Technical Question on identifying rear end/leak on Shoebox Ford

Awesome thanks!

 

The seal looks like it might have been replaced recently, eh?

Sometimes rear ends leak past the pinion splines, the nut will be soggy with gear oil. Whenever I install a yoke I smear sealer inside the splines, to prevent this. Later Ford yoke nuts have sealer applied to them, and the nut is a part you replace every time you take it off, both for the sealer, and for the prevailing torque (locknut) feature.

at least that's how I see it.

 

Thanks, for now do you think I should wipe all of that area off and monitor and see if it leaks statically to see if maybe its just because of no breather? I have to take the driveshaft out anyways because I'm fiddling with an issue with the speedo gears on the TH350 trans.

 

Make sure the vent is clear. Clogged up vent will allow pressure to build inside and push fluid past seals

 

Oops, missed that one

 

Hehe, well apparently the previous owner didn't know anything about vent valves or just didn't care... I took on some serious headaches with this shoebox!

 

They generally have a vent/ bolt that holds the break line T in place, something like this

 

Ah, that's why it was removed... with all the suspension mods and brake line re-routing, etc whoever did the work before didn't care about a vent and just plugged it!

 

I took out what I think is the fill plug and I could feel some fluid when I put my pinky in there. It looks like it doesn’t really leak at all statically. I took the plug out where the breather should go and I’ll have to think of something clever since the airbag is so close to it. Im debating changing the pinion seal or not… I bought a new seal and the tool to keep it in place so I can break the bolt free but wonder if the seal is not too old and it just needs a vent…

 

Forgot to respond to this but I think that bolt would interfere with the airbag when the car is “slammed” with air out. I thought about drilling a new hole but there’s so little room to work I’d have to take the rear end out which I definitely want to avoid.

 

Is the pinion nut wet with oil?

Did you check how much torque it takes to get it to turn a little bit?

usually they won't leak until it's being driven, as the oil level is below the level of the seal.

I want to reach through the monitor and knock some of those big chunks of dried grease off the housing

 

Thanks! Yes the pinion nut is wet with oil. I didn't try to torque on it but can tomorrow morning. Oh that makes more sense regarding the leaking not happening until driving. I'm tempted to just go for it and replace it, I went ahead and got the tool, I'm right there with the drive shaft out (doing work to the trans).

I agree... the car is filthy underneath including some small areas of surface rust... my take is the previous owner had fun with this thing in winter time in Canada... I could be wrong but the evidence I've seen underneath tells me otherwise. I plan to clean it all up once I get it all mechanically to my liking and then use rustoleum rusty primer and coat with satin black in some areas including the frame.

 

Forgot to ask you, what sealant should I use for the splines/nut? Is there a particular approach to that? I'm going to just replace the pinion seal since I'm down there and be done with it as well as replace the fluid. I will get all that crusty dirt off soon so its not a complete embarrassment... luckily I will have the car nice and low when parked

 

Either RTV or a thick coat of a non hardening sealer like Permatex Aviation or #2.

 

thanks is black rtv good enough? I have some of that on hand. I think I have the red as well.

 

I don't think the color matters, and black "hides" better.

 

The car is black so it has that going for it! I'm painting or coating anything I do in black to hide all the bad stuff ;-)

 

Just got to this again. I cleaned off all that crazy amount of dirt/grease I had a huge mound of it and I felt like an archeologist chiseling away to reveal the fossil!

I got beaker bar and bought the special tool and marked everything. I overthought it thinking I would meet some resistance with that nut and I attempted to break it free and it’s not that tight. It’s snug but not torqued hard. That seal looks like it may have been replaced but no history for me to count on. Should I loosen counting number of turns and put it back exactly how I found it? I didn’t feel any play in and out so I assume the lash was set well but I was expecting to torque hard to break it free and that wasn’t the case at all! I probably could have held the wheels with my feet or used a screw driver while loosening the nut. I only drove this car once in April after getting this car so I don’t know if the differential had any issues other than the leak I want to fix but it didn’t seem like it. My guess is to set preload just how it was by counting turns.. any advice?

 

So you really want to continue to drive around with the pinion nut loose? and let it back off more, and have the pinion crash into the differential case? Think about that.

What happens is that the bearing and crush sleeve turn slowly on the pinion and the ends wear, so it eventually lets the nut get loose. When you tighten the nut fully, with the old worn sleeve in place, it isn't thick enough to space the bearings apart properly, and the bearing preload is too high.

If you want to do it right, get the axles out and take the center section out and take it apart, and get a new crush sleeve (are they available?) and measure the pinion bearing preload as you tighten the nut and crush the sleeve, stop when it's where it should be. Oh, you can repack or replace the wheel bearings while you're in there. Along with the axle seals. If a crush sleeve is not available, you can make a solid spacer, or you might be able to "uncrush" it, or add a shim, or some other means of getting the bearings spaced properly.

But if you don't want to do all that, you can change the seal and put the yoke back in and tighten the nut tight, and see if it gets a bit harder to turn the pinion. Use an inch pound torque wrench. If it get tight (more than 15 inch pounds additional drag) before you get the nut tightened to over 100 ft lbs torque, you really to need to do something about it...although I guess the old fashioned method is to just keep the nut loose, and stake it in place so it won't get looser.

I expect we'll get some good stories about how it'll last forever with the nut loose, and they're probably true. Have fun...

 

Thanks! So I suspected it’s probably looser than it should be from the wear of the sleeve and bearing. I can’t take the axles out at the moment or at least not the driver side since I’m close to my garage side. I was hoping not to take the axles or pumpkin out or at least not right now and maybe deal with diving deeper at a later time.

For now I’m going to take it apart and change the seal and tighten it to where I can feel the pinion get tighter to turn or stop at 100 ft lb if I’ve reached that point already. If I’m well below 100 ft lbs by staking the nut do you mean drilling a hole and adding a cotter pin? Also I expect to put maybe 300 miles max a year on this car so maybe not necessary to go too deep for that reason too.

 

Staking means to smack the area where the threads of the nut and the pinion meet, with a chisel or punch, to deform the threads enough that it can't turn. The pinion is really hard steel, however.

You can also use loctite, after getting every thing very clean.

 

so last weekend (or maybe the one before that) I replaced the seal, cleaned up the splines and used black rtv and put it back together. I tightened it to 100 ft lbs and measured about 18 inch lbs or so to turn the yoke. I didn’t try going any further I could feel a slight bit more resistance than where the nut was previously with the marks but not much more. I let the rtv dry for 24 hours and filled it with fluid and so far no leaks but I haven’t driven the car.

I forgot to put loctite and was wondering if I should be ok or if I need to drain and loosen the nut and redo. Do you think I’ll be fine with 100 ft lbs not loosening up? I don’t want to pull the axles and deal with the crush sleeve although I’d be willing to maybe another time later in the year or next year. I won’t be on any highways at all.. just backroads and the 101 in San Diego. Hopefully when I drive it next I won’t hear any new noises from the rear end…

 

should be ok, but check it again before you go on a long road trip. If you're not going on any long road trips, don't worry about it.

 

Thanks for all your help! I don’t see myself ever doing any long road trips ever… I stress about everything too much but I’ll enjoy the car locally and the coastal scenic route of north county San Diego.

 

Hmmm....I just went through the rearend on my 62 Vette, in preparation for a 5000ish mile road trip. Ended up needing new ring and pinion (missing part of a tooth on the pinion).

Road trips are where you really get the full experience of owning and driving an old car or truck. Give it a try...

 

Oh I can just imagine a road trip is where you put your car to the test and get the full experience! Life is short but I’m a single guy with a house and animals and a demanding career so it would be hard to deal with mayhem happening on the road far from home. Perhaps some day though I will be able to do that!