23 replies to this topic

[nzxu1]

Probably a simple explanation here , but what's the difference between the 2 clusters available for an M21 gearbox , ie :

the * 497 * cluster and the * 599 * cluster and do they need their own specific input gear for each one ? .

l've removed the toploader gearbox conversion from my L34 and l want to replace it with an M21 , not only for originality but also to fix all the holes that some mongrel has chopped into the tunnel with a very blunt cold chisel to fit the toploader box .

Clusters and inputs are available new , but l want to make SURE that l order the right bits .

Thanks for any help here

[yel327]

There is only 2 x V8 M21 clusters:

2813497 and 9939484.

The first is the standard V8 M21 cluster (2.54:1 1st), the other is the L34 M21 homologation gear set (2.32:1 1st). Both of these were also used in homologated gear ratio sets for LJ XU-1.

These both use a unique input shaft which is noot interchangeable between the two.

There is no xxxx599 cluster in an Aussie 4spd (I think you've just mis-typed 5 instead of 8), but there is a 2823899 M20 cluster which is the standard cluster for an XU-1. These can be put into a V8 M21 box but as they are an M20 cluster you have to use an M20 3rd gear with them. This ends up giving you a V8 box with a ratio set which was also homologated for L34. 1st gear ends up the same as normal M21 but 3rd is 1.25:1. In the end it's exactly like an XU-1 box but with a V8 length input shaft.

Hope this helps.

I listed all the part numbers on my website: http://www.monaropar.../aussie4spd.htm

[nzxu1]

Thanks yel327 , indeed l did make a typo with the 599 instead of an 899 . The info you've given me is just what l was looking for thanks .......great website you have too . l know that new 2.54 clusters and inputs are available new aftermarket but what about the 2.32 ones ? .

Don't mind the thread hijacking at all sable either , we should be all here to help .....though you wouldn't think so looking at what's going on with some other threads on this torana site at the moment .

There is only 2 x V8 M21 clusters:

2813497 and 9939484.

The first is the standard V8 M21 cluster (2.54:1 1st), the other is the L34 M21 homologation gear set (2.32:1 1st). Both of these were also used in homologated gear ratio sets for LJ XU-1.

These both use a unique input shaft which is noot interchangeable between the two.

There is no xxxx599 cluster in an Aussie 4spd (I think you've just mis-typed 5 instead of 8), but there is a 2823899 M20 cluster which is the standard cluster for an XU-1. These can be put into a V8 M21 box but as they are an M20 cluster you have to use an M20 3rd gear with them. This ends up giving you a V8 box with a ratio set which was also homologated for L34. 1st gear ends up the same as normal M21 but 3rd is 1.25:1. In the end it's exactly like an XU-1 box but with a V8 length input shaft.

Hope this helps.

I listed all the part numbers on my website: http://www.monaropar.../aussie4spd.htm

[yel327]

I'll answer the last post first:

I know of no aftermarket source for the 2.32 input shafts or clusters for L34 or XU-1. The 6cyl version of the input shaft never even got a GM-H part number. I've never seen any of the 3 parts in the flesh, and (don't quote me) I think no L34 or XU-1 ever left the factory with one of these boxes (I'd love to know if one did). Curiously though the cluster and V8 input shaft are listed in the LH parts catalogue as L34 but I think that is simply there to demonstrate they were available. I have a few NOS M21 input shafts I bought a while back but as you say clusters and XU-1 input shafts are only aftermarket now.

Sable, not sure of the T. In Chev cast parts they have the plant code on them like T for Tonnawanda, K for McKinnon, F for Flint etc but I doubt that's the meaning of the T. I also doubt it has anything to do with T meaning 308HC as the M21 V8 box was optional on some 253's as well. Dr Terry might have a better idea on this. Note though that the standard XU-1 box is actually an M20 box with a different cluster and input shaft. For some reason Holden sometimes named their M21 box as "heavy duty" box, but the only part that could possibly be any heavier duty than the M20 and M22 was reverse as it has a unique part number for the M21 (yet they look the same and are interchangeable?). As the XU-1 box uses the same reverse gear part number as the regular M20 it cannot be an M21. I also normally refer to the box by it's 3rd gear, and as the XU-1 box uses an M20 3rd gear I call it M20. Although this isn't strictly correct either, it is definitely not an M21 otherwise later XU-1's would have M21 stamped on the BODY tag. The correct name is probably just XU-1 4spd as it was part of the XU-1 option on a GTR. Holden did homologate an M21 for LJ XU-1 use which may well have been a V8 M21 box using the XU-1 input shaft but if you look at the CAMS bulletin on page 192 of Fiv's book it lists the M21 3rd gear but no different reverse gear, although this could easily have been overlooked. I'd also really love to see an original XU-1 with M21 on the BODY plate as this could mean that someone optioned one of the optional ratio sets in it. Anyone seen one?

[yel327]

No worries. Just make sure you get the right input shaft cover for the 544 shaft and an M20 3rd gear. The aftermarket XU-1 inputs are probably a better bet as they have the later neoprene type seal.

If you ever find that info mentioning the M21 option for the XU-1 let me know. I've only ever seen it in Fiv's book on the CAMS documentation.

[yel327]

7439685 suits the early slinger/scroll type oil seal. There were later XU-1 input shafts with neoprene seals on them (part numbers 2825927 and 9930927) which is what the aftermarket ones are copied from. You use 9930909 with either of these.

[yel327]

I'll look into it. It might just be a later revision.

[nzxu1]

l've just been having a look at a copy of the supplementary factory spec sheet for SLR 5000 L34 option printed in july 1974 and it lists the gear ratios as 1st 2.54 , 2nd 1.85 , 3rd 1.38 and 4th 1.0 with reverse @ 2.54 . No mention of an alternative ratio option of 2.32 1st gear .

[yel327]

That's interesting. The gear ratios listed differ from those quoted for the XU-1 (see Fiv's book, page 192 with the amendment on page 196 for 3rd gear). When you work out the formulas given the XU-1 quoted ratios are correct. Does the L34 bulletin list the teeth counts?

[nzxu1]

That's interesting. The gear ratios listed differ from those quoted for the XU-1 (see Fiv's book, page 192 with the amendment on page 196 for 3rd gear). When you work out the formulas given the XU-1 quoted ratios are correct. Does the L34 bulletin list the teeth counts?

Unfortunately no teeth counts are given , just the ratios . It's on a copy of a 9 page bulletin outlining the differences between a standard SLR5000 and an L34 headed " Supplement S/LR 5000 Option L34 "

[yel327]

Notice how they all quote different ratios. The Motor one is correct and the centre CAMS document lists the teeth counts. This is the identical info to what is on the XU-1 CAMS paperwork, which also has 1st gear as 2.32. When you work it out for yourself you get:

2.30:1
1.65:1
1.25:1
1:1

So i'm not sure where the info on the other two comes from?

Notice also that the normal M20 ratio set (3.05:1 1st) is also homologated for the L34. This is probably the only application of M20 ratios behind a 308.

Edited by yel327, 06 April 2009 - 07:24 PM.

[yel327]

Hi yel327,
Was looking at that M20(923Inp/496Clu) I've got in
the shed & its got a Clutch Shaft cover with part number
9930912, its got a neoprene seal in it, but dosnt seem to
be on your list. Its a consectutive part number with the
neoprene covers on your list but can you tell me anything
about it?

I couldn't find it in any parts book. Might just be one of those pesky casting numbers.

[nzxu1]

l already have several old M20 boxes and was hoping to use the bits from these to convert to a V8 M21 . l have a brand new 497 cluster already and was hoping to be able to get away with buying just a new 9930924 V8 input gear to do the conversion , but from the info provided it would seem that l will also need to find a 2813492 3rd speed gear and a 2813500 1st speed reverse gear also to complete the conversion .

[yel327]

l already have several old M20 boxes and was hoping to use the bits from these to convert to a V8 M21 . l have a brand new 497 cluster already and was hoping to be able to get away with buying just a new 9930924 V8 input gear to do the conversion , but from the info provided it would seem that l will also need to find a 2813492 3rd speed gear and a 2813500 1st speed reverse gear also to complete the conversion .

I reckon you only need the 3rd gear. I cannot see any physical difference between M20/M22 and M21 reverse gear although they are different part numbers. M21 3rd gears aren't all that expensive and don't really wear out either. You could always hold onto the M21 cluster and buy one of the new repro XU-1 clusters along with a new V8 M21 input shaft. Then you can use the whole M20 box and fit the XU-1 cluster and M21 input shaft. Only ratio difference is a taller 3rd gear.