7.25 Rear End

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Humpbackshooter
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7.25 Rear End

Post #1 by Humpbackshooter » Fri Sep 15, 2017 8:25 am

How much trouble is it to rebuild this rear end? I have got it pulled, the grease out of it almost and I'm almost ready to pull the axles. NOTE: I'm going to keep this rear end in the car. I know its a weak rear end, but I'm keeping it original as possible. Only pulling the axles so I can have them punch to 5 lug. The back cover........has been into before because the gasket is the "form-a-gasket", not a formed gasket. Also the bearing seal at the front has been leaking, looking at the signs of grease on the housing. I figure i need to measure from the top of the lip (back cover mating surface) down to the top of pinion gear before i remove the bearing and seal. Plan on cleaning it up and repainting it. Any help/tips would be greatly appreciated.
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ags290
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Re: 7.25 Rear End

Post #2 by ags290 » Fri Sep 15, 2017 12:52 pm

The problem becomes parts availability. When I did mine the bearings and seals were easy to find. A new gear set was almost impossible and trying to find a crush sleeve was impossible. No where near the parts support as on the 8" or 9".

Kevin
Kevin
Early 1965 Mustang with a 170

Humpbackshooter
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Re: 7.25 Rear End

Post #3 by Humpbackshooter » Fri Sep 15, 2017 3:52 pm

Ags.....Thanks for the reply. 10-4 on the parts. After thinking about this today......i think I'll just clean it up and put it back together. I'll still will change out the wheel bearings. Dealing with the crush ring and preload and all that goes with doing this....... is just something that I'm not going to tackle right now.

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Humpbackshooter
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Re: 7.25 Rear End

Post #4 by Humpbackshooter » Fri Sep 15, 2017 3:59 pm

Ags......as far as the front bearing seal, can it be changed without getting into the pinion setting? The u_joint yoke nut in the above pic has to come off to get to that seal. Which is the pinion shaft too? Or will/when I remove that nut.....mess with the settings in the chunk?
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Rinke
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Re: 7.25 Rear End

Post #5 by Rinke » Sat Sep 16, 2017 2:25 pm

Hi,
I just replaced my pinon seal.
It was an easy fix, the most trouble I had was getting the nut loose.
Also get a BF big gripvice to grab the yoke when using an air ratchet, to prevent the gears from rattling against each other (damage :shock: )
The handbook states to mark all settings before disassembly.
Upon reassembly the nut should be turned an additional half turn for the bearing preload. That was the only impossible thing to do. It wouldnt move much past the original setting, even with the biggest air ratchet in the shop.
Put about 0,5-1K K in kilometres on the rear so far, no problems (fingers crossed).
I had minor noises just after the fix, we went on vacation with the car, at the end of the vacation the noise was gone, maybe a burr that had to be smoothed with some driving?

Good luck with the fix.
Rinke
64 Falcon Station Deluxe
3 on the tree
170
3.50:1 rear end
Been collecting dust & adding rust for 30 years
Goal: to keep it all working from okt 2008 till all eternity

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Re: 7.25 Rear End

Post #6 by Humpbackshooter » Sat Sep 16, 2017 10:15 pm

Rinke.....thanks for the info. I cleaned it up today. That's the cleanest its been in oh....maybe 50 yrs. :D I talked with one of the guys at work today and he said that I should go on and replace the bearing and seal. I have gone this far and its out from under the car, now's the time to fix it right and not have to try and change out those parts after I get it back under the car. He's most likely right. But I don't have a lot of experience on breaking down 3rd members. Sooooooo, I'll have to sleep on it and decide later. :?

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bubba22349
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Re: 7.25 Rear End

Post #7 by bubba22349 » Mon Sep 18, 2017 12:08 am

There is a lot of info and part numbers on rebuilding the old 7.25 axle on our Ford six site. One that is a very good group of posts covers it very well, so you might take some time and read it in the below link. Good luck :nod:

viewtopic.php?f=76&t=70657&p=542357&hilit=Mustang+Rear+axle+rebuild#p542357
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

mustang6
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Re: 7.25 Rear End

Post #8 by mustang6 » Mon Sep 18, 2017 3:00 am

Yes, you can replace the pinion seal, just retorque the nut to the amount specified and you will not crush the crush sleeve any further.
Scott

68 Mustang 200 ci, Aussie 250-2V head, Dual Headers, Comp Cams 252H, DSII w/MSD 6AL, T-5, V8 suspension.

65 Ranchero 200 ci, late 170 head, Autolite 1101, 3.03 3 speed, Maverick 8" 4 lug rear with 3.55 gears.

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62Cometman
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Re: 7.25 Rear End

Post #9 by 62Cometman » Mon Sep 18, 2017 12:09 pm

I too decided to rebuild the 7.25 rear in my comet, mainly due to the wailing it was making at the time when i first bought it. Its a pretty simple rear to fix tbh the majority of the parts i actually order from my local o'reillys, except the main pinion bearings and the pinion seal those i had to source from our local DXP bearing and seal compan. Those pieces cost more than the rest of the components combined, but im happy to say that ive put a few thousand miles on the rear since and havent had an issue besides that dang cover gasket leaking, cant trust paper anymore, back to using permatex on everything like i did in tech school :lol:
1962 Mercury Comet 170 ci, Dagenham Trans, 2.83:1 7.25 rear.
She ain't fast but she's fun. 8)

Humpbackshooter
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Re: 7.25 Rear End

Post #10 by Humpbackshooter » Tue Sep 19, 2017 9:14 pm

Bubba.....thanks for the shortcut. Good reading and pics along with pt#s.

6......since I have it out where it's easy to work with, I would like to change the bearing too. That will involve messing with the settings of all parts.:-(

62.....Kinda like the pan on the bottom of the trany. :D

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