Axel Wheel Bolt Pattern Change Needed

[66FordLover]

I have a 66 Ford Truck and want to change the rear axel's from a 5 on 5.5 pattern to a 5 on 4.5 pattern. Any ideas on how to find the correct crossover axels?
I am also considering changing the ring and pinion and could use advice on gear ratios. I converted my truck to a 302 with an automatic behind it some time ago and have now put a mustang II IFS under the front. I am going to lower the back end and bought new wheels to put on with the 4.5 pattern that came with the IFS kit.
With the original Gears I can only do 55-60 mph without the motor rpm becoming excessive. I am going to pull the axel code but do not have that information yet. I do know it is a single speed rear axel as listed on your site.
Any information would be appreciated!

[71PA_Highboy]

What axle do you have?

The easiest way is to call someone like Currie and have them send everything you need.... Might as well convert to disk in the rear as you will have to change drums and may have to change backing plates too....

Good luck.

[66FordLover]

From my questions I am obviously a novice at ripping into a rear end.
Let me ask this. If I want to swap gears to a different ratio and put axels in with the proper bolt pattern, how can I find the critical information I will need to accomplish this task? I believe that a 3.5:1 ratio is what I want to try. I have researched many forums and find that axel length is imperative but cannot find lengths for individual axels. Do I have to rip my axels out and measure them or is there a list somewhere of axel lengths for my pickup? I am assuming that if I know the length and the spline number I can find one with the proper bolt pattern. I am not having much luck getting this done though. Any help would be greatly appreciated. BTW, I have already drilled the drums out for the new bolt pattern so the disc conversion will have to wait. Brakes are brand new. Drums are not.

[hazelnut]

Why can't you have the axels redrilled for the bolt patteren you want ?

[71PA_Highboy]

You could also use adapters... Summit sells them.

You have to be careful with rim offset, but you should be able to do it.

[66FordLover]

Can't redrill because there is an access hole right where one of the new stud holes needs to be in the axel. Adapter plates would work (lots of room) but, I have to pull the axels when I put in new ring and pinion. Thought it would be easy to put in new axels and bearings as well as pinion and ring. I would also like all the bolt patterns to be the same. Plus, how else could I learn all this stuff? I have to learn by doing. Hopefully not by destruction!

[flyboy71]

The easiest way is to call someone like Currie and have them send everything you need.... Might as well convert to disk in the rear as you will have to change drums and may have to change backing plates too....

Good luck.

Currie will cut to length, put whatever bolt pattern you want and spline them. I may consider that for mine. I have yet to find anyone near me who will touch an axle for a redrill. Ive called many shops and all of them drop me like a bad habit when I ask them. Liability concerns, inability to properly heat treat them, dont know how, Whats an axle?, etc.

I have a Grand Torino 9" rear I could use also and have the 5x4.5 pattern. Thats another option also.

[1970 Hi-Boy]

I think the F100 from the early 80's, might have the 5 on 4.5 pattern you are seeking. Might be worth looking into.

[66FordLover]

According to this fine gentlemans post @ http://www.ultrastang.com/info1.php
It looks like I could get a set from a 71-73 mustang and it would be the correct length and spline pattern with the 5 on 4.5 bolt pattern. Is this correct?

[flyboy71]

Probably not likely but possible. Nice answer huh? Not all housings had the center section exactly in the center. I know my Gran Torino axles are 28 spline like the truck but they have small bearings and each axle is a different length. The truck axles are equal length.

[trick]

Have you thought about an axle swap? like one from an exploder (explorer). some had v8's in them with discs. Just my two pennys. Trick

[HIO Silver]

Why not just get a pair of spacers that change the bolt pattern?.. Btwn, $100 and $130 a pair if I recall correctly.

[48prerunner]

The f-100s from the 80s do have a 9" with the 4.5 x 5 bolt pattern that is what I have in my truck, but the rear is wider than a bump rear, not a problem for me as i'm running 08 mustang wheels. with the mustang wheels and my crown vic front only a difference of a 1/4 width front and rear. But I had to put spacers up front for wheels to clear calipers think 3/16" or 1/8" idk. The spring perches on the 80s axle also wider so it will not be a bolt in both wider spring and farther apart, I changed so much on my rear spring set up that I cant tell you how much. 80 axle is also 31 spline.

[66FordLover]

Time Flys, I haven't posted on this one for awhile. Unfortunately, procrastination did not make this problem disappear so I am Still thinking about this one. I will be rebuilding the rear end this winter. I may just swap the ring and pinion and replace axel bearings, buy the spacers and call it good. What I would really like is some comprehensive cross reference documentation. Any one know if it exists for the ford 9". I found lots of documentation but no axel length's. Frustrating to say the least. Thanks for all your posts to date! Very helpful!

[70shortwide]

fwiw I had my axles (1975 f100 9") redrilled. the guy at the machine shop just welded up the access holes and drilled the new pattern.