Ingieuk

Little update. New syncro rings on, new 3rd gear circlip, box back together including rear extension (laygear shaft still not fitted). Even with the 2nd syncro the right way round the reverse idler is still catching, albeit not as much. It seems the neutral point for the reverse idler is too far towards the front of the box. It's a few mm off the distance piece that keeps it out of 1st. If I push the selector arm so the idler is hard up against the distance piece it sits nicely in the gap. So it seems the reverse arm needs adjusting? However from what I've read the adjustment most people make is to bend the arm inwards towards the mainshaft (perpendicular to mainshaft). Whereas I seem to need to push it towards the rear of the box (parallel to the mainshaft). Any ideas? I may also remove the mainshaft and try the original reverse idler again. Current one is a pattern part from rimmers.

It is a relief being able to take unlimited numbers of photos (even if you always miss the key ones). Not sure what I'd have done if I had to get them developed. I certainly wouldn't have taken as many! Managed 40min this morning and have got the box stripped again. I'm tempted to replace the syncro rings whilst I'm in as the new ones I have leave a 1.2mm gap between the engagement teeth on the gear cone and the syncro ring teeth on new syncros and nearly 0.5mm gap on the old ones. I'll try and get a bit better accuracy than 0. 5mm but it's not far off. Once the mainshaft and input shaft are back in I'm going to put some thick Ali plate over the reverse idler shaft to hold the Bush flush and check the 1st gear and syncro hub clearance.

No worries Pete, I should have been more careful noting which way round things were when I took it apart! I hope so Nick, I really do. I'm just waiting for some parts from Rimmers (new gasket set, new circlips, new nyloc) before I strip the box totally. Having got the box out and rear extension off the reverse idler distance piece measures 23.68mm. This is close enough to the 23.98mm original size of the three rail for me. There is no binding on the 1st gear to speak of. The replacement idler is of the same size and teeth as the original. The actuating arm is a slightly loose fit in the idler groove, but can't really do much about that as they are no longer manufactured. Things are going to slow up a bit as I'm staring down the barrel of three or four unexpected night shifts at work. This means my precious 90min a night in the garage after our 1 year old is in bed has gone. Never mind!

I do agree it's an odd design choice and therefore unlikely. It needs to be right this so it sounds like box is coming back out agin😔 I have identified through photos the 1st/2nd syncro hub is the opposite way around to what it was before I stripped the box. You can see from the wear groove if you look closely at the pre strip photo below compared to the post strip one earlier in this thread. Given the hub boss is not even I wonder if that would make a difference. Either way time for the box to come out again.

It certainly could I guess. I'm just not clear on if the syncro sleeve meshing with the idler is by design or not and if it is okay?

Okay so am I right in thinking the syncro sleeve and reverse idler should not be in mesh when in first gear? I found this thread: Which then links to a further thread: https://www.triumphexp.com/forum/spitfire-and-gt6-forum.8/close-ratio-spitfire-gearbox.927491.1259499/page-6#msg-1259499 Which mentions the syncro sleeve and idler are supposed to be in mesh in 1st gear. I can make my peace if its by design, but if its not I'd be worried about trashing something leaving them in mesh? I don't believe the reverse idler is contacting the first gear as I'm sure the distance piece is the correct 3 rail length. From recollection if the mesh was about 3mm the reverse lever must be really bent? Odd it didn't do it with the old idler. So close yet so far! Thanks as ever for this gold mine of experience I can tap into. This car is my pride and joy, plus 18 years my senior so I'm glad there is still the knowledge out to help people look after them!!

This was a photo I took on Thursday before I refitted the top cover. Selected in 1st with the idler and 1st syncro sleeve meshing by about 3mm.

I won't worry too much about those springs then! Still if the box is coming back out I'll get them fitted. It's odd that I didn't notice the sound before the box rebuild if the reverse idler was spinning, but then again there is a load of thick matting, a fiberglass tunnel and a thick carpet between me and it normally. I didn't compare the size/shape of the old and new idlers before I fitted them. Maybe it will quiet down as it beds in. I'll see if I can find those other threads, didn't realise it is a common issue.

I've not put an update on where I've got to for a few days as I've been busy with work. The gearbox is back together, refitted in car with new clutch and overhauled master/slave cylinder. We have had partial success. The good: No oil leaks 2nd,3rd,4th lovely and quiet. Changing down the box seems no problem. So initial indication is the original problem is solved. However... The bad: I accidentally left out the three springs that are fitted before the bell housing and bear upon the layshaft front thrust washer. Doh. 1st gear is a lot noisier than previous. When I was putting the box back together I fitted a new reverse idler (rimmers) no issues with the fitting. I think the reverse idler is turning when the 1st/2nd syncro hub is selected in 1st. Is this right? The idler was also close to the first gear but I thought the reverse actuator would stop it touching. Thanks, Richard

Thanks for the detail on the syncro Pete, good to have a cutaway diagram! Initial impressions of the rebuild kit from James Paddock is good, I'll see how we get on. The bearings are smoother than those that came out, even if they might not last as long. I'm thinking of getting a new reverse idler, I'd hate one of the damaged teeth to fail and wreck all this work. This washer could become a problem though. It is 1" O.D. 7/8" I.D. 1/8" thick, the usual suppliers all state 'no longer available'. I imagine given how it failed it's hardened steel. Any ideas where I might get one? Or even get one made?

No, came off easy with a open spanner and a soft mallet. It is tight that nyloc nut like. I guess you have to be careful not to damage the oil seal too. I found some details that the spacer is 1/8" thick. It's number 29 in attached photo. Definitely lower profile than the main bearing spacer number 26.

Good spot! I'll see if I can find any dimensions for 155756 online.

Ah, okay. So what I thought was a broken circlip is actually a broken spacer. I did think it was a beefy circlip. I'll need to try and source one of those then, part number 155756. Unfortunately Canleys do not stock them. I'm sure I can find an equivalent somewhere. I wonder if the 3rd gear circlip has allowed the shaft to slide back and break the spacer.

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.

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.

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

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.

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

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.

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.

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

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).

Luton might be a bit far! Nevermind let's do it in a socially distant manner on here Thanks all for the help and anecdotes, all very interesting! I spent most of last night getting the box ready to come out. Starter motor off, propshaft flange joint loose, rubber mounts loose and all but two bell housing bolts removed. Just need to remove the slave clutch cylinder tonight and will get the box out tomorrow (with socially distant help!). I've ordered a rebuild kit from James Paddock which includes bearings, needle rollers, syncro rings, layshaft thrust washers, new layshaft, new oil seals, gaskets and circlips. Anything else I should be looking at while I'm in? Master/slave cylinders will get an overhaul, new clutch to go in, new rubber gearbox mounts. Lots to be getting on with over the next few weeks. Rich

Wow okay, it is at its limit then! As it happens when I last changed the gbox oil in 2016 I found a very small piece of circlip, 1mm long. I happened to keep it, and comparing thickness it's identical to the larger piece found today (1.78mm). So maybe this has been on its way for a while!

Yes I think the box is coming out now. Looks like the front oil seal in the bellhousing is leaking too after getting under car. I'm up in the North East near Stokesley. Fingers crossed its the reverse gear then! Didn't realise the 6cylinder gearbox was a weak point! Is it the same box for the 1500 spit just with an extra 2 cylinders and 0.5l?