Author Topic: 085 layshaft bearing  (Read 6637 times)

Offline Sli_Stunion

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085 layshaft bearing
« on: July 06, 2011, 04:05:02 pm »
Hi all,

I'm in the process of changing the layshaft bearings on my 085 gearbox and I'll be doing diff bearings while I'm in there. The car (hence box) has clocked up a nice 193,000 miles since 1997 when I bought it and this is it's first real problem other than new rings and valve seals 2 years ago.
The layshaft bearing at the clutch end looks rather sick, the chrome surface of most rollers and some material under it has gone plus there's a ridge formed in it's outer raceway ring, all making for a nice bushy magnet in there. Otherwise the cogs etc are all fine.  I've got the bearings & seals, (vw stealership) just need some extra pointers...


I've read the post regarding fitting the LSD, great source of info regarding the diff bearings, but can anyone give some pointers regarding:

How best to remove the layshaft outer raceway that's pressed into a blind hole in the case at the clutch end? I was thinking I'd start with heating the case then using ice on the ring and see if I can lever it out, failing that drill 3 small holes from the clutch side and tap it out, obviously re-sealing the holes after. How do the re-furb guys do it?

How much and how do I set the the laystaft end float / pre-load?

I'd like to take a look at the bearings at the other end of the shafts while it's stripped so I presume selectors have to come out and the cogs in the end chamber come off? Do the selectors lift out with the shafts if I pull the bar that the slide thingy slides on (vague but if you've been in there you'll get the picture I hope)

Phew, first post and already asking too much..

Offline hayesey

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Re: 085 layshaft bearing
« Reply #1 on: July 06, 2011, 04:25:44 pm »
Quote
How best to remove the layshaft outer raceway that's pressed into a blind hole in the case at the clutch end? I was thinking I'd start with heating the case then using ice on the ring and see if I can lever it out, failing that drill 3 small holes from the clutch side and tap it out, obviously re-sealing the holes after. How do the re-furb guys do it?

a small slide hammer to tap the bearing race out would probably be best I think.  You can buy tools specifically for it like this:

http://www.machinemart.co.uk/shop/product/details/cht252-5-pce-blind-bearing-puller-set/path/automotive-tools

They shouldn't be mega tight but heating the casing and/or freezing the race with that freeze spray stuff such as this:

http://www.maplin.co.uk/freezer-spray-26296

Or even one of those aerosol air dusters would probably suffice.

Quote
I'd like to take a look at the bearings at the other end of the shafts while it's stripped so I presume selectors have to come out and the cogs in the end chamber come off? Do the selectors lift out with the shafts if I pull the bar that the slide thingy slides on (vague but if you've been in there you'll get the picture I hope)

I've always just taken the selectors out one by one before lifting out the gear assembly.  Just take note of which one goes where and take photos!  One thing that is a pain in the arse is the ball arrangement that the slide thingy you talk about locates onto and operates all the selector rods.  This has to come out and the bolt holding it in is totally inaccessible.  There is a metal rod through the middle of this mechanism.  Then at the end of this, there is a soft alu bush pressed into the gearbox casing with a small hole in it.  Find a suitable size screw and screw it into this hole, then knock out the bush using a slide hammer (or if you dont have one like I didn't, improvise by clamping some mole grips onto the screw head and tapping the grips with a normal hammer!).  Once the bush is out, you can slide the metal rod out I mentioned earlier and the selector mechanism comes in half allowing access to that pesky hidden bolt.  

It's not as hard as I make it sound, it should just make sense as you are doing it.

Quote
How much and how do I set the the laystaft end float / pre-load?

I forget the figures, it's in my haynes gearbox manual at home.  I'll try to remember to look it up.  To measure the end float, do this before you put 5th gear back on and you can just about get a pointy DTI gauge in.

Hope that helps!  Quite an interesting first post.

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #2 on: July 07, 2011, 12:52:12 am »
Hope this helps....

Couldn't be better, many thanks, I kinda hoped you'd chirp in. The LSD write-up is one of the most succinct on any of the forums I frequent, the deciding factor in me having a go at the box rather than look to swap it out. (enough blowing smoke where the sun don’t shine.)

I took a look at the slide-hammer blind bearing puller, the expanding  bits are a neat idea, shame about the £. Any idea if one can be hired? (Nr Warrington , Widnes , St Helens, Runcorn etc) otherwise I may try to improvise something, they look a bit like expanding wall fixings...

I measured the bush thread holding the bar, 7mm, typical nothing to hand, B&Q in the morning.

I spent hours last night looking for the Haynes gearbox overhaul manual, looks like it’s out of print, no mention of it in stock and not listed at Haynes themselves. Anything you can add regarding pre-load / end float (I presume some loading to keep noise down and gears from vibrating against each other) would be a great help.

Offline hayesey

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Re: 085 layshaft bearing
« Reply #3 on: July 07, 2011, 09:31:07 am »
yeah that particular puller is rather expensive, it was just the first link that came up in google of what I wanted to show.  Improvising something is what I'd do and have done for most things otherwise requiring expensive tools.

Shame that manual is out of print.  I'll scan in the relevant bits from mine tonight.

Offline hayesey

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Re: 085 layshaft bearing
« Reply #4 on: July 07, 2011, 09:44:41 pm »
ok well here's a scan of the 084 section of the manual.  Ignore the bits on the very last page which start talking about Golf 020 boxes.

Apologies for the quality of the scans but the manual is totally filthy (I'm going to have to wash my hands now) and my scanner is pretty rubbish!  Hopefully you can make out what you need from it.

http://derby.polog40.co.uk/084_gearbox_manual.pdf

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #5 on: July 09, 2011, 02:43:33 pm »
Thanks for the scans, the figures should be a great help and that's my weekend sorted then.

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #6 on: July 09, 2011, 07:21:31 pm »
I opted to let a garage pull the blind bearing for £10, money well spent given the cost of the tool and I couldn't improvise anything.
loads more removed ready for cleaning, I'm using gunk and an ultrasonic bath where they'll fit.
The sleeve/tube that the 5th gear needle roller runs on wouln't budge so the shaft wasn't coming out.  It's 25 in the exploded diagram, I've written '8' on it in the photo to help when re-building.
I've just been hitting it with a hammer (& wood block) trying to push the shaft through when the whole lot came out, that's bearing included! Aghh, now I've the shaft with the roller surface tube thing, thrust washer and bearing on it.




How on earth am I going to shift that tube, the 5th gear was rather tight so perhaps the shaft / splines are at the upper end of spec. I'll start with the bearing separator and a puller.
« Last Edit: July 09, 2011, 07:39:08 pm by Sli_Stunion »

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #7 on: July 10, 2011, 11:46:05 pm »
Well, all going back together now.
Everything was cleaned, the synchro bits even got a shine before refit, I've never seen the inside of a box looking so nice.
The forks went in easily as did the slider mech that operates them.
The 5th gear needle roller inner sleeve took a boil and good thump to put it back but it's there now, though it's a little more snug than it was. The thrust washer had perhaps 0.25mm play, now it's almost none but being on the outside side of the bearings it shouldn't matter.
5th gear selector went back no probs other than I needed to adjust it after a silly mistake. I didn't turn the nut at the same time as the allen bolt head so I ended up setting it too low. This revealed how easy it is to adjust, even with the box in the car. I reset it for now by engaging 5th using the selector mech and setting the fork height to make sure it was safely selected, then de-select and check it's well clear. I'll go over it again in car using the gear stick before adding the oil.
I'll also pull the torx screws back out as they've a blue coating that I suspect is threadlock, I'll clean them and apply some new stuff.
Tomorrow I'll reassemble the case and check the shafts end float. As they're supposed to be positive I'll use a slightly alternative method, I'll add a few thin shims (actually measured pieces of tin can) into the case gap and re-mate them then measure the float. I hope the output shaft is correct, there's a shim at the clutch end but it's in the blind bearing so staying put if at all possible. There's another at the other end but that's not easy to swap, it means taking the shaft and thus selectors back out.
If all goes well then it's just a smear of sealant, pop the new seals in and refit the flanges, refit to the car and check then a glug of oil.

Where's best for the oil, a stealership? Halfords don't stock it, their nearest of 80/90.

Offline hayesey

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Re: 085 layshaft bearing
« Reply #8 on: July 11, 2011, 09:27:49 am »
I don't think it's too expensive from the dealers no, or GSF should also have the right stuff. 

what have you actually done to the box then?  just took it apart, cleaned it up and put it back together again?  The preload shouldn't need resetting if you've not replaced any bearings.  If you have then really you should assemble it with one of the factory fit shims missing, measure the end float, add the preload factor onto that measurement (from that haynes manual) and then order a new shim from VW of this thickness.  But the factory fitted shims should still be right if you've not replaced the bearings

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #9 on: July 11, 2011, 07:18:30 pm »
I've replaced the bearings...

It was doing the normal failing "whine on lift", "whine under load" or as someone described it, sounding like reverse all the time.  I'd hoped to find it was the diff bearings so pre-ordered a set from VW. When I opened the box they were fine, a little dull but perfectly servicable, it was the output shaft bearing (clutch end) that was giving way. The tapered rollers surface was giving up with patches where they had gone and the roller under it was being eaten away, the race also had a step at the small end, some scratches around it and the magnet was also nice and bushy, all cogs however were fine.

I needed to check bearings at the other end of the shafts hence the strip. I went a bit further by openning the easy to access synchros etc for a bit of a clean. I've got an ultrasonic bath so they went in a few bits at a time. I've replaced diff and output shaft bearings (4 in total), new seals to go on last.

I've a DTI and mag base etc so I'll check the end play then shim accordingly but my fingers are well crossed in the hope I can re-use the originals. I'm using VAG bearings so I've paid enough for a bit of luck to come my way.

UPDATE
All the bearings were in place with factory shims. I re-spaced the box using stacks of 5x 5thou stainless steel washers (0.635mm total) at each bolt and measured the various end floats hence calc'd the pre-loads:
Rotating the shafts I found the diff endfloat to be 0.3mm hence the final pre-load will be 0.335mm, close enough for me.
Input shaft ends up with just 0.1mm pre-load so should be OK, wear limit is 0.5mm by the look of it.
The output shaft was a bit more tricky, I had to hang the DTI under the box so gravity was pulling the shaft down, eventually I convinced myself it's also 0.1 to 0.2mm pre-load, so if my measurements are good and the box holds up then I've been lucky with the shims!!
Box now assembled using Hylomar UB, ready for oil (post fitting) and a few more miles.
« Last Edit: July 13, 2011, 01:41:55 am by Sli_Stunion »

Offline Sli_Stunion

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Re: 085 layshaft bearing
« Reply #10 on: July 26, 2011, 07:37:05 pm »
After a break (week in Cornwall in the rain) I got back with a litle less enthusiasm, all done not though.
I fitted a new clutch as the old Sachs one got a tad oily (clumsy me), it had spent a couple of hours with a small oil puddle sitting on it out of sight, £104 down the pan. I did try to clean it but petrol, Fairy, Swafega .... nothing shifted the stained patch so I picked up a Luk from Eurocarparts, shame the old one showed no sign of wear, bearin was smooth etc.

Anyway, the box is sounding fine again, changes are nice etc though the horizontal shift from 3-4 over to 5 feels a bit short, I'll leave it for now.

Looking back it was all fairly easy with help on here from Hayesey (thanks).

Next I need to sort out the air-oil separator (internal divider is split) and remove a stuck caliper bolt that's rounded!

Offline Andy

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Re: 085 layshaft bearing
« Reply #11 on: July 26, 2011, 10:40:37 pm »
You can often re-vitalise an oily clutch by giving it some shit once installed in the car to burn off the oil - I've done it a couple of times in the past. Possibly a hot air gun might achieve the same effect? On the other hand, it's more time farting around - and still a risk that it'll need replacing at the end of it....

Offline hayesey

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Re: 085 layshaft bearing
« Reply #12 on: July 27, 2011, 09:56:32 am »
I've done it too with my paddle clutch when a failed input shaft seal gave it a good soaking in gear oil. Once I'd fixed the box, I got onto a quiet motorway, put it in 5th and floored it until the clutch started to grip.  That was a couple of years ago and the clutch is still going strong.  yay for helix paddle clutches, expensive but can take some serious shit.