Ginetta G27 build thread

Tyres, exhausts, suspension, strut braces, air filters, brake pads/rotors and anything else for 'dawn raiders'.

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markrnorton
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Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 19:27

I thought I’d start this thread as a few people have asked and secondly I have put it in the performance section as some of the modifications and engineering could be applied to the Z3

Alot of the donor parts for the car are Omega, some are Nissan Skyline, standard and modified, V6 based.

I have always built and modified cars, I don’t do ‘the normal’ , I try and be a bit different, so bear with me on some of what I do.
I also fabricate a lot of parts as well as buy ‘alternatives’ to test, hybrids if you like. Parts machined, laser cut etc etc.
I bought the Ginetta as an unbuilt kit, all the previous owner had done was galvanize the chassis. This G27 came with a 4 cylinder Toyota 1600, which is normally par for the course. Good to give it sub 5 second 0-60. Running gear was based on Triumph spitfire up front and Escort Mk1/2 rear end live axle. I didn’t like the ‘weedy’ Triumph front end and I certainly didn’t want a live axle at the back. It came with what the previous owner described as an Escort axle, he’d welded on all the 5 link set-up as well. What he didn’t check was the ratio, it was a 3.09 – 3.0 Capri. So the axle was 4” to wide anyhow.
Basic spec I wanted was around 200hp with independent rear suspension and meatier front end, still aiming for the 650kgs weight all in.
Moving on, I wanted a v6 manual RWD donor, only 2 candidates really, either S type Jaguar or Omega V6. Jaguar V6 engine is wide and bulky. Vauxhall lump, nice and compact. Sorted.
Bought a nice V6 Omega Estate, MOT and Tax. And am still stripping it ! – got the tax cashed in, sold a few parts already, stripped a lot for donor parts.
So where do I start…

Here’s a few pictures of what I bought to start with….
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And this is what it should look like when finished (maybe not blue and maybe with a different bonnet)
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 19:28

Stripped out the suspension, front brakes and V6 motor and manual gearbox from the Omega estate. Engine and box took about 3-4 hours with a mate to remove. I was originally going to use the ECU and loom, but have no changed my mind. So I ‘hacked most of the connections out !
I will keep the non standard alloys I think for the moment to roll the car about on for the time being (unless I can pick up a really cheap set, then I’ll get rid of them)
Image
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 19:35

First real action (apart from selling the Toyota engine and capri rear axle) was to look at the front suspension. The car came with the ‘weedy’ but perfectly adequate (?) Triumph front end, it just looks wrong to me, so I decided to re-engineer the front using Omega parts from the estate donor.

Here is a couple of pics of the original Triumph front end.
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So after stripping the front hubs and brakes off the Omega, and doing a major clean up, thus:-
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I reverse engineered the front suspension. I made a jig, bolted it up to the original parts, then removed. Bolting up the Omega hub to the jig I worked backwards to the chassis, fabricating mock up wishbones.

Pics of mock up, note that all joints on the car will be rose joints
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I had the parts last cut, drawings first,
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then this is what you get
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once I was happy with the mock up I produced final wishbones etc, and painted
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you get the idea now from this, rose jointed to chassis
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 19:37

Wishbones are made of CDS seamless steel for strength and rose joints used are the ultra high performance versions with nylon inserts. bolts all 8.8's

pic of spaces I made and joints
Image
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 20:23

Final assembly going onto chassis
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Offside and nearside upper and lower wishbones. You can see the mechanical upper joint, this is a biggy at ¾”, and the fabrication to attach it to the hub upper. Lower ball joint is standard Omega, it made sense to use one there, less work to do !
Brake disks I will renew closer to the end of the build , but I will use standard V6 ones as they are plenty big enough to stop a 650 kgs car. I will however buy drilled and grooved disks, I have to source some lightweight alloy calipers too.
Also, I have reversed the Omega hubs so the steering control arm points forward (to suit the Ginetta)
Image

Next problems was shock absorbers for my new front end
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Mon 11 Feb, 2013 20:25

The front shocks that came with the kit were shot, big time. Heavy AVO in need of a re-build and rubber bushed. Apart from that they would not fit my new custom front end. So after a bit of measuring and head scratching I decided to have a pair of shocks made.

After a bit of interweb searching, a few shows and a few magazines, I chose to go with Protech shocks, spoke to a very helpful guy there, we ran through exactly what I needed, he made a few comments and we settled on the set-up. He made them up very quick, 3 days. They are coilovers so have adjustable platforms for ride height, light alloy construction with adjustable rebound and compression damping.
Delivered super quick, they are fantastic quality and very very light. Excellent quality too and a very good price with springs.

I had to have an educated guess at the rate as I have no reference point, so went for 325lbs and 7” long.
Image

It appears to have worked out well so far, front suspension action looks good, geometry is spot on (so far).
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Now for the steering rack and rear end.
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Southernboy
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Re: Ginetta G27 build thread

Post by Southernboy » Tue 12 Feb, 2013 06:13

Looks really good work !!
I hope you're still going to have that hub blasted and re-coated ??
"Normal is overrated"
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Z3 Upgrades and Additions

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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Tue 12 Feb, 2013 19:11

The steering rack is one of the only bits of 'original' i will use, its again Triumph Spitfire. A compact rack and 'un-assisted'. Not many modern alternatives and to be honest there is nothing wrong with it.

A quick clean up, re-grease, new gaiters and solid aluminium mounts and
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One issue that did result from using the Omega front hubs is... the Spitfire track rod ends don't fit the hubs
Enter my local helpful motor factors....and 10 mins later, triumph stag rod ends.
they fit a treat.
Stag ones at the bottom of the pic, spitfire at the top. As you can see the diameter of the 'end' is larger and fits tight into the steering arm on the hub
Image
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Tue 12 Feb, 2013 19:22

You may have guessed, that most of this work was done at the latter end of last year, trying to catch this thread up so its 'now'

anyhow, next issue , now the front was sorted, was the rear end

originally the ginetta was a 'live axle' car with the crude escort/capri rear end on a 5 link set up. I really wanted to modernise this build and create something different. so the capri axle was sold and an independent set up sort.
The obvious choice was the Omega back end from the donor car. This has several inherent problems.
1. axle and half shaft set up is 10 inches wider than the ginetta
2. diff is a standard type diff, LSD's are extremely rare in an Omega, basically you'd have to find an ex police car (fitted standard to these)
3. the diff is huge on the Omega and probably weighs far to much for my liking (I want this build light weight)

So, taking these points into consideration I aborted the use of the Omega setup

Enter my solution
Nissan Skyline/S14 rear end

Good plus points for the Nissan rear end are:-
1. can take abuse
2. many different diff ratios available
3. Lots of cheap LSD's , open and two way diffs
4. roughly the right width
5. plentiful supply

Downside is it has a complicated set of connecting arms at the hub ends, but this can be overcome (also gives infinite adjustability)

The 5 stud hub is a different pcd to the vauxhall, but more on this later.
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Tue 12 Feb, 2013 19:25

This is the diff I ended up getting, a bargain £100, nice and tight and an LSD with the correct ratio of 3.916:1
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you can see it has a take off for a diff cooler, not sure I will need this just yet.

anyway, another clean up session and...
Image

it also has a pick-up at the nose end for a speedo
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Pierrick
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Re: Ginetta G27 build thread

Post by Pierrick » Tue 12 Feb, 2013 23:07

I'll follow this with attention!

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pingu
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Re: Ginetta G27 build thread

Post by pingu » Wed 13 Feb, 2013 12:55

Looks great :D .

I'm interested in the suspension. It looks like you adjust the camber by adjusting the thread length of the rose joint in the upper wishbone, but this will also change the effective king-pin inclination angle. I would have slotted the holes in the four brackets in your drawing. This would allow camber changes that wouldn't affect KP inclination.

How did you decide on the effective KP Inclination angle? It looks like your KP angle is quite large. This would suggest you are planning on quite a lot of body roll, which for a 650kg car surprises me.

I'd love to do something like you are doing, but I do all my work on the driveway until I get another man-cave :shock: .
Pingu

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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Wed 13 Feb, 2013 13:22

kpi angle and consequent projection is within 5mm of wheel centre. so i beleive its in the ballpark, i cant remember the angle i measured it at, will check again and get back.

I dont really have any hard and fast guidelines with the front geometry, apart from original pick up points.
All points of contact are rose-jointed and as such infinately adjustable

I have done as much research as i can, but its still a bit of experiementation, it may create an evil beast, or something that can be tamed with time and adjustment.

I may even have to re-make the front end again, not sure

good point about the slotted holes though Pingu.
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as-racing
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Re: Ginetta G27 build thread

Post by as-racing » Sat 16 Feb, 2013 16:08

Looking good, always good to see some custom fab work!

Don't worry if you find you've got too much KPI, the result is increased positive camber on turn in - but that's what castor is for! Just dial plenty in and you'll be fine. Will feel it in your arms though from the feedback through the steering wheel!!

Top damper mounts look a little iffy though, I take it that's not the final set-up??
A quick clean up, re-grease, new gaiters and solid aluminium mounts and
Image
What's the plans for this? Road/race/track?

Andy
Follow the Britcar Production Cup BMW Z3 build blog at http://www.asracingblog.com

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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 16 Feb, 2013 17:54

Andy

yes, not the final mount to the top of the dampers, they are located correctly though. a shot from the underside may be in order I guess
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 16 Feb, 2013 18:02

Been doing a bit of groundwork at the back of the car. Cleaned up the new diff, now I need to locate and fit it to the chassis.

Being originally designed for a live rear axle the chassis has no fixing points for this independent set-up. Not sure how the half shafts will sit either, they may need cutting down to suit the new hub positions.

Anyhow, levelled the chassis, left to right and front to back, this took about 20 mins to do this properly, shimming it here and there. Then set about dummy setting out the rear wheels in the arches, running a plumb line down through the wheel centres.

This gave me the drop line and effective centre of the hubs/shafts. I projected this drop line accros the chassis and ensured I marked the chassis perpendicular to this projection. I started using the laser marker, but it ended up easier to see with string !!
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The diff actually locates quite nicely toward the rear of the chassis and close to the cross rails, so it should be easy to fabricate a drop down support for the rear of the diff.
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I need to fabricate the front diff cross-member first and make some nylon bushes. Once I get the nose supported and positioned I can then double check front/rear/left/right positioning and then get the rear of the diff supported and fabricated.

The diff cooler, if I run one, will be positioned later in the rear end build.
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 16 Feb, 2013 18:04

this was a positioning mock up of the diff, perfect fit, made for the job !
Image

took a few dimensions and came up with a bracket for the rear of the diff, will get it laser cut now.
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need to just sort the front mounts and turn down some bushes
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 16 Feb, 2013 18:07

Update on where are have got to now.

received all the laser cutting back, this is most of it as i have used the diff parts.
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Stainless exhaust flanges came out nice, not sure what pattern i will use yet, but both types match up perfect with the head/gaskets

I had marked the front brace position with the diff in, then welded in the front brace with some addition over gussets for added strength and to minimize any tendency to 'twist'.
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here on in it got fiddley, i had to position the diff back in, on all the new brackets i had lasered, level the car, level the diff and then centralise. took a while with a few laser guides and inclinometers but got there. I have only tacked the front supports in and one seam weld on the rear hanger. i have also tacked 2 trianglulation pieces in, and will also fit two vertical drops to the rear to stop that twisting in the chassis.
i am a bit paranoid about the twisting as i watched a kit car programme the other day where the chassis twisted at the rear due to a non standard engine and diff being used (not this kit). so i am over egging things a little, but it should be capable of taking alot of punishment now

Image

Image

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i will remove the diff tonite and carry on welding it all in so its all at full strength.
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 16 Feb, 2013 18:09

now painted
Image

diff positioned with nylon bushings I made up
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Image
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Pierrick
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Re: Ginetta G27 build thread

Post by Pierrick » Sun 17 Feb, 2013 21:29

Nice! Another step in the right direction!

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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Fri 01 Mar, 2013 13:17

Well I have taken a few days off work to get started on the rear suspension

bought a bagfull of rosejoints, had the metal laser cut and bout some tubing !

first off cut and positioned two uprights to support the wishbones
sorry about the crappy pictures
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then a quick weld up with the mig
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then weld in the tabs for holding the lower rose joints
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then zapp, my mig started playing up, snagging and hissing. I think the gun and lead have died ! its been well used though. so decided to get a new mig this morning. spent a bit more than what I intended, but. ITS MEGA
Image

its does MIG, TIG and ARC. all in one. its amazing, so smooth and infinitely adjustable

must push on ...
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markrnorton
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Re: Ginetta G27 build thread

Post by markrnorton » Sat 02 Mar, 2013 16:32

sorted the new hub plate today
Image
got the tabs and joints place, then spaced with washers and welded them into place
Image

got it bolted to the wheel now, measured the new wishbone length and tacking them together, most of the time is spent measuring and setting up.
Still modifying

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