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Replacement ball joints

Posted: Wed Mar 13, 2019 3:39 am
by cobbadog
Hi,
I just replaced both front ball joints on the steering arm that runs across in front of the axle. Fortunately who ever replaced the old ones use anti seize grease on them and once the clamp was released they unscrewed by hand all the way. Fortunately I measure across the arm from outside to outside of the old ball joints and counted the number of turns I undid them. As I replaced each side I noticed a problem and that was I could not screw them back on the same amount of turns. After fitting both new ones on and then measuring the overall width was wider by 20mm (3/4").
I have 2 questions please.

1 - What is the thread size and pitch on the steering arm? I measure 18TPI using a Whitworth thread gauge.
2 - Why is it wider and not screw on as many turns?

The end result when fitted is around 40mm toe out which is not correct.

Re: Replacement ball joints

Posted: Wed Mar 13, 2019 7:53 am
by db2d
The description you have given suggests to me that the ‘ Trackrod ‘ is not a David Brown part. I8 TPI is 7/16 BSF, this is much smaller than the original. One end should have a right handed thread and the other a left hand. The tracking should be set to 1/8 inch toe in.

Re: Replacement ball joints

Posted: Thu Mar 14, 2019 5:42 am
by cobbadog
That is correct but the parts ordered for a David Brown 30C from davidbrownparts.uk sent the correct parts from their parts list. The LH threaded one has a part number of 15618 and screws on by hand. So what ever the thread is they make the ball joint to suit that thread. My thread chart does not list this 18TPI and 11/16" OD on the male thread. This is what is annoying me as I would like to know what it actually is.
Here is a picture of the 18 TPI thread gauge sitting completely in the threads and is labelled as 18G - 5/16
I've even tried looking up UNF threads but it is not a 60' pitch as the 55' pitch fits lovely.

Re: Replacement ball joints

Posted: Fri Mar 15, 2019 7:12 am
by db2d
If the steering levers are in the correct position on the stub axles there is normally ample thread on the trackrod for adjustment.

Re: Replacement ball joints

Posted: Sun Mar 17, 2019 4:02 am
by cobbadog
Thank you db2d, Peter from david brown spares also suggetsed that. So when I can get back to it I will do just that.

Do you know what thread pitch and size thes are? It has been suggested that it is 5/8" UNF - 60'
It appears that there is an 11/16" x 18TPI BSF and may be the correct pitch at 55'

By moving one of the steering arms on the top of the stub axle will it make the arm from the steering box too long?

Found this chart as well and opens a Pandoras' Box -

http://www.bareco.com.au/files-tierod-un1

On this list it shows that MF and Ford have the same thread size of 11/16" but have a different overall length as shown in column C and may be why the new ball joints when fitted give me a wider measurement than the originals.

Re: Replacement ball joints

Posted: Wed Mar 20, 2019 4:38 am
by cobbadog
As suggested I moved the steering arm around on the spline and now can have the correct adjustment of toe-in. Tomorrow I will re-adjust the length of the steering rod from the pitman arm to the front to suit after centralizing the steering box.

Re: Replacement ball joints

Posted: Wed Mar 20, 2019 8:04 am
by db2d
The parts in the link are not for the DB tractor model that you have.
As I have stated,when the system is set up correctly there is ample adjustment on the trackrod for tracking purposes.
Bear in mind when centralising the steering box for the fitting of the drop arm and drag link adjustments that the turning circle is sharper when turning right.

Re: Replacement ball joints

Posted: Thu Mar 21, 2019 4:53 am
by cobbadog
Thanks db2d,
Yes I was listening to what you suggested. Fortunately it is all sorted out but it doesn't explain why the new joints are wider than the old.
got on with the next issue and solved it as well today and that was the 3 point linkage issue I had as it was not lifting as high as it should to be able to engage the lock pin in the highest position, now it does so today has been a win win.

Re: Replacement ball joints

Posted: Thu Mar 21, 2019 7:48 am
by ollek
There is no reason to want an explanation to the situation you have, as it looks to be obvious that someone has, in the past, fitted unsuitable parts.

Re: Replacement ball joints

Posted: Fri Mar 22, 2019 3:16 am
by cobbadog
I think the parts I replaced are original and not replacement but it did have the steering arm moved around the spline for an unknown reason and now this has been fixed by moving it around by 1 spline on the stub axle.
I say that the old parts I removed are quite possibly original as when I clean off the layers of paint it then shows the original colour and this has only been painted over once since new as it would appear at some stage this may have been used during the second world war by our RAAF going by the blue paint and white numbers it had beneath the grille on the flat section.

Re: Replacement ball joints

Posted: Fri Mar 22, 2019 7:18 am
by db2d
The war was over quiet a few years before your tractor was made.

Re: Replacement ball joints

Posted: Sat Mar 23, 2019 3:26 am
by cobbadog
That is true db2d but they still had them in use out here long after the war and I was wondering why this blue paint with white numerals/letters are painted on the tractor. It just may have been a part of the plant and equipment line up. I have been onto our record keepers at the War Memorial and typical of us Aussies, not many records have been kept on vehicles. They do have a good list of troop carriers and tanks but not one piece of info on plant and equipment so far found.

Re: Replacement ball joints

Posted: Sat Mar 23, 2019 5:35 am
by ollek
The 30C, and the 25C and D, was in production from 1953 to 1957 and the war ended 1945. The first tractor completely designed and built by David Brown was the VAK1. This tractor was produced from 1939 to 1945. Then came the VAK1A (1945 to 1947), followed by the Cropmaster with different specifications.

Re: Replacement ball joints

Posted: Sun Mar 24, 2019 12:07 am
by cobbadog
That is right ollek but as I mentioned we kept putting these tractors into work long after the war. They worked on the thoery if it isn't broken don't fix it or this works well lets keep buying them. Hence the possibility that the later models did go into the services but obviously not during the war but more like service vehicles.

Re: Replacement ball joints

Posted: Sun Mar 24, 2019 5:33 am
by ollek
Oh dear, there was no 30C made before 1953, the war ended 1945 and you have said you have a 30C. Are you now talking about something else than a David Brown 30C when you say "these tractors", and if so what model are you referring to? The tractor must be a VAK 1 if it was used during the war, and NOT a 30C.