Thread: Ford help

Tweet

Hi, I have a 79 Ford f150. I have a problem with the rear end but don't know much about them. I was having a kind of banging noise so I replaced the u joints and while I was under there noticed the nut that holds the u joint holder was loose so I tightened it and put the u joints in. I still have that banging if I let off the gas and get right back on it. Any help would be appreciated. I believe I have the 9" rear end. My chilton book shows the only match to mine is the 9" but, not sure. Again, any help would be helpful.

When you say...

the nut that holds the u joint holder was loose so I tightened it

do you mean the big nut that holds the yoke on the pinion shaft coming out of the differential - the one in the lower left, centered between the four holes for the u-joint retainers? (ignore the yellow arrows - this picture was to ID a 9" rear)

Ford 9.jpg

If that big nut was loose then you likely have a bad pinion bearing and may well have ruined your ring & pinion gears, too. The "clunk" you're hearing is excessive lash in the ring & pinion spacing.

Yes, thats the one. So, I am going to have to replace the bearing, ring and pinion gear? That pic looks exactly like mine.

If you caught it early it could possibly just be a had pinion bearing. You might try that first, and see if your "clunk" goes away. If you need a shop to mess with it a good off-road/4x4 shop will be doing gear setups all the time, and are generally more reasonable than shops that only do one occasionally. Watch for a guy with a lifted Jeep with big tires and ask him where is goes to get his heavy work done.

I try and do all the work myself, cheaper that way. I am fairly knowledgeable mechanically, not a master but, I like to learn new things. How hard is it to replace the bearing on one of these? And how do I find out which one I need? there are so many different ones out there. Thanks for helping me here.

I was thinking of replacing the seal when I said you might try replacing the bearing. The seal can be done from the front, but you'll have to pull your axles to drop the pumpkin to change pinion bearings - there's a rear bearing by the gear and a front bearing that goes in from the outside. You're talking total disassembly of the differential section, so it makes sense to change all the bearings, and check your gears, too. Here's a blowup picture.

9inblowup.jpg

It's not rocket science, but you've got to get the pre-load right on reassembly with new parts or you can trash a set of gears in short order. If it's the stock rear end you should be able to get the right kit from your local NAPA, or your favorite parts store.

With your tranny in neutral (or drive shaft dropped) how much rotational slop do you feel in the yoke? How about any lateral movement of the yoke, which would be bearing slop? Maybe jack up a wheel and use it as a lever to rock the differential back & forth to see of you find your clunk before dropping the center section out.

OK. Dumb question but, from the picture, wouldn't the pinion gear just slide out if I took the front part out and not take the whole thing apart? Seems like I could undo the 5 bolts holding that part together and the rest would stay in its place. No? Also, I removed the tag from my rear to clean it. I do have the 9" and it says I have 2.75 gear ratio. Is that good? If not, what ratio would I want for speed and acceleration? I don't want to break any land speed records but I like doing burnouts....alot.

OK, I reread your last post. I did twist the yolk and wiggle it, the only play I saw was the nut being loose. There did not seem to be any excessive movement from the shaft. Maybe I did not tighten the nut enough? Almost seemed like the splines on the pinion gear shaft were maybe loose or stripped a little?

save yourself a ton of grief and get a junkyard punkin .. maybe step up to a 3.25 gear .. you should have a 28 spline punkin ..

X2, 3.25 is just about the perfect ratio imho... and it'll be so much faster to find a take-out and swap'em.

Yeah, you're right about the pinion retainer, but Hoss & Mike are on the right track. Getting a salvage yard punkin is the right way. If you see metal in your case & lube it'd be a good idea to flush out the housing good before putting the replacement in place.

Thanks for all the information, been very helpful. I am going to get new ring and pinion from a reputable company and I will give the 3.25 gears a go. Next is the transmission, then the engine.

Not to pee on your campfire but do you have the tools necessary to set up a 9 inch Ford rear axle? The task takes pullers, a press, torque wrenches (more than one size), an indicator with a magnetic base, and a few other possibly specialized tools. Understanding of the principles of the setup are essential also. A Chilton's manual is useful as a door stop, little else. You might inquire locally about the cost of a R&P install with some written guarantee of the task.

I have most of the tools but what exactly is an indicator you are talking about? Is that like a tool for showing angles or..........? I am more then likely going to get the parts then have the local speed shop or someone that deals with these things do it for me. I would like to learn to do this myself though so I wont have to pay someone the next time I have to work on a differential.

To set up a 9" correctly, you need a dial indicator and the fixture to measure the pinion depth, along with the knowledge of how to correctly set the backlash..... Mike is correct in saying that you would be better off to hire someone experienced with setting up gears to get it done right. Years ago I bought a complete set up kit from Speedway, think back then it was $150.00 or so. Along with the new ring and pinion you'll need an install kit (bearings, crush sleeve, etc) to go with it.