1964 Thunderbird Rear differential

[Shadrack]

So, My uncle always told me that many people rebuild an engine, add some HP and wonder why 3 months later they need a new transmission and rear end. He said to start from the back and work your way up.

I am doing the leaf springs on my car. Currently, I am spraying all the bolt down with atf/acetone mx - it melts stuff pretty well lol. I also bought some liquid wrench "project farm - via YouTube."

Here is the deal - While I have the car down like this, I noticed the rear seal in the diff, the pinion seal?? is leaking pretty badly, it is nasty under there. From my understanding, the 64 has a 9 inch rear so its pretty good. I am considering dropping the whole thing and taking it to have new seals installed and maybe rebuilt for future horsepower upgrades. My intention in a couple of years - max - is to pull the motor, total rebuild, and install a streetable cam, high flow intake and heads from Edelbrock. Probably will stick with stock manifolds, headers are a pain.

Anyways - here is the question - should I pull the rear diff and have it rebuilt? How much does something like that usually run? 500-600?

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[inspector]

I had my 65 dif rebuilt a few months ago.It was making a lot of noise. Replaced all bearings, seals pinion etc. Cost about $1200 Canadian. If yoursis like mine, nothing had been done to it since new. Dif oil was stiff as wheel bearing grease. If for no other reason than that it's a good idea to take it apart and clean it. Only after you have it apart can you tell what parts need to be replaced.

 

[Shadrack]

So, My uncle always told me that many people rebuild an engine, add some HP and wonder why 3 months later they need a new transmission and rear end. He said to start from the back and work your way up.

I am doing the leaf springs on my car. Currently, I am spraying all the bolt down with atf/acetone mx - it melts stuff pretty well lol. I also bought some liquid wrench "project farm - via YouTube."

Here is the deal - While I have the car down like this, I noticed the rear seal in the diff, the pinion seal?? is leaking pretty badly, it is nasty under there. From my understanding, the 64 has a 9 inch rear so its pretty good. I am considering dropping the whole thing and taking it to have new seals installed and maybe rebuilt for future horsepower upgrades. My intention in a couple of years - max - is to pull the motor, total rebuild, and install a streetable cam, high flow intake and heads from Edelbrock. Probably will stick with stock manifolds, headers are a pain.

Anyways - here is the question - should I pull the rear diff and have it rebuilt? How much does something like that usually run? 500-600?

I also wanted to ask - should I consider changing the gearing?

 

[Shadrack]

I had my 65 dif rebuilt a few months ago.It was making a lot of noise. Replaced all bearings, seals pinion etc. Cost about $1200 Canadian. If yoursis like mine, nothing had been done to it since new. Dif oil was stiff as wheel bearing grease. If for no other reason than that it's a good idea to take it apart and clean it. Only after you have it apart can you tell what parts need to be replaced.

WOW 1200 bucks - that would be 902.70 in the USA. Not bad, but not in my budget currently. Hmm, I may call around and get some prices. It is just a 9inch Ford rear right? Should/could I upgrade the gearing? I anticipate 400 HP and some point and the wheels.

 

[inspector]

My understanding is, you change gear ratios if you want more power on the low end or more speed on the top end. Weather changing gears will make them last longer is beyond me.

 

[Grahamp]

Perfect time to check the rear end and replace seals and check the pinion gears which are several hundred dollars if you need to buy a new set. You could replace with a higher gear ratio which would improve acceleration with a 400 hp motor but make cruising a little busy. Not sure whether the standard automatic gear box will handle 400 hp, and whether the rear end is hefty enough. I also have a GTO Judge which produces 365 hp and that needs a toughened up rear end assembly. 400 hp may be enough to wreck your existing axle but not sure, worth checking.

 

[Shadrack]

Thanks guys, most appreciated! I think what I will do is call around to some shops check out some quotes - heck, try and find someone who can do it lol - and maybe just get them to go over the diff and replace the seals and whatever else needs to be done. Just because I get to or achieve 400, doesn't mean I have to use it...often.😉

 

[Shadrack]

Hey guys and gals,
So when I call, I should say something like: I have a ford 9" rear end outta a 64 tbird that has some leaking seals, I would like those replaced and someone to look over the unit and replace what is needed? Unit is out of the car, would like to bring it to you.

Just want to make sure I do not sound like a total idiot.

 

[Grahamp]

Sounds good - you may just have to replace the seals, clean up the gears and gear case, refill with differential oil and you’re done. If the axle does not make any noise, very unlikely you will need to change out the gears. You also should check out the rear brakes and drums and replace worn parts, also make sure the drums are round and match the brake lining curves

 

[thunder2010]

A ford 9inch is the toughest diff out there if I would change the oil and change the pinon seal yourself its not hard, just remove the driveshaft, mark the position of the nut and the yoke, then remove the nut and the yoke, then you can pry out the seal....after that tap in the new one preferably with a seal guide or a socket the right size to tap it in straight, then reverse the procedure, when torquing the nut tighten it about an eight of an inch passed the mark and your done

 

[ak7an]

You might want to find out what gear you currently have.. I know a lot of the 64's had 3.00 gearsets. Without an overdrive transmission that is a pretty decent ratio. Go here https://www.randysworldwide.com/calculators/rpm , play around with this and see what changing gears will do to your RPM's at whatever speed you input.. If you do want to put more torque to the pavement you would want to go with a lower gear ratio, which is a higher number.. And as was stated before the Ford 9 inch is almost bulletproof.. Tough as nails and hard to destroy, although I did manage to shell the spiders in my 78 Bird..
Take Care
Ed

 

[jack-in-sac]

So, My uncle always told me that many people rebuild an engine, add some HP and wonder why 3 months later they need a new transmission and rear end. He said to start from the back and work your way up.

I am doing the leaf springs on my car. Currently, I am spraying all the bolt down with atf/acetone mx - it melts stuff pretty well lol. I also bought some liquid wrench "project farm - via YouTube."

Here is the deal - While I have the car down like this, I noticed the rear seal in the diff, the pinion seal?? is leaking pretty badly, it is nasty under there. From my understanding, the 64 has a 9 inch rear so its pretty good. I am considering dropping the whole thing and taking it to have new seals installed and maybe rebuilt for future horsepower upgrades. My intention in a couple of years - max - is to pull the motor, total rebuild, and install a streetable cam, high flow intake and heads from Edelbrock. Probably will stick with stock manifolds, headers are a pain.

Anyways - here is the question - should I pull the rear diff and have it rebuilt? How much does something like that usually run? 500-600?

If you remove the "pumpkin" yourself and take it to a shop that specializes in rear ends that will save you some cash.You wii only be charged for the work done. If you just drop the car off it costs more because they will charge for the rear end center section work and the Rn'R for getting the center out to work on and replacing it in the car. As to the gears, it may likely have 3.00 gear set. A lower gear ratio will give you quicker acceleration but lower your gas mileage. Decide what you want to use the car for, then proceed with modifications to achieve that goal. Plan first to avoid expensive mistakes.

 

[Shadrack]

Sounds good - you may just have to replace the seals, clean up the gears and gear case, refill with differential oil and you’re done. If the axle does not make any noise, very unlikely you will need to change out the gears. You also should check out the rear brakes and drums and replace worn parts, also make sure the drums are round and match the brake lining curves

When I pulled the rear tires it seems like the person who had it before me had good intentions. They had painted drums ford blue, and thee wheel cylinders look good/almost new. The pads look solid with good meat...but the hardware looks old. I might just do a brake job on both sides for the learning experience and to know it was done right. I am still spraying bolts down, and hitting them with a wire brush every day - usually before bed, so I can shower after lol. The person did change out the brake lines...but they left everything around them rusty....pet peeve of mine I guess, I would have at least scrubbed the area down and applied some rust converter. Looks like I am going to have the pleasure of that anyway because I will be dropping the "pumpkin," soon as well.

 

[Shadrack]

If you remove the "pumpkin" yourself and take it to a shop that specializes in rear ends that will save you some cash.You wii only be charged for the work done. If you just drop the car off it costs more because they will charge for the rear end center section work and the Rn'R for getting the center out to work on and replacing it in the car. As to the gears, it may likely have 3.00 gear set. A lower gear ratio will give you quicker acceleration but lower your gas mileage. Decide what you want to use the car for, then proceed with modifications to achieve that goal. Plan first to avoid expensive mistakes.

So all they really need is the pumpkin part, not the whole deal? That makes sense, brain farting over here, sorry about that. I don't really plan on making a speed demon outta it, but everyone loves lots of low-end torque🙂 - well at least most of us🙂 I have made some expensive mistakes thus far because of lack of planning - that is so solid advice, going to have to think about this a bit. Could always do a diesel swap LMAO 🙂

 

[Shadrack]

You might want to find out what gear you currently have.. I know a lot of the 64's had 3.00 gearsets. Without an overdrive transmission that is a pretty decent ratio. Go here https://www.randysworldwide.com/calculators/rpm , play around with this and see what changing gears will do to your RPM's at whatever speed you input.. If you do want to put more torque to the pavement you would want to go with a lower gear ratio, which is a higher number.. And as was stated before the Ford 9 inch is almost bulletproof.. Tough as nails and hard to destroy, although I did manage to shell the spiders in my 78 Bird..
Take Care
Ed

Thank you very much for that link, I will play around a bit. I have been thinking about going with a different transmission for a bit. I have heard the C6 would be a good choice. I like the cruise-o-matic but I am not sure how practical it will be going forward. I will have to consider this as well - you guys have given me a GREAT deal to think about.

 

[Shadrack]

A ford 9inch is the toughest diff out there if I would change the oil and change the pinon seal yourself its not hard, just remove the driveshaft, mark the position of the nut and the yoke, then remove the nut and the yoke, then you can pry out the seal....after that tap in the new one preferably with a seal guide or a socket the right size to tap it in straight, then reverse the procedure, when torquing the nut tighten it about an eight of an inch passed the mark and your done

I watched this being done on YouTube, older joernone - or John I think. He did this and it kinda spooked me in that he was talking about checking tolerances and specific torque specs and so on - I was like...maybe I am water a bit too deep for me.
However, from what you are saying, I might save myself some serious money if I do this and learn a good bit - sounds easy enough. my fear is messing up the driveshaft - I mean aren't they balanced? I guess as long as I am careful it should be okay.

 

[64ZCODE]

Driveshaft was balanced by the factory. Disconnecting it won't change that.

 

[Shadrack]

Driveshaft was balanced by the factory. Disconnecting it won't change that.

Thank you Doug! That helps a great deal - I feel so lucky to have you guys, I hope I can give back as much as you have given me. Thank you all. Doug, hope all is going well - still dark but there may be a way out - I'll on you soon.

 

[OneAmongOthers]

A Ford 9” is easy to pull. Pull the wheels, drums then unbolt the 4 bolts holding the bracket. The axle shafts the. Slide right out. The third member or “chunk” is bolted to the axle housing from the front. Disconnect the driveshaft and then the nuts holding the third member on. You may need to pry on the housing of the chunk to get it to break loose. Be careful! The chunk is cast iron and VERY HEAVY. Nice thing about ford 9” is when you pull the chunk you pull all the gears with it.

 

[OneAmongOthers]

Also remember when reinstalling it you need new copper crush washers and a gasket. Don't skimp and slop on gasket maker. A little can be used to help seal and hold on the gasket. the nuts can be reused if they are not all rusted out. Also check for the axle tag. You can get some more info on it if the tag is still on the car. If you want I have some pictures of my rear disassembled. The are pretty much the same thing. Except my rear is coil. Was the 64 tbird coil or leaf?