1995 Ginetta G27 4.5 V8

[Darkspeed]

Mar 18, 2018 21:01:55 GMT metalshapes said:

Looking at your pics and pics of G4's, I never realized how close the main body panels are.
I don't think I'd be able to stop myself from getting the early cars body panels, and turning it in a longer/wider G4.

Because the G4's were just so stunningly beautiful...

It has been done plenty of times and not always in an open an honest way - There are number of "G4's" in the USA which are modified G27's. The GOC has had to be the bringer of bad tidings to a number of owners of cars that are not what the were reported to be. A couple of them have been historic class racers that other racers wanted clarification on from the club.

The DARE G4 was also available in a LWB version - The series 4 and the G20 gave more of a nod to the original G4

This is a chopped G4 bonnet to suit a G27



I am undecided on the final look of the car but a nod torward the original is probable but the proportions of the original are so good its hard to change them and it not look a little off.

[Darkspeed]

Anyway lets have some noise



There is a further click with Chris Harris in this car and its just a two barrel intake and red lined at 7000.

[Darkspeed]

Bought some steel to complete the front suspension stengthening and modifications - next on the list of purchases is an Escort MK2 quick rack followed by sorting out some 1/4" mild steel plate.

Shorter stand to buy a bit of extra room



Steel - plus alloy for the coolant tubes on the Strato's



My version of cars and blossom. - Our apple tree with the centre tub sitting on the bonnet!



Tomorrow is the day set aside for starting the suspension works.

[underhauled]

I was at brands hatch for the btcc last month and the ginetta series both junior and senior was amazing.

Keep up the good work.

[Darkspeed]

May 11, 2018 17:46:10 GMT underhauled said:

I was at brands hatch for the btcc last month and the ginetta series both junior and senior was amazing.

Keep up the good work.

The Ginetta series does have some good racing - shame about the WEC aspirations and the Manor team debacle putting pay to any sort of Le Mans showing.
I shall try and keep up the good work when I eventually get really started on it - As I got distracted by the work on the Strato's the day set aside for the work on the front suspension was given up to that and the Flowbench.

I will get on with this.

[Darkspeed]

I have ordered up the quick rack for the G27 and added to the list a full set of Polybushes to sit on the wishones that do not yet have any brackets to mount to! it is some sort of progress. - So I keep telling myself.

[Darkspeed]

So the season has moved on - all the blossom has fallen off the tree and now its full of little apples !

I have been ordering a few parts here and there for the project and today decided that I would have play with polybushes - as it has also been a subject with differing opinions on other threads this is my take.

The Ginetta G27 uses a Triumph derived suspension system - now people may look over the parts on this car and chassis and say "no bloody Triumph ever left the factory with those bits on it" and they would be correct - the uprights are bespoke the lower ball joints Saab and the upper a rose joint the steering arms bits of old gate - but the rack was Spitfire and so to an extent is the geometry and many left the factor with Triumph wishbones and uprights.

The bolts that fix the wishbones to the chassis are 3/8 UNF and the bushes are Triumph as well. You could probably take all the front suspension off of this G27 and offer it up to a Spiftfire and in a fashion it would fit and work.

This car came with a very odd selection of bushes fitted - some Nylon top hat bushes with not sleeves and some black Powerflex bushes with the crush tubes chopped down! This car had a 330 BHP/ton power to weight ratio and a 364 ftlb/ton Torque to weight ratio !

The Nylon I had to chop the rim off to push them out.







Not good.

Last week I was looking at setting up the upper and lower wishbones into a jig for doing some welding in order to progress the mounting of the steering rack and the chassis fabrication for the upper wishbones and I found that the alloy spacers that I had used for the G21 wishbone fabrication bid not fit... Hmmmm I thought these wishbones use the same CDS tubing as I used on the G21 so why don't they fit. The reason being that I turned the tubes out to the correct 13/16 ID that is required to match the Triumphs and Ginetta just left the ID as stock. - Well you can with sufficient force ram a square peg into a round hole or a Triumph rubber bush into a Ginetta wishbone and it will do its job - sort of.

However when you decide to upgrade to performance polybushes on your Ginetta that uses Triumph bushes you are going to come unstuck. Firstly not only are the tubes on the wishbones the wrong ID but they are also wider than the Triumph so the crush tubes are too short.

Anyway I bought myself a cheap set of Floflex / Deflex Orange 80 Shore poly bushes so I could see if I could get them to work correctly. I saw no point buying a set of SuperpoloyPowerflax bushes as they will fit no better than cheap ones.

So I bought a couple of drill bits - one being a 13/16 to bore the tubes to the correct ID.

So the out come

This is what happens when you fit polybushes to undersize tubes - this could be undersize due to poor manufacture as in my case or corrosion etc. in many others - The difference was 19.8 and 20.6 - just .8mm diameter or .4mm on the radius. So what does that piddly little difference make when fitting.

You can see that they both fit - but you can see the deformation in the narrower tube





And the bore was difference was 10.2 verses 11.5 - bear in mid that a 12.7mm tube needs to go in there.





And when you press the sleeve in - if there is not enough room for the volume of the poly it tries - well you can see.




The tubes are also far to short for these bushes so if your typical owners fitted these they would tighten them to a point of bending the chassis brackets and pretty well clamp the suspension solid. And no doubt eventually snap a wishbone and shout all over a forum how utterly curse word polyflexpowerpapsuperflow bushes are and how they nearly killed him. No, the installer tried to kill the driver not the component.

So for me to get this correct I have needed to ream the bushes correct and will need to fabricate new crush tubes to provide the correct length to just compress the poly - I will have a stainless crush tube and the bracket will be of a size to allow fitting of stainless penny washers so that the Poly is sandwiched in stainless that will not rust up or corrode and the friction surfaces to the poly will remain consistent but I may look at cutting spirals into the poly for lube retention.

Right then lunch over.

[flyingphil]

Late to join this thread, but there is so much useful information - and yes, I too have a weakness for RV8 power!
Many Thanks for taking the time to post and update.

[Darkspeed]

Welcome aboard Phil hopefully there will be something for people to take away from these rambles and posts.

And let's face it, there is much enjoyment to be had squeezing as much engine and power as you can into a tiny little car just to see how bloody scary fast you can really make it go. Almost as much as seeing just how many shire plodders an old naturally aspirated RV8 can kick out.

Just been sitting here typing, having dinner and doing some trig calcs for the position of the lower wishbone brackets for sufficient Caster trail adjustment - like you do -

[Darkspeed]

I do hope its still an RV8 in this thing.

[Darkspeed]

Whilst in G27 mode

All wishbones bored to the correct ID and the poly's fit nicely - Stainless tube 1/2" x 16SWG ordered - Trig done and need to have 15mm of forward adjust-ability built into the lower wishbones to provide 3-8 degrees of Caster trail. I do have some 1/2" x 16SWG mild so may make up a couple of temporary crush tubes for testing.



Tomorrow I will cut and drill the lower wishbone brackets and may even tack them on and then have a look at the engine as I need to get that buttoned up.

[Darkspeed]

Time for a break -

On the G27 - Like the G4 G15 and G21, the front Caster is built into the chassis. This is due to the original designs being based around the Spitfire, which due to having a trunnion must have the Caster built into the angle that the lower and upper wishbones have in relationship to the chassis. You cannot move the wishbones fore and aft - as you can with uprights with upper and lower balljoints - to alter the Caster angle when you have a trunnion, you have to move the whole lot.

The angle that the chassis has built into it is -






Which is sort of okay. However, if you add a little rake of say 20mm to the chassis, due to the quite short wheelbase this reduces to a normal running Caster angle of -



Which again is okay, sort of, but I prefer to have a little more Caster for stability and 5.5 degree's as a minimum when running. As we are losing 1.2 degrees due to rake and I want to be able to adjust between 5.5 and 7.5 with rake I need to add 1.8 to 3.8 degrees to what I have - My dinnertime trig telling me 17mm gives me 4.0 degrees so that will do.

Some 40x3mm Mild strip has been marked and cut and just need to be drilled and then stuck on.

[Darkspeed]

Lunch stop


Drilled - spent a lot of time measuring as I want the brackets all aligned, parallel etc. rather than the pick and mix approach that Ginetta took to angles.




All four brackets tacked on - Time for further measuring and contemplation.





Also noted that the original installation of the upper rose joint was far from perfect as can been seen from the contact witness marks.






Another cup of tea then back to more measuring cutting drilling etc.

[Darkspeed]

Just cut the grass so in for another cup of tea to replenish the loss of the earlier cup... It's getting warm out there.

Did some measuring and thinking and came up with this.





I had given thoughts to do the same with the lower wishbone and give it two settings for height but figured a couple of positions on the upper is all I really need. Couple these two positions for the inner mount on the upper wishbone with the ability to raise and lower the position of the rose joint on the top of the upright and there is plenty of scope for tuning the geometry and lots of scope for getting completely lost and having it handle worse than ever

Better get metal chopping.

[Darkspeed]

last day of a couple of days holiday just relaxing and playing with cars and time for lunchbreak.

Delivery man has just dropped off some stainless I ordered over the weekend for the crush tubes enough to produce 24 tubes 8 per car so that's enough for both the G27 and the G15 plus a few spares.





Enough brackets for both sides have been cut and drilled.



And its starting to take shape.



With the easy part over with now its time to figure what angles and lengths the rectangular box needs to be cut at to make all this work.

[Deleted]

At this point would there be any point in changing damper mount position(s).
Would it gain you anything or is the method used currently sufficient?
I ask as I am curious, not informed.

[Darkspeed]

Jun 19, 2018 14:11:46 GMT @quickrack1 said:

At this point would there be any point in changing damper mount position(s).
Would it gain you anything or is the method used currently sufficient?
I ask as I am curious, not informed.

As it happens - the damper mounts are being moved:-

A) Because there is no upper mount at the moment as I cut it off.
B) To reduce the angle of lean and give a greater rising rate effect.

The original mounting type is a pin - and if you lean a pin type...







I may also remake the lower wishbones with the lower pivot closer to the ball joint - that way I can run a slightly lower poundage spring for the same chassis spring rate which makes life easier for the damper. Damper mounts will be changed to spherical ends and alloy body types.

[samta22]

Bookmarked and following with interest.

I have a 3.9 sitting waiting for a rebuild that is destined for my MG project with a difference. One day perhaps.

In the meantime I did spot this one at the RR weekender with a 3.9 under the bonnet. - looked very tidy.

[Darkspeed]

G33 - Nice enough cars but not a great fan of them really, just one step too far in the evolutionary cycle. Better not elaborate as some owners are very odd and take things far too seriously, and boy they really get upset when people suggest they are not real Ginetta's - G32 being the last Walklett design. Not bad looking apart from the rather odd angle the door fillet and the screen cut make and the asymmetric jowly cheeks in front of the front wheels. Once you notice the front its hard not think that the mould had a stroke when it found out it was producing yet another G4 derivative You will never be able to tell a G33 owner that less is more..... I should stop now -


Machined up the spacers for the poly bushes - The difference in sticktion between the polished stainless and the temp mild steel sleeves that I made is quite marked.

[Darkspeed]

Those following the Strato's build will know that I have been dabbling with CAD. The main reason for this was that I was having a slight issue with getting all of the front suspension parts aligned on the G27. I figured that it would be easier to get it all drawn up with all the dimensions and angles in place. As very good CAD programs are easy to get hold of with loads of simple tutorials on YouTube to get you started its was the best path.

Now all I need to do is power up the chop saw and see if I can make the bits in metal.



I can see a full 3D G15 chassis appearing in another thread in the near future .... well maybe not that near Although I will be drawing up a roll cage for one as a bit of practice in the very near future.