I trashed my third member in my 63 f100. So what should I look for to replace it? The housing and axles look OK, but the punkin is totally shot.

Should I just replace the punkin or the entire rear axle?

What years of trucks (or cars) should I be looking for? I'd really like to keep it to a straight bolt-in/no-mod install.

 

Hi Sam, You don't give us much to chew on, but the center sections bolt in. Pull the axles out a couple in. on both sides and it will unbolt and drop out.

What happened? Be carefull and don't pay to much for a replacment.

John

 

Punkin, spline count and ratio are important. You should know what yours are before you go shopping. Millions of 9 inch rears are out there. I'd look under pickups from 61-72.

 

It was the stock housing with 28 spline axles and the PO had replaced the punkin with 3.50 gears. The original gears were 4.10. I'd like to stick with something more around the 3.50, but right now getting it back on the road is a priority. (I may be doing a frame swap a year or so from now)

Not sure what happened or why, but the end result is a bearing got chewed to bits, alot of teeth are broke or scored, and the lube looks like silver metalflake paint. The first sign of problems was a very violent BANG when I down shifted one day. There had to be a problem before that, but I probably couldn't here it over the whine of snowtires and the cherry bomb exhaust - in other words, my truck is real noisy anyhow.

Any other vehicles I might be able to use? All our junk yards around here only seem to keep trucks back to mid 70's.

 

A lot of early 60s to late 70s mid and full size Ford passenger cars used 9" rear ends.

 

Sam,
light duty F series F100 & F150s thru 79 all have 9" FoMoCo rears. They all were 28 spline unless they weren't "light duty". Like Camper Special, trailer special, Heavy GVW
rated, or had a big V8 and a Long Bed (LWB)etc etc.

ALL 28 spline Center sections will fit all 28 spline FoMoCo axles regardless of year or application. They also all fit in same housing 28 or 31 spline center sections use same gasket. So the reverse of that means that Passenger car rears can be used in Trucks if both had 28 splines. There may be some differences in pinion yokes, but there are all kinds of U-Joints available to make it hook up.

You can spot a 9" from outside a vehicle by looking at center section from the side. If the "hump" in pinion carrier sticks down as low as bottom 2 bolts, holding ctr section in axle housing & you can't get a deep socket straight on to those nuts, it's a 9". If you can, then it's a 8", which looks an awful lot like a 9" to a lay person.

I agree with John, don't pay too much for a used one. Also make sure you get all the debris out of your axle housing before you stick a new centersection in there, and I always throw a pint of STP in my rears on general principles. . . . .then I add spec'd MPO or MPGO to top it off.

GOod Luck
FBp

 

Went to a junk yard down on the river that keeps stuff around longer - found a 69,73,77 and 79(?) that the entire axles ($100 for the whole rear axle) were close in dimensions. the 69 is exactly the same. The other three need the spring perches moved and are about 2" wider at the flanges, but have the 2-1/2" brakes. I figure I might just want to replace the entire axle.

Didn't get down and dirty enough to check for gear ratio's - that'll have to be next time.

Any way to know 28 from 31 spline without pulling an axle out?

 

Sam, 72 was the last year of the narrow width. 68-72 have the upgrade larger brakes and offset axle bearings if you are thinking complete swap.

You can just change out the center section, but I think I would buy a whole section for a hundres bucks, just to get the axles & brakes. The 68-72 axles will fit your rear, but you will need to change the backing plate to make the hubs mate up.

John

 

Sam, if the ratio is ok for you, I would buy the 69 axle. Swap in the entire housing. That would give you the brake upgrade. Then sell your original housing, axles, and brakes to some hotrodder building a 48-56 F100. It will bolt-in for them and they get the 9" upgrade! Everybody's happy that way!

 

I'm planning to do a r&r on the housing and all if I can. It just depends if it's ALL in useable condition after I get it home. The 69 had the wheel off, so one brake drum was in the dirt - that concerns me.
Is the track width on a 73-79(?) actually 1-3/4 wider?

Thanks fellas - I really need the input on this.

 

Yeah, 73 and up thru the mid-80's the track width is wider as you noted. It's not just the spring perch spacing.

I wouldn't worry too much about one drum in the dirt. Most of the internals including the drums can be found at your local parts store if they're rusted too bad.

 

If the housing is OK you mite think about redoing the 3rd menber with new gears and bearings, that way you are not buying more problems from the bone yard. Had mine done for about $250. I put in new axkle bearings when I put the 3rd menber back in.

 

If you change out just the center section, make sure you have a way to put the grease in when you are done. The fill plug on the older 3rd members was on the housing itself, and not on the 3rd member. We will not get into how I came across this bit of info.............................

 

my current housing has the filler plug and I just bought full axle out of a 69 f100. May be a few days before I can get it - the junk yard can't get to the truck with a fork until the ground drys out a little. When I get it, gonna crack it open and see what I got. $100.

As for salvaging my old third member, even the carrier is heavily scored. There just isn't anything reusable except the yolk. I'm not even sure the splines on the axles are good.