Diff leaking around the bolts
 

We've just returned from our National Model A rally. Over 1500 miles and the car didn't miss a beat. Averaging about 80 kph (50 mph) on the open road, it returned 23 mpg (that's about 18.5 to the US gallon, I think) Not disappointed about that but now that I'm home, I have a job to do on it.
I'm guessing that the guy who restored the P/U in Manitoba (Canada) didn't know what he was doing when he chased the threads in the diff centre and that left them too loose to seal. Oil leaks around the larger end of the axle housings - so much so that I had to top it up twice during this trip. If there is an easy and a hard way to do a job, I prefer the easy one so this is what I propose doing. I'd like feedback if my plans are unworkable so as to save me turning an easy way into something else.:D
I devised this while driving and I think I have a way of doing this repair without the diff centre coming out of its bearings wich would make reassembly a PITA.

1. Drian the Diff.
2. Jack up the rear of the car and put jack stands under the chassis
3. Dissconnect the brake rods
4. Using a spring spreader, undo the shackles and leave the spring in the U bolts
5. Lower axle assembly and put blocks under the centre and one end
6. Remove the hub from the other end, undo the bolts around the axle housing and slide the axle housing outwards about an inch
7. Clean/repair and seal at the gaskets and around the threads. I thought I'd use Permatex #3 for that.
8. Refit axle housing and hub
9. Repeat on the other side.
10. Reassemble (including put oil back in it!!)

By doing one side at a time and leaving the hub on the other side, I think the diff centre and axles will stay put while the housing is moved out. I will only need enough room to get a finger in there with a rag over it soaked in petrol to clean it before sealing it so 1" should be plenty.

Re: Diff leaking around the bolts
 

Are the bolts tight and not sealing or are the bolts not tightening up? Is it just leaking around the bolts? or are the housing bells leaking.
It its just the bolts not sealing but being tight you can take string and goob it up with
avation #2 or #3 liquid wind the string around the bolt and tighten them up again. If the bells are leaking, bigger problem as the gaskets are shims as well as being gaskets.
If you separate the bells you might or probably will destroy the gaskets.
You may have to pull the rear end and do it right.
Maybe the guru of rear ends, Tom Endy will chime in here.

Re: Diff leaking around the bolts
 

Since the housing gaskets set the carrier bearing preload that's a bad idea.Pull the assembly out of the car,set it up so you can work on it,spread spring and pull radius rods and go through the axle,search Tom Endy rear axle rebuild.

Re: Diff leaking around the bolts
 

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Re: Diff leaking around the bolts
 

Before tearing it down drain and flush the banjo housing. Then just remove the bolts 1 at a time, clean them and use some blue locktite (my favorite) or gasket shellac. You might not have to do anything further.

Re: Diff leaking around the bolts
 

I'm with J Franklin on what he suggested. 1 bolt at a time. Take the bottom bolts out to let most of the oil drain from there plus the drain plug. Jack one side up to tilt the center to get more oil out. You will need to get the threads in the housing as clean and dry as possible.

Re: Diff leaking around the bolts
 

I would re-torque all 20 banjo bolts to 35 ft. lbs. You will probably find that the two forward bolts on each side are loose. For some reason these four bolts tend to come loose. I believe there is some squirming of the rear axle housing that goes on.


If this does not stop the leaking, drain the banjo and remove each bolt one at a time and coat the threads with Indian Head seal and re-insert and re-torque.


Tom Endy

Re: Diff leaking around the bolts
 

Re: Diff leaking around the bolts
 

I've got a diff here that I "rebuilt" when I didn't know what I was doing.

Leaks like a sieve too.

Re: Diff leaking around the bolts
 

Thanks for the replies so far guys. I am aware that the gaskets set the peload on the carrier bearings and if one os so munched up that I have to replace it, I'd do so with one of the same thickness. I've tried taking the bolts out one at a time and sealing them but not with a piece of string (or cotton?). I am not aware of Indian Head sealer - never seen it here. This edit is because I have just googled Indian Head thread sealer. I found a blister pack for $US4.99 with delivery of $65.74. Welcome to our world!!
Looks like I will try to find some Permatex #2, drain the diff, clean the bolt threads and the female thread in the housing, wrap some cotton on it and reinsert, torque to 35 ftlb and pray.
I also wondered about a soft(ish) flat washer under the head of the bolts and some yellow teflon tape..
I dismissed babana peels!

Re: Diff leaking around the bolts
 

Use loctite 515 on the thre ads,if the gasket is RS, take the old one out measure the thickness,get a new one ,cut it so you can slip it ove the axle,saving pulling it all to bits,when you make the cut ,do it in a dovetail so when you assemble it it will not leak,and put some 515 on the dovetail ,put the dovetail join at the top.
We are having a great trip home,tonight at Warren,
Car and Carol both going great.

Re: Diff leaking around the bolts
 

Lawrie, Good to hear. Is that a bush camp? Too wet for that here or am I just getting soft?
Does loctite 515 work on oily threads?

Re: Diff leaking around the bolts
 

Modern sealants work better on antique cars than period sealants..permatex #2? indian head shellac? really?why not tamp a little oakum in there?

When you disturb a fixed housing adjustment you are basically resetting the preload. When you assume a leaking housing gasket is set at proper preload you make your first mistake,you double down by smearing sealant without regard to its loaded thickness altering the setting.Don't lowball your model A,do it right.

Re: Diff leaking around the bolts
 

You can get Indian Head on ebay.com.au from Lithuania for about $2.30 postage.

As it is a flamable liquid you might end up in the "midnight express" jail if you try to buy it.
I'm sure someone on Fordbarn could send you a cake with a file in it, if that helps.

"Modern sealants work better on antique cars than period sealants..permatex #2? indian head shellac? really?why not tamp a little oakum in there"

From what I remenmber, when Mitch (a modern day mechanic) was on this forum, he used Indian Head and didn't have any leaks.

Re: Diff leaking around the bolts
 

Come on, it's Australia, them's all outlaws down there, and they can bake their own cakes with files right there in the hoos-cow.

Seriously, Elvira has a minor version of this problem, and I did as Tom Endy suggests, with good success. Then, 6 months later, a few drips appeared again. Thourough cleaning and careful watching indicates leaking bolts again, not the gaskets. (I think!). Bolts are still tight, but seeping. (Best solution suggested by friends so far, run it without oil, when it burns up, replace it with one that doesn't leak. But, I'm going to not do that. I also rejected welding it all together. My friends are so helpful!)

Might go for new bolts, and lots of thread hole cleaning, locktite on the threads since it should stay put, plus more string/Teflon tape to fill the gaps around the bell..

I don't like leaks, even small ones that only drip now and then.

Re: Diff leaking around the bolts
 

Cooking with dung for heat works too.Glad old Mitch has success with indian head, good for him.. suggesting old school solutions might be fashionable,modern sealants work better..and yes,I'm one of those 'modern day mechanics' too..

Re: Diff leaking around the bolts
 

Ditto

We used it on GM 6-71 diesels that leaked oil everywhere, worked great.

Try the easy ways first, if they don't work then go to the more complicated way.

Re: Diff leaking around the bolts
 

Re: Diff leaking around the bolts
 

From a newer member and A hobbyist.


I understand both sides of this. The; if it isn't broke don't fix it, and the as long as you are there, freshen worn parts. I read all the multiple opinions, and hopefully learn and retain the info.


IMO it depends on the owner and the condition of the car.


If the owner is not a mechanic, and car condition is unknown, perhaps best to inspect and freshen parts if things are disassembled for something else. Another reason is reliability and not constantly wondering what's next when condition is unknown.


For the more experienced members with cars in great shape, known history of the car, cars well maintained, and are mechanics - I totally agree with just fix what is needed for the current issue.

Re: Diff leaking around the bolts
 

I prefer Permatex High Tack gasket sealant over #2. You can buy it in spray or brush on. I've used it on my differential housings, transmission, and over 6k miles no leaks. I also used Ultra Black under the head of the bolt and medium strength on the threads.