14 replies to this topic

[Liam S]

Hi all,

I have a Borgwarner M86 LSD out of a Crewman, I’ll be using for the Torana, my questions are;

- running 17x10’s on rear will I get away with shortening to 1400mm face to face, and retaining shock mount position, or am I better off moving the bottom shock mount position?

- does any company sell bracketry for LH-LX Torana to Suit B/W? A lot seem to stock 9” only, and the B/W are smaller tube?

- Retain existing LSD, or install a Harrop Truetrac suited for 30 Spline axles and have axles recut to suit?

Thanks all.
Liam


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[LJ RB30]

Brackets,

https://www.mcdonald...ement-bracketry

basically who ever is cutting your diff down will make them fit.

 

As for the bottom shock mount its usually best to move inwards to give you the most tyre clearance.

 

Stock LSD's in good condition are fine is you don't do skids, circlework, racing of any kind or have some grunt..................

 

So personally an upgrade in the beginning will save issues later, but cost is always a factor.

[Liam S]

Brackets,
https://www.mcdonald...ement-bracketry
basically who ever is cutting your diff down will make them fit.

As for the bottom shock mount its usually best to move inwards to give you the most tyre clearance.

Stock LSD's in good condition are fine is you don't do skids, circlework, racing of any kind or have some grunt..................

So personally an upgrade in the beginning will save issues later, but cost is always a factor.

Hey mate,

Thanks for the advice, I agree, I’d prefer to throw the Harrop Truetrac in straight up and this cements it.

As for the moving of the shock mounts, I presume there is a min/max amount I can move them in, would you happen to have those available?

Thanks for all the advice, appreciated.


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[LJ RB30]

Hi Liam,

My car being an LJ will be obviously different to yours but i have a BW75 in mine that i have moved the lower shock mount to on top of the lower trailing arm mount to give clearance for 15 x 7's. 

Initially i had clearance with road tyres but then moved up to wider circuit tyres & slicks, still on 7's, & i had rubbing issues so i moved the lower shock mounts in as far as i could without remaking the top mount ie only adjusted top mount with a hammer to not add side loading of the shock.

[bat 53]

crewman diffs had bearing problems 

just saying 

[rodomo]

crewman diffs had bearing problems 

just saying 

Must have been a factory set up issue? I bought my Crewman with 104k on it and it had been overhauled. Another 120k on it now and not a problem. LSD in mine.

[Liam S]

Interesting, doing a bit more reading into this they seem to be evident pretty early on in the piece. Mine has 150,000km on it and it’s not noisey at all, to the point of me noticing anyway.


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[RoyalPlum76SS]

Hi Liam, how far have you gotten with the M86 diff build?

I am doing an M86 into LX also and have only just seen your post so might be a little late with info but here goes...

 

IMO 'RodTech' in Adelaide do the best bracketry, it is very OEM looking.

 

My diff is to be shortened to 1400mm also. My wheels have 4.75' backspace with fairly flush tyre profile i.e. not bulging out much. I mocked up my wheels with a bare standard housing (axles, brakes etc removed) but with a correct size spacer to emulate the diff being 1400mm in length. I fitted my old Koni shocks and then measured the minimum distance between shock and tyre, which was 12mm.

If your b/s is the same as mine and you think you want a tad more room, you can easily have the bottom bracket moved inboard by 10mm, without effecting anything too much (I think I will do this) Any less b/s than mine will of course give you more clearance straight up.

 

When selecting a new centre and/or new axles, make sure the spline pressure angles are matched accordingly. The 30 spline crewman M86 axles have a 30 degree pressure angle (60deg included) whereas the Ford M86's have a 45 degree pressure angle (90deg included) My KAAZ centre has 30deg angle but not sure what the Harrop centre is machined at, so best to check with them.

 

Re the bearing problems, lots of Crewman diffs (majority were M80's) had bearing issues right from the get go. As far as I have been made aware, a lot of it was attributed to very poor cleanliness at the manufacturing stage. They could not keep up with demand at the time, so were assembled and shipped out the door often without fully removing metal contaminants like swarf etc

 

Who is doing the fabrication/conversion for you?

 

 

[Liam S]

Hi Liam, how far have you gotten with the M86 diff build?
I am doing an M86 into LX also and have only just seen your post so might be a little late with info but here goes...

IMO 'RodTech' in Adelaide do the best bracketry, it is very OEM looking.

My diff is to be shortened to 1400mm also. My wheels have 4.75' backspace with fairly flush tyre profile i.e. not bulging out much. I mocked up my wheels with a bare standard housing (axles, brakes etc removed) but with a correct size spacer to emulate the diff being 1400mm in length. I fitted my old Koni shocks and then measured the minimum distance between shock and tyre, which was 12mm.
If your b/s is the same as mine and you think you want a tad more room, you can easily have the bottom bracket moved inboard by 10mm, without effecting anything too much (I think I will do this) Any less b/s than mine will of course give you more clearance straight up.

When selecting a new centre and/or new axles, make sure the spline pressure angles are matched accordingly. The 30 spline crewman M86 axles have a 30 degree pressure angle (60deg included) whereas the Ford M86's have a 45 degree pressure angle (90deg included) My KAAZ centre has 30deg angle but not sure what the Harrop centre is machined at, so best to check with them.

Re the bearing problems, lots of Crewman diffs (majority were M80's) had bearing issues right from the get go. As far as I have been made aware, a lot of it was attributed to very poor cleanliness at the manufacturing stage. They could not keep up with demand at the time, so were assembled and shipped out the door often without fully removing metal contaminants like swarf etc

Who is doing the fabrication/conversion for you?

Hey mate,

Fantastic info there. I grabbed some brackets from McDonal Bros Racing and Southern Differentials in Childers QLD are doing the conversion. He is an extremely knowledgeable bloke so will discuss those extra points you made to him.

Plan is still to move the shock mounts inboard a further 10-15mm for wheel clearance (going 5” backspace).

Thanks for tips mate will let you know how they go.


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[WhaleOilBeefHooked]

Sorry I don’t mean to hijack your post, But as I’m no longer going ahead with the conversion then I’ll be selling my Borg Warner M86 diff, Was from a good friends XR8 ute with 78000 klms on it and only ever used on a farm, He stoopidly went up the side of a hill / tight slope at wrong angle and rolled it which crushed the cabin, Ute was a write off, He was lucky to have walked away… I’ve had it at a reputable diff shop as was planning on converting to my LJ, All that’s done to it is they electric hacksawed the axle ends from housing and sandblasted it, Removed and inspected the LSD centre… Majority of conversions requires generic billet axle ends anyway…I was informed its got 30 spline axles, Dana 3:23 LSD and 60 degree pressure angles, Was told these are the strongest of M86’s, And also it’s in fantastic condition for a second hand differential… Highly unlikely it even hit 80 klmph as never registered nor been on public roads all it’s life… Comes with fraud discs, axles, handbrake cables and everything except the original axle ends… Please message me if interested…

[RoyalPlum76SS]

Liam

I also meant to add that if you are wanting to change to a 1350 size uni flange on the M86 then you might find it difficult to source many options. For a while I could only find one online, which was a 'Speedmaster', available direct via the US or also sold through a dodgy speed shop in Sydney, whom my diff shop owner wasn't keen on dealing with.

Anyways after many phone calls I ended up chatting to Hardy Spicer who said they don't actually have listings for cars to look up, but they do have a large pdf file of all the uni joint flanges they sell, which can be used to reference the critical sizing/spline count etc of the flange required.

After much reading, low and behold, hidden in the depths of the file info was an exact match with a simple "suit Commodore and Falcon" as a side note.

So if you are wanting to get rid of the ugly 'cage' type flange, here is the part number for the Hardy Spicer 1350 uni flange for M86...

 

3-4-6211-2

It was around $180 through H/S at Darra (Brisbane)

 

Andrew,

Thanks mate but I have 2 of them already!

BTW being a Ford version of the M86 the axle splines would be at a 45 degree pressure angle (90 included angle) as opposed to the Holden version which is 30deg (60deg included) The 45deg is suppose to be the best angle for ultimate spline strength, but you'd need a hell of a lot of HP and Torque to test the point of failure of either.

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[TempesT]

Questions lads,

How are your chosen diff builders shortening them? Cut the tube and reweld, drill the plug welds to the housing and cut/press back in or weld new axle end on?

Have a m86 in the shed and was looking at this today.

[WhaleOilBeefHooked]

Most I spoke to in Sydney that actually had a jig to handle it were cutting axle ends and replacing with generic billet, Then because I wanted torana p.c.d. They were recommending new billet axles as shortening, respline & change of stud pattern all weakened the originals… This wouldn’t be necessary if you wanna run fraud rims…

[TempesT]

Thanks for the quick response! Can you flick me a pm with some of the Sydney shops you had spoken with? My 86 is out of a crewman and was most likely going to end up with commo stud on the fronts.

[RoyalPlum76SS]

Thanks for the quick response! Can you flick me a pm with some of the Sydney shops you had spoken with? My 86 is out of a crewman and was most likely going to end up with commo stud on the fronts.

Diff Technics or Craft diffs are the 2 I have been dealing with.

Both have done them before and are well versed in proper procedure for welding diff bracketry to cast steel i.e. pre heating before welding etc and both quoted almost exactly the same amounts for what I require of them.

 

Food for thought...IDK your intentions for wheel look, but Commodore stud can be limiting for old school style deeper dish rim choice i.e commy rims, in general, had a lot more positive offset.