Oily speedometer

[AEX 31]

Barrie,

Thanks again for helping out with this. Please see the attached image showing that the speedometer does indeed run clockwise. I believe the masses of silicone was put there when I had the old gearbox refurbished in England some 20 years ago. The work was done by a reputable firm that possibly had stumbled upon this dilemma themselves?

I have discussed this with another AC enthusiast and as much as I would like to find out the reason for the oil making its way up the cable I have now decided to try and stop the oil at the start of its journey. Hopefully fitting a minute lip seal at the end of the drive shaft will do the trick.

I will certainly post an update as soon as I have tried this. The seal I have ordered is 15 x 10 x 4 mm and won't be with me for another week. Some slight machining to both the brass drive shaft housing  as well as on the end of the srive shaft is, god willing, the solution.

Jonas

[nicksonsticks]

Hi Jonas, I'm finding my self tuning in each day now for the next episode of "oily speedo", desperately hoping for another clue to help us find the culprit!......
I have had a thought which could be a possible cause, or if nothing else one more thing to eliminate. Oil foaming, I'm guessing that when you changed the gearbox you would have also changed the gearbox oil. Is it definitely the correct oil?  Not just the correct viscosity but also the correct specification, modern oils have lots of varying characteristics, for example some oils will have anti foaming additives, others high detergent qualities, others may be be particularly suitable for brass synchro, (GL4 for brass not GL5).
I'm fairly new to the world of AC's but I'm sure there is someone on the forum who could let you know the best oil to use.
Hope this is of help.
Nick

[AEX 31]

Hi Nick,

Thanks for your input. I'm using Millers Classic Sport 20w50 oil in my gearbox. I did check this with Billy Bellinger that built the gearbox, he also does the gearboxes for Jaguar Classic, i.e. the ones that are used in the D-type, XKSS amongst others, and if my memory serves me right he said this oil would be fine to use. I'll double check!

I have been toying with the idea of using a thicker oil, but people in the know has told me that it probably wouldn't make any difference. Again, I'm lost here!

So I'm still struggling to understand why this has happened. However I did speak to a mechanic here in Sweden that has worked on other English cars from the same era and he claimes that the speedometer problem I've encountered is not that unusual for sports cars at least from the 1950's.

So I guess, it would be interesting to hear if anybody else, ever has had this problem with and AC engines Ace with a Miss gearbox?

Thanks Nick. Any other thoughts anybody?

Thanks. Jonas

[Robin A Woolmer]

Moss Gearbox spares  in SC parts web shows an O ring on the pinion housing & they do have paper gaskets for the end cover, i assume these would be similar for the AC Moss Gearbox!

Robin

[AEX 31]

Dear Robin,

Thanks for your input. I did look through SC parts website and I can see both o-rings and gaskets but they appear to be for later cars. The equivalent, from a period perspective  would be the XK 120 I guess and the speedometer drive in these doesn't seem to have any o-ring. I could be wrong of course.

Jonas

[AEX 31]

Barrie,

I found this image on the internet, copyright Ian Strange. As you can see the only oil passage seems to be through the bearing.

I also enclude an image of my gearbox prior to assembly hoping that maybe somebody can spot a missing link.
There are no bearings in the images so maybe not that helpful! But who knows, stranger things have happened.

Thanks Jonas

[B.P.Bird]

J,
Very strangely I met a 428 owner last week who has the same problem. As a last resort I Googled speedo. cable oil leaks and was surprised to find how common it is on various cars. The consensus is pressure build up in the gearbox and the cause lack of venting and/or overfilling.
As suspected your speedo. drive casting should vent via the bearing in to the main gearbox housing. As the matching numbers gearbox didn't have the problem and the modified replacement does there must be a relevant difference between the two. Either the whole gearbox is not venting to atmosphere or the speedo. drive housing is not venting to the main housing. I know you installed a vent and if this is working then there must be some kind of restriction between the speedo. drive housing and the rest of the gearbox. I would return to the thought that the addition of synchromesh to first gear may have obstructed the rear main shaft bearing ?
B

[AEX 31]

Thanks for all the valued input concerning my oily speedometer. I might not fully understand the cause of the problem even though I feel Mr Bird's theory sounds very plausible. Regardless I have modified the speedometer drive housing to hopefully solve the problem.

With valued input from a fellow AC enthusiast I had the shaft grind down to be able to accommodate a small lip seal (15 x 10 x 4 mm). Then as luck would have it a small O-ring fits nicely on the square peg from the speedometer cable, that sits in the speedometer drive axle so to speak.

Hopefully this will keep the old speedometer unlubricated! I will keep the forum updated if this is a solution or not, if anybody will ever experience the same dilemma.

Which I sincerely hope no one does!

Jonas