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Discussion Starter #1
Hi
Have a 74 spider. Just replaced diff pinion seal, but noticed that there is some kind of solidified rubber seal material in the gaps of the splined joint. Does anyone know what this is? I guess its there to prevent leak of gear oil, but I have not seen this discussed. Does it have to be reapplied? What is it?

Thanks for your wisdom.

TS
 

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you might find that what you think is a solidified rubber stuff, is just old solidified grease.
Id just clean it off with a rag.
The rear section of the driveshaft has a grease nipple for greasing the sliding joint.
It is important to keep that slip joint greased, if it wears excessively you get knocking.
Photo(from BB) shows an earlier giulietta rear prop section, but same thing.
there is no gear oil in there to leak.
 

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Discussion Starter #4
Thanks to you both for the response. I am referring not to the splined joint on the driveshaft, but to the splined section on the pinion where the disc/pinion nut assembly inserts into the differential. In the end I replaced the pinion seal and liberally greased the pinion shaft splines before inserting the disc etc over the shaft into the differential. It seems unlikely that diff oil will get out along the pinion shaft since the driveshaft disc bolts tight to the disc on the differential, but I will soon find out.

Any way, just a bit puzzled by why someone had plastered some kind of silicon on the end of the pinion shaft as it emerges from the diff.

BTW, found the pinion seal hard to remove, but found great suggestion in the BB to drill holes in the seal metal ring, then use sheet metal screws to gain purchase to pull the seal directly out with vice grips. Worked like a dream. I would have been really stuck at that stage without the suggestion.

One other comment, there was a finely coiled spring that came loose as I was removing the seal, it seems to bed into a groove around the base of the pinion shaft in the diff, covering some bearings there, I just pushed it back into place. No idea what this does but if anyone knows about this I would be curious to find out.

I find there are surprises at every step in this car..so much I don't know.

TS
 

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The stuff on the splines may be Loctite as per Alfa TSB 15.01. Please click below to read it.

...there was a finely coiled spring that came loose as I was removing the seal,...I just pushed it back into place.
Oh oh. That spring is part of the old seal. It fits around the OD of the inner lip on the inside of the seal. The new seal has this spring too. You do NOT want this extra spring floating about in there. It should be removed ASAP.
 

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Discussion Starter #6
Hey Jim,
Thanks for picking up the offhand comment about the spring. Clearly it's best to confess all on the BB! I actually took out the car today with the loose spring in the diff, and sounded OK but I will definitely open it back up and remove it. Hoping it will come out without removing the new seal since that seems to result in destruction of the part. While in there, I will apply the loctite as suggested.

Sounds like that loose spring might be a source of some rear end chaos if it happens to get caught up on the works in the diff......

Live and learn as I bumble my way through fixing up the car.

Thanks again for the helpful and important input.

TS
 

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Discussion Starter #7
Question about pinion nut torque

Papajam: went back into the diff again but couldn't fish out the errant spring without removing (and destroying) the newly placed pinion seal. Anyway, it's gone now and I am reassembling the driveshaft/diff connection. Going to have to wait for new seal, bought two just in case.

I wonder if anyone can shed some light on this question, 1974 spider, I'm replacing the pinion seal. The pinion nut was very easy to undo, barely any effort required so it was obviously nowhere near the specified setting. On reassembly, should I leave it as it was, just snugged in, or should I bring it up to specified tightness (I read 80 ft pounds)?

As mentioned above, looks like someone had applied some kind of blue silicon sealant to the splined pinion shaft. Papajam notes that Loctite 27 is recommended in tech service docs. How critical is this? I am concerned that I might never be able pull this thing apart if the stuff is applied.

Any suggestions or thoughts?

Thanks

TS
 

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Torqueing the pinion nut to the 58-101 lb/ft spec may result in the pinion locking up solid. This would be the result of the pinion bearings & races (aka cones & cups) having worn a bit. As the bearings wear, the pinion bearing preload decreases as does the torque on the nut. So tightening the nut back to specs will also increase the preload. Of course, the preload is adjusted with shims, not pinion nut torque.
I think it would be best to leave the nut as it was. You want to able to turn the pinion by hand with only a little bit of resistance.
 

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FWIW, I've used loctite 290 (green wicking threadlocker) there.
Another place I've found it useful is at the rear wheel bearing seals, between the axle tube and the metal outside of the seal. (It needs surfaces to be free of oil/grease though, before application.)
/Neil
 

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Discussion Starter #10
OK
That's helpful. Thanks Papajam and Neil.
As I was removing the pinion seal, I used a drill to put a couple of small holes in the metal rim so that I could pull it out with vice grips on two self tapping screws. The drill bit broke, and I didn't think too much of it until after I got the pinion seal out. I looked around under the car for the broken bit. I couldn't find it. Now, the garage floor is pretty dirty, and it's very possible that the piece of drill got flung out or kicked around somewhere remote, but I am a little anxious about the possibility that it somehow ended up in the differential. I did look carefully inside the diff around the pinion shaft, with mirror and touch, and found nothing in there. The diff turns by hand just fine. I am wondering whether, to be absolutely sure it's not in there, I should remove the base plate on the diff and really look around in there while turning it by hand.
I am rather embarrassed to be in this situation, should have plugged the opening before I started drilling. I am going to look again around the garage when I have some daylight over the weekend, but I don't know if I'm going to find the missing piece of drill. On balance, even if the chance of the bit falling into the diff and going deep out of sight immediately is remote, the consequences of such an event would, I am sure, be dire if I started to drive the car.....

Any suggestions?

Thanks

TS
 

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Magnet? sweep the floor and as far as you can get in the bearing?
 

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Discussion Starter #12
found it, and questions about trans mount

I found the piece of drill bit, that's a relief, it didn't get into the differential. In the end, I tightened up the pinion nut so that it was tighter than before, but not much, and the flange was easy to turn by hand. In reassembling, I left the pinion shaft spline dry, and instead put a little gasket seal between the pinion flange and the drive shaft flange, so that any oil leaking out of the diff would be sealed in at the married flanges.

I am going to replace the transmission mount, since I am sure it's too flexible. There are a couple of rubber discs flanking the drum shaped mount. These seem to be flapping around, not packed in tight on either end of the mount. Is this wrong? Should they be a tight fit to provide support?

Any thoughts would be great

Also, is it necessary to disconnect the flexible coupling Guibo before working on the transmission mount?


Thanks again,

TS
 

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On my car those rubber discs have always been loose, they're more of a precautionary measure than a real support, as far as I see it.
You can leave the giubo together while changing the tranny mount, but you will need to support the transmission with a floor jack / wood / whatever so it doesn't sag too far. There are lots of threads about how to change the tranny mount. Some sort out a way to press it out. I've found a propane torch works well, to heat up the alu loop from the lower rear "angle of attack", expanding it enough that the bush is loose enough to just push out with the new one. To each his own preference.
Neil
PS Another thought is that while the tranny mount is down, it's not a bad opportunity in fact to remove the giubo to be able to inspect and grease the tranny output shaft olive and the bush in the nose of the driveshaft - if you don't know when this was last done. FWIW.
 

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Discussion Starter #14
That's very helpful. Thanks for the practical advice. I will have a go this weekend. I was able to find some posts on pushing out the mount, sounds like a mixture of heat and cold is the way to go. I will also use the puller/1 1/2 inch pipe cap rig that has been described.

Thanks
TS
 

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Replacement for Loctite 27?

The stuff on the splines may be Loctite as per Alfa TSB 15.01. Please click below to read it.
Hi Jim,

I can't seem to find any information on the internet about the properties of the Loctite 27 Sleeve Retainer product mentioned in TSB 15-01 reproduced below.

Of course Technical Service Bulletin 15-01 is over 40 years old, but it does indicate this procedure/requirement applies to all 105 and 115 models. So I'm thinking I should use some type of sealer/compound on the splines of the differential pinion yoke on my S3 Spider after I replace the pinion seal (since it could actually be leaking from the splines and not the seal).

I don't want to use just any Permatex/Loctite/RTV product, especially one that might glue the yoke to the pinion shaft so tightly that it can't be removed later, or one that can't deal with the associated heat, oil or vibration.

Any ideas about what a suitable replacement might be for the Loctite 27 Sleeve Retainer product (which now seems to be out of production)?

TSB 15-01 says the Loctite 27 Sleeve Retainer product is used "to ensure a tight fit and prevent noises upon acceleration or deceleration".

Chemists, mechanical engineers, modern adhesive experts please chime in. What type of "sealant" or "sleeve retainer" product should I use on the splines of my differential pinion yoke when replacing it?
 

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I've talked several times with Loctite tech support on the phone for questions like this, at least I always found the UK guys helpful. I don't know if it's still like this (the last time was 5-10 years ago), but they were typically two guys on the phone together, it was like talking with those car guys on NPR.

Green 290 is/was described as a bearing/sleeve retainer, and I'm sure the loctite webpages would use that description for a set of product now still.

But I would guess that 27 became 270 and 272, if I was betting a beer on it....

/Neil
 

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How about Loctite 241?

I happened upon the below page (17-21) in the Alfa Romeo 1985-1989 Spider Workshop Manual.

In the SEALANTS AND SURFACE FIXING AGENTS table near the top of the page, it specifies Loctite 241 as the required Sealant for the "Pinion spline clutch for transmission coupling flange".

Do you suppose the "Pinion spline clutch for transmission coupling flange" is the same thing as the "splined pinion yoke" that slides over the differential pinion shaft and bolts to the rear propeller shaft flange?

If so, could this Loctite 241 sealant be the newer (and currently available) version of the Loctite 27 Sleeve Retainer product that was recommended for use in TSB 15-01 in 1974?

Anyone out there ever seal their differential pinion splines with this Loctite 241 product (or use it on something else)? Could you share what you used it on and describe how it works?
 

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