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ZF s5 18/3 rebuild

Post by Robin from France » Subscribing Member » Mon Jul 03, 2017 8:48 am
Joined: Thu Jan 02, 2014 2:17 pm
Posts: 77
Hi,

another quick gearbox question, I'm afraid.

I've acquired a ZF s5 18/3 box for my cf340 2300 petrol. It's already fitted with a ZF four-speed, which solves a number of problems, so now I'm looking at the five-speed box. I've read through the related posts, and looked at the technical manuals, and realise what needs doing. My questions are fairly basic:

I intend to remove the main shaft for machining - do I have to dismantle it entirely?

I also intend to service the box and check for wear. If there is nothing visually damaged (it all rotates and selects gears as it should) then what would be a good compromise? I would intend to change the input and output seals, and as many bearings as I can esaily get my hands on.

The only wear I can feel is in the input shaft which has side-to-side play.

Any ideas greatly appreciated, as usual.

Oh, and do I need a Google account to download the relevant manual?

Robin

Re: ZF s5 18/3 rebuild

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Post by Phil Bradshaw » Club admin » Mon Jul 03, 2017 12:12 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3733
Machining of the input shaft to make a longer input shaft (Opel CIH, GM diesel) fit your Vauxhall OHC engine? (Mainshaft is the rear shaft which carries the synchro hubs and intermediate gears.) Ideally this should be done on a shaft grinding machine, i.e. remove input shaft which entails dismantling for the input pinion synchro dogs to clear the teeth of the countershaft gear cluster. However, careful application of a hand grinder to the shaft while still fitted in the transmission apparently can achieve the same result; I can't remember who did it this way though.

If bearings are to be renewed then consider replacing all while the transmission is in pieces - front and rear ball bearings, mainshaft spigot roller bearing, countershaft cluster taper roller bearings, mainshaft gears needle roller bearings - and make sure that the clutch spigot bearing in the back of the crankshaft is serviceable. Without the correct service tools (e.g. to extract and install front ball bearing without further dismantling) expect to dismantle the transmission so that a conventional press can be used to dismantle/reassemble shaft assemblies.

Some radial play in the input shaft is to be expected until the transmission is fitted in the vehicle and the spigot on the input shaft engages in the clutch spigot bearing in the rear of the crankshaft.

Google account isn't needed to download files from your Library folder but it might be a good idea to renew your subscription, due last May ... :)
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: ZF s5 18/3 rebuild

Post by Robin from France » Subscribing Member » Mon Jul 03, 2017 12:22 pm
Joined: Thu Jan 02, 2014 2:17 pm
Posts: 77
Wow, so much information. Thanks Phil, and thankyou for reminding me about my subscription too.

I've just removed the bell-housing and there's oil leaking from the front seal, so that needs doing. I'll remove the input shaft and get it machined properly, and then do the best I can with seals and bearings. I'm assuming thet seals and bearings are easy to find - there seem to be a number of suppliers around.

Thanks again,
Robin

Re: ZF s5 18/3 rebuild

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Post by Phil Bradshaw » Club admin » Mon Jul 03, 2017 1:01 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3733
I've seen ZF service kits (bearings and seals) on eBay from time to time so it looks like supply isn't so bad.
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: ZF s5 18/3 rebuild

Post by Robin from France » Subscribing Member » Tue Jul 04, 2017 10:01 am
Joined: Thu Jan 02, 2014 2:17 pm
Posts: 77
Ok, here we go! On the right, ZF four-speed with Vauxhall input shaft, and on the right ZF five-speed with Opel input shaft:

Image

The camera angle doesn't help perspective. A quick measure gives 32mm longer extension from bell housing flange to end of shaft. I will measure more carefully! The shaft needs to be shortened by this, clearly, and also the release bearing tube needs to be shortened a little too. The splines on the input shaft will also need shortening, but, hopefully, enough will remain to let the clutch plate slide to it's disconnected position.

A friend who runs a light machining company is coming round later to take more accurate measurements.

I also need to look at the total length of the box to be able to shorten the propshaft, but I'll wait until it's installed to do that.

The next step will be to work out how to remove the input shaft - scary!

Robin

Re: ZF s5 18/3 rebuild

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Post by Phil Bradshaw » Club admin » Tue Jul 04, 2017 11:27 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3733
If you can find a long bolt with the same (metric) thread as the drain plug then weld the bolt head to the top flat of a piece T-section piece of steel to clamp in a suitable vice so that the transmission is supported upright and can turn on the bolt threads. From memory bolt length of about 100mm should be about right.

To secure the transmission in any position fit a lock nut to the bolt; top face of the nut should be finished smooth to prevent marking of the alloy transmission case (or add a plain thrust washer between nut and case). Weld a piece of flat or bar to the lock nut to make a convenient handle, bent downwards to avoid knuckle damage against the transmission.

Finish the assembly by adding a sleeve over the bolt for the lock nut to bottom against so as to limit protrusion of the bolt end inside the transmission and prevent contact with internal components.

It can be a bit of a fiddle to fit the assembly to the transmission without damaging the casing thread then awkward to manoeuvre the lot into the jaws of a vice but it makes the job a whole lot easier in the long run. :thumb:
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: ZF s5 18/3 rebuild

Post by Robin from France » Subscribing Member » Wed Jul 05, 2017 6:43 am
Joined: Thu Jan 02, 2014 2:17 pm
Posts: 77
Thanks Phil - I saw that in the manuals and it's clearly a good idea.

My friendly machine operator dropped in last night, and had a look - there's clearly no difficulty with the machining on a lathe. Here are the mausurements he took:

Total length from housing to end of input shaft: Opel = 162.4mm Vauxhall = 130.6mm (need to remove 31.8mm)
Total length of release bearing carrier tube: Opel = 80.3mm Vauxhall = 67.6mm (need to cut off 12.7mm)
Narrow section for central bearing in flywheel: Opel = 40mm Vauxhall = 22.2mm (need to machine 22.2mm more after shortening the shaft)
Chamfer on splines 2.5 mm to machine too

The splines and shaft diameter are identical, which is a relief.
Now I'm going to start looking for bearings and seals.

Robin

Re: ZF s5 18/3 rebuild

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Post by Phil Bradshaw » Club admin » Wed Jul 05, 2017 9:16 am
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3733
There's other tools that can be made up too, or avoided with a bit of ingenuity. :thumb:
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

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