Scimitar mission creep

[Escadrille Ecosse]

10 hours ago, thebrookster said:

You only get full points if you complete the gearbox rebuild outside on a windy moor, bare-chested, wearing the kilt and using the sporran for tool storage. 

Sod that for a larf ..... 

[Nick Jones]

1 hour ago, Escadrille Ecosse said:

Sod that for a larf ..... 

At least he left out the bit about beating yourself with a gorse branch…. 
 

Not had the “pleasure” of dealing with an LT77 to date but I am going to have to learn how to fettle MX5 gearboxes, and maybe even a W58. The latter isn’t as slick as it once was. It’s done about 200k - the last 50 with me.

[Escadrille Ecosse]

10 hours ago, Nick Jones said:

At least he left out the bit about beating yourself with a gorse branch…. 

I think that bit is generally best left out....

10 hours ago, Nick Jones said:

I am going to have to learn how to fettle MX5 gearboxes, and maybe even a W58. The latter isn’t as slick as it once was. It’s done about 200k - the last 50 with me.

Hmmm. No experience of either but gearboxes are always an 'adventure'. The worst I ever had to work on was a 5 speed Austin Maxi. If for no other reason than there were a number of internal nuts all of which seemed to be torqued to 200+ lbft.

As for the LT77 as well as Mr Haynes finest I also found an excellent forum topic by a lad doing the stripdown and rebuild of one. It's actually from Defender so there are a few differences but he also does TR7 boxes (which mine is) and has pics of those too.

Got on with the stripdown today. On the whole it has been pretty straightforward aside from the sheer weight of the bloody thing. Needs to get held in the vice for some of the work and lifting up high enough for that was challenging.

My universal flange removal tool in action

Then the rear case comes off to access the oil pump and 5th gear set. All looked pretty good there although some obvious wear on the teeth of the eccentric gear pump.

Then the front cover plate comes off. Front main and layshaft outer races showing signs of wear. probably cauget just in time.

Then the thing needs lifted into the vice to remove the main case

This was probably the worst/most frustrating part of the job so far. I could not get the case separated. In the end I put the front cover back on with a spacer on the layshaft and gently tightened up the bolts. Lifted very easily on the dowels so took it all off to find that the weight of the case had dropped the damn thing back down tight. So back on with the front cover. Still a nightmare to remove as it turned out that the dowels which are supposed to stay in the centre plate decided to come out with the case. And they are very long.

Getting the main and layshaft out after that was easy.

Spent the rest of the afternoon cleaning the case, centre plate, etc and removing the bearings. The bars on my bearing extractor aren't long enough to get the mainshaft centre bearing off so I have ordered a couple of bits of threaded rod from ebay. Something I have been meaning to do for ages anyway. And I have still to pull the taper race out of the back of the input shaft.

The gearbox internals seem to be in excellent condition on the whole. Nothing chipped or broken and no real wear on any of the selectors, etc. I suspect the box was overhauled at some point in its life perhaps. Although I have still to get the 1st/2nd selector off it is obvious why 2nd gear had become so slow to change as the clearance on the synchro is at least half that of the first gear.

[Nick Jones]

House bashing (on a fairly grand scale) during the week...... gearbox wrestling at weekends.  Retirement seems like hard work....... 

Gearbox looks like it will live without a huge parts spend..... a stitch in time.....

[Escadrille Ecosse]

Got the mainshaft stripped down and everything washed in petrol followed by acetone yesterday. Stinky smelly job.

Then today started putting it all back togther which has gone mostly OK so far. Interesting comparison between the old and new synchro rings. The new ones don't have the machined ridges instead they have a coating of some kind. I checked the synchro clearances for a comparison. Old 2nd gear was .025", 5th gear .035". New synchros 0.040" so hopefully that does the job.

Fitted all the bearings and then started re-assembly on the workmate instead of the bench/vise. If for no other reason than I don't have to lift the bits quite so high!

That was the second attempt. The mainshaft goes in with the selectors and rail. Far too many degrees of freedom and as a result 1st/2nd synchro hub got bumped and displaced one of the slippers. In trying to get it back the whole bloody thing exploded and I spent the next hour trying to find the one missing slipper - including going through the waste bin. Had pretty much given up finding the damned thing when I moved a rag on the workbench for about the nth time and there it was. Just lying there laughing at me.

So back together and time to put the case on. Which was a bit of a trial as it needed pulled in on bolts against the very tight dowels. Only to find that I forgotten to put the bloody first motion shaft back in after the synchro hub incident! So lever the case back off and, shaft in and back together. Then try to fit the selector spool retainer in the top of the casing only to find the spool has turned round and slipped out of the reverse fork. Oh for forks sake! So off with that bloody case once more, sort the spool and this time all goes in right. At least it cleaned up the dowels a bit.

Main case assembled and held in place with temorary bolts until I get 5th gearset fitted and the rear end on. Then it's round the front end to set the main and layshaft pre-loads.

 

[Nick Jones]

13 hours ago, Escadrille Ecosse said:

moved a rag on the workbench for about the nth time and

 Not just me then….

In fact…. Sounds pretty much like my normal gearbox assembly procedure…. Start in hope and optimism, rapid descent into frustration, followed by protracted battle ending in profound relief about 3 hours after it should have…..

Practice makes perfect. 1 gearbox every 3 or 4 years doesn’t count.

[Escadrille Ecosse]

10 hours ago, Nick Jones said:

Practice makes perfect. 1 gearbox every 3 or 4 years doesn’t count.

I think you have hit the nail squarely on the head with that one.

[Nick Jones]

Especially when they are entirely different gearboxes.  My total tally goes something like....

Spit 1500 OD. About 3. A long time ago.  All fairly successful, though simple re-arrangement of the least knackered parts available tends to mean you get to repeat the jobs fairly soon when you are beating the machine without mercy!

Vitesse/Dolly 1850.  Various combinations of 3 rail and 1 rail, D and J -type. About 5. 4 a long time ago, one about 3 years ago.  Mixed success.  Start point is almost always very damaged.

Spit IV with D type.  About 5 years ago.  Still going with Alan OTU's oilite spigot bush.  Synchro could be better.  1/2 hub set too slack.

Golf GTI Mk3.  About 12 years ago.  Actually pretty easy, though I was mostly in there to swap out the reverse idler for one that actually had some teeth on it.

VW 085 from a Seat Arosa. About 8 years ago.  The full monty and a bit of a bastard with some DIY-hostile feature, but very successful in the end.

Tinkering around the edges of an MX5 NA.  Didn't really get into it fully and turns out I should have.  Unfinished business......

Planned:

Learn how to do MX5 ones.  Parts not readily available.

Learn how to do W58.  Parts available but pricey.

[Escadrille Ecosse]

A little more progress on the gearbox. But not as much as hoped unfortunately.

Got 5th gear assembly fitted. The layshaft gear, its spacer and the synchro hub are all a very tight fit on the splines. So as when I was fitting the bearings they got a gentle heat in my slow cooker .

Not the houshold one I must add but a cheapie, originally bought for the purposes of melting chain wax for bicycle chains it has turned out to be £13 very well spent.

However I hit a snag in that I was unable to get a replacement circlip for the 5th gear synchro hub which is part of the end float restraint. And on reassembly found that it is not only very slack but also quite worn from turning on the shaft. Presumably on account of being slack. 'Adjusted' it back which mostly sorted the grip on the shaft and turning it over fixed the axial play but not very happy about it. It is of course an odd size. After much hunting of the web I have found a replacement which is ordered. But means finishing off assembly of the back end on hold.

So over to the front end which requires setting the preload on the main and layshaft bearings using selective spacers. Fight faff of a job.

Mainshaft set up with the dial gauge (I actually put a ball bearing in the end of the shaft to get a better measuring surface) then lever the it up and check the float. And repeat many times to get a 'good' reading. Then a case of adding up the float, spacer thickness and preload value (in this case 0 to 0.001") to work out the required new spacer then hope it is still available in the size you want. And repeat for the laygear which needs a preload of .001" to .002".

If you need a thinner spacer than the one you have it's going to be a bit of a swine to measure - the book helpfully assumes you have access to the full set. But 'fortunately' both mine are slightly thicker and both are available. So ordered today but front end held up until they arrive.

In the meantime I am going to set about cleaning up the block to get that ready for the engine rebuild.

[Nick Jones]

Progress is progress….

Shims are a PITA.

 

[PeteStupps]

On 9/18/2022 at 2:12 PM, Escadrille Ecosse said:

So as when I was fitting the bearings they got a gentle heat in my slow cooker .

For a moment I thought this was a pic of the bellhousing! Maybe for a slightly smaller engine & box combo...

Sounds like fun and games anyway, hope the rest of the rebuild goes smoothly.

[Escadrille Ecosse]

15 minutes ago, PeteStupps said:

For a moment I thought this was a pic of the bellhousing! Maybe for a slightly smaller engine & box combo...

3 minutes ago, PeteStupps said:

Sounds like fun and games anyway, hope the rest of the rebuild goes smoothly.

Ah well....

Layshft shim is available in the size I need. Mainshaft shim is actually not available. Bugger. So I ended up ordering a thicker shim that needs grinding down. By 0.32mm which is too much to do myself on a stone so another trip to the machine shop required. But I am stuck at the house today waiting on a delivery - sometime between 8am and 6pm. And it's the August bank holiday on Monday.

And also got an email informing me that the circlips are also not available now.

Good news is that I got the crank and flywheel back from the machine shop yesterday. 10 thou grind on the crank, flywheel refaced, clutch dowels replaced and everything washed in the tank. All for 100 quid.

 

[Nick Jones]

8 hours ago, Escadrille Ecosse said:

Good news is that I got the crank and flywheel back from the machine shop yesterday. 10 thou grind on the crank, flywheel refaced, clutch dowels replaced and everything washed in the tank. All for 100 quid.

Bargain!!

How can circlips be NLA?

[Escadrille Ecosse]

On 9/23/2022 at 6:53 PM, Nick Jones said:

How can circlips be NLA?

Quite. A rather odd size but nonetheless. In the end I nicked the one from the spare gearbox which is also a little worn but not as badly. Hopefully they well become available again soon. A relatively simple job to swap out.

Meant I could get the back end of the gearbox rebuilt and now it's just waiting on getting the shim ground to size.

Then got back on to the engine at long last. Bit of cleaning of things like the sump and timing cover before swapping out the cam bearings.

Made up a tool from various bits knocking around the garage (including bike bottom bracket tools!) and pulled in the new ones while pushing out the old ones. All except the rear bearing which has a very wide land. So I knocked out the blanking plug then removed the old bearing before pulling in the new one and replacing the plug.

Used masking tape to protect the bearing surfaces but otherwise all went very smoothly.

The old bearings were worn very oval.

[Escadrille Ecosse]

Gearbox shim grinding proved to be quite awkward to get done. However it occurred to me that the 77 in LT77 referred to the shaft spacing and maybe the bearings were also a common metric size?

Turns out the mainshaft bearings are 62mm OD which is a DIN size and it is possible to get generic shims in various standard thicknesses. Using one of the thinner Rover shims I could make up the difference with a 0.3mm and 0.25mm shim.

Got them fitted and the gearbox reassembled bar the remote.

This is a cut down (about 6 inches) to suit the gearlever position in the Scimitar. Shortening the linkage to the lever was a bit of a bodge I was never that happy with so going to make up a revised version before it all goes back in the car.

And making slow progress on the engine. Replace the core plugs and yesterday got the crank in

Along with cleaning up and installing four of the pistons.

[Nick Jones]

58 minutes ago, Escadrille Ecosse said:

Turns out the mainshaft bearings are 62mm OD which is a DIN size and it is possible to get generic shims in various standard thicknesses

Yes…. Good find.

Excellent progress being made.

[Escadrille Ecosse]

Some more progress over the weekend. Along with some further issues to address

Pistons in, cam and timing cover/water pump/oil pump on and the 'good' ie no bent valves cylinder head cleaned up and fitted.

The standard oil filter fouls the steering rack so I fitted a remote filter with an adapter on the filter head. Unfortunately I could never get this to seal 100% so I splashed out on a Mocal remote plate that bolts directly on to the pump body. This required the purchase of couple of right angle hose fittings. The standard body has a threaded connection for the fuel pump pressure switch and one for the pressure gauge. The new one has only one. So either a T piece or tap the boss for the second one. Not decided yet.

The other issue is the pressure switch which is the SD1 type and has three connections and is now NLA. Only single pin ones are available. I modded the wiring loom for the pressure switch last time around and looks like I'll have to do it again to drive a remote solenoid. Bugger.

The other problem to fix is the manifold. The left hand one was a right sod to get off. Turns out it doesn't quite match the port spacing. On my engine version the dipstick fouls the bar that joins the front and back pair of manifold flanges so it was cut off by the guys who fabbed up the manifold. And it obviously distorted. So I bought a cheap MS flange off ebay and welded a bit of tube to the back as a brace. I'll take it back to the fabricators for them to do the 'adjustment'.

[michaeljf]

Hello Colin, Looks like you are tackling the problems well as they arise. Hang in there. Regards, Michael.

[Escadrille Ecosse]

Too much on at the moment but I cleaned up the second head yesterday and replaced the two offending valves. The issue is quite visible

[Nick Jones]

8 hours ago, Escadrille Ecosse said:

The issue is quite visible

It is….. It’s going to work better with the straight one.

[Escadrille Ecosse]

Spent today on the gearchange for the box sorting the various issues that made the shift even less precise than that supplied by the factory.

To get the lever in about the right place I had to shorten the remote by quite a bit.

Which also meant modifying the selector rail extension. This was my Mk1 version. Unfortunately I couldn't get a really tight fit onto the main rail and it just got more sloppy over the years.

So I made upt a Mk2 version which can be securely clamped to the flats on the main rail. And replaced the worn ball and socket with good second hand ones.

Next issue was doing something about the crap design of the lever retaining cap.

The little tab breaks off not unsurprisingly and the lever then floats around, which is exactly what had happened to the one that was on the box. These are now unobtainable, because they break so often, but I had a spare and to prevent a repeat I made up a reinforcing bracket that got spot welded on.

Only thing left to do now is set up the lever centering spring positions and fit and set the reverse detent plate. Both of which are straightforward but time consuming.

[Nick Jones]

Time consuming details that are so worthwhile 

[PeteStupps]

Proper mission creep! But definitely looks worth the effort. That reinforcing bracket on the lever retainer is very tidy indeed.

[mpbarrett]

On 10/30/2022 at 7:22 PM, Escadrille Ecosse said:

Spent today on the gearchange for the box sorting the various issues that made the shift even less precise than that supplied by the factory.

To get the lever in about the right place I had to shorten the remote by quite a bit.

Which also meant modifying the selector rail extension. This was my Mk1 version. Unfortunately I couldn't get a really tight fit onto the main rail and it just got more sloppy over the years.

So I made upt a Mk2 version which can be securely clamped to the flats on the main rail. And replaced the worn ball and socket with good second hand ones.

Next issue was doing something about the crap design of the lever retaining cap.

The little tab breaks off not unsurprisingly and the lever then floats around, which is exactly what had happened to the one that was on the box. These are now unobtainable, because they break so often, but I had a spare and to prevent a repeat I made up a reinforcing bracket that got spot welded on.

Only thing left to do now is set up the lever centering spring positions and fit and set the reverse detent plate. Both of which are straightforward but time consuming.

lots of good work going on.

What does the bent bit of rod with the end sitting on the two bolt head either side of the gear selector, do?

mike

[Escadrille Ecosse]

2 hours ago, mpbarrett said:

What does the bent bit of rod with the end sitting on the two bolt head either side of the gear selector, do?

It's the hairspring for the gear lever bias. The bolts set the height of the fingers which set the neutral position of the lever.

OEM is at the 3-4 gate although personally I think 1-2 is better