Help! My Big7 is stuck in 1st gear!

[Dave Mann]

Perhaps I should have added that the only way back to our hotel was back up the steep hill, this took 3 attempts. The first it promptly jumped out of first gear, the second I learnt to balance the amount of power versus my left hand holding it in gear only to meet a modern coming down with no passing place, the third time we made it.
Many years later when I fitted a 4 speed box in an RN I chose a 2 synchro box.

[Jeff Taylor]

There was a Big 7 gearbox for sale on ebay within the past couple of weeks, but I can't seem to find it now. Regarding availability of gearbox spares, I'd suggest contacting:

Austin Big 7 Register and Austin Big 7 Spares (Robin Taylor) - email: robin.e.taylor@talktalk.net - send S.A.E for list of parts available.

[Jeff Taylor]

Here's the Big 7 box I mentioned on eBay - it ended 10th July and is now apparently sold for £50 + £25 carriage - item number was 153992664673 - it might be worth contacting the seller just incase the 1 bidder has pulled out of the sale. He had other Big 7 parts, for example a water pump for £30, all now apparently sold. 

As someone who's been messing about with 1930's cars for 47 years, I would suggest it's always worth buying a few spares such as a gearbox and even more so a water pump for a Big 7 which could prove difficult to find if it were to suffer irreparable damage.

   

[John Raeburn]

A Big Seven water pump????
J

[Steve kay]

Wasn't that a wartime bolt on, attach to the PTO for putting out fires?

[Jeff Taylor]

Ah my apologies, I'm not at all familiar with the Big 7 engine - did the Austin 8 or 10 have a water pump perhaps?  The guy selling the Big 7 gearbox described the pump as Big 7 which is why I mentioned it. Here it is, a cast alloy outer casing with steel pulley and blade. It has a part number on top which appears to be 10SE8505.B.

   


  Screenshot 2020-07-12 at 19.27.21.png (Size: 250.35 KB / Downloads: 268)

[larrylamb11]

I did see that Big7 gearbox on eBay, but didn't bid on it as the description is sparse, to say the least - no mention of whether it even rotated and in my experience when someone lists something as 'untested' that usually means 'checked and it's actually buggered, but I don't want to mention that...'. I was also suspicious that in the pictures it's obvious that the top cover has been removed and it's pictured with 1st gear engaged! I wouldn't be at all surprised if it was in the same state as my box....

Looking inside my box from the top I think I spy 2nd gear detent balls visible... should I be able to see them? 

It does look like it's suffered the classic failure that many above have reported previously....

[Parazine]

Fortunately, 90% of the Big 7 gearbox is identical to the last of the Ruby type gearboxes. The 10% difference is in the casing and the 1st motion shaft. So a late Ruby gearbox (with oil seals) will yield the spares necessary to effect a repair.

[Bob Culver]

Another box is no gaurantee. the synchro cone must not be too worn and the 2nd gear not free to float endways. !st gear engagement depth must be adjusted moderately whereas deep engagement seems the instinctive thing to pursue. The wrong selector ball allows the selectors to float and worn forks allow the gear to float.
I dunno what owners do about very worn cones. I often wonder if simple rings could be pressed/shrunk  on without all the elaborate and very precise broachings. 2nd gear seems amenable to something.
With most makes of gearbox care is necessary with the interlock removed. If the syncro balls pop entirely out there is no option but a complete dismantle. Can be irksome when still in the car!

[larrylamb11]

Ok..... having wrestled and sworn at this for a good two hours, I have the box on the bench 

I think we have found our problem....
IMG_2910 by larry lamb, on Flickr

and these were in the oil....
IMG_2905 by larry lamb, on Flickr

With that errant spring removed I was able to shift the 'box back into neutral - yay! 

IMG_2911 by larry lamb, on Flickr

The next question is how do I get those errant balls and springs back in the 2nd gear synchro and why did the gear stray beyond it's normal range to allow the balls to pop out? There doesn't seem to be anything further amiss in the 'box, but there must be something awry - so what do I need to 'fix' to stop this happening again?