Sigi_H

Normally used springs will be shorter. But surprisingly the new ones from Devon where. I believe it is not a fault, to compress them a little harder as stock. But it will be possible, that the OD becomes slipping when engaged, because the hydraulic pressure is to low. But this will point to another problem

Noone can recommend the right thicknes I believe. I think 2 mm will work. Since there is 3 mm wire thicknes and 12 windings, the spring will not go on block at a given length of about 53 mm

slipping when disengaged does not need any oil pressure. The springs provide the force needed. Spring Length of spring D-outer D-inner Wire thicknes windings used (Buckeye Triumph) 52,6 – 53,2 14,9 8,9 2,97 12,5 used (my old OD) 54,1 – 54,2 14,9 8,9 3 12,5 new (Devon4x4) 53,7 14,9 8,9 3 12,5 since I found out the above, I think it is better to put one or two shims (washer) under the springs in order to pressurize them. Sigi

if these are the two seals sitting face to face on the shaft to the LT230 they are 40x52x7 mm edit: I see, they are.

I am afraid, it is so ...

I didn't check the transfer box yet. That will be the next step on the weekend. When I was rebuilding the OD, I did not take the orange sealed NTN bearing. As this is a known weak point, it's also possible. I think I will put a catch tank to the breather of the LT230 as well. Put to the right level, this can prevent severe overfilling.

I prepared all parts to measure the pressure. But I don't know the size of the thread of that screw on the bottom of the OD, in order to prepare an eye fitting and a banjo bolt for the steel braided hose I took. Does anybody know?

That's plausible, but the OD was rebuilt 12,000 km ago. That's why I don't really believe it yet. Because there is often too little oil in the OD, it normally doesn't engage. The behaviour not to disengage is only possible with gear oil in it. That's why I really want to measure the pressure in order to see a pressure profile and see the reason for shifting or not shifting. I built a provisional catch tank from a PET bottle, to see if oil is coming from the breather.

You are absolutely right. This was just a test, to learn more about the hydraulic pressure. Results point to the necessity of measuring the pressure. Even it was absolutely the wrong oil (it is too slippery) there was no slipping. The fact, that it did not disengage reliably may point to the solenoid valve, which got stuck with the high viscosity.

Hi all, I am the one who was writing the article at landypedia mentioned above. https://www.landypedia.de/index.php/Überholung_eines_GKN_Overdrives It was a hard peace of work reading all that stuff, but worth every line. Since I am not a specialist with GKN ODs, I do have problems with mine as well 🙂 My suggestion (and I am about that) is to measure the hydraulic pressure of the OD. In my eyes, it can be made at the screw, which sits beside the plate on the bottom. I think the hole will just go into the oil chanel of the solenoid. My experience with mine is, that it will disengage when it becomes hot. I made some experiments with oils. With ATF it disengages after about 25 km. Half ATF and half engine oil extend it up to 40 km. Only engine oil will make 50 km. Now I tried 75W90 gearbox oil ... and found it engaging quite reliable and long ... but it did not disengage anymore. Only if revs are really down. It seems to be very dependent on viscosity. Another problem seems to be disappearing oil. I put the vent hose into a catch tank, to see if it disappears here. I did not check yet, if it disappears into the LT230. I heard about it, but don't think so. Sigi