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October 17, 2026, 04:35:49 AM

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[winton]

Hay all
I picked up bw 411's today from a pintara with offset to suit lsd center (it came off a LSD as far as I'm aware the offsets are different , I haven't compared it to the 411 open Wheeler gears I'm running ATM), and after some knowledge from any one out there  that has.used a spool with 28 spline axles and used LSD to.
Currently I am running 411's with 25 spline and killing axle very easily, how reliable are 28 spline with a spool?
or since IV now got 411's to suit LSD would I be better off fitting a LSD center?  
I plan to use this diff for 200 to 400 meter fun  

Cheers guys.,Winton

[BigNorm]

lsd by a long shot. in theory they have a bit of give and will slip before the axle breaks. spools are good if u dont wanna turn and also enjoy the late saturday night broken axle swap routine.

u ever had 4.11's before? i put them in for about 1 week. i hated them. i had em in black betty and traffic lights  being manual with 17" rear wheels i was in second gear before the back wheels hit the white line. i'd be in overdrive by 60.

[winton]

Gday norm
Yeh got 411's in it now, using a auto box, I like them carnt get good traction but. Good tiers should fix that , and I like the wheel spin
(Added in my post that I'm currently using 411's, befour I seen u had made  ur post .ur not going crazy ;-) )

[Bucster]

LSD for me, i hated the noise thw diff and tyres were making just geting outta the driveway, i am sure that spools are still illegal for street cars.
Cops pick up pretty quickly when your trying to park in tight spots, car parks etc,

 :drive:

Bucster

[winton]

I don't mind that the car doesn't do tight turns so well, it mainly come down to reliability and cost, if I upgrade to 28 spline axles (r31 & falcon axle)  and keep the spool setup I'm guna have to have the axles redrilled every time I need to replace them at a cost of $50 for the axles and then another $150 to redrill them,  but I'm not sure how long the 28 spline  will last with a spool.
If i go LSD the axles should b fine but I'm stuck with a Borg Warner center, I'm not sure how reliable the bw lsds are. I will be rebuilding it with new parts when I put the lsd together ( if I go that way)
All the cars IV had with the bw lsds didnt work all that good.but they had high K's on them

Oh and yeh the spools are illegal. I once  took a defected car over the pits with the spool still fitted and the inspector didn't notice it was fitted lol :pcman:

[BigNorm]

there is a tf in qld running a lsd with billet axles and with bw centre which runs low 11's all day.

[Undefeated]

The cortina has the 0575 diff and a 0575 or 0578 (78 series btr) centre is the same.

The 78 series/0578 will have 28 spline. The 28 spline axles are also thicker than the 25 so i doubt you could snap them unless pumping huge power.

The 250 corty has the big ring 2.77 gearset, if you put other gears onto its centre it wont mesh with the pinion as its ofset. You will need the 0575/0578 centre thats not ofset.

If going 0578/78 series gears the housing will need machining out as the pinions different  from a 0575. The 0578 also has a crush bearing that cant be reused.

Basicly the tollerances are very good in the centres and as long as you retain the spacers on the side of the centre and reuse them in there respective sides it should be close if not spot on with the new centre.

The pinion crown wheel mesh is also ok as long as you go for a 0575 gear set as that dosnt change given the corty has a 0575 housing.

So get a 0578 lsd, use 0575 gears, and reuse the spacers from the housing you have to set it right.


I found all this out when getting 3:55 gears into my 2:77 housing, the centre is to offset to just put the smaller gears on it and wont mesh, a 25spline lsd centre allows it all come together (but if going 28 spline axles a 0578 centre is ok )

So now i also want 28 spline ( for my turbo motor) and have a 0578/78 btr LSD 28 spline centre so will sort some axles, (reuse my current spacers putting them back into there respective sides) and some AU axles or equivlant in the correct length.

Also another part thats good and gives more reliability is the new style covers that pre load the bearing caps that stops the axles bouncing around a bit and stiffens the housing a little over the tin hat.

A 0578 lsd 28 spline diff is all you should ever need on the street, guy up the rd from me has 575rwhp in his commy with a std 78btr and std lsd, it twins up no worries.

The confusion by many is that the std commie btr diff has "high Performance" written on the tag, but those are not lsd diffs! There single pegger 28 spline. This had led to a bunch of commodore guys and others daying there lsd dont work, but they never had a lsd to begin with. Lol


The propper 0578/78 btr says LSD High Performance.


It dont matter but as you wont use 0578 gears, but you can use the lsd centre in your 0575 housing to get you set up for 28 spline axles.

Other options are a KAAZ 2 way or a true trac centre.

[fmd]

What model Cortina are you running this rear end in?. If it's a TC or TD, save yourself the hassle and get a 9" from a ZD Fairlane, they fit without shortening the axles or tubes. That way you can change centres easily. I used to do this and had two centres, a 2.75:1 for long distance driving and a 3.7:1 LSD for town cruising. You'd just need to have the front rotors 5 studded if you're still running original 4 studs. 28 spline axles in a 9" don't break easily.

[Undefeated]

nup
I love the 9" too but its bragging rights only and even then.

You go 9" then theres the triangulated 4 link bracketry that needs setting up, tail shaft, and there heavy.

Its going to cost 2k + to get that in there and it wont be any stronger with 28 spline axles.

The 0578/BTR centre is a 4 pinion centre, the 28 spline, axles are strong. Most important it will handle almost anything thrown at it.
 .

9" is old school but a tuff borge diff is all somebody needs unless trying for low 8s (because theres 8sec cortinas with borgs in them)

Times moved on.

The cost of converting to a basic 9" would pay for a nutts borge diff, 31 spline kaaz ..the full works that would give you something good for 8s

But a std 4 pinion, 28 spline lsd set up is all but unbreakable on a streetcar (they were behind heavy HSV 5.7)  especialy something light as a 1150kg 6cyl (td) cortina, only thing is the std cone lsd (like all lsd ) will wear out over time , but honestly  if its that serious a motor a True track or 2 way kaaz or even just mini spool in the 4 pinion 28 spline btr/ 0578 centre is the answer, no way will that break.


9" is dead. (Unless your blown , tubbed, injected, ladder barred and definatly not driving down a public road ever)

[BigNorm]

i agree. unless u'r producing mega horsepower a 9" is heavy and probably overkill. as i said before with a couple of decent axles a std cortina diff will handle over 300hp. i have 2 cortinas with 9 inch diffs in them, 1 of them is definitely overkill, the other has an alloy carrier and sheetmetal housing to reduce weight but i'm hoping for about 500hp with that one.

[fmd]

Like I said in my other post regarding the 9" diff, I don't believe it's for bragging rights or anything like that. I'm going 9" again on this re-build, why, because I can't get the ratio I want in a BW 7.5, I believe the shortest ratio is 3.5. I don't want to go below 3.7 and I may even go as short as 4.0:1. Another plus for me with the 9" is the big increase in braking afforded by the use of XW Ho'ey drums. These are a lot bigger and wider than the larger station wagon brakes from Cortinas. We run XR wheel cylinders in them to tone them down enough to stop them lockng up, which is what they do when you use the XW wheel cylinders.4.0:1 might sound a bit short for some people, but when you couple it to an overdrive unit such as a Gear Vendors unit, in top gear it converts the final drive to around low 3's.The ability to change diff centres easily and quickly is another plus for the 9" rear end.I fitted a drain and a fill hole to my 9" and with a modified trollley jack, the job of swapping out a centre became a lot easier. Don't get me wqrong though, I still think the BW 7.5 are a good and strong rear end. I started out with one in the car with the 1st build. It was a 2.92:1 with LSD and it never gave any trouble on the street or at the drags, but in the end it all came down to ratio selection and availability.

[xlecortina]

fmd: R31 skylines had 3.7 and 3.89 ratios for the borg warner. Pintara's had 4.11 as well. So if choice of ratios are your biggest reason for a jump to 9 inch, you might still be ok with the borgie

[winton]

Pretty sure 3.7 was the shortest ratio, came in some  4cyl wagons.
 Edit .Cortinas that is , te?
Double edit. Not sure if it was only limited to wagons

[BigNorm]

from memory it was only the 4 cylinder wagons which had 3.7 although i have seen a 3.9 which is now in jman's coupe.......or was

[mk2347tf250]

the 2.77 centre is a stand alone gear set end carrier all other gear sets in solid axle 25 and 28 spline gear sets r interchangeable,some pinion leignths r different but can be shimmed easily enough, 4cyl autos got 3.5 manuals 3.7 wagons and sedans ef falcon onwards lsds r the pick for 28 spline but spools r more predictable / reliable the last of the tfs got rubbish 23 spline shit.