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Hi all👋 here is my new toy


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9 speed 4l,4h and overdrive although mine is currently just a 4 speed 😂. Yes I have seen some pretty rotten cabs, hopefully this one is as good as it looks on the surface. Although I would still like some better doors. It's only done 4000 miles so mostly suffering from a lack of use.

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On 1/22/2021 at 11:37 PM, Richard Farrant said:

I recollect one of these coming in the workshop once with air leaking into the gearbox. There is a diaphragm in the front of the gearbox and it is accessible from the aperture in bottom of bell housing. I was told to fit two diaphragms as it was common for them to leak. Not an easy job, but better than dropping the gearbox out.

You were quite right about the diaphragm Richard, not much left of this one and it was doubled as you said too.

Do you recall if they are just a flat piece or if they were formed? If flat I'll just get some reinforced rubber sheet, maybe slightly thicker. What's it's purpose? Does it preload the layshaft bearings?

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Edited by Motleyholt
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I do not recall how it worked to be honest, the vehicle was recovered to the workshop and I was detailed to fit the diaphragm and although about 35 years ago, I do remember being told to double them and that it solved the leak. I do not have any manuals on the Foden box so cannot elaborate on this. Glad to hear my advice worked though!

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Also I have removed and repaired all the bits that operate the hi/lo/overdrive today. Not a fun job but got there in the end, to say it's tight to access and remove is an understatement. But if you have stuck, sticking or slow changing hi/lo/overdrive then it can all be done without cutting the floor out, removing the body or removing the gearbox. All you need are very long arms, a good yoga course for flexibility and patience. If you undo the four air pipes, drop the air first, remove the rear air cylinder and undo the 8 nuts which hold the selector housing on then you will find it doesn't quite come out! If you then remove the breather and the metal air pipe along the chassis rail then with a little bit of twisting it will come out. 

My rear cylinder was seized on the inner cylinder and the detent was so corroded that nothing would move. But as the cylinders are the same but the rear has a second stage internally all I did was swap the main piston from front to back, clean everything up and reassemble. Job done....in about 7 hours 😂

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4 minutes ago, Richard Farrant said:

I do not recall how it worked to be honest, the vehicle was recovered to the workshop and I was detailed to fit the diaphragm and although about 35 years ago, I do remember being told to double them and that it solved the leak. I do not have any manuals on the Foden box so cannot elaborate on this. Glad to hear my advice worked though!

Very much appreciated it would have taken me a while to spot the air pipe at the front of the box let alone discover the diaphragm. With what I had left I would have assumed it was just a gasket and something else had failed inside.

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Diaphragm sheet arrived today so cut them to size using the old ones as templates. Cut a piece of 8mm hydraulic pipe and ground the end to make a hole punch. Wiggled it all back in and discovered it's not symmetrical.  Took it back out, reversed the diaphragms and put it in again. It's impossible to tell if you have got it all flat and in place, due to the tight access and the clutch shaft, but a steel rule slid between all the parts gave me the confidence to tighten it all up.

If you look closely at the second pic you can just see where the air was leaking through!

Third pic is the clutch housing cover and a new cork gasket.

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Quick update, things didn't quite go to plan with the gearbox diaphragm. Filled the gearbox with oil and started the truck, air built up nicely no leaks from the box. After about ten minutes there is a squeaking noise, at first thought the release bearing needed some grease then the air pressure drops and the dreaded hiss from the gearbox starts again. It turns out that the plate the diaphragm presses on is turning with the layshaft and was rubbing through. I've yet to investigate as to why. Hopefully it's just jammed up with the old diaphragms.  

On the plus side I now have a full set of indicators and after I blanked off the diaphragm air pipe I tried the hiab out. Hiab all functions but it only has one working leg. The hydraulic cylinders that operate the safety locks have seized up and need an overhaul. 

Also gave the whole truck a grease up and there are a lot of grease nipples, I still keep finding more!

I'm constantly surprised how many differences there are between fh70 trucks made in the same year. The donor truck has grease nipples on the cab locks, mine does not. Mine has diff lock switches built into the air chambers  and all the others I've seen have an external switch, see pics. I wonder if there are any identical?

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42 minutes ago, Motleyholt said:

Quick update, things didn't quite go to plan with the gearbox diaphragm. Filled the gearbox with oil and started the truck, air built up nicely no leaks from the box. After about ten minutes there is a squeaking noise, at first thought the release bearing needed some grease then the air pressure drops and the dreaded hiss from the gearbox starts again. It turns out that the plate the diaphragm presses on is turning with the layshaft and was rubbing through. I've yet to investigate as to why. Hopefully it's just jammed up with the old diaphragms.  

 

 

 

Maybe this is why the original diaphragms were destroyed? I do not have any info here for the Foden gearbox to help you on this, but feel sure someone here will know.

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I'm hoping the plate can be popped out via the letterbox and isn't captive behind the bearing cover. Otherwise it will be time to remove the body and the gearbox, which will not be so much fun. Will find out at the weekend.

If anyone has any pictures of a gun tractor or owns one I would like some detailed info on how the winch is plumbed in to the hydraulics. I have all the main components but am missing some of the pipes and connections. I would like it to look as original as possible. Any info much appreciated. 

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The weather wasn't conducive to working through the letterbox to examine the diaphragm issue today so I set about some of the odd jobs. First was to refit the front panel stay so it can be opened and closed properly without the aid of a broom. And to get all the lights working. The head light switch was swapped for one from the donor cab, which I had already liberated, cleaned and tested. Just a matter of unscrewing the dash, hanging the old switch out the way, fitting the new switch and swapping the wires one by one.

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Then went through all the other switches with some contact cleaner, working them on and off until they started working reliably. 20210207_162901.thumb.jpg.4673b26ce6b2e034663afff2d0f21986.jpg

Fitted a label from a land rover until I have time to print a label to match the original.  

Fitted a couple of bulbs, cleaned a few bulb holders that were making poor connections, replaced the rear marker lamps as the rubber was completely perished  and now all the lights work. Horahh. Although to start with when main beam was switched on the heater blowers started running! Then after a few operations normality resumed. Will need to check that one incase small furry critters have been in somewhere. I have aquired, from the auction site, some new old stock lamps to replace the perished rubber mountings on the other lamps which will be fitted soon. Impressively even the convoy lamp works.

Also have a fog and reverse lamp to make things safer for other road users. You wouldn't want to drive into the back of one of these, it would ruin your day😂. The Foden's were fitted with the switches and I assume the wiring for the extra lights. But the lights are an optional fitment.  Does anyone know where they should be fitted?

Also replaced the wiper blades, just fitted some refill blades as main metal parts are chromed and will outlast all the modern replacements. Pumped the tyres up as it was a bit of a drag on corners with the pressures at 10 psi.

Next on the list is to rebuild the side exit exhaust so the silencers can do their job again.

And the diaphragm...and a service...and the steering ball joint gaiters....and the air leaks....and the crane leg....and replace the coolant hoses...

Well you all know how it goes

Edited by Motleyholt
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