Ex-Racer Spitfire Mk1 Rebuild

[Escadrille Ecosse]

Had a delve in my records!

The composite spring was uprated to match the stiffer front end and I went for 340 lb/in in the end (turns out this is pretty much GT6 Mk3 territory) with a reduced arch of 3/4".

Cost in 2005 was 290 US dollars - plus the dreaded import duty!

I also found my drawing of the modified uprights. Dated from before I even got the car so I was obviously thinking about this early on!

[Escadrille Ecosse]

Been working on making a new mould for the doorskins this last week or so and also decided to get serious about sooking up the dust from cutting the glassfibre - and eventually carbon fibre.

Creates lots of very fine dust which gets everywhere unless you have the vacuum cleaner on all the time and then it blocks the vacuum bags in no time at all. next thing you know the place is covered in dust.

After a bit of research on the web I went kind of nuclear with this one.

From right to left

1. Extract hoses to the jigsaw and a collector hood

2. A cyclone separator which takes out the big bits and most of the small stuff and deposits it in the first blue bin

3. Water filter draws the air though water in the bottom of the drum and takes out pretty much everything else

4. The workshop vac which provides the sook and has a HEPA type filter to take out any remaining fine dust.

All joined up with 2" plumbing fittings, a selection of reducers and bits of ducting. Not exactly quiet but it does the job very effectively.

 

[Nick Jones]

Proper job 

[BiTurbo228]

Ah very interesting! Thanks

I was thinking about the composite leaf springs and how they might be used to combat one of the other issues with Spitfire/GT6 rear suspensions. It's less of an issue with swing axles, but the rotoflex rear end suffers from quite high roll centres as a result of the level upper link. If you could make a leaf spring that's pointed downwards a little at rest by de-arching the spring (so lowering the car by 3/4" or so without the need for a lowering block), you can move the roll centre downwards which helps with rear grip.

Will post some more of my findings on my thread rather than clutter this one up with rotoflex issues!

[Escadrille Ecosse]

6 hours ago, BiTurbo228 said:

I was thinking about the composite leaf springs and how they might be used to combat one of the other issues with Spitfire/GT6 rear suspensions. It's less of an issue with swing axles, but the rotoflex rear end suffers from quite high roll centres as a result of the level upper link. If you could make a leaf spring that's pointed downwards a little at rest by de-arching the spring (so lowering the car by 3/4" or so without the need for a lowering block), you can move the roll centre downwards which helps with rear grip.

Will post some more of my findings on my thread rather than clutter this one up with rotoflex issues!

Ah, I see what you're getting at with the geometry. Interesting to see where you get with that.

[Escadrille Ecosse]

Been busy working on the bodywork of the car over the last couple of weeks. Lots of preparation work but not a lot of visible progress all to get the fitting up of the doors and bonnet all sorted before I make the final mould sets for the carbon fibre panels.

I acquired a steel bonnet and a friend of mine gave me hand with his van to pick it up shortly before lockdown began

There are quite a lot of new panels in there and it is generally in very good condition although it comes with plenty of minor dents and areas where repair panels have been let in. So still plenty to do.

However our son is back from university and with the help of him and my wife we managed to lift it onto the car this afternoon. It's a right heavy bugger compared to the old glassfibre bonnet and that's for sure. And awkward as there's not a lot of room to swing the thing in the garage with the car on the hoist.

The wife's winter bike in the background along with some of my collection of bike wheels!

[Escadrille Ecosse]

It's never straightforward is it.

Spent the morning trying (unsuccessfully) to line up the bonnet left/right across the car before giving up and going off to attack the hedge (again).

Finally dawned on me that the inner arch was touching the air box!

The box was made to fit the space under the old glassfibre bonnet with a fag paper of room to spare. I didn't make that bonnet but obviously the inner arch on that one was slightly narrower than it should have been.

Does explain why the tyre would occasionally touch that side and not the other.

Bit annoying though as I will now need to make another air box to fit the new hole!!

Hey ho...

[Escadrille Ecosse]

Spent today fitting up the bonnet hinges so I could open it to remove the air box and square things up on the car. Took far longer than expected and then followed that up with a few hours of fairly physical panel alignment. Pretty much nothing to see from all that effort so I thought I would add a bit more to the back story of the rebuild.

When I originally rebuilt the car I cut off the off the outer ends of the front crossmember including the hinge brackets and replaced them with a very basic aluminium hinge arrangement that bolted directly onto the stub of the crossmember and the grille surround on the glassfibre bonnet.

The front valance bolted directly to the bottom of the bonnet eliminating all the brackets for that as well.

Incidentally the duct tape on the oil filter is there to make sure the ring of magnets used to help catch metal particles don't get knocked off.

As part of the current rebuild I wanted to restore the original hinge and valance mount arrangement. Partly out of originality but also to give more clearance under the nose of the bonnet as my version rotates 'down' rather than 'up' as Triumph intended.

This involved replacing the whole front crossmember as the remaining bit had been bent and it was easier to get everything lined up rather than trying to scarf bits on the end.

While I was at it I added some swaged holes. Saves a trivial amount of weight but looks cool. Blame BiTurbo for that as I copied him!

I recovered the original hinge chassis brackets, derusted in citric acid. Realised then that without the diagonal cross member bracing pieces the crossmember is too floppy. I didn't have these bits and the available replacement sections are the Mk4/1500 version and quite expensive. So plan B was to make my own out of some 90 degree exhaust manifold bends that I had left over from making the V8 manifolds for the Scimitar.

Not only cheaper and lighter but look a bit 'technical' - and vaguely like the bracket mounts used on the Le Mans cars.

This lot was all welded together as a unit before welding to the car. I ran out of CO2/Argon for the MIG while welding the brackets onto the crossmember so finished off with pure CO2 hence the rather proud welds. Won't do that again.

Then etch primed and painted

Colin

[BiTurbo228]

Haha there's something about swaged holes that just make something look proper even if they only save a trivial amount of weight! 

Love the tubular crossmember supports. Might have to steal that idea as they look a lot lighter than the beefy box section amd don't have a great deal to hold up

Also, V8 scimitar? Do tell. Always loved a scimitar... 

[Escadrille Ecosse]

Thanks mate. Can't beat a bit of gratuitous swaging.

Scimitar is a 1979 SE6A. Two previous owners and a load of history. Got it in 1998 to be the family car when I left BAe and lost the car lease deal we got with them. Came with the 3L V6 Essex and 4 speed overdrive, power steering and a full leather interior (ideal for young children).

75k miles and good bodywork, but some poorly executed mechanical works that took a while to get all sorted out. For example the front wishbones were upside down/back to front on one side which meant the car sat low on one corner. TR6 front end and I knew what the problem was and an easy fix but meant I got it for a good price.

Car was daily driver, shopping car, family holiday car, tow car so used a lot and by 105k miles the Essex which was never that nice anyway was very down on power. Even a standard Essex rebuilt is a small fortune and tuning exorbitant and limited. Also the modified Transit side loader gearbox is pretty ghastly and also needed a very expensive rebuild. A mate had a 3.5 Rover and gearbox from an abandoned TR8 project so I got that and then managed to acquire a good 3.9 block. This was in 2006.

Bores were honed and crank journals polished and the rest of the bits, new pistons, bearings, ARP main and conrod bolts, uprated cam, hydraulic lifters, new rocker gear, etc all came from Real Steel. Incredibly cheap compared to Ford and Triumph stuff.

Went in remarkably easily, a wee bit of modification to the gearbox tunnel at the bulkhead to clear the drivers side cylinder head and a new gearbox mount and propshaft. I also got the remote gearchange shortened so the lever comes out in the same place. MGB V8 water pump and pulley and alternator mounting bracket. Heater hoses were a bit of a faff as there isn't much room but found some Landrover bits that fitted with a momemade water pipe. A chopped down V8 radiator top hose also does the bottom hose. Seredipity.

Exhaust manifolds were the biggest issue as the routing is difficult and there is nothing remotely suitable available so I had to make my own using one of the kits. Wasn't sure about MIG for stainless steel so made them out of mild steel. Lasted until two years ago so not bad. Got Stainless Fabrications in Falkirk to make me stainless steel ones to go with the custom 2" exhausts they did for me about 8 years ago.

Tacho also needed sorting. That was easy as I got a hold of a cheap Stag one and swapped the innards with the one in the Scimitar. Think that cost me £10.

Also made up some new brackets so I could reuse the original power steering pump. I also had to make a new turret brace round the front of the engine but that was about it really.

Initially I reused the SU carbs but kept an eye out and eventually got hold of a 4 barrel Weber and manifold which is much better. Power is around 200 - 210 bhp. Makes a superb noise and is quite quick, especially for a car of its age. And the tall gearing makes motorway driving tolerable. Excellent tow car too.

I changed the original dealer Wolfrace wheels for the Revolution 4 spokes and lowered the suspension about 1" with specially made springs uprated and dual rate on the back.

Paintwork was decent when I got the car. It had been resprayed a few years previously in the original red to cover over the red and beige (I kid you not) original 1970s paint scheme. Was getting a bit tired and the seals were all starting to go so I had it resprayed again about 12 years ago now.

 

[Escadrille Ecosse]

Slow progress  on the Spitfire recently. Lots of other stuff on around the house, including building a new race bike for the lad and then moving him back to Edinburgh in a new flat

However work has been proceeding slowly on making up the patterns for the door moulds. The door apertures on Spitfires all seem to be a slightly different shape, especially regards 'twist' in the vertical plane between front and back. The old steel doors I had to make the original moulds and doors for the racer were no exception and stuck out at the bottom rear corner of the car so the moulds had a similar twist.

I got round this making up the the GRP doors by fitting the shell to the car and then building in the twist when fitting the skin temporarily with pop rivets. Oncve everything was bonded together they fitted pretty well.

The carbon fibre skins will be too still for this so need to be moulded to the exact shape. I made up a pair of GRP skins from the old moulds then created a frame in the door aperture onto which the skins are bonded with Tigerseal. The frame is made from GRP skinned PU foam board also bonded together with Tigerseal. Once everything is cured it is very rigid and I can get all the gaps perfect before final finishing in preparation for making up the infusion moulds.

PU foam board framing...

Skin stuck on and all held in place with tape while the Tigerseal cures

[BiTurbo228]

Looking good  I hadn't considered using tigerseal to stick FG parts together. The slight rubberyness of it should allow a bit of damping and flex in panels that might otherwise crack when they're flexed. Thinking mainly about the brackets that attach the bumpers to my X1/9 which are not the most sturdy of things...

[Escadrille Ecosse]

Drivers door skin well and truly glued and I've taken the whole assembly off the car while I fill and and sand it to a size and shape that actually fits the car properly. Long and tedious process.

Meanwhile some of the other stuff done to the car to make it more suitable for driving on the road, with a passenger and without ear defenders.

The engine was built with a one-off lightweight aluminium flywheel, with the steel ring gear and a steel insert to take the small 6 1/2" clutch. This was all done to keep the weight down but as I had suspected, and hoped otherwise, the standard clutch was completely inadequate for standing starts with sticky tyres and even with an uprated cover from Canleys would still slip unless you were very careful.

Replacing the standard friction plate with a paddle one made an enormous difference but made driving in stop-start traffic a chore and too much of this tended to overheat things and crack the steel flywheel insert. I had no other issues at all from running such a light flywheel.

For normal driving I wanted to replace the four speed box and after considering lots of options decided that a close ration OD box was the simplest option. I have had reliability issues with these on the back of the six cylinder engine but way back in the days before Kippings were selling their mainshafts I ran my own ghetto conversion on a Mk4 for years without problems.

I had a spare close ratio gearbox and managed to get hold of a 3-rail overdrive box built on a Kippings/Canleys  mainshaft and used these to build the final article.

Again in the interests of driveability I wanted to replace the 6 1/2" clutch with the bigger Ford 7 1/4" and initially considered modifying the aluminium flywheel to take the bigger clutch as the steel insert needed replacing anyway. However owing to limited amount of material available on the back of the flywheel this wasn't possible so in the end I went with a lightweight steel one instead.

A bit of faffing with mounting plates but otherwise everything went in fine without cutting the tunnel.

Propshaft is a standard 1500 spit with the CV joint on one end. Perfect size for the 3-rail OD box and is a lot lighter (and cheaper) than the sliding joint type which I would have had to get specially made as well. Cost me a tenner, a bit of elbow grease, paint and CV joint grease!

At the back I replaced the 4.55:1 gripper plate diff with a 4.11:1 diff. This was built up by Mike Papworth using the old Quaife unit and Marina CWP set that I gave him.

I'm planning on fitting EFI to the car so depending on how I get on with the doors I'll start on the sensors for this next.

[BiTurbo228]

Nice work lots of quality bits going into this build, and some good decision-making between race-spec parts and bits that'll work well on the road.

I'm a fan of the 1500 CV-style propshafts too. What end have you got the CV on though? Looks like it's the gearbox end from what I can see in the pictures which is the wrong end! CV should be at the back as far as I can tell.

[Nick Jones]

What he said 

As to the Propshaft angles - I confess I’ve never checked. But every small chassis Triumph I’ve owned, modified or standard, has had a “rumble” of varying severity. The Vitesse one is balanced on the car with jubilee clips....

As for the practice of fitting a CV and a UJ on the same shaft..... how does that work - surely it shouldn’t?

[Escadrille Ecosse]

Thanks gents.

2 hours ago, Nick Jones said:

As for the practice of fitting a CV and a UJ on the same shaft..... how does that work - surely it shouldn’t?

Yes, exactly. It doesn't really make sense. I do remember lots of discussion on the top of the CV jointed propshafts over the years - why and which way round - in various places and from before t'Internet. But honestly cannot remember the conclusions.

I did have quite a long internal debate with myself on the subject however I have an original print of the Lindsay Porter / Peter Williams book "Guide to Purchase and Restoration...." published in 1988. There are a couple of photos in there of them dismantling a 1500 Spitfire and the CV joint is clearly positioned at the front end. Given the date and condition of the car it looks as if it had never been taken apart so it is reasonable to assume that's the way the factory built that particular car at least.

There is also a caption in the book stating that the late propshafts were 'fitted with a rather odd looking baked bean tin front end'.

Don't know whether or not that definitive but that's what I went with in the end.

I did actually try to fit it the other way round out of curiosity but it is very awkward that way round with the body on the car.

Nowadays of course, unless you're lucky the whole issue is completely moot as the CV joint propshafts are NLA and you have to go with the sliding joint type regardless.

My experience of the balance of these has been somewhat uneven as well unfortunately.

Colin

 

[zetecspit]

3 hours ago, Nick Jones said:

What he said 

As to the Propshaft angles - I confess I’ve never checked. But every small chassis Triumph I’ve owned, modified or standard, has had a “rumble” of varying severity. The Vitesse one is balanced on the car with jubilee clips....

As for the practice of fitting a CV and a UJ on the same shaft..... how does that work - surely it shouldn’t?

I had to play with my prop angles after a disaster.

Re UJ's, a local chappie invited himeself round for some help with a badly vibrating herald. It was strap drive, and they looked iffy at best.

Something in the back of my mind said that you can remove the straps, turn the flange through 90 degrees (putting it out of phase) and bolt up solid, all in situ. So I did, on the premise it couldn't make it worse. Hey presto, vibration free herald. And yet the UJ's were out of phase. Go figure..... (saying that, herald single piece prop quite long, so that may help)

 

[BiTurbo228]

Huh, interesting. I'd definitely have pegged it as having the CV at the back end as the gearbox points almost directly at the diff, minimising the speed change in the UJ and the CV neatly takes up any angular difference. Plus, that way the UJ should take the brunt of the wear which is the replaceable end.

The issue these fix is less the balance of the propshaft but more the pulsed variation in speed of the propshaft with misaligned UJs. You could have a perfectly balnced prop, but with a UJ running at a silly angle it would feel awful because it's changing the speed of the prop behind it from fast to slow and back again in quick succession (same as using one of the UJ extensions on a socket at a high angle).

It's probably a lot less noticeable on cars like this with low hp and torque figures (and, I should say, little enough weight that you don't need massive power just to shunt them down the road). When you start getting much heavier and torquier cars it can start playing real havoc with downstream drivetrain components.

[Nick Jones]

Why do you think which way around it is fitted makes any functional difference? I can’t see that it does.....?

Practically it might make sense to put the potentially maintainable UJ (grease nipple) at the back where it can be reached..... this being the usual reason given for putting the sliding spline on a double UJ shaft at the back.

What foxes me is the logic in putting a CV at one end rather than a second UJ to cancel the non-constant velocity provided by the first. Clearly it does work though.

[steveJM]

I understand the theoretical benefit is to have the cv where there is greater angle. And th UJ at the grearbox end which. If pointed directly at the diff. Will have minimal angle. ... but i can confirm my 1500 shaft always had the cv at grear. Never given any thought. 

[steveJM]

... Straight UJ from gearbox will give constant velocity output.....

[Nick Jones]

I’ve always considered that the overall angles and offsets were shared equally between the two joints. Have I been looking at it wrong all these years?

If I do ever manage to get an MX5 gearbox and Subaru diff in a GT6 I reckon the remaining prop length will be so short I’ll be able to repurpose a CV driveshaft!

[BiTurbo228]

Yeah single CVs in driveshafts make most sense when you're not able to properly align UJs to cancel out angular momenetum changes. In the Spit that's because the flanges aren't on the same plane, meaning one will over-cancel the other (or under-cancel, whichever side you're looking at). On my BMW 330d it has a CV at the end of a two-piece driveshaft, which is there because with 3 joints there isn't another UJ to cancel out angular momentum changes so a CV will sort that.

Oh, the other reason they could have done it is to sort some plunge on the driveshaft without having splines (I know they had issues with the splined driveshafts on the big saloons, and it'd be the same bunch of engineers doing both so they might have just decided thy don't like them). Possibly they needed some plunge as the thrust bearings on either end of the prop weren't beefy enough. For the Spitfire it probably killed two birds with one stone.

I should also mention that I don't think it's necessarily a critical aspect for these cars. They do seem to work fine with the double-UJ shaft. The lower-power variants of my E46 had a UJ on the back of their driveshafts too, with only the higher power variants using a CV (330d, 330i, M3 etc.). It's from that I was wondering whether the misaligned standard UJ setup might contribute towards breaking diffs in high power 6-cyl cars. I expect it's a major consideration only when you're feeding enough torque through components that they might start to become marginal, or as a best practice effort to get things as nice as you can get.

[Escadrille Ecosse]

With the prop the front joint is pretty much straight on to the gearbox because of the way the engine and box are angled.

It's only at the back where the prop joins the diff where there is any angular deflection. 

With a UJ at each end this will result in a variable angular velocity as they don't cancel each other out.

This would seem to be the explanation for Triumph fitting the CV joint - providing the CV joint goes at the back.

Triumph doing it the other way round seems odd. Which was why I had the internal debate on which way to fit the prop on my car.

Having said all that I don't think it matters much which end it goes from a vibration point of view because of the relatively low power (and short length of the prop).

I suspect the real reason Triumph made the change was for cost reasons. The CV joint does the job of both a UJ and a sliding joint while being significantly cheaper and simpler.

[PeteStupps]

On 8/4/2020 at 8:27 PM, Escadrille Ecosse said:

Again in the interests of driveability I wanted to replace the 6 1/2" clutch with the bigger Ford 7 1/4" and initially considered modifying the aluminium flywheel to take the bigger clutch as the steel insert needed replacing anyway. However owing to limited amount of material available on the back of the flywheel this wasn't possible so in the end I went with a lightweight steel one instead.

A bit of faffing with mounting plates but otherwise everything went in fine without cutting the tunnel.

This is all very interesting - I've got a D-type OD on the shelf but need to collect some more ingredients before fitting it. 

Can I ask where the flywheel came from? And a lightened flywheel doesn't make it a pig to drive in traffic...?