Rear end

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Big.J.007 said:
'96 and later Chrysler Corporate rear 8.25 10 bolt changed from 27 spline to 29 spline. The Ring and pinion stayed the same throughout the years into the 2000s... There is a carrier break though.. if you have 2.45s the higher ratio gears will not bolt up to that carrier. look for 96 and older for guts. 3.21 or 3.55s should serve nicely.
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So if say it is 2.45 , you said higher ratio gears will not bolt up but if I get the gears (3.21 or 3.55) out of a 96 or older they should fit?
 
33IMP said:
The mustang rear could probably be used, as is. The explorer rear uses a long axle and a short one, and needs to be narrowed (probably cheaper than a mustang). You don't mess with flanges, you take a section out of thelong axle side, and use another short axle.
You would probably have to shorten your driveshaft and adapt for a ford size u-joint. Also, of course, remove the four link stuff off the mustang, and add new leaf spring pads. Explorer still uses leafs, but the pads will still have to be moved.
Unless you feel you NEED more beef, getting your 8 1/4 squared away is a better idea. Im gonna use an 8.8 explorer under my 57 chevy sedan delivery with a 454, in place of the plastic stocker. (NOT really plastic, but you get my meaning).
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Beefing up the 8.25 seems like it would be the easiest as in not doing to much cutting an modifications?
 
504DusterIR said:
So if say it is 2.45 , you said higher ratio gears will not bolt up but if I get the gears (3.21 or 3.55) out of a 96 or older they should fit?
Click to expand...
2.45 Ratio uses it's own carrier.. No larger numerical gears bolt up.. You would need both carrier, and ring and pinion if it's open 2.45.
 
Be careful checking the rear end like rumblefish described. Because sometimes, an open differential will get enough gear oil resistance that it will turn both wheels the same direction. The way I do it is, raise the rear end, put it in park or in a grea if it's a manual and try to turn the rear wheels. If they will not turn either way, you have a sure grip. Of course it's possible the cones or clutches could be worn slap out and it acts like an open diff and turns the other tire the opposite direction, but that's pretty rare.
 
504DusterIR said:
Beefing up the 8.25 seems like it would be the easiest as in not doing to much cutting an modifications?
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Absodanglutely. The 8.25 is plenty strong. No need to upgrade it. Just change it to a sure grip or locker as desired.
 
If you want a suregrip, assuming it's open now, you would have to change the carrier anyway, whether it's a one-off 2.45, or any other ratio. And then add the gear ratio of your choice.
Like said above, it could be a completely wasted sure grip (known to have happened), but it's highly unlikely.
 
Almost forgot. If you have an open, but a ratio you can live with, you could get a power Trax lock right to put in your open carrier. You wouldn't even have to mess with pulling the carrier out.
If you don't like the ratio you have, a new suregrip and gearset is the way to go.
 
the higher the engine goes, the less oxygen there is to oxidize the fuel, and so the engine loses power.
If your 318 pumps 140psi at 100ft elevation, which is not uncommon; then by 4000ft, it will be down to 120psi, and by 8000ft, down to 100psi.
But it's the exact same engine.
Plus, the higher it goes the richer the carburation gets...... which also kills power.
At 4000 ft elevation, the Scr would need to be bumped up to 9/1 from 8/1 just to get the 140psi pressure back, then the carb would need to be rejetted and the ignition timing might also be different.
From 100ft to 8000ft, the Scr would need to climb up to nearly 10/1 again just to maintain the paltry 140psi.


That's why I started asking people for elevations, if I can't get your address from the avatar., for which I can then go to the internet.

This is also why if a guy says he's gonna hop his 318 up to operate at 5000 ft; I tell him to forget about it, just get a bigger engine. You can't hardly get enough Compression ratio at sea-level and by 5000, you better just supercharge it.

Here is an example
stick a 340 cam into an 8/1, 318.
Right away, at sealevel the pressure drops from 140 to 122psi. So it's already a dog on the bottom end.
Now take it to 5000 and the pressure has dropped to 97psi, that thing is a dog from bottom to top.
To get the pressure back to 140, would take an Scr of 10.2, and
and to get it up to 160 where it needs to be, would take 11.2.

Now, how are you gonna get a 318 up to 11.2 ?
Well firstly, throw away the 72plus cc heads. then throw away the 8/1 pistons.
To get to 11.2 Scr, with 3.94 pistons, would require a total cylinder volume of , less than or equal to 64.9cc.
So, the pistons have to be up at the deck, the Quench is gonna be tight, the gasket to use for 11.2/1 is the FelPro 039s the pistons need eyebrows now for the 340 cam, and the heads have to be closed chambers.
Can it be done? sure, but at what cost!
Just get a bigger engine.
The higher the elevation gets, the bigger the problem gets to be.

You said your engine was soft on the bottom. the short answer is; That's because it ain't getting enough air, and/or, it ain't compressing it enough.
Pressure makes heat, makes Power.
No pressure= no power.
Sure you can band-aid the situation with a higher stall and bigger gears....... but the engine is still soft.
Sure you can make it quicker in FIRST gear with a higher stall, and gears. But in Second with a TF transmission, the typical street convertor is no longer a tool. Now the gears come into play. But when you get into Third, and start winding it up, now it's on the engine. That soft engine is now huffing and puffing and wheezing itself half to death, cuz it's, um, soft. and if you put too much gear in it, maybe your lifters pump up and maybe they drive the valves down into the pistons, and yur heads are done.

Butum, if you just want a lil more go in first Gear, I really like my 2800, lol.
 
504DusterIR said:
Ok what if it's 2.76?
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You might want to think about swapping gears before doing it. 2.76 with a 26" tire gets you 2500-2600 RPM cruise at 70....3.55's, the engine is cranking at 3300-3400 at the same MPH. you could also look for a 998 transmission out of a 5th ave/diplomat. they have a 2.74/1.54/1 1st/2nd/3rd instead of 2.45/1.45/1 they also have a lockup converter. the deeper first gives you the same gear multiplication as a 2.45 1st with a 3.09 rear end....if you plan on taking the car where you'll be cruising on the interstate, 3300 RPM gets real old real fast.
 
Just to get this straight-

The Dakota changed body styles for the 1997 model year.

Are we sure the spline count on the 8 1/4 axles changed the year before that?
 
YY1 said:
Just to get this straight-

The Dakota changed body styles for the 1997 model year.

Are we sure the spline count on the 8 1/4 axles changed the year before that?
Click to expand...
Yes, Body style changes have nothing to do with spline counts.. if we really need to be technical it's 96.5 year change.. so easier to say 96 vs saying look for this month over that.
 
504DusterIR said:
Dang lol
Click to expand...
Just Scody playing mind games with the terminology. Many names used. Each division had its own name for a differential that supplied torque to both wheels.
What you might want to look for is a Dakota 8.25" with disc brakes and the Mopar flavor of a positive traction carrier. If it is a bit wide, the long tube can either be pushed out and shortened to match the short side, or it can have the required amount cut out of the center of the tube. Then purchase a new short axle and have both drilled for the 5 × 4.5 bolt pattern and the discs also. The Dakotas use a lot of 3.55 gears which IMHO is a good street ratio.
Another option would be the Ford 8.8" from a Ranger. 3.55 and 3.73 are common gears there with Traction Loc. If the RPM is a bit high the 3.31 gears would be good and tend to be quiet.
 
33IMP said:
The mustang rear could probably be used, as is. The explorer rear uses a long axle and a short one, and needs to be narrowed (probably cheaper than a mustang). You don't mess with flanges, you take a section out of thelong axle side, and use another short axle.
You would probably have to shorten your driveshaft and adapt for a ford size u-joint. Also, of course, remove the four link stuff off the mustang, and add new leaf spring pads. Explorer still uses leafs, but the pads will still have to be moved.
Unless you feel you NEED more beef, getting your 8 1/4 squared away is a better idea. Im gonna use an 8.8 explorer under my 57 chevy sedan delivery with a 454, in place of the plastic stocker. (NOT really plastic, but you get my meaning).
Click to expand...
The Exploders came with 31 spline axles. The Mustangs generally had 28 spline.
Rangers with the 4 noise maker probably had a 7.25" and 28 spline axles. With the 4.0 V6 they probably have a 8.8" with 28 spline axles. Rangers are narrower than the Exploder and Mustang.
 
Big.J.007 said:
2.45 Ratio uses it's own carrier.. No larger numerical gears bolt up.. You would need both carrier, and ring and pinion if it's open 2.45.
Click to expand...
To fit the higher ratio (smaller number) gears, the flange on the carrier is moved over a bit. This gives room for the larger diameter pinion gear required. The ring gears are also machined specifically for the application, so they do not interchange. I suppose you could make a spacer to use the lower gears with the carrier, but you would have to know the exact thickness required and the bolts could be a problem. For the precise machining required, better to purchase the required carrier.
 
Pull your cover and evaluate what you have before you start spending $'s on something you may not need.
 
harvenator said:
Pull your cover and evaluate what you have before you start spending $'s on something you may not need.
Click to expand...
I have yet to pull the cover off ,I have got some much good information so far to go Forward with
 
The pics make it look like an 8¼"... no bolt count yet?

It could be a Sure Grip (Posi is a GM term as I recall), but it could be suffering from worn out cones. These can be restored by someone who knows what they're doing with some machining.

You really couldn't tell that there was only one wheel spinning on your 'research only' takeoffs?
 
My "Research-only takeoffs" Spin Both Wheels with an Open-Rear! Why the hell is that?


both.jpg
 
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