Diff

[Mylittlepony1966]

What diff upgrades are common for a 66 coupe. Not a fan of the single pegger. Not real sure on the ratio, don't need a 9 inch just after a LSD of some sort.

[AussiePhil]

Hey pony,
Jump on YouTube and watch something like this.
It all depends on your needs.

https://youtu.be/R5v6hXYcEz0

Cheers Phil.

[Mylittlepony1966]

Thanks Phil will do.

[AussiePhil]

Hey Kevin,
I noticed you’re from Townsville, I bet it’s a bit warmer than here in Bathurst at the moment it’s currently 1deg.
Good luck Phil.

[Mylittlepony1966]

Yep, much warmer  mate.

[GLENN 70]

What you want is a true trac centre and depending on what size rims and tyres you may want around a 3.25 ratio .

[derwin66]

I tracked down a lsd centre and put 3.55 in the back of mine.  It works well.

[Mylittlepony1966]

Thanks gents.

[USA066]

As Glenn says, I’m running a 3.25 ratio true trac centre in my 66 with 331ci engine. Fantastic, no pulling to one side when I give it a boot full.

[Mylittlepony1966]

USA66
that pulling to one side gives me the screamers.

[GLENN 70]

What do you guy means by pulling to one side ?

[Mylittlepony1966]

When you feed it & as it changes gears it is a nasty uncomfortable swerve. In my case anyway

[AussiePhil]

Hey Kevin,
I’ve had my car for six years, when I bought it was supposed to have a Currie LSD and Strange axles.
First time I pulled the wheels off the axles had Currie stickers on them, so I suppose it’s got a Strange LSD.
Until I need to do something about it (it’s a big job just to have a look) I’ll just guess it’s a Strange spring clutch LSD.

Cheers Phil.

[GLENN 70]

Does it feel like it wants  to change lanes when you get up it  when it changes gears ?

[AussiePhil]

Hey Glen,
No, definitely not, it’s definitely got some sort of LSD, I’m just guessing what type. Strange have many versions!
The axles are dated 97 and the car was imported in May 2000.
I take it the Fox body engine, transmission, tail shaft (has a Drive Line Services of San Diego sticker on it) 9” housing and differential and four wheel brakes were all fitted in the US.
I’ve lost contact with the previous owner (he is no fool and in the motor industry) and an ex MOCA official.
I’ve just got a printout he sent of the details and modifications.
I think he just mixed up the axle and LSD brands typing out the sheet.

I would say it leaves two black lines, but that would be inappropriate and illegal!

Anyone with torque steer should also checkout sloppy steering!

Cheers Phil.

[AussiePhil]

Does it feel like it wants  to change lanes when you get up it  when it changes gears ?

Hey Glenn,
I see what you’re all saying now about when it changes gears, no she’s a manual transmission.
Is that what everyone is talking about, I was a bit misled, I’ve never had a high powered auto before!
And was thinking what are these guys talking about!

Cheers Phil

[USA066]

Glenn and Phil,
It wasn’t really an issue with the 289, but now that I have a higher powered auto, it was pulling to the right under load. Nothing dangerous or anything like that, but the Truetrac sorted it. Now it drives straight under load, fantastic investment. Mine is still a C4 auto.

[AussiePhil]

Glenn and Phil,
It wasn’t really an issue with the 289, but now that I have a higher powered auto, it was pulling to the right under load. Nothing dangerous or anything like that, but the Truetrac sorted it. Now it drives straight under load, fantastic investment. Mine is still a C4 auto.

Hey Colin,
I noticed you’re in Bunbury WA, you Glen and Kevin in these warm places.
It’s 6 degrees here in Bathurst at the moment.
I suppose if you don’t the cold you can move!
All the best and hope you enjoy your Mustangs.
Cheers Phil.

[GLENN 70]

A common problem when our old mustang get a big power boost is under power they can tend to veer to the right . That’s not the diff or the front end ,it’s the old leaf springs are weak and bend under power . It’s the rear end causing the driving problems ,

[AussiePhil]

A common problem when our old mustang get a big power boost is under power they can tend to veer to the right . That’s not the diff or the front end ,it’s the old leaf springs are weak and bend under power . It’s the rear end causing the driving problems ,

Hey Glen,
I totally agree with you, it’s probably torque boxes or lack of and rusty old bodies flexing also.
Have you ever watched American YouTube how to videos, they’re all rust buckets.
I think Australians have given a lot a second life with love and care!

So that brings up another subject, Unibody Subframe Connectors.

They are so easy to fit, Global West make a totally bolt on one.
I made and fitted the Dazecars design one.

Cheers Phil.

[GLENN 70]

I have subframe connectors on my 70 mach 1 . Depending on the brand some are harder to fit than others . Mine is around 500hp plus so they are a good idea to stop the body twisting .

[AussiePhil]

Hey Kevin,
Have you checked your rear axle housing is straight.
If it’s crabbing that won’t help!
I think a normal wheel alignment they check rear axle housing alignment, even passenger side behind the drivers side a little won’t help, better the other way if it’s steering to the right.
I’ve got a four link rear end so I specifically asked for it the be aligned.

And one last silly question (but it’s got to be asked, don’t be offended) are your rear tyres the same size (width and diameter).

Cheers Phil.

[AussiePhil]

Hey Kevin,
I’ve really been investigating this pull you have.
There is very little on YouTube about rear wheel drive torque steer or pull from a differential.
There is heaps about front wheel drive torque steer.
I think Glen has nailed it unless it’s the obvious I’ve just pointed out, sloppy steering, uneven front wheel alignment (very different camber or caster or you have toe out) axle housing alignment, wheel size or air pressure difference.
I really can’t think of anything else.
It’s got me baffled, but I don’t reckon it’s your diff, but Robbo may be right!
I have been proven wrong many times!
Through a diff in anyhow, it can’t hurt!
Cheers Phil.

[AussiePhil]

Hey all,
All this Differential talk is making me think I should pull my axles and remove the third member and have a look to see exactly what I’ve got.
They reckon that’s the correct way to change the oil anyhow.
I’ve just sucked it out with a Brake bleeder vacuum pump connected to a big glass bottle with two connections on the cap, one to the the vacuum pump and a hose stuck into the bottom of the diff to the other connection that has a hose to the bottom of the bottle in the past, I just keep pumping the vacuum pump every ten minutes or so until there is nothing left, the oil is always clean coming out and is changed regularly.
I’ve all my modifications noted anyhow so it would be nice to know exactly what is in there.
I’m guessing it will be a Strange spring clutch LSD.
Cheers Phil.

[GLENN 70]

Jack the rear of the car up ,put on axle stands . Then turn one wheel ,if both turn the same direction it’s a LSD , if the other one turns the other way it’s an open ,if the other wheel doesn’t turn it’s a true track . Sure there are other diff centres but that’s what most will have .