gears/posi

Anonymous · Post by **Anonymous** » Mon Sep 27, 04 6:14 pm

how hard is it to fit different gears in an 8 3/4" axle? & maybe a posi as well??

Alex · Post by **Alex** » Mon Sep 27, 04 6:21 pm

If you get a comlete centre section it is just a bolt out/bolt in deal !

Pete · Post by **Pete** » Mon Sep 27, 04 6:21 pm

Depends on the Centre section type - 741, 742 compared to a 489.

The first 2 are shimmed, the 489 uses a crush washer design tha tis a pain (i.e. needs specialised tools). i think Mancini do a kit to replace the crush washer with a spacer & Shim kit.

Dave-R · Post by **Dave-R** » Mon Sep 27, 04 7:45 pm

I have rebuilt my 489 three times now and have perfected my technique and understanding of the mesh pattern.

Carefull measuring will get you the shim thickness for correct depth of mesh (back of the bearing) first time and a honed out temp bearing that can be just slid on and off makes checking it easy although i now know where I can get the correct bearing puller for that.

The spacer to replace the crush washer on the 489 is a good idea that also allows you to re-assemble the pinion as much as you like if the depth of mesh is not right.

I have not done the other types but they must be the same except for the crush sleeve?

Jeff · Post by **Jeff** » Mon Sep 27, 04 8:16 pm

PLEASE!! I need to see pics of your 66!

Anonymous · Post by **Anonymous** » Mon Sep 27, 04 10:22 pm

look here might help http://moparmusclemagazine.com/howto/15 ... ear_mopar/

Anonymous · Post by **Anonymous** » Wed Sep 29, 04 5:49 pm

Thanks for all the info,how do I i.d. the axle? where abouts are the markings?? all I need know is a lower ratio diff! I have sent you some pictures of my car jeff,this is a brilliant site!!!

Blue · Post by **Blue** » Wed Sep 29, 04 6:10 pm

The casting no. you need is on the left side of the diff near the bottom, it is only the last 3 digits you need, it will be 741, 742 or 489.

Anonymous · Post by **Anonymous** » Wed Sep 29, 04 11:05 pm

thanks blue I`ll check it this week end

db · Post by db » Sun Oct 03, 04 9:03 pm

This thread and Cannonballs ad for various suregrips has prompted me to learn more bout diffs...
The Belvedere has a spool with Strange shafts and i'll need to change to a suregrip, so....
I plan to mainly use it on the road, but more plaything than everyday use, with occasional track time.
I'm intending on a 3-400 bhp smallblock (i'd like more but reality gets in the way...) and the biggest tyres i can wedge under the tubs- Andy Neal had 29x18.5" MT's. I'll need the axle shortening if i ever want to get the wheels out again o'course and i assume i can get heavy duty shafts to pretty much any length?
Can anyone (Dave...!) suggest a good ratio to go for? What would be the best way to go about working out the best axle length/ wheel width/offset combination?
My casing has ladder bar plates, etc, so i think i'd be better off getting it shortened rather than swap it, can anyone recommend someone to do the work?
Would i get the shafts 1st?
How would i tell what condition a suregrip was in- i take it you have to split it.
Sorry to throw so many questions at you all, i have a lot to learn!

Alex · Post by **Alex** » Sun Oct 03, 04 9:52 pm

Why do you need to shorten the axle?? theygot the wheels in so they will come out again!

Dave-R · Post by **Dave-R** » Mon Oct 04, 04 8:49 am

Alex wrote:theygot the wheels in so they will come out again!

Alex is right. Andy is no fool. He will have allowed for this somehow. Does simply jacking the chassis not allow the wheels to drop enough to get them out?

To decide what gears you want in the axle dowload this microsoft excel thing of mine (I assume you are fitting a torqueflite?)

http://www.challenger440.pwp.blueyonder ... Cchart.xls

Just put your tyre size in on the chart and play around with the axle ratios. I personally like to pick a gear that places peak torque at 75mph.

db · Post by db » Mon Oct 04, 04 10:18 am

Aaay lots o fun thankyou Dave

You're right about Andy knowing his stuff, he kept the wheels and the shorty Dana axle it's wearing in the pic and sold the car with slicks on smaller wheels and a stock width mopar 8 3/4" , canny fella!!!
I'm not sure about the tyres clearing the arches when it's jacked up cos with the coilover setup there aint a heckova lot of travel, i guess at worst it would mean whizzing the bottom shok mount bolts out....
Am i right in saying that the Strange shafts i have will only fit a spool? I believe they're 31 or 33 spline (Moparman can u remember?) and a Suregrip is 28?
I have to admit also that a lot of the reason for a shorter axle is the deeper dish wheel (vanity, oh vanity

) but that wouldn't justify the expense if there was no practical advantage to use as an excuse!

Finally (for now...) What would be a sensible minimum clearance twixt inner fender wall and wheel rim, allowing of course for tyrewall. I'm guessing maybe an inch or so?

Jeff · Post by **Jeff** » Mon Oct 04, 04 10:35 am

Paul... We have the same (similar) body style. I have a much narrowed rear end (oer). To get the wheels off you jack up car very high and take out bolts on the bottom of the ladder bars. slowly drop the axle while supporting thr car body. Then whip off wheels! Easy! Shame you aint got the Dana. Waita min has Hugh still got Mick Paynes axle? That would be perfect, it was out the 66 Coronet braced n narrowed by mr H.

Dave-R · Post by **Dave-R** » Mon Oct 04, 04 10:53 am

PaulThompson wrote:You're right about Andy knowing his stuff, he kept the wheels and the shorty Dana axle it's wearing in the pic and sold the car with slicks on smaller wheels and a stock width mopar 8 3/4" , canny fella!!!

Now that made me laugh.

What would be a sensible minimum clearance twixt inner fender wall and wheel rim, allowing of course for tyrewall. I'm guessing maybe an inch or so?

Depends how well your axle is located and how well the tyre fits the wheel you are using. To be VERY safe an inch is fine. But normally if you can get your fingers in the gap that is enough.