84 replies to this topic

[rodomo]

Keyed thing? Do you mean the funny nut on the input shaft? Multigrips should do it.
Having said that, that G/box is a dinosaur and might be worth something?
I'd be going later box with a dynamic front seal if the car is nothing spesh?
The input shaft you have is not a positive seal.

[S pack]

Keyed thingy is the 3/4 selector hub on the front end of the mainshaft.

Agree a pair of large multi grips on the edge of the slinger nut flange should be enough to undo it from the input shaft.

[sibhs]

What to look fors here:
http://www.gmh-toran...-or-bust/page-5

Great info there, thanks for writing that, helps make sense as to how it works.

 

 

If you want to go M21 ratio you will need to get a 497 V8 cluster, a 492 third gear, and an XU1 input shaft.

Alternatively XU1 ratio cluster and XU1 input shaft. Aforementioned parts are available as reproductions.

 

In either case you will also need to get an oil seal type front cover.

So what stopped oil coming out the front of my box??? or did they leak like a sieve?

I'll check my spare box, see if that got the seal.

[sibhs]

Keyed thing? Do you mean the funny nut on the input shaft? Multigrips should do it.
Having said that, that G/box is a dinosaur and might be worth something?
I'd be going later box with a dynamic front seal if the car is nothing spesh?
The input shaft you have is not a positive seal.

Keyed thingy is 3/4 selector as Dave said.  Multi grips I'll try for input shaft slinger nut, turning the opposite way.

[76lxhatch]

I would expect the hose would be ok for refit but not to remove old shaft, seeing my shaft is stuffed I will cut it down to size. Cheers

Correct, but you only need a short drift to remove it. A solid shaft is better if you have one

[RallyRed]

Hi Marty,,...I don't know about these boxes. However, I believe Yel327 is all over them like a rash. He could advise whats what, '
and whats reqd for any mods.

Edited by RallyRed, 14 August 2014 - 08:49 PM.

[sibhs]

Got that pesky 3/4th syncro set off. Studied it under the magnifier and no sign of burrs. Decided force was required. Used my modified puller which has thin grabbers. Just gave it a little pressure and it released.

[N/A-PWR]

Good Job Marty,

 

ah, yes, worn in it's ways over the years,

 

just needed to get into the unworn position then.

[sibhs]

Next is to press the main bearing and adapter off. All parts cleaned and sitting in old oven trays.

[N/A-PWR]

Just for interest Marty,

 

I placed all parts in a row, on a white rag, as they came off,

 

and then take a photo for reassembly information.

 

 

Is because, all jobs are usually something different to what we normally do.

[sibhs]

Dragged my spare box to the bench and unbolted the housing.

Found the reverse actuator to be in good condition. Front seal type looks the same which is bad.

 

 

 

 

 

Question time: is the m21 a lot better box than m20? I'm talking driving ratios.

 

Can someone put a picture up of the front bit that has the improved seal.

 

Is that the only part required to make it a better seal?

 

Does anyone have a spare?

 

Cheers

 

Marty

Edited by sibhs, 15 August 2014 - 06:40 PM.

[kiwi-lilj]

That one looks familiar. :-)

[sibhs]

That one looks familiar. :-)

Yeah, it might of just paid for itself. :-)

[Ice]

M21 M20 both all aussie shit boxes but they will do the job as long as you dont pay out on them

[S pack]

Personally I prefer the taller 1st, 2nd & 3rd ratios of the XU1 M20 over the std M20.

 

Nothing radically wrong with the slinger type front seal (if you can actually call it a seal). Just don't park the car facing downhill on an extremely steep slope.

 

If you want to go the proper oil seal route you will need to get the later oil seal type input shaft as well as the oil seal type front cover.

[sibhs]

Thanks guys,Learning more about these things every day.

 

Stripped my second box to check gears etc and found some interesting things. This box has a seal types front shaft but the slinger type front cover. 

 

Next this box has a single piece reverse idle gear and the first box a two piece.

 

 

Second box main shaft has the modified coil oil groove as seen here.

 

 

Noticed my three speed box had the seal front cover, so the third box gets dragged to the bench.

 

 

Here is the difference in the front covers.

 

 

 

 

 

Marty

Edited by sibhs, 17 August 2014 - 08:35 PM.

[N/A-PWR]

Good work having different Boxes to Compare Marty.

[rodomo]

The box with the slinger oil seal, 2 piece reverse idler and if it's an early casing? Would be worth a buck or 2.

[sibhs]

So what's valuable about this box if it's what you think? What car could it be from. Which number do I look for? Caseing cast number or the serial looking number stamped. Most gears are stuffed and cluster does have wear inside. Front shaft and fourth seam ok. Thanks Rodomo

[S pack]

Marty, casing cast date and serial number most importantly. The box if all original should be 1971 to late 1973 or early 1974 cast date.

Where the 2 piece reverse idler goes through the rear of the box casing should be a hole not a cut out like the casing for a box with one piece reverse idler.

[MustardGTR]

Not sure if they have sorted overhaul kits out these days, but year ago you were supplied with a input shaft bearing where the retainer clip was much thicker than the original. If you didn't swap it out with the original (thinner clip) you where guaranteed to crack the flange of the front cover when tensioning up the bolts.

I was one of the ones that learnt this lesson the hard way. Definitely worth checking!

 

Second box main shaft has the modified coil oil groove as seen here.

 

 

The oil groove on the main shaft was common machining modification made to the shaft when the finish in that area had deteriorated/ scoured. I think first gear runs over that area of the shaft and you will find the gear that came with this shaft has been retrofitted with a bronze bush.

It's a good thing to have if someone intends on hammering the little Aussie box.   

 

[sibhs]

Hard to read. Something 112 <br />T362729

[S pack]

Marty, looks like 11L2   11 November 1972. Definitely an early 70's box casing. Worth money to someone who wants period correct cast date gearbox.