Mk3 GT6 Second Gear

[Pete Lewis]

ive just made   some sticky yummy bread pudding not too heavy  loads of sultana's   etc    does that count ???

Pete 

[NonMember]

3 hours ago, Ingieuk said:

Got the master/slave clutch cylinders off now. The state of the fluid is a little embarrassing. It's like mud. Quite how the clutch was operating I don't know. Any tips on what dissolves old gummed brakefluid? Brake cleaner didn't seem to touch it.

The brown crud on the outside where the piston circlip is usually responds to a bit of mechanical persuasion - poke at it with a small screwdriver tip or a wire brush. It helps if you can push the plunger in for better access.

3 hours ago, Ingieuk said:

 I need to loosen it off to get the plunger out (air lance to the clutch line should shift it once loose).

Don't use compressed air! I know it's tempting if you have it but you build up a lot of pressure of highly compressible gas. When the piston shifts, the pressure is still there for the whole of its travel, accelerating it until it shoots out like a bullet. A grease gun works far better - it builds the pressure with incompressible liquid. As soon as the piston moves, even a tiny bit, the pressure drops. Thus you remove it in a safe and controlled manner. Or, once you've got the crud and circlip removed, you may find tapping, poking, or leaving the piston in the vice, open end down and full of brake cleaner, overnight will do the job.

[Ingieuk]

43 minutes ago, NonMember said:

The brown crud on the outside where the piston circlip is usually responds to a bit of mechanical persuasion - poke at it with a small screwdriver tip or a wire brush. It helps if you can push the plunger in for better access.

Don't use compressed air! I know it's tempting if you have it but you build up a lot of pressure of highly compressible gas. When the piston shifts, the pressure is still there for the whole of its travel, accelerating it until it shoots out like a bullet. A grease gun works far better - it builds the pressure with incompressible liquid. As soon as the piston moves, even a tiny bit, the pressure drops. Thus you remove it in a safe and controlled manner. Or, once you've got the crud and circlip removed, you may find tapping, poking, or leaving the piston in the vice, open end down and full of brake cleaner, overnight will do the job.

I like the grease gun idea, just need to make a fitting up to attach my gun to the threaded fluid outlet. 

I think I'm going to need to do the same for the brake master cylinder anyway. Any idea what the thread on the flare nut is? 

Tea and cake sounds good. Certainly going to be some big mugs of tea consumed before I've sussed this box out. 

In terms of removing the box, I guess a jack under the engine sump to lift the rear of the gbox free of propshaft and pull? Workshop manual is rather sparse on the removal operation. 

Rich

[johny]

Yes spread the load on the sump with a piece of wood and try not to leave the gearbox hanging off the engine unsupported. Then be careful the input shaft doesn't fall on the clutch assembly as you withdraw the tip from the flywheel. Can be done by one but best with someone on both sides...

[ahebron]

What I learnt recently when I pulled the gearbox out of the Vitesse is that you can rest engine back on two pieces of wood wedged between the chassis and the rear engine plate on both sides once the gearbox is out. No need to worry about leaving the sump supported.
[]\( * )/[]

Adrian

 

[Pete Lewis]

and on a Herald /vitesse you can remove the heater  air distribution box but on a GT6 / Spit its different you may need to rotate the unit to get the clutch housing , through the aperture

and to support /lever  the box off a 6ft 2x2" timber to lever between chassis and the box , 

on refit  fit temporary long studs in  a couple of the top block threaded tappings , to aid alignment and to back up how || the box and eng plate are parallel rather than eyeball use a odd bit of timber as a sight /gap gauge as what looks in line never is and refit can become an argument as to who's going to win

pete

[Nick Jones]

7 hours ago, Ingieuk said:

Thanks Johny/Pete, I'll see when I get up to that bit. 

 

Got the master/slave clutch cylinders off now. The state of the fluid is a little embarrassing. It's like mud. Quite how the clutch was operating I don't know. Any tips on what dissolves old gummed brakefluid? Brake cleaner didn't seem to touch it. I need to loosen it off to get the plunger out (air lance to the clutch line should shift it once loose).

 

Mangey old deposits of brake fluid dissolve in fresher brake fluid or warm water. I prefer to avoid using anything mineral oil based with brake parts as the EPDM rubber used for the seals really doesn’t like mineral oil.

Nick

[NonMember]

3 hours ago, Ingieuk said:

I think I'm going to need to do the same for the brake master cylinder anyway. Any idea what the thread on the flare nut is?

I think the hydraulic fittings are 3/8" UNF - you can get grease nipples with 1/8BSP threads, which is nearly the same but not quite.

[Ingieuk]

Thanks all, gear box is out and on the bench. Sump is supported on some blocks of wood. Couldn't get the clutch off as it would turn the crank (duh, should have thought that would happen), so I'll knock up a clamp mounted off the block studs onto the gear teeth on the flywheel. I think I'll take the glove box out for the refit as I've put a dent in the mahogany dash from one of the remote attachment studs on removal 😥

On the plus side I got the clutch master cylinder apart - similar to the grease gun idea I assembled the system on the bench and pumped the slave cylinder until the piston came out.

Looking at the box there is little to no damage to any teeth on the mainshaft. Looks like the reverse idler is missing a couple of edges. Inside of the bellhousing was very oily, the front seal was hard and brittle. As expected the rear drive flange nut was rather tight but got it off.

Is there a minimum thickness for the ends of the selector forks? The 1st/2nd input shaft side looks a little thin.

 

[Ingieuk]

Just reading through the next steps of removing the layshaft. Both the Haynes and workshop manuals require a 16.64mm x 165mm piece of steel rod to drive the layshaft out. 

I guess this is so that the roller bearings are captured. Given I'm going to be replacing the layshaft and bearings is it important to do that in this disassembly?

I can see how having the rod available for assembly will be advantageous as you could assemble needle rollers on a shaft, drop the lay gear in, then drive the rod out with the new layshaft. I should be able to do the same by cutting down the old layshaft to 165mm I assume.

[Nick Jones]

22 minutes ago, Ingieuk said:

Couldn't get the clutch off as it would turn the crank (duh, should have thought that would happen), so I'll knock up a clamp mounted off the block studs onto the gear teeth on the flywheel

I use a 1/2" open end spanner sat vertically in the ring gear at the top.  Its jaws drop neatly into the teeth and its shoulder wedges perfectly under the top-most bellhousing stud.  Then just flip to do up again.

 

24 minutes ago, Ingieuk said:

Looks like the reverse idler is missing a couple of edges

That's the chunks you found.  Don't worry about it!

 

9 minutes ago, Ingieuk said:

Both the Haynes and workshop manuals require a 16.64mm x 165mm piece of steel rod to drive the layshaft out

A piece of wooden dowel of roughly those dimensions works fine.  It's only to keep the rollers in place as you say.  I'd do it anyway.  You know where they all are that way!

DO NOT junk your old layshaft unless it's actually really knackered.  If it's just burnished (marks you can see but not feel) or even just slightly pitted, it will still be better that the rubbish available today - and you can spin it through 180º (rotationally) so the high loads are taken on the opposite side.  If it is properly knackered then chopping it off short makes the perfect tool.  I have one in my special tools drawer.

How much wiggle is there on the tip of the input shaft?  This gives clues about the state of the mainshaft tip bearing.  Nice work on the clutch slave btw - that's a trick I use on stubborn brake calipers.

Nick

[Peter Truman]

any feedback on the selector fork thickness, interested from a future reference standpoint some 25years ago I brought my son an Alfa 33 when I had the engine rebuilt by an Alfa mechanic on checking the gearbox he advised the gear selector forks were badly worn and replaced them, he indicated the wear was a known Alfa driver issue ie young hot heads holding the gear knob whilst driving kept the forks in contact,

 

[NonMember]

It's hard to say just from the photo. How do they compare with the slot in the hub? They don't look too bad to me but I'm no expert.

[Colin Lindsay]

21 hours ago, ahebron said:

[]\( * )/[]

Reminds me of the rear view of the neighbours floppy-eared dog...

[Pete Lewis]

if the old shaft is worn yes cut it down as a dummy, but as said dowel even a bit of hose will work to aid refit

if the 3rd gear circlip has failed no need to strip it all down unless you really need to  you can fit new clip with the mainshaft in the case 

but have to drop the cluster to knock the stem gear out , when using a drift to punch bearings out take care to keep it in the case cut outs and away from the chip shields 

 

had a look at the rear circlip yet is it ok ??

Pete

[Ingieuk]

14 hours ago, Nick Jones said:

I use a 1/2" open end spanner sat vertically in the ring gear at the top.  Its jaws drop neatly into the teeth and its shoulder wedges perfectly under the top-most bellhousing stud.  Then just flip to do up again.

 

That's the chunks you found.  Don't worry about it!

 

A piece of wooden dowel of roughly those dimensions works fine.  It's only to keep the rollers in place as you say.  I'd do it anyway.  You know where they all are that way!

DO NOT junk your old layshaft unless it's actually really knackered.  If it's just burnished (marks you can see but not feel) or even just slightly pitted, it will still be better that the rubbish available today - and you can spin it through 180º (rotationally) so the high loads are taken on the opposite side.  If it is properly knackered then chopping it off short makes the perfect tool.  I have one in my special tools drawer.

How much wiggle is there on the tip of the input shaft?  This gives clues about the state of the mainshaft tip bearing.  Nice work on the clutch slave btw - that's a trick I use on stubborn brake calipers.

Nick

Not a huge amount, a couple of mm at the tip. I'll measure the selector fork thickness and see if there are any tolerances buried in the workshop manual. 

 

Got the box stripped down this morning. A bit of threaded rod worked well to push the layshaft out. Layshaft is in very good condition, just polished marks where the rollers were. Mainshaft tip and input shaft inner surfaces look good, no pitting. 

The circlip in the rear extension was in 5 pieces. Likewise the 3rd gear circlip was in 3, it shows evidence of being misaligned and then having something bearing on it as it has some diagonal wear marks on it. 

Another interesting finding was the 1st/2nd syncro hub. There was only two springs and no balls in the hub. Upon removing the layshaft there were two springs and one ball bearing in the bottom. I think they have fallen out during knocking the mainshaft bearing out,however I can't find the other two balls. 

I'll clean it all up and measure all the tolerances tonight

[johny]

Sounding good, are the bearing surfaces in each end of the laygear good as well? Careful with the synchro hubs as there might be very small spacers in the bottom of the holes where the springs and balls go that are used to set the correct spring pressure. Also good to check the synchro rings for wear to their grooves and how far each ring will go onto it's respective gear cone. You could swop the rings around as 2nd and 3rd usually have had the hardest life...

[Pete Lewis]

who said circlips then   pleased you got the culprit

balls may have escaped as you  had excess endfloat and possibly the sleeve has overstroked  allows the things to ping out and escape .

the release loads are in the manual  easy to test while assembled in its poly bag !!!  just press on the bathroom scales or if knowones looking the kitchen  scales 

just press to click pop the sleeve over the detents and watch the load reading , 

Pete

[Ingieuk]

5 hours ago, Pete Lewis said:

who said circlips then   pleased you got the culprit

balls may have escaped as you  had excess endfloat and possibly the sleeve has overstroked  allows the things to ping out and escape .

the release loads are in the manual  easy to test while assembled in its poly bag !!!  just press on the bathroom scales or if knowones looking the kitchen  scales 

just press to click pop the sleeve over the detents and watch the load reading , 

Pete

I know! Excellent deduction. I guess this would give sufficient movement to prevent 2nd gear engaging. This all started when I was slowing down for a roundabout, I wonder if with the 3rd gear circlip already well on it's way a (by my own admission) slightly-too-high-revs downshift was enough to say ta-ra to the rear circlip. I guess we will see when it all goes back together, that will be a nervy first drive.

 

7 hours ago, johny said:

Sounding good, are the bearing surfaces in each end of the laygear good as well? Careful with the synchro hubs as there might be very small spacers in the bottom of the holes where the springs and balls go that are used to set the correct spring pressure. Also good to check the synchro rings for wear to their grooves and how far each ring will go onto it's respective gear cone. You could swop the rings around as 2nd and 3rd usually have had the hardest life...

Layshaft bearing surfaces look very good too. I do wonder if this box is a not too old recon. I know the owner previous to me did very few miles. He purchased it from the original restorer. The cases have been (quite poorly) powder coated and its flaking off in a lot of areas but then stuck very well in others. I think it will just get a coat of engine enamel when I'm done, no one will be looking that closely!

Syncros wise I've got a new set coming so unless the new ones are poor quality, this set will be kept as spares.

[Ingieuk]

Tonight I've gone through the checks from the workshop manual. 

Laygear end float 0.356mm (range 0.178-0.330mm). Might need new (just 1? Only need to take a little slack up) thrust washers.

2nd gear end float 0.05mm (range 0.05-0.15mm)

3rd gear end float 0.05mm (range 0.05-0.15mm)

Overall mainshaft bushes end float 0.1mm (range 0.1-0.25mm

1st/2nd syncro detent load 9.8kg (range 8.5-9.5kg)

3rd/4th syncro detent load 10.1kg (range 8.5-9.5kg)

The syncro balls were in the bottom of the case. Think they came out when I removed the mainshaft as if they had come out before I would have seen them when I looked through the oil I dropped out. No shims on any of them. Good thing really as the springs fell out of 1st/2nd and I don't know where each came from. 

Just drawing up a parts list that are not covered by the jamespaddock overhaul kit. Also trying to decide if I tackle the selector fork mechanism or just leave it. Anyone know if the square headed bolts that secure the selector forks locate in a recess in the shaft? Don't want to mess up any alignment unnecessarily. Though even I find the tolerance for the fork ends I may need to replace them anyhow. 

Thanks for the ongoing help. 

Rich

[johny]

1 hour ago, Ingieuk said:

I know! Excellent deduction. I guess this would give sufficient movement to prevent 2nd gear engaging. This all started when I was slowing down for a roundabout, I wonder if with the 3rd gear circlip already well on it's way a (by my own admission) slightly-too-high-revs downshift was enough to say ta-ra to the rear circlip. I guess we will see when it all goes back together, that will be a nervy first drive.

 

Layshaft bearing surfaces look very good too. I do wonder if this box is a not too old recon. I know the owner previous to me did very few miles. He purchased it from the original restorer. The cases have been (quite poorly) powder coated and its flaking off in a lot of areas but then stuck very well in others. I think it will just get a coat of engine enamel when I'm done, no one will be looking that closely!

Syncros wise I've got a new set coming so unless the new ones are poor quality, this set will be kept as spares.

Wonder if we're talking about the same thing here. I've just opened up a box and the layshaft is very good and must have been replaced at some stage but the LAYGEAR surfaces are shot. Mind you don't know what I can do about it anyway!

New synchros can look great but but have a reputation for being the wrong material spec and not lasting very long....

[Ingieuk]

7 hours ago, johny said:

Wonder if we're talking about the same thing here. I've just opened up a box and the layshaft is very good and must have been replaced at some stage but the LAYGEAR surfaces are shot. Mind you don't know what I can do about it anyway!

New synchros can look great but but have a reputation for being the wrong material spec and not lasting very long....

Sorry that's me getting mixed up. The layshaft is in good nick, as is the bearing surfaces inside the laygear. 

The laygear seems like a part that is quite difficult to get hold of, none of the usual suspects (Canleys rimmers etc) stock recon ones. I wonder if an engineering fabricator could skim the bearing surface for you? That might mean new slightly larger rollers. I wonder if that area is surface hardened and how deep it goes?

I need to measure up these syncros, by eye they go further onto the cones than I thought they would. 

[Pete Lewis]

the problems with some repro baulk rings is they were turned in a lathe held in a 3 jaw chuck this distorts the ring and you get a lobe effect with will not Ring( twist and press) gear cone they must be turned on a mandrill so fully supported 

we used a firm called Otto Fuchs the only material to pass any testing  our geabox manufacture ceased in 93 so no idea who makes the stuff now

but rimmers sell german baulkrings which i have in the 2000

many suppiers offer  two standards at two prices

if there was no clashing before it failed i would stick with what you have 

on the sleeve and dog teeth its important the teeth/spline had a well define 55deg ??    chamfer  /\/\/\ not chimbled 

pete

[Ingieuk]

Interesting stuff. I'm starting to think I shouldn't have ordered the rebuild kit now as I'm only going to use the needles, circlips, bearings, one thrust washer and oil seals. Leaving a thrust washer, lay shaft, four syncro rings, syncro springs and syncro balls languishing in my tool box. 

I also have a circlip conundrum to work out. The circlip at the rear of the extension that was in pieces is around 3mm thick, the circlip groove is 1mm. It looks like it should have the same type with the two little eyes as on the rest of mainshaft (other than 3rd gear). The question is which one is right? The exploded diagram doesn't reference this circlip at all so I have part numbers to go off. 

I've attached a pic with both types and the requisite groove for comparison. 

[johny]

Theres no circlip on the rear bearing it's just the spacer that comes up against the shoulder at the end of the shaft and then the bearing pushed on next all clamped together by the flange nut. The bearing is fixed on the shaft but can move in the housing to allow for thermal expansion...