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Aussie 4 speed v Muncie, what's the difference?


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#26 yel327

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Posted 26 August 2013 - 09:06 AM

supports nothing ...they stopped making muncie gearboxes in 1974 from 70 to 74 they used muncie fine spline with the turbo 400 output (32 spline) ..
then from then on they used the borg warner super t10s 2nd design,..in all the chev powered cars..
as far your saginaws go there tad stronger than your aussie 4speed...the t10 boxes made during the latel 50s 60s were probaly on par with your saginaws..
i don't need to read posts as i come from a drag racing back ground and have used both muncies and super t10s with great success and no there strengths..
and yes i've stripped as many boxes as i care to talk about and know how they tick and there weakness and strengths are..
personally speaking a saginaw doesn't rate let alone a aussie 4speed..


If you don't read the post then don't comment on the post! I think that's fair.

I'm not disagreeing with anything you have stated, nor are you contradicting anything I have said btw! We both agree Aussie 4spds are a piece of plastic. I agree Saginaws are at best marginal behind a small V8. And I think we both agree that. a 1970's ST10 is stronger than a Saginaw but below the best of the original Muncies. Original GM Engineering documentation will state the torque ratings of their boxes. I'm almost certain it will show that the M22 was no longer required once the high output big blocks were finished in the early 70's. The last of the LS6's was 1971. LS5 was around in 1972 but it was a shadow of the L88/ZL1 and LS6. That is why they started using the Borg Warner box, it was probably an economic decision too, Borg Warner box was probably cheaper than building their own.

#27 76lxhatch

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Posted 26 August 2013 - 09:35 AM

And I think we both agree that. a 1970's ST10 is stronger than a Saginaw but below the best of the original Muncies.

The way I read it, unclefestasl34s disagreed with the latter part of this statement, my understanding is also that the original Super T10 is on par with a Muncie. The gearset is perhaps a little less forgiving than the M22, but I think its generally accepted that the original casing was a little better which makes up for it. The Muncies are known for housing deficiencies (although these generally don't show up without some serious abuse! the exception being leaking oil if too thin a grade is used). Note that if you're comparing the best of the Muncies then the best of the Super T10s had an iron case designed to withstand more abuse.

The wider ratio Super T10s are generally considered inferior in terms of torque handling, but this is more a reflection of simple physics of gear ratios than poor build or design. Muncies never had ratios like this, there are now a couple of options in new boxes but improved materials and processes provide improved torque handling also.

Original GM Engineering documentation will state the torque ratings of their boxes.

From what I've managed to put together this is not so, there is no factory torque rating number, only guesstimates by third parties.

That is why they started using the Borg Warner box, it was probably an economic decision too, Borg Warner box was probably cheaper than building their own.

I don't believe the engine changes were that much of a factor as the Super T10 is/was quite capable, the economics may well have been.

#28 yel327

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Posted 26 August 2013 - 05:03 PM

OK, I get it now.

I have always been of the belief the Muncies were discontinued as the M22 was no longer required for big power/torque engines, thus there was no justification to build the other versions either and economics and future Engineering requirements dictated the Super T10 was good enough. I'll see if I can find again where that came from, I have read it somewhere.

I also just dug out the Petersen clutches and transmissions manual, it talks about the evolution of the GM 4speeds. It talks about the replacement of the original T10 with the Muncie as the Muncie was a stronger box. It isn't where the reference about the deltetion of the Muncie comes from though. It does say though that the T10 didn't change much between 1957 and the 70's except from about 1961 the case changed to alloy, and like the Muncie the ally case is the weak point. It says the longevity of the T10 is testament to its good design

 

 

GM will have Engineering manuals somewhere stating the design limits of these boxes. I've seen them for HT Holden, and the design limits for Saginaw, and the 2 x HT all synchro 3spds are in there. plus the Opel box. If GMH have it so does GM. There should be the same thing around for HQ showing the Muncie (which in HQ is a Pontaic M20) and also the 4 x aussie 4spd varieties. It'd be interesting to see what they put on the V8 M21. We know they are hardly up to the task.

 



#29 76lxhatch

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Posted 26 August 2013 - 08:24 PM

Happy to be proved wrong but I can't imagine any official torque rating numbers; no doubt there will be reports as to whether they are suitable for certain applications. I guess if you have a yes for a certain engine and a no for another you can assume a number in between

#30 yel327

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Posted 27 August 2013 - 08:50 AM

GMH did, i'll see if I can look at it again when I get a chance. It was many years ago I saw it. When I saw it the attention was on the HT V8 3spd and how much higher it was rated than the 6cyl and later V8 versions.

#31 Sir LC

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Posted 12 April 2018 - 11:33 PM

Possibly a silly question...but I'm looking to overhaul the Aussie 4 speed I have and was wondering whether the Muncie gearset / layshaft etc. would fit inside the Aussie casing?

 

Cheers



#32 warrenm

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Posted 13 April 2018 - 06:50 AM

Definitely not. 



#33 myss427

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Posted 13 April 2018 - 08:56 AM

Over 1/4 bigger, everything in a Muncie is bigger stronger.



#34 I'm a Red Motor fiend

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Posted 13 April 2018 - 12:25 PM

How much power are you making and how much money can u spare? If the answer to both is more than enough, just buy a muncie.

#35 ReplicarSLR

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Posted 13 April 2018 - 02:42 PM

This has been said and done dozens of time before, the Aussie 4 speed (Aussie ones) M20 or M21 were ‘upgraded’ and I use that term very very loosly for use behind Aussie V8, from the original 6cyl design, but they, in reality are a small HP, small Torque gearbox good for a stock streeter not driven hard. Run the Munchie or T10 and you wont look back if you have big HP or Big Torque.

#36 Sir LC

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Posted 14 April 2018 - 11:03 AM

I thought that would be the case.

I was originally thinking of upgrading the box to the '200kw aussie 4 speed box' that some do with the larger layshaft etc.

On a side note I've noticed that the xu1 899 cluster doesn't appear to be available new anymore?

At this stage goal is 300hp+ at fly. Will look into the Munice and T10 more.

 

Cheers fella's.



#37 TerrA LX

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Posted 16 April 2018 - 08:02 AM

Possibly a silly question...but I'm looking to overhaul the Aussie 4 speed I have and was wondering whether the Muncie gearset / layshaft etc. would fit inside the Aussie casing?

 

Cheers


basically, an aussie 4 speed is a very poor adaption or an aussie three speed, where they have tried to cram 4 gears in the space of three, if you closely inspect the meshing of the gears you can clearly see this, in this event, the three speed is actually stronger than the 4 speed.
There has been some success with having the whole internals remade, if you are dead set on retaining the aussie box, your brother in law not Peter Holinger is he???



#38 warrenm

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Posted 17 April 2018 - 07:14 AM

Muncie on the right, Aussie on the left, as you can see the difference in the length of the two box's.

Attached File  Muncie Aussie (600 x 337).jpg   55.78K   1 downloads






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