Spyder Zetec chassis with Twink and original suspension

[Tintin]

Hi all!

The +2 project I started about ten years ago is finally next on the finishing list (after two Nortons and a Shovelhead.... )

Initially I bought a lot of stuff to start a Spyder Zetec conversion but this looks to be impossible to be road legal by now here in my part of the world. Hence I decided to go the more original version. Now there is some question (of which I think I now the answers but there's tons of Norton and Hardly-Dangerous info clogging up my brain so I'm on the Lotus knowledge recovery road so to say....)

1. Does the following combination work out in general:

- Spyder Zetec chassis
- TwinCam engine (I just realised now that it should be called a TriCam btw....)
- MT75 gearbox
- Scorpio differential (with Spyder-sourced drive shaft)

I know that I have to sort out the side shafts myself but that's a relatively easy one as I know a few people in GKN motorsports... )

2. Are the Spyder Zetec A-arms ("kinematically") identical to the Lotus items? In other words: Can I fit the front Spitfire stuff and the rear Chapman struts in the same way as the Sierra/Spyder uprights front and rear (the difference between the Spyder RCS and the orginial system is clear to me in general)?

Thanks in advance!



Tim

P.S.: Yes, I asked Spyder the same question. A few weeks ago....

[stugilmour]

Tim, my car is a (sort of) version of your proposed build, so might help with a few details. My '69 Plus 2 LHD Federal includes:

• Spyder space frame compatible with MT75 (but not compatible with Zetec; see detail below).
• Original Stromberg head Twin Cam.
• Spyder supplied MT75, complete with clutch, flywheel, drive shaft.
• Stock Lotus diff, rebuilt with 3.55 final drive and diff brace retrofitted.
• Stock Lotus rear towers with Spyder supplied springs, strut inserts, bushings, & adjustable wish bones.
• RD Enterprises supplied CV conversion (Four CV design with updated replacement output shafts rather than Spyder two CV type).
• Spyder supplied front wishbones, trunnions, steering rack, height adjustable spring & shock assembly, bushings, etc.
• Stock brakes complete with dual boosters, working hand brake, ..
• Stock size 5 1/2" x 13" Minilite wheels with stock size 80 profile tires.

I am presently working up a Tall Block with Weber head conversion to add a bit of power. My stock TC really needs a bit more power in the heavier Plus 2 for modern driving conditions. Don't know what the power of the engine is though, just my experience. For reference, we used 40 over pistons, stock Federal cams, SU carbs that the previous owner had installed, Pertronix electronic ignition, shaped steel exhaust header pipe, lower compression head gasket to avoid detonation issues, and modified cooling system.

When I bought the Spyder frame I thought I was getting a full Zetec model, but this was not the case. To be Zetec compatible the frame should have a semi circular cut out in the front crossmember / vacuum tank to accommodate the Zetec front pulley length. I figured retro-fitting this cutout locally was beyond what I wanted to take on, so going with the Tall Block instead of a Zetec. If you are ordering a new frame from Spyder consider which version you need; I think the most flexibility would be offered with a Zetec frame even if you are installing the TC. The picture below shows a Zetec space frame, and you can see the pulley balancer cutout.

Zetec frame

This picture (which used to be on the Spyder site) shows the MT75 fitted up to a Twin Cam. Not super clear, but note the front cross member is not modified for the Zetec.

MT75 in a Spyder space frame with a Lotus TC

With the Twin Cam and MT75, my shifter is slightly further aft than my stock four speed, maybe an inch or so. I actually find this more comfortable than stock, but it required a bit of fettling with my early version solid plastic console and an aftermarket shift boot.

My Spyder frame (purchased maybe seven years ago) was equipped with threaded transmission mounting holes for both the MT75 or stock four speed. We did need to modify the supplied transmission mount height a bit, but was not a big deal. Not really sure why we needed to modify things.

The TC / MT75 combo fits in the Spyder frame fine, and is reasonably easy to remove for service. I modified the supplied shifter lever though; it needs to be easily removable from the top to allow the transmission to clear the tunnel. The Spyder supplied MT75 clutch uses an axial slave cylinder which connected to the stock master cylinder; I want to change the connection a bit though to make it easier to disconnect. Looking over my Spyder invoices I noticed they supplied the flywheel; hoping for my new engine I can get the flywheel supplied by the engine builder and the Spyder clutch assembly will just bolt on.

A full MT75 repair manual for the gearbox is available here:

http://www.fordscorpio.co.uk/mt75.htm

The MT75 bolts to the TC, but requires a different starter, ring gear (I think), front plates to keep road debris out of the clutch, different reverse light switch, etc. Some of this stuff I had to figure out here. Under dumb mistakes, note the MT75 uses metric bolts to attach the integral bell housing to the engine, so do not use your SAE fasteners and strip the bell housing threads. While I have the gearbox out I am going to add Spyder's new anti-sizzle design to the linkage, which is presently pretty loud.

Getting the TC exhaust around the MT75 bell housing is tight. Ideally I would have an oval piece to increase ground clearance at this critical spot. I might fuss with this a bit with the new engine.

I find the combination of 3.55 final drive, stock wheel size, and MT75 overdrive fifth (0.82 I think?) perfect for modern driving conditions. 3,500 rpm translates to 80 mph (~130 kph), which is great for cruising with the TC. However, this is low enough on the TC torque curve to really require shifting down to pass, which I am hoping will be improved with the new engine. The fifth is completely unnecessary on the track. The rather low MT75 first gear works OK with the taller final drive and CV's, and works very well when creeping along in traffic.

Sorry I have no experience with the Spyder dual wishbone rear suspension, but I would absolutely consider it. The stockish setup I have has a heck of a lot of body lean in the rear. This is fine for road use, but is pretty extreme on the track. I don't intend to track the car any more though, so I am OK with what I have. Really didn't feel any need for a limited slip setup on the track with the modest TC power. I do wonder if the English Axle is up to the higher power output of a Tall Block or Zetec though; so far no issues though.

One additional thing to consider with the TC is improved sump baffling. We did a version of Col's ebook design to prevent oil starvation, and it seems to work fine. The Tall Block build will use a different design, but the engine builder stressed that this mod is definitely required.

You mentioned getting in touch with Spyder to get some info. I have found it better to phone Sean and talk to him. If you gave a bunch of particular details to discuss, send an email and then follow up with a call in about a week. If you follow up by phone he has probably read over whatever you sent and can speak to it in detail.

HTH

Stu

[Tintin]

Hi, Stu,

thanks for the answers, helps a lot sorting my mind ....

...
[list][*]Spyder space frame compatible with MT75 (but not compatible with Zetec; see detail below).
[*]Original Stromberg head Twin Cam.
[*]Spyder supplied MT75, complete with clutch, flywheel, drive shaft.

I already have a frame and as I intended to build a Zetec I bought the Zetec version back then. The cut-out on the front cross-bar you mentioned is there so if the difference between the two versions is that a TC has more clearance in this area than needed that's fine.

The MT75 could be bought dirt cheap a few year ago and I have a very nice one from a low-mileage Scorpio with the hydraulic clutch release you describe.

The problem I got with the Zetec was a combination of two new laws here in Germany: The introduction of low-emission areas (and I happen to live in one since two years now) and the tighter rules for historic vehicles to be eligible for H-Number plates.

The Zetec is a no-go for the later which means I'd have to have it emissions-tested to be classed as EURO1 or not be able to park it closer than about 5km from where I live. Not a big problem in general as it would probably already be enough to put a catalyst in somewhere when running a Lambda-controlled EFI but the homologation test is 1500?. And another 1500? if it fails. And another 1500? if it fails again.... plus the discussions how to "lead seal" a programmable EFI.

So I decided to go for the more original route...

[list][*]Stock Lotus diff, rebuilt with 3.55 final drive and diff brace retrofitted.

I already have a Scorpio LSD diff but I need to find out the ratio.... My Elan +2 donor still has the original diff installed but that is in need of a full rebuild.

[*]Stock Lotus rear towers with Spyder supplied springs, strut inserts, bushings, & adjustable wish bones.

This probably what I'm going to use in the first place - source from said donor car - but I also have the rear Sierra-based RCS stuff here.

The questions are:
Is the lower wishbone the same for all three versions? That means a) Spyder uprights with outboard Sierra brakes and Sierra hubs, b) Spyder RCS fabricated uprights for Lotus "semi-inboard" brakes and Lotus hubs and c) Lotus-struts with all original running gear?
And secondly is the Sierra-hubs-RCS identical in terms of the upper wishbone to their Lotus-based RCS?

I will probably call Sean in due time, good to read that he's still around.

[list][*]RD Enterprises supplied CV conversion (Four CV design with updated replacement output shafts rather than Spyder two CV type).

I think for my planned version of Lotus hubs and Scorpio diff there is no conversion readily available but that's not a big deal as these CV shafts are modular systems anyway and there are nice sources for one-offs (well two-offs... ) around here.

[list][*]Spyder supplied front wishbones, trunnions, steering rack, height adjustable spring & shock assembly, bushings, etc.

This sounds as you're still running the original Spitfire vertical links etc. It would be interesting to know whether the fabricated Spyder uprights use the same geometry for the lower joint as this is slighly different.

Getting the TC exhaust around the MT75 bell housing is tight. Ideally I would have an oval piece to increase ground clearance at this critical spot. I might fuss with this a bit with the new engine.

I'm wondering whether there is enough space inside the frame to run a tube - or maybe two to gain more cross section - close to the drive shaft and exit next to the differential. This would solve the ground clearance problem.

You mentioned getting in touch with Spyder to get some info. I have found it better to phone Sean and talk to him. If you gave a bunch of particular details to discuss, send an email and then follow up with a call in about a week. If you follow up by phone he has probably read over whatever you sent and can speak to it in detail.

Yes, I'll probably do that in the next few days.

Best regards,


Tim

[stugilmour]

Sounds good Tim.

Yeah, for sure your detail questions will be best answered by Sean.

Yes, I am essentially stock configuration in the front. Spyder wishbones that are stronger than stock. The height adjustment was critical though to get sufficient ground clearance for the exhaust.

Kind of hard to describe the clearance issue, but there should be no need for re-routing the exhaust pipe. The clearance limitation is right at the bell housing; the rest of the pipe has plenty of clearance. With my Dave Bean supplied four into two into one Twin Cam header pipe, the bell housing is located close to were the two into one piece sits. This becomes the lowest part of the car. The spacing between the front and rear wheels is such that bottoming out on speed bumps is unavoidable, right where the exhaust clamp needs to be.

I believe they have similar issues with the Zetec builds as well (completely different header), as the clearance limitation is really a function of the bell housing rather than the specific engine (if that makes sense). I think Alan has been working with Spyder on this issue, but of course they are focused on Zetec builds rather than the Twin Cam. I think they are working up a short oval section to go around the bell housing lip. This is similar to the approach Jay Leno used on his radical Elan build, although that car used a different gearbox.

I just added a bit of ride height to the front and drive over speed bumps carefully. Here is a picture of my car showing the resulting height. Truth be told, I probably had it a bit too low originally and was using 70 profile tires. With the 80 profile tires and adjustable front height it can be made to work OK.

Ride height picture. This one is with 80 profile tires. The rear ride height looks good, but note I am fully loaded in the boot for a two week trip.

If I were doing my build over again I would have liked to add adjustable height in the rear as well. Something to consider if you end up needing new uprights.

I figured you had regulatory issues when I saw your location. Our Province here is pretty lax, but other Canadian's are not so lucky.

I believe the RD CV's are similar to what everyone uses. They are definitely Volkswagen sourced. When I needed to replace one I just took it in to my local VW independent and he matched it right up. Perhaps someone else can tell you the exact VW model to use; my first attempt at buying on line got the wrong one. If you do use the stock diff, definitely replace the output shafts though; mine showed evidence of twisting after fifty years of use.

Sounds like a fun project.

Stu

[Spyder fan]

Tim,
I was told that the Zetec chassis is dimensionally identical to the standard chassis but with a few alterations to allow fitment of an MT75 gearbox and also the extra work to the front crossmember to allow for the front pulley on a Zetec motor.
You can use standard Lotus/Spitfire front suspension and hubs as well as standard rear A frames and Chapman struts, there is the option to use Spyders RSC rear suspension which can take the bearings for the standard hubs or the Ford derived hubs. If you use the Ford derived hubs the A frames are different, but the dimensions and pick up points are the same.

I converted my +2 over 8 years ago, if I were doing it now I wouldn't use a Zetec, but would modify a Lotus Twincam and run it on throttle bodies.

I'm sorry to hear that local legislation in Germany is making life difficult for you, will you have to run the twin cam on it's original carburettors, or can you have fuel injection?

This is the new Jenvey Heritage throttle body, that looks just like a DCOE!

[denicholls2]

You can use standard Lotus/Spitfire front suspension

I'm confused because I don't see a minor correction from others here yet, but don't all of the Plus 2's use the (larger disks, different calipers, slightly beefier spindles) GT6 uprights instead of the Spitfire ones used on the Just 2 and Europa?

Or am i the misinformed one? Minor difference if you have the parts, but not if you're sourcing replacements...

[Spyder fan]

Sorry,
I was just quoting Tim, he said Spitfire in his original post. The answer is still the same in that you can use the original +2 running gear and suspension on a Spyder Zetec chassis or a mixture of original and Spyder suspension components.

[Tintin]

Hi all,

thanks to all for the input so far, very informative.

Regarding the front suspension: I think my donor had Spitfire stuff in terms of discs etc. - and judging by the quality of the craftsmanship on some other areas this would be a perfect explanation why a car would have larger dia brake discs at the rear.....

Other "interesting" ideas by the world class tinkerers I've spotted so far: A homemade U-joint conversion with 3in long bolts which in order to clear the U-joint bent outwards when bolting up (maybe this was considered a saftey feature as it was impossible to unbolt anything - angle grinder to the resuce...); a FIAT rev-counter ; collapsible steering colum internals in a non-collapsible housing which has about 2in longitudinal play (must have been very interesting driving the car with a steering wheel rocking back and forth); and I'm wondering why the gearbox was painted yellow - obviously a rattle-can paint "job" with a certain tolerance towards surface cleaning.

I will double check with a local 'umph expert what I really have, luckily there is a Spit/GT6 specialist about two clicks from my workplace.



Tim

[rgh0]

Rear disks always bigger on both Elan with Spitfire/ Herald front brakes and Plus 2 with Vitesse / GT 6 front brakes. Rear disk size was about clearing the outer donuts

The front uprights and spindles used on Knock on hubs in both Elan and Plus 2 were GT6 / Vitesse and for bolt on hub Elans were Triumph / Herald

simple really

Spyder front suspension points the same no mater what suspension fitted.
Rear strut top and lower A frame mounting points also the same. Additional pivot mounting point provided on Spyder chassis for their top wish bone of double wishbone rear suspension.

suspension arms need to match the hubs and uprights used but chassis does not change as far as I am aware

like I say simple really

cheers
Rohan

[Tintin]

Rear disks always bigger on both Elan with Spitfire/ Herald front brakes and Plus 2 with Vitesse / GT 6 front brakes.

I'd be tempted to say by now that the Plus2 has 254mm aka 10in specified front and rear....hm.


Tim

[Spyder fan]

It's all simple until you start adding details

[Tintin]

Just as a clarification if anybody should ever stumble across this in future searches: According to the official WSM it's 10in on both axles for the Plus2.

Very interesting to know that my donor obviously came with Spitfire discs at the front, they are definetly smaller than the rear ones, just checked this, I need to have a closer look at all this stuff again before I refurbish and reassemble it. Therefore thanks again Forum for correcting me on the Spitfire error! So it's GT6 at the front then.... and the best thing is that the fun is finally back in this project, it has been floating around in ist unfinished state long enough by now!


Tim