356A T2 ZF steering box surprise

[roy mawbey]

After owning my car for about 6 years, around 40 years ago decided to check the ZF steering box oil level. The box at that time never leaked. So undid the allen screw on the top of the box and looked down the filler hole. and virtually filling the area was the the top of the worm, the oil level was not able to be seen. The factory workshop manual said fill to the just below the bottom of the tapped oil filler hole. Not seeing any oil level I poured some SAE 90 gear oil till it came up over the top of the worm assembly.

Soon after I noticed a small puddle of oil on the garage floor. then the same occured when I used the car and parked it back it back inside the garage again.

This has gone on for 40 years with me re-filling on a regular basis the amount I thought I had lost.
Over the past 15 years of so I came to the conclusion it was the bottom seal on the box failing.

I then read up more on the complexity of removing and stripping the box down, as it seemed many had a similar problem. First I determined there was no drain plug on the ZF and its not an easy job to do. Then a good guy on the abcgt forum advised you can suction the oil out.

So I made up around 2 months ago a suction item. This was using a medical syringe you can buy in a chemist to which I attached a pipe small diameter from a hand wash bottle. It would work but then found no room to get it past the obstructive worm!

Then then the 'uereka' for moment for me arrived. I looked at the schematic drawing and opened the drivers door and turned the wheel onto full lock. Low and behold, the oil entry was clear for me, the first time in 40 years! I had always kept the wheels straight ahead never assuming the internals of the box moved around the casing!!

So, I siphoned out the 250ml of oil so black and dirty after being in there for 57 years. Then refilled to the correct oil level position.

Now after some weeks regular driving the garage floor is free of all leaks, not a drop!

I thought it would be worse with new oil, but I wonder if I have always been over filling the box and some sort of hydraulic action in the box movements has forced oil out of the seal?

I wonder if other guys have had a similar experience and wondered like me why you could not see the oil level? or even if they did strip the box to replace seals?

I do realise now how daft I was assuming all this without moving the steering wheel but you never know others might be as daft as me

Roy

[Hendrik Moulds]

Can't be the same box, but on the PreA I check the oil level at least once a year and top up to the bottom of the thread as you said.
Get a bit of leakage but not a small puddle like you.
Not thought about the mechanism moving like that inside the box, may have to have a look at that next time I check the level.

[Ashley James]

I had my ZF steering box rebuilt by ICS In Birmingham and got it back filled with LM2 Semi liquid grease. I queried this and they told that they'd been doing it for many years because it was so difficult to keep oil on old boxes.

My Healey has Penrite Steering box oil in it, which is also recommended for Derby Bentleys because they're prone to stickiness. It's like a thick motorbike or chain saw oil in that it has long chain molecules, so stretches like Evostick and is less prone to leaking. I think it also has friction reducing additives in it.

[neilbardsley]

I had my ZF steering box rebuilt by ICS In Birmingham and got it back filled with LM2 Semi liquid grease. I queried this and they told that they'd been doing it for many years because it was so difficult to keep oil on old boxes.

My Healey has Penrite Steering box oil in it, which is also recommended for Derby Bentleys because they're prone to stickiness. It's like a thick motorbike or chain saw oil in that it has long chain molecules, so stretches like Evostick and is less prone to leaking. I think it also has friction reducing additives in it.

Semi liquid grease in mine too when it came from the states

[roy mawbey]

The ZF is different to the pre -A cars that ran the VW type box. I agree many fill their boxes with grease now but I was a bit worried about tram lining on contact area's. The thick oil you speak about I really did consider, but I was of the opinion my box after filling with new 90 grade would leak like a sieve which of course it didn't!!

We will see if it continues to operate so well over time.

Roy

[mycar]

To be honest Roy, I would have thought you would have sorted this out by now.

46 years.

Sheesh !

[Dingbat]

If they leak I put new seals and EP 90 , the seals are not a terrible job to do, seems somewhat of a cheat to get around an oil leak by filling the box with something that won't leak. I am not sure about any difference the internals moving inside the box make to the volume of oil as the internals are submerged all the way through their cycle, it's always worth checking to make sure the top of the box is tight as I have seen them work loose.

[Dingbat]

By the way Porsche did not leave the VW boxes as found, they had a rig that ran the boxes through lock to lock whilst running a special running in oil through them , after some time the boxes were adjusted and fitted, so the cars had a nice light smooth steering action.

[roy mawbey]

Mike,

Made me grin, but actually in a couple of months it will be 48 years! And dingbat yes, I was ready to almost to start getting the pitman arm off and everything else but do you know, after finally solving my starter motor problem this year laying on my back the thought of doing the same in the front sort of put me off The miracle that happened by just changing the oil really, no really, surprised me and I do still wonder if overfilling was the cause. (the top casing is leak free)

Maybe the leak will return we will see, but if it does the really thick oil like mentioned above or Millers classic worm steering box fluid at a round £18- a liter might be the next step.

At the moment I get in the car with a smile and a clean garage floor.

Roy