Crown Wheel and Pinion Replacement Options??

[Grant]

Only a pleasure. Let us know the outcome.

[Overdrive]

So today the mechanic said there is nothing he can do. But he did have suggestions: a) change the right rear tyre which has a flat spot (although it is almost new) (b) get the offending extra fuel tank made smaller because its dangerous where it is so close to the prop shaft. The tank is aluminium so special welding skills are needed.
Here are the photos (sorry about the quality)

Offending fuel tank1.jpg (36.05 KiB) Viewed 2420 times

Offending fuel tank2.jpg (23.52 KiB) Viewed 2420 times

Offending fuel tank3.jpg (26.38 KiB) Viewed 2420 times

Rub mark.jpg (29.18 KiB) Viewed 2420 times

So regarding the tyre I swopped it for the spare and ...... Marked improvement. I will get the other side checked out - maybe it also has a flat spot.
Regarding the tank the choices are either a new 135 litre tank from Northern Offroad for R7 800 or get about 50mm cut off the existing tank to give the prop shaft more room for about R1 500 to R2 000. What should I do? The holiday money banker is inclined towards the latter. I have found a guy who is willing to do the tank and my mechanic will take it out and put it back when he has made it a bit smaller.

But when I was having a look underneath I noticed that there is a "rung" of the ladder chassis passing under the propshaft about 6 inches back from the gearbox. It looks like the prop shaft is scraping on this cross piece. I don't know how it could move that much - its about 3 cm. Of course its much thicker than it is supposed to be because the propshaft is on back to front. So that's a new problem that none of the 4 workshops its been to have picked up. I will have to sleep on that one.

[ricster]

Hmmm... I had a half a shot in the dark.... tyre flat spot...

I told you Rod... no hand brake turns in the patrol after my gluwein.....

This is very interesting reading... Its a tough call on what route to take. New tank and change the prop around... or cut and weld existing and turn the prop around..... Well depends on how well your guy can weld !!

[Clem]

I do wonder whether that reversed prop shaft is not the problem. Remember also that you are now applying force on the slip joint in the opposite direction. i can tell you firsthand that the mere fitting a rubber coupling the wrong way round can do exactly what you are experiencing.

[Peter Connan]

But when I was having a look underneath I noticed that there is a "rung" of the ladder chassis passing under the propshaft about 6 inches back from the gearbox. It looks like the prop shaft is scraping on this cross piece. I don't know how it could move that much - its about 3 cm. Of course its much thicker than it is supposed to be because the propshaft is on back to front. So that's a new problem that none of the 4 workshops its been to have picked up. I will have to sleep on that one.

This is exactly what I have been going on about. And it's just because of the extra thickness.

I would have the existing tank modified. On the basis of not keeping all your eggs in one basket.

[Overdrive]

I think Peter was absolutely right. In the pic below you should be able to make out the silver scrape marks that the cross member has made on the newly painted propshaft. And this is driving around town! So I think the only sensible thing to do now is to reverse the prop and put it on the right way round. This will mean trimming even more than the planned 50mm off the fuel tank but there just doesn't seem to be another option that involves keeping the existing fuel tank, even if it is a bit smaller. I have asked the guy who is going to do the aluminium welding to try and figure out how many litres I will loose.

Fat end of prop scrape marks from cross member.jpg (31.12 KiB) Viewed 2395 times

Now here is another puzzle, at least for me. I thought I would replace the fuel filter for this tank and drain it completely to speed things up tomorrow. When it was nearly empty the flow was reduced to a trickle but it just kept on trickling and trickling. So it must have been getting fuel from the main tank somehow. But the odd thing is that this "self filling" has never happened on the road. When it was empty it stayed empty until I refilled it. Can anyone explain this?

[Tinus lotz]

Diff in pressure between to tanks ??? Gas from one tank pushing feul over ? Where are the tanks connected?

[Peter Connan]

You will need to explain to us how the system is connected?

[Overdrive]

Tinus I also thought that so when it started happening I opened the fuel filler cap in case there was pressure but it didnt seem to make any difference.
Peter there is a switch to turn on a small electric pump that pumps fuel from the extra tank into the main tank - you can see the fuel gauge going up as you go along. When you are filling up the main tank fills first and then "overflows" into the extra tank. The details are a bit tough as I didn't install it but from observation the obvious things are: there is a large diameter pipe from the near fuel filler cap to the top of the tank tank for filling it. Then at the bottom of the tank there is an outlet and the fuel line pipe leads through a fuel filter to a pump and into the main tank I think - its very difficult to see. At the top of the tank there is another fuel line diameter pipe coming from up near the main tank but I cant see exactly where it goes. When this happened the main tank was about half full so I am excluding overflow.
On my previous patrol there was a similar tank but when you switched over to it the fuel pump pumped the fuel to the motor and the surplus was "recycled" to the main tank but that was only with the motor running. My guess is there must be some system of pipes which is allowing fuel to flow to the motor and back to the auxiliary tank somehow. I cant figure it out.

[Clem]

I think Peter was absolutely right. In the pic below you should be able to make out the silver scrape marks that the cross member has made on the newly painted propshaft. And this is driving around town! So I think the only sensible thing to do now is to reverse the prop and put it on the right way round. This will mean trimming even more than the planned 50mm off the fuel tank but there just doesn't seem to be another option that involves keeping the existing fuel tank, even if it is a bit smaller.

Glad you seem to have identified the primary cause. Maybe drop the tank (which has to come out anyway), reverse the prop and drive the car first to fully confirm?