4.5 Clutch

Transmissions, Transfer Boxes, Axles, Drive Shafts
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iandvl
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4.5 Clutch

Post by iandvl »

My vehicle overnight appears to have developed a clutch issue. For some reason, the clutch is very, very stiff. I originally thought I was imagining things, but braving the traffic in to the office today, I realised it is definitely super stiff - the vehicle is uncomfortable to drive in traffic.

The fluid levels are all fine, and from the bit of reading I've done on the matter there is very little adjustment one can do on the clutch.

My limited reading on the matter would indicate that it is the booster. So I'll check the vacuum pipe this afternoon when I get home. However, while I am busy is there anything else I can check ?
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Re: 4.5 Clutch

Post by Spike »

Quite likely the diaphragm spring on the pressure plate that has collapsed. That's been the cause of stiff clutch pedal for me in the past
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Re: 4.5 Clutch

Post by iandvl »

Spike wrote: 24 Feb 2022 08:59 Quite likely the diaphragm spring on the pressure plate that has collapsed. That's been the cause of stiff clutch pedal for me in the past
Blegh. That is not good news. I was hoping it was not something big...

I'll check the vacuum lines this afternoon. Perhaps I am lucky...

On a side note: I've done about 200k km on this clutch. So it is probably time for a new one...
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Re: 4.5 Clutch

Post by Francois Theron »

A vacuum leak will most probably give you idling issues. Too high or erratic.

My guess is also pressure plate.

Replacing a Patrol clutch is not for the faint hearted! That gearbox is one huge beast!
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Re: 4.5 Clutch

Post by iandvl »

Well, a big relief. It is a vacuum issue.

I presume the vehicle is running nicely as it is an issue with one of the vacuum pod things. The fitting where the pipe connects was presumably broken off (not by me, and very poorly stuck back on again) quite recently - going by the look of the glue.

It was not I, but I shall say no more on that matter.

Cannot post photos at the moment. I will update this thread again in the morning.
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Re: 4.5 Clutch

Post by iandvl »

Also, on the topic of idling and similar. The vacuum comes from the intake manifold.

The 4.5 has two 'vacuum pods' at the back of the engine bay, near the firewall. One is for the clutch (perhaps brakes too - I have no idea). The other for the diff lock (or perhaps brakes too - I have no idea).

According to the manual, factory standard vacuum tubing all have non-return valves, so unless there is a vacuum leak between the manifold and the 'vacuum pod' your idling should not be affected, although the vacuum-powered other things (boosters, locker, etc) will be.
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Re: 4.5 Clutch

Post by Peter Connan »

Glad to hear it's something simple Ian.

Sure Dawid must have plenty of those little canisters lying around?

Just for interest's sake, I had a similar issue a while ago, which turned out to be the seal around the shaft of the vacuum booster.
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Re: 4.5 Clutch

Post by iandvl »

A final post on this matter - with some photographs.

I just felt I had to make the post, as the amount of foresight and care that was involved in the design of the Y61 (and presumably the other variants as well - but I don't know them as I know my Y61) never ceases to amaze me.

The vacuum system on the Patrol comprises of (in my case) two pods / canisters just in front of the difflock solenoid close to the firewall on the passenger side of the engine bay. The vacuum is created by a steel pipe from the intake manifold, and all rubber hoses have non-return valves in place. The pods are there to maintain vacuum so that it should still be possible to press the clutch and brakes relatively easily even when the vehicle is off. As with all things vacuum, I don't think it is always perfect - should the vehicle be off for a while, I'm sure the vacuum will leak and this will result in the clutch being harder to press if the vehicle has been off for a while. When starting the vehicle though, the vacuum will build up again and the clutch will be softer thereafter. I read many reports of this from our Boggan friends in Oz yesterday whilst reading up on my possible issues. I can also remember experiencing the same thing on the one or two occasions when my truck has been standing for a bit. One can literally feel the clutch get softer as one starts the vehicle.

In any case, the one pipe on the left-hand pod was broken off. There was an indication that it must have been repaired quite recently, based on the glue at the base. As I mentioned before, I'm not going to dwell on that.

I stuck the pipe back on using super glue after which I gave it a liberal dose of epoxy. This has worked - the clutch is fine again now. Anthony has a spare vacuum pod for me, and I'll collect it at some point and install it.

I think the only thing I'm confused about is that although my clutch was very stiff, the brakes were totally unaffected. And yet the various diagrams I've seen on the TB45 motor indicates that the brake booster should run off the same pod as the clutch. This makes no sense, so I'm going to have to see exactly where the brake booster vacuum pipe is connected. Perhaps it runs from the other pod ? I shall investigate this at some point in time.

This is a photograph of the broken pod.
Broken-1.jpg
Broken-1.jpg (989.25 KiB) Viewed 4530 times
And this photograph should illustrate the non-return valves on the rubber pipes. The yellow arrows on the pipe indicate which way around the pipes should be and there is also a visible thickening of the pipe at these locations. These thicker bits are the non-return valves. If you remove the pipe and blow through it, you will only be able to blow through it in one direction. One can also note the liberal amount of epoxy around the broken pod in the background of this photo... :rolling: :rolling:
Non-Return.jpg
Non-Return.jpg (768.94 KiB) Viewed 4530 times
In any case, I'm happy it was not a collapsed diaphragm. And I learnt something new yesterday too. And, as I mentioned earlier, the design decisions made during the design of the motor and relevant peripherals is absolutely astounding.
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Re: 4.5 Clutch

Post by Francois Theron »

Good news!
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Re: 4.5 Clutch

Post by iandvl »

Just for information. The reason why the brakes were not affected by the vacuum leak is that they do not run via the vacuum pods. The brake booster gets its vacuum directly from the intake manifold as per the attached diagram.
BRAKE.png
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Ian de Villiers

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