an axle, smashed both bearing caps, gouged out the back of the housing and split the bottom of it open... I may have been doing something silly at the time...

[FastEHHolden]

I'll have to drag out the old trade books...I'm sure I was taught to set crownwheel preload first and then calculate pinion height.

Edited by FastEHHolden, 03 March 2010 - 07:50 PM.

[76lxhatch]

I have learned that the pinion gears should be shimmed up to provide ALMOST no lash. I would like to know if this is correct or not? <-Anyone know for sure?

Sounds right to me, you need some lash or the gears are effectively locked together but this doesn't need to be much, and finer tolerances mean less impact from shock loadings you were talking about. This applies only to saving the spider gears of course (edit: which is what I assumed you meant when you said pinion gears, not the actual pinion)

Edited by 76lxhatch, 04 March 2010 - 06:18 AM.