What type of diff is this ?

[71 Bee Man]

G'day guys,

sorry to be a pain, but I blew the diff in my Dodge the other day, and I haven't got a clue what I've actually got. And no, I wasn't being an idiot, just a really long trip, a whine starts which turns into a howl....she's had it.

Anyway, I haven't pulled too many apart, and I'm not sure if it's a Sure Grip or not....can anyone help me out with what I have ?

Thanks,

Peter
Sydney, Australia.

[mikepmcs]

It is the 3rd member of a 8-3/4 with a 3.23 Cone Style Sure Grip.

v/r
Mike

[71 Bee Man]

It is the 3rd member of a 8-3/4 with a 3.23 Cone Style Sure Grip.

v/r
Mike

G'day Mike,

thanks very much. So basically, I do have a Sure Grip, Limited Slip Diff ?

Peter

[mikepmcs]

Yes, you have a sure grip.

Sure Grip is the Chrysler name for a limited slip differential.

Explanation of cone and clutch style, you have the cone style.

http://www.moparts.com/Tech/Archive/axle/13.html

Here is comprehensive set-up info.

http://www.mopar1.us/setuprear.html

v/r
Mike

[BB1]

It aint no cone style. It's a clutch.

[mikepmcs]

Nope pretty sure it's a cone style. Not trying to start any argument at all but I have both styles.

it explains it in the thread i posted above as well.

v/r
Mike

Sure Grip - cone type
In order to "rebuild" it you have to take it apart (which it sounds like it already is), then machine .030 off the face of each cone (the face that meets the case). When you put it back together, just put some .030 shims between the cones and the spider gears. Pretty cheap to do plus it saves you from buying a new sure-grip unit.

you machine the bottom of the cone, so instead of the cone bottoming out in the case, it will ride on the sides again alowing it to have some level of lock up again,

[mikepmcs]

Sure Grip - clutch type
If it's a clutch type sure grip (741/2 casting), there will be "pins" in the hole where the axles go in. I've seen sure grips at swap meets that are missing the pins. They might give you a little hassle finding some but they are avail.

[BB1]

I looked at mine and it looks the same as his, and I know it's a cone style, sooo your right.
Nice info. 

[mikepmcs]

 

v/r
Mike

[Chryco Psycho]

definatly cone style

[71 Bee Man]

v/r
Mike

Thanks everybody....really appreciated.

I hope you can understand that this is the first U.S Mopar I've owned - all my others have been Australian Chargers and they don't have the same gear.

One more thing.......as mine is a 3.23, I was told that if I'm keen on changing the ratio, nows the time to do it. I don't really have a problem with the 3.23, but I guess it'd be nicer to have that initial accelleration of the mark.

Is there another ratio that you guys recommend as a "standard application", or is that what I already have. Some have suggested a 2.92 for highway economy, but I'm trying to strike a good medium. I also don't want the engine revving it's head off at 70 mph.

Finally, Mikepmcs........thanks heaps for the diagrams and links.

Peter
Sydney, Australia

[mikesbbody]

peter, i think you should try some 3.55's i have them in my charger. I drove a 71 rt with 3.23's and mine had alot more pick up but of course the top end would not be like the 3.23's i drove a car with 3.90's it seemed abit much imo

[mikepmcs]

3.55's seem to be the gear of choice.

I have 3.23's myself that I changed out last summer getting rid of my 2.7's.  Still not enough snap for me, so i'll be stuffing 3.91's in there.  I don't care about highway cruising or anything I just want light to light action so for me it's the right combination.

It all depends on your whole package including tire diameter.  What rear tires are your running, that also can have an outcome on the RPM's a little.

You have a 383 4bbl auto correct?  Any mods to the motor or is it stock?

v/r
Mike

[71 Bee Man]

3.55's seem to be the gear of choice.

I have 3.23's myself that I changed out last summer getting rid of my 2.7's.  Still not enough snap for me, so i'll be stuffing 3.91's in there.  I don't care about highway cruising or anything I just want light to light action so for me it's the right combination.

It all depends on your whole package including tire diameter.  What rear tires are your running, that also can have an outcome on the RPM's a little.

You have a 383 4bbl auto correct?  Any mods to the motor or is it stock?

v/r
Mike

God only knows what's been done to my motor in the past.

Truth be known though, it's a very smooth motor. It's actually a 69 block, but it is really nice to drive. Not too lumpy, just has a nice deep throat to it and never gives me trouble.


I've done the wheel diameter thing......
wheel diameter in inches X 3 divided by ratio = mph @ 1000 revs.

At 2,500 revs (highway estimate) my current setup gives around 61 mph with the 3.23.
With a 3.55 that drops to around 55 mph.

Is the difference in accelleration worth it ?

Peter

[mikepmcs]

It is to me.

I'm a bad example though. 

v/r
Mike

[71 Bee Man]

It is to me.

I'm a bad example though. 

v/r
Mike

Thanks Mike,

I'll keep it in mind. I'm taking the centre to a diff specialist tomorrow to have a look at it and see what's gone wrong. Hopefully it's something he has parts for and can get her going again.

Peter

[mikesbbody]

hi peter, to me the difference is worth it i prefer the lower gears over the likes of 3.23's just more pick up, quicker off the line it all comes down to how you drive your car, how your car is set up etc etc i dont do too much highway driving but on the highway the 3.55's are fine. i wouldnt mind trying some 3.9's in my car keep in mind if you are paying someone to make the swap for you everytime you do it its gonna cost you but you can alway swap back to your 3.23's (if they are not damaged)

[71 Bee Man]

hi peter, to me the difference is worth it i prefer the lower gears over the likes of 3.23's just more pick up, quicker off the line it all comes down to how you drive your car, how your car is set up etc etc i dont do too much highway driving but on the highway the 3.55's are fine. i wouldnt mind trying some 3.9's in my car keep in mind if you are paying someone to make the swap for you everytime you do it its gonna cost you but you can alway swap back to your 3.23's (if they are not damaged)

G'day Mike,

well......I'm having a bad day. Apparently my diff guy - after taking a glance at the centre - reckons I need a new Limited Slip centre. See the attached picture. I'm stuffed. I don't know how I'm going to afford this right now.....might have to stay on blocks for a while. All the places I'm checking sell them for around $450, but on top of this I have to pay postage to Australia.

I'll keep looking. Even tried Ebay for a decent used unit. Mind you, this is aside from whatever else needs fixing.

Peter

[mikesbbody]

sorry to hear about that peter! the problem you and i have is living so far away! and its not a light part! if you get really stuck, i have a 8.3/4 sure grip sitting around however 1. i dont know what kind of suregrip it is what i mean by that is its not a 742, or a 489 case and i know the gears are stupid highway 2.9's or something.

[71 Bee Man]

sorry to hear about that peter! the problem you and i have is living so far away! and its not a light part! if you get really stuck, i have a 8.3/4 sure grip sitting around however 1. i dont know what kind of suregrip it is what i mean by that is its not a 742, or a 489 case and i know the gears are stupid highway 2.9's or something.

G'day Mike,

I might actually take you up on that, but at the moment I'm checking with a guy whose in one of the Dodge Clubs down here who may at least be able to help me out with a diff out of a Phoenix. I don't care if it's Sure Grip or not.....I just want to get her mobile again and then worry about sorting out what's wrong with mine.

Those stupid highway gears would probably love it down here. 

Peter.

[71 Bee Man]

sorry to hear about that peter! the problem you and i have is living so far away! and its not a light part! if you get really stuck, i have a 8.3/4 sure grip sitting around however 1. i dont know what kind of suregrip it is what i mean by that is its not a 742, or a 489 case and i know the gears are stupid highway 2.9's or something.

Mike,

I don't suppose you or anyone else can answer this but.........
The Phoenix diff this guy has, has a flange which is 3 1/4 inches wide (where the uni joint bolts on).
The flange on my car is 3 7/8 inches wide.

Is it possible to buy a universal joint which accomodates both sizes ? They have that kind of thing out here for Ford 9 inch diffs with different sizes.

If I can sort this problem out it's a good chance I can get mobile shortly.

Peter

[Pouria]

Hello friends;
As it is the right subject of gears, I decided to ask my question here. I own a 73 Charger with upgraded 340 motor. The output is believed to be around 400+HP at the rear end. The diff is a 8-3/4 with welded housing. how can I identify the ratio? Is it a Sure Grip? If it is not, do you recommend Auburn Gear LSDs for my application? I care about high speed more than initial accelaration because I believe that the motor is powerful enough to move the car fast even with low ratio gears. Which ratio do you suggest for me? I live in Iran, far away from US. I may be able to find stock diff out of other mopars of the same age here, but Chargers are really rare! Which car I can use for this? There are plenty of Coronets and darts mostly with 6Cyl . motor.

Yours - Pouria

[doctorpimp]

Hello friends;
As it is the right subject of gears, I decided to ask my question here. I own a 73 Charger with upgraded 340 motor. The output is believed to be around 400+HP at the rear end. The diff is a 8-3/4 with welded housing. how can I identify the ratio? Is it a Sure Grip? If it is not, do you recommend Auburn Gear LSDs for my application? I care about high speed more than initial accelaration because I believe that the motor is powerful enough to move the car fast even with low ratio gears. Which ratio do you suggest for me? I live in Iran, far away from US. I may be able to find stock diff out of other mopars of the same age here, but Chargers are really rare! Which car I can use for this? There are plenty of Coronets and darts mostly with 6Cyl . motor.

Yours - Pouria

Hi Pouria,
Please go to the main section http://www.dodgecharger.com/forum/index.php/board,16.0.html and repost your question, under a new topic.
We'll try to keep on one subject here for our Aussie mate. 

G'day Peter!
Now I'm not 100 % sure, but I think that you may be able to repair that suregrip by welding the cross pin to the case.
It could be a quick fix, that could see your car back on the road while you scour for a clutch suregrip unit from the US...
Some of the more experienced guys may know for sure - Chryco Psycho, firefighter3931 - don't try it until confirmed 

[mikesbbody]

sorry to hear about that peter! the problem you and i have is living so far away! and its not a light part! if you get really stuck, i have a 8.3/4 sure grip sitting around however 1. i dont know what kind of suregrip it is what i mean by that is its not a 742, or a 489 case and i know the gears are stupid highway 2.9's or something.

Mike,

I don't suppose you or anyone else can answer this but.........
The Phoenix diff this guy has, has a flange which is 3 1/4 inches wide (where the uni joint bolts on).
The flange on my car is 3 7/8 inches wide.

Is it possible to buy a universal joint which accomodates both sizes ? They have that kind of thing out here for Ford 9 inch diffs with different sizes.

If I can sort this problem out it's a good chance I can get mobile shortly.

I dont know fo sure or not peter since my experience with these is limited, but im sure there's someone here that knows but it sounds like you may be mobile sooner than you think! i have 2 spare 8/3.4's the suregrip i mentioned and a open 489 case both have (imo) useless highway gears lol! the suregrip is not a 741, 742, or 489 i have no idea where it came from i would like to know have thought about posting to possibly find out.

[71 Bee Man]

FIXED........

for the time being at least. Today I had the option of installng a 741 centre and having to have a spare tailshaft shortened to accomodate the different size flange...

OR

tightening up the pinion nut (which I noticed was pretty loose on removal) and seeing how she went.

Well.......I tightened the nut, filled her with oil, and she runs like a dream. Mind you, I still have to get a new Sure Grip centre because mines not real healthy, but money doesn't permit that at the moment anyway. Basically I'm just happy if this temporary fix can buy me some time till I can afford to get the whole diff sorted out.

Many, many thanks for all the advice.....I've learnt a lot about diffs wheich I never knew before now.

Peter
Sydney, Australia.

[mikesbbody]

im glad to hear it worked out the main thing is she's back on the road 

[71 Bee Man]

im glad to hear it worked out the main thing is she's back on the road 

I took her for a fairly good run today - down the freeway - and everything seems good. There is a slight noise, which may be new tires, but it's nothing I'm worried about, let's put it that way. At least it buys me some time to get the parts I need to redo the diff.

Peter