Mopar Muscle Association UK

What tool do I need to undo the drain plug on the (presumably) 7 1/4 rear axle of my South African Barracuda? Scrabbling around on the floor with various bolts, it looks as if it might need a 1/2" or 7/16" Allen key and my set only goes up to 3/8"!! (I've leaked some oil from the housing so I need to check the level of oil.)

I am assuming that I have a USA rear axle rather than an Aussie Valiant rear axle but I don't know for certain as my Plymouth and Aussie Valiant workshop manuals do not give equivalent data for the respective axles. If there is a difference, can anybody tell me what to look for? (Submit pictures, perhaps?). I don't have any tags attached to the housing but there is a casting number. However, I'd need to scrape a lot of paint off to read it.

Thanks for your help in advance.

I'd find a long bolt with a head that fits the hole nicely,then bend the bolt at 90 deg and use it as the key.

aussie axle has borg warner cast into the nose either side of the "crossing paths" borgwarner logo just before the pinion seal
and has a cover plate on the back of the axle held on with 9 bolts
with a filler bolt in the cover.

Mopar 7 1/4 is not the same as the borg warner M78

M78 is 7 3/4 axle and in LSD form is really quite good. standard open form they are likely to die if you do daft things

although i believe all small Mopar axles used a borgwarner design for their LSD units.
i doubt very much but shims and bolts could be swapped between the two

the cone centre is a borg warner thing i believe.

whole design now made by spiceraxle

http://www.spiceraxle.com.au/products.htm#beam


either is eminently suitable for a slanter or 273 or 318 v8 in standard form and driven like a normal person would drive

both can be rebuilt

if you need info on who sells bits for the m78 let me know.
most bits can be got from US and AUS.

you car could have either.

both are salisbury style axles. i.e. have a cover plate and the guts come out the back in bits

they are not banjo axles where the full center complete and undisturbed can be pulled out the front once the axles are out.
which makes the manhandling when rebuilding a bit more fun

Mopar only did 1 banjo and that's the 8 3/4.

aussie axle uses Aussie brakes but a full brake of the correct size swaps over

Dave

aussie axle M78 used in aussie cars and probably SA cars from 67 or 68

VE era aussie valiants

they used the 7 1/4 before that.

M78 came in 2.77:1 (360 v8 cars only) 2.92:1 3.23:1 3.5:1 ratios if you are doing a bit of tail shaft /wheel spinning to ID

later came others up to 5.1:1 but thats mid 90s stuff for pickup trucks that live at the bottom of very deep holes

Dave

there a pic of the US 7 1/4 on this thread

http://www.moparuk.com/forums/viewtopic.php?t=71

Thanks for the quick replies, guys! I've just been down to check, I see now, it's definitely a USA axle. I'll try the bent bolt idea out.

I don't think you'll find a bolt to fit because from memory that plug has a square section centre. Will a 3/8ths or 1/2 inch ratchet fit directly into it with no socket attached ?

I've just had a closer look at the drain plug with an inspection lamp. It's not a hexagonal recess but looks more like a torq recess. I've taken these photos which hopefully will show what I mean. If this is a torq recess, where do I get a tool to fit?

I suppose I could I alternatively just undo the peripheral bolts, remove the diff cover and get the plug out by screwing it out from the inside but it's a lot of hassle.

I'm wondering about my loss of rear axle fluid and if the unit is being pressurised somehow. I've never seen the axle off the car but I'd like to know about the covered vent. I've poked a wire up and it's just doubled over. Is there a slot in the axle housing below this vent cover that allows the breathing effect or is it a small circular hole? You can't see anything underneath the vent cover as it's so small and I'm wondering if it's blocked inside (or maybe no hole has been punched through if there was a bad day at the Chrysler factory!)

Any ideas, guys?

Yes. It is plain to see what that is. It has had something hammered in and is now buggered.

You need to weld a nut to it. That should sort it.