66 bronco rearend

bocksta · Feb 24, 2004

I have a friend who has a 9" out of a 66 bronco . He said he thought they were about the same width . The bronco rear is 58" from flange to flange an the 66 stang is about 57.25 flange to flange .Now thats not to bad ,But i have a set of 17" X8 TTIIs with 4.75" backspacing that are still in the box . Will the rims still fit without cutting down the bronco rearend . If this rear has to be cut down is it true that the axles cannot be re-splined. What do you think ? I am told that it is a posi but am unaware what gearing is in it.It may still be worth buying .

1320stang · Feb 24, 2004

Well, you're only talking about 3/8" per side. Rolling the fender lips should take care of that. If it does need to be narrowed, I doubt you'll have to have the axles resplined, just cut a 1/2" off per side and re-bevel the ends with a grinder and clean up the ends of the splines with a small triangular file. When you pull the axles, you'll notice a sort of line where the splines go into the carrier. This is the spline engagement. Typically I've seen about an inch of un-engaged spline sticking out. You can't go all the way up to the ends of the splines as ther is a little movement in and out of the carrier. If you're going to have to narrow, you might take into consideration if you'll change the drums out for discs in the future. Sometimes the disc setups are a little wider than the drums, just take that into consideration. Just narrowing the housing using your old ends will run you from $75-$150 at a chassis shop that has a jig.

96 DOHC Cobra · Feb 24, 2004

The width is close to the Mustang's, but it'll still needa lot of work to make it useable under your car. The Bronco's leaf spring perches are on top of the housing. The Mustang has them underneath. The Bronco also has the 5 X 5.5" bolt circle (like pickups). The Mustang is a 5 X 4.5" circle.

1320stang · Feb 25, 2004

96 DOHC Cobra said:
The width is close to the Mustang's, but it'll still needa lot of work to make it useable under your car. The Bronco's leaf spring perches are on top of the housing. The Mustang has them underneath. The Bronco also has the 5 X 5.5" bolt circle (like pickups). The Mustang is a 5 X 4.5" circle.

Huh, I thought the early broncos had the 4.5" bolt circle. I know that the '80 - whenever they stopped making them F-100's had the 4.5" bolt pattern whereas the F-150 had the 5.5". I'm not sure about the 70's F-100's, but having never owned an early bronco, I didn't know. The pattern can be redrilled, but you'd also have to worry about the size of the hub the wheel has to fit over. Might be better just to order a set of aftermarket axles. Are the early broncos 28 or 31 spline?

SandSprite · Feb 25, 2004

i think my 9" might be out or a bronco. it has good gears (3.70) and is a trac-lock. the tag was still on it, and it measures about 58" drum face to drum face. Pretty sure the pattern is 4.5 x 5. I think it's a small bearing housing too. it's 28 spline. I think Larry is right that the smaller "truck" vehicles (bronco and f-100) got the smaller 9" rears with small bearings, 28 spline, and 4.5" on 5-- not positive on that though.

edit: yea, i need to get the spring perches installed in the right places for a classic mustang. hopefully that won't cost too much.....

bocksta · Feb 25, 2004

I still have to go and look at it an check .I dont think it would cost to much to have the perches installed. www.kevinstang.com/ninecase.html and www.mustangsandmore.com/ubb/fordreardimensions.html is a good source for 9" ford info i found it yesterday .Gives rear dimensions an what cars to find them in .Also gives axle types for the rearends .

D.Hearne · Feb 25, 2004

As far as I've seen the only pickups that had the 4.5 inch bolt pattern were the 80-85 or so, F100's. All the earlier F100's and Bronco's I've ever seen had the 5 X 5.5 bolt pattern.

bocksta · Feb 26, 2004

66 -77 broncos have a 5-on 5 1/2 " diameter bolt circle ,i wonder if i could use my 8" axels and drums on this .Anyone know?

D.Hearne · Feb 26, 2004

You can as long as the axles are the right length , the bearings fit the axle ends,and your drums are the right size. And the spline count is correct for the differential.

SandSprite · Feb 26, 2004

bocksta said:
66 -77 broncos have a 5-on 5 1/2 " diameter bolt circle ,i wonder if i could use my 8" axels and drums on this .Anyone know?

if the bronco rear is small bearing and 28 spline, it should work as long as the splines engauge enough. compare the axles length and note the distance between the bearing and the axle "face" (where the drum/wheel sit). the extra 3/4" (you said the bronco is 58", the mustang is 57.25") may be there. or measure the housings flange to flange and compare.

you will have to use you old brakes or get different drums (or possibly drill the bronco drums).

67coupestang · Feb 27, 2004

All broncs were 5x5.5. 66 would for sure be a small bearing. one thing worth mentioning is although the total width is good, the bronco has a slightly off center pumpkin...

latamud · Oct 1, 2004

Well, I guess this is kinda late but I used a 66 Bronco rear end. I had to get the bolt pattern redrilled, and the drums, remove the shock mounts and weld on new spring perches, it was a PITA. Versailles was a much easier swap. But the bronco rear did come with 4.11 detroit locker so that was a plus.

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