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6 Cylinder Saginaw Box


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#1 _boyrex_

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Posted 11 October 2012 - 09:31 PM

Hi all,

Just trying to gather some information regarding a Saginaw that I recently purchased for a new project.
The box has a Holden Bell housing and has the factory rat trap fitted.
It came complete with Indy Hurst Shifter/Linkages/Tail Shaft/ Cross member/ Cross Member mount etc....
This in a hot LJ Torana.
The output shaft has a single grove.
Can anyone tell me what ratios this box may have so that I can select an appropriate rear end ratio to suit.

#2 yel327

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Posted 11 October 2012 - 10:30 PM

Pull the side cover off and get some numbers. And/or count the teeth on 4th gear (input shaft).

However if it has a Holden 6cyl bellhousing on it, it is more than likely a HK-HT commercial 4spd M22 (this box was standard on HK-HG 6cyl ute/van if a 4spd selected). First gear is 2.85:1 on one of these. It was however possible (but very rare) to option an M21 behind a passenger vehicle with 6cyl. These were 2.54:1 1st gear. Note that the M22 was also optional behind 6cyl on some passenger vehicles.

M22: 2.85:1, 2.02:1, 1.35:1, 1:1.
M21: 2.54:1, 1.80:1, 1.44:1, 1:1.

Note that the M21 and M22 designations (and M20 for the Opel box) are unique to Australia. These boxes will have different option codes in the USA, as do other US boxes (eg TH400 is M41 here but M40 in the US). So use the ratios to identify the box if buying bits from the US, not the Aussie option codes.

If you bust the box, just replace it with a Muncie with the standard input and outputs shafts. It'll fit up using all the stuff you have with some minor tweaks. Saginaws are stronger than Aussie 4spds but not incapable of being junked behind a strong red 6.

Edited by yel327, 11 October 2012 - 10:33 PM.


#3 Ice

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Posted 11 October 2012 - 10:52 PM

I have a sag box behind my 202 and have had the engine rev to 6500 to 7000 rpm and it loves it as for ratio for the diff im running 3.55 lsd and so far nothing has gone bang had 3. 08 open my box has the holden bellhousing and the box is out of 69 camaro as comfimed by a forum member

#4 _boyrex_

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Posted 12 October 2012 - 06:41 AM

If I count the number of teeth on the 4th gear, How many would I expect for 2.54 and 2.85.
Also what are numbers on the gear sets to identify difference between M22 and M21?
If it is an M22 what are the gear change characteristics like, I was hoping to use a 3.08 diff ratio with the box.

#5 warrenm

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Posted 12 October 2012 - 08:24 AM

If the Sag has a single groove around the input shaft, it should be a 2.54 1st gear.
0 groove 2.84
1 groove 2.54
2 groove 3.11
3 groove 3.5

#6 _boyrex_

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Posted 12 October 2012 - 10:20 AM

Will a 3.08 diff ratio work well with 2.54 box (If that is what theortically is the ratio of this box)?

#7 76lxhatch

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Posted 12 October 2012 - 10:38 AM

If its out of the car just mark the input and output shafts and do some counting, that will give you all the ratios.

2.54 first with a 3.08 diff is pretty tall for a six but should be OK as long as you don't do a lot of stop start driving

#8 _boyrex_

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Posted 12 October 2012 - 10:41 AM

Can anyone recommend a clutch brand and part number that I can purchase for it.
Are the Aussie 4 clutches the same as for Saginaw?
The car is intended for street and I will be using the original Rat Trap

#9 76lxhatch

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Posted 12 October 2012 - 04:12 PM

It should have the same 10 spline input shaft as the original, Exedy make good clutches

#10 _boyrex_

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Posted 13 October 2012 - 06:02 PM

Hi, does anyone have any photos of Saginaw installed in a LC/LJ.
Photos and description of modifications to transmission tunnel would be appreciated.

#11 Ice

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Posted 13 October 2012 - 06:10 PM

i have one but no photos mods to the tunnel will all depend on the shifter you use but i had to open mine up a little on the passenger side

#12 yel327

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Posted 13 October 2012 - 06:11 PM

I haven't seen one done, but look at what they do to HK-HG, HQ with the Muncie and LX with the T10 and you'll get a good idea. Clearance issues won't be box related, but shifter and/or linkages.

#13 _boyrex_

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Posted 13 October 2012 - 07:34 PM

The shifter is a Indy Hurst Shifter that sits about 2 inches from the centre of the trans output.
Would I need to use a Monaro saginaw 4 speed tunnel hump or do I just pump out the tunnel?

#14 Ice

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Posted 13 October 2012 - 07:56 PM

I just cut mine a little to clear my shifter just mod your tunnel to suit your shifter not a big job

#15 _boyrex_

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Posted 13 October 2012 - 08:49 PM

DIid you centralise the shifter by adding in a 2" offset plate or did you leave as is?
Also what console did you use?

#16 _boyrex_

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Posted 17 October 2012 - 08:13 PM

Hi ICE,
Do you have a photo of the mod you made to accommodate the shifter.

#17 _boyrex_

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Posted 19 December 2013 - 10:52 AM

Hi All,

 

I have almost completed all the body work on the LJ and now am up to the dummy fit up of the 6 cylinder Saginaw Gearbox with Indy Hurst Shifter.

The shifter is offset and will require massaging the tunnel and possibly opening up the shifter hole.

Does anyone have any photos or suggestions to modify the transmission tunnel to accommodate the shifter and linkages.

Also will there be any clearance issues when I modify tunnel in relation to the standard LJ seats.

 

Better to ask questions first before blindly hacking away !!



#18 Ice

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Posted 19 December 2013 - 11:45 AM

First of all try and fit the box in with the linkages on in the car the box is not the problem its the linkages touch the side of the tunnel so we had to slightly tap out the tunnel only a little so the linkages were free to move without getting jammed all the time as for the shifter mine is a custom one that someone built and it has a step in it to get it closer to the centre of the tunnel but you still have to cut the hole a little to acccomadate the shifter
as for console im just using a speco rubber boot

Pm me your mobile number if you like and i can send you some pics of my box and shifter set up as its out of the car atm
cheers gene.

Oh and no problems with the seats at all

#19 76lxhatch

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Posted 19 December 2013 - 01:49 PM

You can modify the shifter and linkages instead of the tunnel
IMAG0311_zpsc5ebf186.jpg




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