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I need to replace the rear pinion seal on my 79 spider. I see discussions here on the subject but I don't see the actual procedure to follow. Could anyone point me to that information, or better yet post the procedure if you have performed this yourself.
 

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Just finished this job for the second time in ten years.

There are several good threads on the subject of pinion seal replacement. The useful advice and important information is spread among them.

My suggestions are to:

use the correct socket for the pinion nut. (I bought the socket, a new pinion nut, and replacement M9 bolts and nuts from ClassicAlfa in the U.K. Place the web order on Thursday night. Had the bag of parts waiting for me in my mailbox on the next Monday. ClassicAlfa had the items for 2/3 the price of the U.S. distributors. And shipping from the UK to California was $6 cheaper than shipping the same parts from Colorado.)

not use jack stands. Use a proper lift or ramps. The torque needed to loosen and tighten the pinion nut can be enough to dislodge a spider from jack stands.

mark the parts that you take apart. The relative origination of the two yokes on either end drive assembly is important. To increase the chance of getting things back together correctly after cleaning all the dirt and oil off the parts use a dab of paint to make alignment marks on the parts you disassemble.

use the MB crank seal. It is a better design made from a more durable material.

use retaining compound (not thread locker!) on the splines. User "papajam" posted the Alfa Technical bulletin (TB). BTW, the retaining compound given in the TB is no longer sold.

make sure you can spin the wheels after tightening the pinion nut before attaching the drive shaft. (You should also really check the torque that was needed to remove the nut and use the same amount when you reinstall the nut. Did you know that you can't get an accurate and thus a useful torque value when loosening a nut? To determine the torque, make reference marks so you can tell where the nut was before you attempt to loosen it, loosen the nut, then retorque the nut until the reference marks are again aligned. The torque needed to get the nut positioned so the marks are realigned will be close to the torque value you should use to tighten the nut after you replace the seal.)
 

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Attempting to replace the pinion seal.

I am trying to change my pinion seal and cant seem to turn the nut. I have the tool I bought and I broke it trying to turn the pinion nut. I did unpin the nut so I am not sure why it will not budge. Any suggestions? Is it a reverse thread type of issue? Any help would be great. The manual is not very helpful on this.
 

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not reverse thread , its normal thread. And you relieved the 'staking' of the nut collar into the pinion groove as well you say -- check to make sure that all staking is relieved , sometimes there are two stake spots. The nut should turn off counterclockwise. I am hard pressed to imagine that you broke a good tool (ie one that wasnt defective) since its only about 100 ft/lbs nominal (I think the range is about 80-120 ish)
 

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Pinion seal replacement

Will check on the staking. It looked as if I had removed it all. You are right to suspect the tool. It looks as if it is made of aluminum. The vendor CA sent. Me a new one but I am afraid to put too much tork on it. I should have just made my own. Thanks
 

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Will check on the staking. It looked as if I had removed it all. You are right to suspect the tool. It looks as if it is made of aluminum. The vendor CA sent. Me a new one but I am afraid to put too much tork on it. I should have just made my own. Thanks
Something is not right.

I had to use over 120-foot-lbs to get one of these nuts off and used an impact wrench to do it with a "tool" from CA (Classic Alfa).

How are you locking the differential in place when you are trying to remove the nut?
 

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Pinion seal replacement

Trying by hand. The book has a special tool for locking the difference but I am having a hard time finding it. And the nut tool I bought from CA states not to use an impact tool on it.
 

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Trying by hand. The book has a special tool for locking the difference but I am having a hard time finding it. And the nut tool I bought from CA states not to use an impact tool on it.
A photo or two of what you are dealing with might help board members help you.

Also describe what happens to the car, the rear wheels, and the pinion shaft when you attempt to loosen the pinion nut. I, for instance, can get the rear wheels to rotate when I attempt to loosen the pinion nut when I don't lock the pinion shaft (sometimes just setting the e-brake is all that is required. I made a lock that is modeled on the Alfa tool. It is on permanent loan to my local mechanic because he broke his Alfa tool that he inherited from his dad who was a factory trained Alfa mechanic and he replaces pinions seals on spiders a couple of times a month.

Talking to my local Alfa mechanic last night when I returned some tools I had borrowed to him he said that a long ago he stopped bothering to unstake the pinion nut when before trying to remove one. He says that the stakes only hold to like 100 ft-lbs.
 

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Thanks everyone. Currently I have it on jack stands. So I ad a hard time locking the diff. I will attempt to finish it on ramps instead.
 

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Trying by hand. The book has a special tool for locking the 'differential' but I am having a hard time finding it. And the nut tool I bought from CA states not to use an impact tool on it.
Having read several threads on differential seal replacement, I ordered the 'questionable' tool and seal from C/A. Knowing that the seal and nut had been undisturbed for over 35 years, I prepared myself for the impending 'battle royal'. I planned to do the job Friday morning when the garage was cool. Well rested; I would have over four hours to work on the '66 Duetto.

After marking the driveshaft flanges with a flat round punch, it was removed. The nut had one tab from the tab washer bent into it. There was also another tab bent the other way and fitted in to a hole on the splined yoke under it to keep it from rotating. I noticed that the nut would rotate about 1/32" either direction before the tab from the washer stopped it. Once the tab washer was un-staked, 'by hand' the nut easily unscrewed with help from the C/A tool.:surprise: The nut was only finger tight.

A buddy who builds Alfa and Porsche engines showed me a trick to help minimize oil leaks when installing the front main seal. First the location on the pulley that the seal rides on was polished with some 600 grit 'Wet or Dry' sand paper and cleaned. We coated the outer diameter of the seal and a few threads on the accompanying drive shaft with a thin layer of Permatex Ultra Black, just before installing the seal. The inner diameter of the seal and the rotating shaft that it "seals" were coated with a thin layer of 'Lucas Red and Tacky #2'. I used the same concept on the differential flange and seal. For good measure, I removed the drain plug, gasket and finned bottom plate on the differential. All pieces, plus the nuts and split washers were cleaned in mineral spirits and reassembled with ultra black on -both sides of the gasket.

IMAG0414.jpg

Now I need to rent a steam cleaner to clean the entire underside of the car...

Mark
 
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