Esprit Turbo project car - part3 - the further continuation

[LOTUSMAN33]

Fabian

A good engineering shop can grind to those tolerances using a mag plate to hold.

Trouble is the Covid lock down so the shops are generally shut at the moment.

Once this chaos is over I can do for you if you’re happy to wait?

Dave  

[drdoom]

Have you mike'd the rotor and annulus for thickness measurement? We'd be the better for having that data in our trove.

[Lotusfab]

14 minutes ago, drdoom said:

Have you mike'd the rotor and annulus for thickness measurement? We'd be the better for having that data in our trove.

No. I can measured and post the thickness of the new rotor and annulus if its of use? The trouble is the part thickness may vary unless it comes from the same manufacturer, which is doubtful. 

Thanks for the offer Dave. I will get my mate who has an engineering shop to grind off 1.5 thou from the rotor. I'm not accepting anything less than perfect on this build! Heres some bits! 

I measured the free length of all the sprngs and had to replace about 60 per cent! They have been cleaned and are ready for reassembly. The crankshaft has been cleaned and is ready to go.New liners, Mahle pistons, new rings, new bolts! I bag all parts now, until they are ready for install. I even wrap the engine! 

When it comes to setting the seal to 2.5 mm a two pound coin is exactly the correct width! 

[Lex Templar]

On 04/07/2017 at 21:18, stephenwhyte said:

Here you go Fabian

Fabian, just going back a long way in your thread. I recently discovered the early Turbo cars and post 81 cars have a different vent shape under the bonnet..the early cars share the s1/s2 arrangement and the black bits are different slightly. Just a bit of trivia really.

 

[Lotusfab]

Studs in and torqued. Apart from four that I need to get. Work stopped till I can get them! 

[drdoom]

Looking good so far! Valve springs are among the most stressed components in a car so good thing to be particular in that regard. As to the oil pump bits it seems to me that the thickness would be a critical dimension, hence the request for data.

Cheers

[Lotusfab]

Andy measured his old rotor and annulus. The rotor was almost a thou thinner than the annulus. Taking into account wear I believe the rotor was thinner than the annulus when new. Because the new annulus and rotor are the same thickness the rotor end float is insufficient and make the pump tight. The fix on the box  is to use two gaskets if tight. This puts the whole this out of spec. So its off to the engineering company! 

Have measured the big end clearances using plasti guage. They are all bang on in the middle of the spec. The end float on the crank is just under 4 thou with std thrust washers,  very pleased with that! Just need to check the main bearing clearances. Coming together nicely! 

Sweet!

[Lotusfab]

Really clean!

[Paul Coleman]

Well, what else would you be doing in lockdown?

[Lotusfab]

10 hours ago, Paul Coleman said:

Well, what else would you be doing in lockdown?

Its helping my resto no end!

[Lotusfab]

Seal done. 2.5 mm.

[Lotusfab]

Oil Pump

Well I can confirm the replacement rotor is in fact manufactured incorrectly. I measured the end float with plastiguage, previous readings on here. I have just measured my old rotor on the inside where there is no wear and the new one. Heres the result, in inches - no I'm not American but I find it a lot easier! I concluded from the plastiguage I needed to take of 1.5 Thou from the rotor. I did not adjust these figures they are straight of my digital micrometer.

 The new rotor is exactly 1.5 thou thicker than the old one! The solution of using two gaskets cannot work as it puts the pump out of spec. With my pedantic engineering hat on I plan tonhave the machine shop adjust the rotor to the correct thickness. Beware of any off the shelf parts for this car. I have found so many issues with them. On another note I have to say Dave Changes has been keeping a close eye on this build, for which I am very grateful. Thank you, very much appreciated.👍

[Lotusfab]

My mate didn't have a grinder. Oil pump rotor now 0.5023 inches. Done with wet and dry paper 400/800/1200 and a flat surface with a digtal micrometer. I took measurements of all sides constantly to ensure it was brought to spec evenly. It took a couple of hours. Placing pressure only on the centre and rotatary motion. Alll reassembled now and spot on brand new end float and tip clearance specs.

Now packed with graphogen and ready for install! 

[red vtec]

On 09/04/2020 at 12:44, Lotusfab said:

Was the wet bike in the movie? Odd its there otherwise!

yes it was actually the first ever wet bike!

[Lotusfab]

One of the used camshafts I bought is unusable! I believe they can be welded and machined back to spec, but I don't have any experience of this and its bound to be expensive. I measure the diameter of each bearing and cam housing opening. Interestingly I found the bearings are all different diameters reducing from front to rear. It was designed like this probably to help inserting the shaft in the housing. One cam shaft was about  0.05 mm smaller than the other camshaft, due to wear. With the housing cleance being 0.05 to 0.09 mm I cant use this camshaft. So guess I'm looking for another one! 

There is an internal grub screw inside each camshaft. This must be removed so you can clean all of the oil ways. 

Getting there though. Like all these things if you are going to do it properly you have to take your time and it takes as long as it takes. I would be streets ahead on this now the big problem being getting parts due to the lockdown.

 

 

 

 

[Lotusfab]

Gearbox

remember I rebuilt this. It was smooth, gears worked really well and it was quiet. When I took the engine out I drained the gearbox oil and found glitter like flakes on the sump plug. This might well be ok, but I took it to a specialist. I asked them just to check where the flakes were from the pinion height, backlash and preload. When I got there they stripped it, so I couldn't take it away and said it needed a full rebuild- which I was sceptical about. Anyhow, they rebuilt it and found some issues.

We had some disagreements in between, probably because I know a lot about it! Anyhow when I went to pay them they said they had taken their replacement bits out and were returning the box! I asked them why and they said it was because I was liable to find a problem with their work. Interestingly they offer no gaurantees on their work, just parts! Very strange behaviour indeed. Be careful who you pick for these jobs. I gave them a fully serviceable gearbox and ended up with a pallet load of bits! Anyhow, they do know their stuff they just have an unacceptable way of doing business. They did identify issues that I had missed. As usual stuff that isn't in the manual. Anyhow I have forgotten about them now and am rebuilding the box again. Like the engine build I now know so much more. I already have the pinion shaft all back together and installed. I need some parts. Could easily rebuild it in a day if I had all the bits.

Heres what I gave them and what I got back.

So for anyone who wants to rebuild their gearbox its not difficult if you spend time studying the manual amd the internet.

Heres the bits you won't find in the manual.

The Synchros have a radial sequence. There are three detents inside each of the synchros. They must line up with the ball bearings so there is a synchro neutral postions. The synchros can be measured for wear by the gap between them and the gear. 

The sychros take some sideways loads and have a thrust face. This needs to be checked when you inspecting them.

the selector shafts can only be pulled outbone at a time unless you remove all of the interlocks, which isnt necessary! 

Pinion height is set uing the lotus tool. No one has this. So look t the end of the pinion. On it is scribed a number. This is the distance from the face ofvthe pinion head to the line of the gearbox face. So there are many ways to meaure the pinion height. I used a straight edge cross the gerbox half and had made a piece of plastic rod 63.95 mm long using a micrometer. I used this tomcheck the pinion height. Before you measure you must hve the distance washer installed in the shaft, the speedo nut done up to torque and the pinion shaft pushed fully forwards so the rear bearing is in contact with the rear housing.There is no reason other than wear why the pinion height should be wrong. 

After that you set preload. There are two methods. A spring balance or mathmatical. Its difficult in the manual to understand what you are trying to achieve as it always refers to dial guages and lotus tools. Well they overcomplicate it and its very simple.

Bearings have to be squeezed together slightly when they operate for optimum performance and life. This is called the preload. Method 1 in the manual means putting distance pieces and shims next to the diff bearings to squeeze them together just the correct amount. Lotus decided if you squeeze the bearings into a distance which is 0.3 mm too short that is the correct loading. This is all method one is trying to achieve. Measure the distance there is between the two bearings and select the correct size distance pieces and shims to squeeze the bearings together.

You can them wrap a cord around the diff, pull it with a spring balance and read of the breakaway loading. Its not clear in the manual whether this figure is with or without the pinion shaft engaged? This is my only remaining question concerning the gearbox. 

The last thing to do is set the back lash. Read easily witha dial guage and adjusted by moving the shims around. These just move the crown wheel closer and farther away from the pinion which affect the free movement ( backlash of the CW). If the back lash is correct the crownwheel must be in the correct place. Lastly smear marking compound on the CW and rotate the CW whilst holdingbthe input shaft to stimulate a load. Look at the tooth pattern. There should be a mark middway on the tooth and central. Job done, easy! 

Im not pretending to be an expert but just writing down what I have learned that may be useful to anyone else who is rebuilding their gearbox. It is of course much easier to take it to a specialist If you know one you can trust!

 

[Lotusfab]

The only other thing I would say is these gearboxes are nearly forty years old. You could fault lots of parts that arent perfect. You have to decide what is acceptable and what isn't. For me if its is smooth, quiet and works properly why replace it? If its not broken don't fix it! Hope this helps.

[Chillidoggy]

You took it to a gearbox specialist because you found glitter flakes in the oil, but that was OK, because there was nothing wrong with it? If there was nothing wrong with it, there shouldn’t have been any glitter flakes in the oil, which could well have been gear case-hardening failing.

[Lotusfab]

The flakes were on the plug. I only took it to a specialist because they said they would check the pinion height, backlash and preload in a day, so I could take it away the same day. When it was taken apart it was clean, apart from some flakes on the ledge next to the reverse gear. I let someone drive it when I took it to get the suspension adjusted. They crashed my reverse gear. I suspect this is where they came from. I wanted a cross check of my measurements and thought it would save me time as I'm rebuilding the engine. It was a big mistake taking it there and would still be in the car if I hadn't had to take the engine out. Still never mind I now have the time to reassemble the whole thing. They even took the diff apart!

Heres my bearing removal to replace the diff bearings. And the detents in the ring.

 

 

 

[Choppa]

On @CHANGES "412BHP that will do nicely" thread two people mentioned glitter flake build up on the magnet in relation to GTO gearbox upgrades as being perfectly normal, its only big slivers that should cause concern

[Lotusfab]

10 minutes ago, Choppa said:

On @CHANGES "412BHP that will do nicely" thread two people mentioned glitter flake build up on the magnet in relation to GTO gearbox upgrades as being perfectly normal, its only big slivers that should cause concern

Thanks Colin. It didn't worry me too much after a full rebuild. Still I have the chance to rebuild it and replace some parts. They might have worked perfectly well ffor the next twenty years, but because its out might as well change them. I managed to get a brand new 3/4 synchro. The diff bearings are so cheap I'm replacing the old ones - even though they are serviceable. I get a second chance to measure the preload and set the backlash! 

[CHANGES]

13 minutes ago, Choppa said:

On @CHANGES "412BHP that will do nicely" thread two people mentioned glitter flake build up on the magnet in relation to GTO gearbox upgrades as being perfectly normal, its only big slivers that should cause concern

 

  On 02/02/2019 at 14:42, cweeden said:

The magnet on the right looks like a nice Christmas tree, is that what you would expect the magnet to look like on any gearbox or is it just that this was bedding in or due to the failure (although I would only expect the bigger bits as per the other picture)? 

I'm asking because mine looked a lot like that shortly after the GTO upgrade a few years ago (but not many miles ago) and I was told it's normal but just checking. 

cheers

-Chris

That magnet is much as i would expect on any box strip, just a bit extra on this one due to failure.   You always seem get a fine deposit on them , nothing to be concerned about..      Any chunky bits or fine slithers is a different matter .  The stuff on the magnet when you wipe it off has a feel more like a graphite than iron filings..  when you rub it between your thumb and finger it should not feel lumpy.  ( which mine did in this case , but expected)....  Hope that helps put your mind at rest.. 

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The above is the  post mentioned ,   What I believe Fabian had was flakes which are more serious and quiet rightly worth investigation..    As I stated above the if deposits on the magnets feel like a grease , no issue , but if any granular or flaky slithers  should be looked at..    

 

[Andyww]

Metal granules could come from the reverse gear being crashed. Every gearbox I have looked at (which admittedly is not a huge number) has the "points" on the sides of reverse idler worn off to some extent, where it has not engaged properly.

[Lotusfab]

Missing parts arrived! So here we go again! I put too much Loctite 518 last time. This time about 1.5 mm bead.

So new bearing half shells, new big end bolts, new oil pick up pipe - slight necking last one, new liners, new pistons, new head studs, new pulleys round tooth, new fixed tensioner! All bearing clearances all checked with plastiguage. Below 1thou on mains! Superb machining by Lotusbits. Just about the right turning force without it being too stiff! I believe the mains clearance increases as ut heats up, maybe Dave changes can confirm? So these clearances need to be spot on to get decent oil pressure.

[Lotusfab]

Thinking of adding a fire supression system before I put the engine back in. In my S1 I installed a life line 4.5 Litre racing system. Would be easy to insall now before all the trim goes in.