Nick's US-spec GT6

[GT6 Nick]

Update time! The gearbox guy warned me in August that he had a lot of work on, and he wasn't kidding. My W58 only came back a couple of weeks ago. New bearings, seals and at least one synchro, and $1200 later it's as good as new.

Before it goes back on the engine and in the car, I'm taking the opportunity to sort out three annoying issues. Only three, I promise.

(1) The Conversion Components kit to mate a Toyota gearbox to a Triumph engine included a clutch thrust bearing carrier, but I was never happy with it. It works, but the carrier slides too far forward on the sleeve around the gearbox's input shaft. It hangs almost halfway off, and I'm worried that as the brass bearing carrier wears, it'll start to tilt and hang up on the sleeve. The solution is to make the W58's sleeve about 13mm longer, which will take some welding and machining. The thrust bearing is also spaced forward on the brass carrier, and again it isn't as well supported as I'd like. 

Hopefully both problems can be fixed by a clever machinist. The alternative would be a concentric clutch slave cylinder, but I'm not sure any of the Toyota-specific kits available would fit my Toyota - Triumph hybrid without some machining. And if anything goes wrong with a concentric clutch cylinder, the engine and gearbox would have to come out. Again.

(2) Before the engine came out, it occasionally made a rapid tapping noise that I could feel through the clutch pedal. Theory A was some part of the dodgy clutch mechanism contacting the flywheel, but no, that's all clear. Theory B was something in the timing gear, maybe the vernier camshaft sprocket's little bolts coming loose. No, they were fine. So Theory C is that the stainless windage tray in the alloy sump is getting tapped by a big end. I haven't put the engine on the stand to drop the sump yet. I don't want to disturb the timing because...

(3) Camshaft timing. I never got around to adding a camshaft position sensor when I first got it on the road. They aren't strictly necessary, but they help with programming and controlling sequential injection. I couldn't add one to the vernier sprocket, because the adjusting bolts stick out further than the little flying magnet. I didn't want to try a pickup on the camshaft's redundant fuel pump lobe, as that would have involved machining the camshaft fuel pump lobe. It's a pretty rare camshaft, a gift from Andy Thompson with PI race history (overkill but sounds awesome and is still very torquey). Running a camshaft sensor on a cut-down distributor introduces uncertainty from the gear drive. But, a few months ago I was watching a Power Nation video on building an EFI Chrysler Slant Six, and they fitted a camshaft sensor to a steel camshaft sprocket.

So that's what I'll do! It means going back to a non-adjustable camshaft sprocket, but standard sprockets have a bit of adjustability depending how they're mounted, and to be honest, I doubt a degree or so will make a difference that I can feel. Something about the perfect being the enemy of the good...

So, watch this space...

Edited January 27 by GT6 Nick
Clarity and spelling

[Nick Jones]

How very excellent to see a post from you Mr Moore! 
 

Confirmation that not only are you alive and kicking but still working on perfecting the mallard monster.

Watching your clutch works with interest as I need to revisit this on my Vitesse W58 conversion although I’m don’t think there are many common parts between the two.

 

[RichardB]

5 hours ago, GT6 Nick said:

Running a camshaft sensor on a cut-down distributor introduces uncertainty from the gear drive.

How much would you reckon this causes a variance in the timing? I opted for the cut down distributor on my Spitfire but admit I hadn't really considered accuracy losses from the gear drive.

Agree with your caution on the clutch bearing, making progress though which is always good.

[GT6 Nick]

11 hours ago, RichardB said:

How much would you reckon this causes a variance in the timing? I opted for the cut down distributor on my Spitfire but admit I hadn't really considered accuracy losses from the gear drive.

Agree with your caution on the clutch bearing, making progress though which is always good.

In truth, I doubt it matters. (Although a proper engineer would want to test that guess with a sensor on the camshaft sprocket and another on a distributor body).

There's a tiny bit of backlash in my distributor gears, probably only a degree or so. If the gears are under continual load from the oil pump, even that tiny amount shouldn't introduce errors. And again, I'm trying to avoid the perfect being the enemy of the good. But in this case, a magnet on the camshaft sprocket is an easy solution.

I'll also weld a crank angle sensor bracket to the timing cover while it's off. A bit of crackle black paint and it'll look factory.

 

[RichardB]

Thanks Nick, makes sense. I do like the idea of the magnet on the cam. The distributor sensor worked great with hardly any effort but it does look a bit odd. Please do share a photo or two once you've got it made up.

Messing around with injector timing settings once the engine is running sequential is interesting. The changes are very subtle and I got to the point where I thought I probably need a more sensitive way of measuring the angle.

[GT6 Nick]

A workmate recommended a local machinist and fabricator, Metal Mik. Mik's workshop was a showcase in metalwork. A custom Model A chassis here, an English wheel in the corner... I showed him the clutch thrust bearing mechanism, and he’s making a longer thrust bearing carrier so that it remains stable and doesn't slide off the end of the input shaft's sleeve. A simple fabrication job, when you have a lathe, mill and block of brass.

Back in my garage, I was able to swap the vernier camshaft sprocket for a solid one. The camshaft had previously been dialled in, and I was able to bolt on the solid sprocket without disturbing the timing. Next, I drilled and tapped a hole in the solid sprocket, and made a sharp punch to mark where the hole in the timing cover should be drilled. Once the cover was drilled, I fitted the flying magnet and locktite'd it in.

A pointy bolt.

A locktite'd magnet.

Unfortunately my current garage isn’t wired for my welder, so I dropped the cover off to Metal Mik to weld on an M12 nut. He’ll also weld some lugs to mount a better crankshaft sensor.

Edited February 16 by GT6 Nick
Clarity

[GT6 Nick]

Small update, and some pondering...

The camshaft sensor and timing cover are done. I've made a cardboard template of a better crankshaft sensor bracket to get replicated in steel - I can cut and fold the steel, but my flat's not wired for welding. I'm still waiting for the new thrust bearing before the engine can go back in. Once again, hurry up and wait. 

In the meantime I've been pondering the EFI. It has Megasquirt, and to be honest that's one reason why the car was built but then the project stopped and the car sat in the garage looking gorgeous. I had a car that ran OK if you babied it, but it needs to be running sweetly before it goes for engineering certification. And it needs to be certified before it can be road-registered. I drove it (illegally) a few times when I lived in country NSW, but I'm not a tuner, and I was risking detonation (high compression) or getting booked by the fuzz. It needed to be set up properly by a tuner. I was slowly figuring it out, but then the gearbox started squealing, so it got tucked away in the garage.

Unfortunately the nearest tuning shop that will work with Megasquirt is 900km away in Brisbane. I know Megasquirt is the cheapest (but still good) ECU, but factor in at least one 1800km round trip in my Pajero towing the GT6, plus trailer hire, (lots of) petrol, motels, and no guarantee that the car could be set up in one trip, and it's not that economical.

But, a good thing about Mackay is that it has a thriving car and motorsport culture, and no shortage of tuning companies with dynos. I talked to one today - five kilometres from my place! - and they're familiar with locally made aftermarket ECUs like Link, Haltech and MoTec. To buy one of those ECUs, swap over the wiring and get it professionally dialled in on a dyno might cost a couple of thousand dollars, but I'd have a professionally tuned car, and local support ten minutes away. I think that's the way I'll go. Anyone want to buy a Megasquirt MS3 Pro?

Edited March 22 by GT6 Nick
Clarity

[Nick Jones]

Hum. The whole point about MS is that you have full access to everything in it via Tuner Studio and have the excellent auto-tune feature too.  Not things available from the “brands” as they want you beholden to them and their distributors.

I reckon that with Tuner Studio and its tools you can get at least 80% of the way there, though slightly complicated if not able to legally drive on the road.

Is it really not possible to come to an arrangement with a local dyno provided you can bring the laptop with  Tuner Studio and enough expertise to drive it?

[mpbarrett]

I think I agree with Nick, you can get full control if you are using a MS system.
I haven't used a rolling road on my Herald but its not perfect but a very useable system that I feel I can trim and play with, and not dependent on a custom system or a guy doing rolling road tweaking.
The MS system gives so much control and the ability to roll back if you have completely screwed it! And you can learn so much much rather than someone else doing it for you.

mike

 

 

 

[rogerguzzi]

Hello All 

                I agree as well Spitty has not been on a rolling road but gives near as dam it 45 mpg overall!!!

Plus pulls like a train when needed and has suprised a couple of TR6 mates!!

The down side for me is I can not stop tweaking it and not all ways for the best?

Still is that not why we all go for systems like this as we are tinkerers?(and cheap skates?)

Or just buy a MX5 ect no no no !!!

Roger

[GT6 Nick]

What I didn't mention is that to continue with Megasquirt, I'll also have to buy a new laptop. My old one is very old (c. 2010) and the battery is long dead. It works when plugged in, but not on the road. I much prefer using a Mac, so the only reason to buy another PC laptop would be to resume the battle with Megasquirt.

As for being locked into a proprietary brand of ECU, to be honest I don't see myself constantly tweaking the curves to chase horsepower. Once it's smooth and reliable I'll probably never look at it again. If it does get sick, I'd rather be able to take it to an expert who can diagnose it in an hour, than spend my days off reading and re-reading the manual and trying to make it less broken. And if I want to go properly fast, I have a Daytona 675 and Ducati DesertX (gratuitous bike shots follow).

A very silly Triumph.

And a slightly more sensible Italian, trial-fitting its new luggage.

I asked about tuning the GT6 on a local dyno with Megasquirt (if I bought a new computer) but the shop I talked to (and the one recommended to me by several people) are pretty busy. You book half a day, and if the first couple of hours are spent figuring out the software, that's time wasted. But what really made me think was watching a video where a bloke in Sydney quite sensibly popped a Ferrari 360 flat-plane crank V8 into a Seventies Alfa. He got it running with a Link, and then took it to a tuning shop who were able to set the fuelling and ignition curves in about two hours.

Very silliness.

 

Edited March 23 by GT6 Nick

[Escadrille Ecosse]

29 minutes ago, GT6 Nick said:

As for being locked into a proprietary brand of ECU, to be honest I don't see myself constantly tweaking the curves to chase horsepower

To me that is one of the great benefits of an ecu based system. Get it right and then forget it.

[GT6 Nick]

One last update before I head inland again for work. From time to time on my illegal black-ops tuning runs in NSW, the GT6 engine made tapping noises that I could feel through the clutch pedal. Oil pressure was good, and when I sent the gearbox away for a rebuild, I checked that the noise wasn't coming from the bastardised Toyota/Triumph clutch.  The vernier camshaft sprocket was fine too.

Today I pulled off the sump and found the cause. The Racetorations' alloy sump surge plate had moved (it isn't clipped or otherwise held in place) and #4 big end had been gently tapping on it. If you need a chunk gouged out of stainless steel, it turns out that ARP bolts are just the thing. The bloody plate must have only popped up at the front, as there aren't any marks under # 5 and 6 big ends. So, I'll have to make a new plate and figure out how to stop it moving upwards. I can't see any metal debris in the crankcase, but I'll clean it out thoroughly and check the bearings before I bolt the sump back on.

 

Looking good here...

No marks on #4.

But check out where #4 was making contact. The marks where 1, 2 and 3 big ends run are my doing, as I found the sump (designed for a GT6) didn't quite accommodate a 2.5 crankshaft. I'll tidy them up a bit more before the sump goes back on.

Edited March 24 by GT6 Nick
Disambiguation

[Nick Jones]

11 hours ago, GT6 Nick said:

What I didn't mention is that to continue with Megasquirt, I'll also have to buy a new laptop

Tuner Studio versions exist for Mac and Linux.
 

For Windows though I recently bought a used touchscreen laptop from eBay for £40. Having checked it actually worked I invested another £40 in a new battery and £25 ish on a small SSD. Then I got carried away (probably unwisely) and “upgraded” it to W10. It’s a bit slow now so I may revert.

So you don’t have to spend a fortune to get something functional, though if you don’t like messing with PCs….

11 hours ago, GT6 Nick said:

As for being locked into a proprietary brand of ECU, to be honest I don't see myself constantly tweaking the curves to chase horsepower. Once it's smooth and reliable I'll probably never look at it again.

Your car, your cash, your choice.
It wouldn’t suit me (hence my originals post) but I understand and respect your point of view.
 

As a foil to that and as a cautionary tale to pick your platform carefully, I’ve had several detailed discussions (usually at the open bonnet of one of my ‘squirted cars), with folks who’ve spent an absolute fortune on EFI conversions and are very unhappy with them because the tune is poor and the only companies able to address this want a four-figure sum for a RR session and are miles away. The more local one being the original perpetrator and therefore untrusted! 

One of these discussions at a small local show, plus a run up the road in my PIe, resulted in the TR5 owner buying an MS3, fitting  it himself, tuning it himself (with some very minimal input from me) well enough to be “much better” than previously, then had a final polish on the same RR I’ve used. All for well under what he’d been quoted to get the original tuned. He gained mapped ignition too. Something the original Weber Alpha system did not have. Obviously it helped enormously that the guy is very hands-on and had some helpful skill-sets. 

To be fair, this was a while back and all of these unhappy folks had Weber Alpha systems. The hardware is fine. Excellent even. The ECU (at the time) somewhat basic, and the business model exploitative.  One hopes that the considerable market competition has changed things for the better!

[Escadrille Ecosse]

7 hours ago, Nick Jones said:

To be fair, this was a while back and all of these unhappy folks had Weber Alpha systems. The hardware is fine. Excellent even. The ECU (at the time) somewhat basic, and the business model exploitative.  One hopes that the considerable market competition has changed things for the better!

I think that's the key point here in both posts. A system that has proper local support. Doesn't have to be DIY to achieve that.

Can be a local RR with the necessary expertise or a local 'Nick Jones' .

12 hours ago, GT6 Nick said:

The bloody plate must have only popped up at the front, as there aren't any marks under # 5 and 6 big ends. So, I'll have to make a new plate and figure out how to stop it moving upwards.

Why not just weld a couple of steel tabs onto the sump to hold the front of the plate down? Probably don't even need to be fixed to the plate, or worst case a couple of pop rivets.

A little local 'releaving' of the sump with a hammer and sand bag under the front rods is normal for the 2.5 with the GT6 sump.

[Nick Jones]

I reckon the surge plate is perhaps expanding when hot and bowing upwards into the path of the crank.  A bit of reshaping to introduce an initial downwards bow ought to ensure that that's the way it goes when it heats up.

TBH, if you are not planning on track days or auto-solos, I don't think it adds anything you need.  Though it's not as overdone as the one I made..... (and is probably partly responsible for my oil temperature issues)

[Nick Jones]

On 1/27/2024 at 3:40 AM, GT6 Nick said:

Update time! The gearbox guy warned me in August that he had a lot of work on, and he wasn't kidding. My W58 only came back a couple of weeks ago. New bearings, seals and at least one synchro, and $1200 later it's as good as new.

Before it goes back on the engine and in the car, I'm taking the opportunity to sort out three annoying issues. Only three, I promise.

(1) The Conversion Components kit to mate a Toyota gearbox to a Triumph engine included a clutch thrust bearing carrier, but I was never happy with it. It works, but the carrier slides too far forward on the sleeve around the gearbox's input shaft. It hangs almost halfway off, and I'm worried that as the brass bearing carrier wears, it'll start to tilt and hang up on the sleeve. The solution is to make the W58's sleeve about 13mm longer, which will take some welding and machining. The thrust bearing is also spaced forward on the brass carrier, and again it isn't as well supported as I'd like. 

Hopefully both problems can be fixed by a clever machinist. The alternative would be a concentric clutch slave cylinder, but I'm not sure any of the Toyota-specific kits available would fit my Toyota - Triumph hybrid without some machining. And if anything goes wrong with a concentric clutch cylinder, the engine and gearbox would have to come out. Again.

 

Just been fiddling about in this area on mine, and partly as the result of the above, have done some detailed measuring.  Our numbers probably don't exactly match as mine is a home brew bell housing and I suspect is a bit shorter that yours.... though, if you are using a GT6/Vitesse flywheel, if yours is more than a very few mm longer than mine you need to consider the spline engagement as mine is only just (by literally 1mm) fully engaged.

Pic shows plate and spigot bearing positions.  Spigot is not extended, spigot bearing position is in the flywheel.

I'm using the original Supra carrier and a bearing which is the same 19mm height as the Supra one but has a more radiused contact face. I'm not using a spacer.  My gearbox has a nice forged steel arm rather than a pressed one, but that's not really relevant.

Relative to the front face of the bell housing, the distance to the front of the bearing when fully back is 86mm. The most forward position it can go to before getting tippy is 55mm. The position of the clutch fingers when assembled with a new plate are 68mm back and it needs no more than 6mm to clear and I think the 0.625 M/C will give me 8mm.  This should be it's most forward position as it moves back as the clutch wears.  So I'm ok, though a little closer than I'd like (5mm).  If I could find something easily adaptable to space the bearing forward 3 - 4mm, I might yet do it for a little more margin.

[GT6 Nick]

Thanks Nick, I'll check how far the clutch plate runs on the splines.

And your comment about forged vs pressed clutch arms has me wondering. My conversion kit came with a pressed arm, and despite a dab of grease on the ball, it squeaks. I didn't know that there was a forged version of the arm. They look well made, especially in the ball-socket area. Hmmm.

[GT6 Nick]

While I wait for the new clutch bearing carrier to get machined, I've been changing the rear red Polybushes. They were replaced when I first assembled a rolling chassis back in about 2010, but over the last few years they've crumbled. It's not wear, because the car hasn't been driven. Every time I moved the car around in the garage, I'd find a pile of red crumbs. The best explanation I've found is that the urethane may have contained water when it was mixed. It doesn't seem to be a common problem, so I've replaced them with new red Polybushes. 

So far I've replaced the easy ones - radius arm, spring eyes and rotoflex inner wishbone. The diff needs to come out to replace the four big mounting bushes. Sigh.

One of the radius arm bushes. They all look like this.

Most bushes replaced, just the diff to go.

[Martin]

I‘m no longer a supporter of polybush. Had them deteriorating on the Vitesse in a very short time. Superflex rules. 

[Nick Jones]

Well, that’s disappointing and very irritating. Another vote for Superflex. I’ve worn a (very) few out but never had any fall to bits.

[PeteStupps]

That's thoroughly annoying, and a bit of a worry. I fitted Polybushes to my Spitfire a few years ago; will have to inspect more regularly.

Ridiculous but familiar story of new parts being garbage.

Edited May 5 by PeteStupps

[Escadrille Ecosse]

Quality control with the Superflex certainly seems superior.

[Escadrille Ecosse]

On 5/5/2024 at 12:07 AM, GT6 Nick said:

While I wait for the new clutch bearing carrier to get machined, I've been changing the rear red Polybushes. They were replaced when I first assembled a rolling chassis back in about 2010, but over the last few years they've crumbled. It's not wear, because the car hasn't been driven. Every time I moved the car around in the garage, I'd find a pile of red crumbs. The best explanation I've found is that the urethane may have contained water when it was mixed. It doesn't seem to be a common problem, so I've replaced them with new red Polybushes. 

So far I've replaced the easy ones - radius arm, spring eyes and rotoflex inner wishbone. The diff needs to come out to replace the four big mounting bushes. Sigh.

One of the radius arm bushes. They all look like this.

Having seen that and the pic posted by @Mark I had a look at the PU bushes on the Spitfire which are mainly red and date from 2008-10 period. Not sure whose they are but all seem to be in good condition still.

Must have a look under the Scimitar. Pretty sure the fronts are OK but a while since I looked at the back where there are quite a few. Four trailing arms, Watts linkage, and coil-overs.

[GT6 Nick]

Somewhere, Mr Polybush is laughing his socks off. Their whole car, all-in-one-box suspension bush kit contains every bush you need, except the rear diff bushes. Maybe that's because pulling the diff out is such a pain that most people wouldn't go that far. Well I did, because I had to. And surprise surprise, no rear bushes. Quite bothersome, that. A pair of bushes are now on their way from the Mother Country. But in the meantime, the rebuild stalls, again.

The various bushes mostly removed themselves, which was helpful.

This lovely thing from Hitachi Heavy Industries was a little awkward to get out. I suspect it will be quite awkward to get back in because it is heavy, and longer than the original. Last time I just put the diff in the middle of the garage and assembled the car around it.