I wanna make a change to the rear end on my truck but right now money is an issue. I just looked up prices on a 9" Ford rear end and its ridiculous. Is there any changes that I can make or have done to the stock rear end to make the truck do better on the highway as far as speed? Any suggestions will be greatly appreciated.

 

I bought a 1960 9 inch out of a junked truck for $100.It bolts right in and works great.I did put 3-70 gears in it after a time.

 

online prices of 9 inch rear ends will be high. i would look here in the tech info and find what year fords came with 9 inch in the width you are comfortable with and hit the junk yards. you might get lucky and find one with a tag that has a 3.00 (or similar) tag for good highway speeds. things i would keep in mind when searching yards is if the housing is leaking could be a bad sign. also if it is off the ground it would be easier to inspect. also consider the explorer 8.8 with disc

 

A question for me that may help us both....do 28 and 31 spline gears interchange?I have seen Lincoln rears with as high as 2.21s....

 

Remember, if you go with an explorer rear end, the bolt pattern is different, so you couldn't use your current rims.

 

Hey OKC,
We put a 2001 Explorer 8.8 in our truck. The bolt pattern matches up with the after market Mustang II IFS we put up front. We paid $125 at a salvage yard - giving us 3.73 gears, limited slip diff., & rear disc brakes.

It does require some adjustment out back - we had to move the shock mounts. The other thing is you have to use Wheel Spacers to get them to line up right with your truck. The Explorer is about an inch or two narrower than stock.

(The axles don't look like much at the salvage yard but they clean up fine).

Ben in Austin
1950 F1

 

If you mean the ring and pinion themselves, yes, they are the same. But you can't pop a 28-spline axle into a 31-spline pumpkin without changing the side gears inside the pumpkin.

Are you sure the Linc rear end wasn't a 2.71? That was pretty common, but I can't imagine what use a 2.21 would be.

 

It could've been 2.71,It was quite a while ago I had a 69 Lincoln.I thought 2.21 sounded right though.It really floated,seemed to have endless top end.Thanks for answering my gear question.What does a person change in a 31 spline posi to use 28 spline gears?I have never had one apart am also curious.I have a 81ish truck posi complete I would like use the center but every thing else I have is small bearing 28 stuff.
Thanks Dave

 

Why not change the axles to match the centersection? Axle companies like Strange will make you a set of street axles in any spline, length, bearing and bolt pattern for a reasonable price.

 

Good info,I didn't know that.

 

Changing spider gears (side gears), assuming there are 28-spline versions available that work with the posi, requires complete disassembly of the carrier assembly. Spider gears are much cheaper than new axles. Here's a good discussion of things to look for: 9" ford posi info on spotting one ?? - THE H.A.M.B.

You might pay attention in particular to this post: THE H.A.M.B. - View Single Post - 9" ford posi info on spotting one ??

 

To my knowledge, a 2.47 is the highest gear ratio for 9-inch. 2.50 was fairly common also. GM had some taller ratios, and I think the smaller Ford rearends like the 7.5 (?) had taller ratios. Look under mid-late 70's cars for the tall gears, before OD trans became popular.

As for the question on the rearend, 57-66(?) are the right width. Just get one from a junkyard, not a new built 9-inch. Most 9-inch are 28 spline unless out of a newer truck or high perf car. 28 spline is plenty for almost any street car, your tires will break loose before the axle has any problems. Yes, 31 spline is better and a bit stronger, but I think the older trucks for donor are all 28 spline.

 

Wow good stuff!!Everything but how to rebuild it....

 

Don't know much about rear-ends. Would it be normal to reach 75+ MPH on a stock 54 rear end?

 

I could be wrong here but for some reason I am sure a 69 lincoln I had came with a 2.21 in a 31 spline.edit...I just reread my old post but it of read 2.21.