489 case

Anonymous · Post by **Anonymous** » Mon Aug 21, 06 2:17 pm

Not sure if this helps but I am awaiting a set of 3.23's from Wil to go in my 72 Dart's 489 case instead of the 4:11's I currently have. I have a build sheet that specifies that's what I'm running but until we open it up we are not 100% sure. The car currently does about 60mph at 3000 revs which sounds about right for the ratio.

Dave-R · Post by **Dave-R** » Mon Aug 21, 06 2:40 pm

Yorkie wrote:I'm wanting a suregrip for the Coronet and looked at the numbers on the diff case thats in at the moment and it's a 489 which I understand is the stronger case.

Correct. It is the strongest unit but all the 8.75" axles are pretty strong.

Is it better to buy a new posi unit and gears and have it built up rather than pot luck with a second hand unit.Or is the cost too much,looking at 4:10 gears.

A new ring and pinion is about $200.

A limited slip unit (clutch type sure grip) is about $400

The other bits needed to rebuild a diff such as bearings, shims etc would be about $100.

To rebuild the diff yourself following the clear instructions in the workshop manual would cost about a days work. The only hard bit is measuring and adding up.

I showed Trev Young how to do this a few months ago and he agreed he could have done it himself if he had known how.

The cheap option would be to buy or swap a complete used diff but the chances of finding a complete unit to your specification are remote.

It sounds like you and Autoholic could do some sort of deal though?

Kev · Post by **Kev** » Mon Aug 21, 06 4:22 pm

And fit an aftermarket spacer shim rather than the standard pants crush sleeve.

(Only on 489, 742 uses a shim spacer)

Pete · Post by **Pete** » Mon Aug 21, 06 5:24 pm

What gears do you have at the moment Yorkie?

Anonymous · Post by **Anonymous** » Mon Aug 21, 06 10:05 pm

Yes I believe it is

RobTwin · Post by **RobTwin** » Mon Aug 21, 06 11:02 pm

Our Satellite has 3.91's and also runs at 60mph/3000rpm, so yours maybe more like 3.91 than 4.10 Steve

Maybe....

Anonymous · Post by **Anonymous** » Tue Aug 22, 06 12:22 am

Buy it all new,at least you know it won't fail (funds permitting),they take a lot of stick & have probably taken it.False economy is for fools.

& before anyone ribs me for that,I said FUNDS PERMITTING.

Dave-R · Post by **Dave-R** » Tue Aug 22, 06 10:24 am

How can you not be sure what gears are in the axle?

It is easy to find out if it has a sure grip or not. Just jack the back of the car up. If you turn one wheel the other will turn in the same direction.

If it has got the sure grip it is even easier to see what gears you have.
Just count how many turns of the propshaft you get for one turn of the wheel.

If it is just over 4 turns you know it has to be a 4.10:1, just under 3.91:1.

Dave-R · Post by **Dave-R** » Tue Aug 22, 06 10:27 am

Adam68 wrote:I said FUNDS PERMITTING.

You can buy a complete diff ready to bolt-in for $1000.

Dave-R · Post by **Dave-R** » Tue Aug 22, 06 11:31 am

RobTwin wrote:Our Satellite has 3.91's and also runs at 60mph/3000rpm, so yours maybe more like 3.91 than 4.10 Steve

Maybe....

Depends on how accurate the speedo and tach are and of course what diameter tyres you have.

TYREMAN · Post by **TYREMAN** » Tue Aug 22, 06 6:26 pm

RobTwin wrote:Our Satellite has 3.91's and also runs at 60mph/3000rpm, so yours maybe more like 3.91 than 4.10 Steve

Maybe....

Thats true mine is at LEAST 3k at 60mph and i have 3.91(on the Duster)

Anonymous · Post by **Anonymous** » Tue Aug 22, 06 7:49 pm

Yorkie wrote:
Dave wrote:
Adam68 wrote:I said FUNDS PERMITTING.
You can buy a complete diff ready to bolt-in for $1000.
Slowley getting tempted towards new

Hurry up about it & get completly tempted.

Mopar Muscle Association UK

489 case

Re: 489 case