ZS VVC track car project

[Skillen]

Mark, just a question on your wings/arches, did you cut extra clearance for your wheels from the arch metal? Looking at when you bonded the kit on, there is a line across the arch and I wasn't sure what it was indicating. Did you do this for the rears?
I only ask as I need more room for mine.

[Mark S]

Originally Posted by Skillen

Mark, just a question on your wings/arches, did you cut extra clearance for your wheels from the arch metal? Looking at when you bonded the kit on, there is a line across the arch and I wasn't sure what it was indicating. Did you do this for the rears?
I only ask as I need more room for mine.

The metal front wing is temporary, and yes, there is a lot of arch work for clearance.

This is what the inside of the front wing looks like, the return lip will be trimmed flush before this is fitted, should give you an idea...

[Mark S]

shakedown at a very cold oulton park today.

The car ran without any issues until the last lap! perfect timing, and just a small fix, but all things considered, it went rather well for a car that's not turned a wheel for 6 years!!!


I had put a guestimated baseline setup on the car, hoping it was somewhere in the window, and the day proved it was...

AM - rather wet, so ran on race wets with a wet setup.
The car was very well behaved with the wet setup (not an optimal wet setup) and exceptionally easy to drive. Brakes were being bedded in during this time.

late AM, a dry line was appearing, we kept on the wets, the chassis is kind to its tyres even on a dry line with wets, running 10 secs a lap faster at this point.

PM, changed to slicks during the lunch hour and went back to a dry chassis setup. Once again the car was well behaved and very neutral, at a guess track temp was c3degrees, tyre temps were measured at mid twenties on the front - that's how cold it was out!!! Slicks need 60-70 degrees and we weren't even scratching the surface, an improvement in times showed.

There is another rather fruity setup in the chassis, but it needs a good summers day and a fresh driver for that one, coz it will be tail happy!

BRAKES
The brakes are gob-smackingly good. Better than 4-pots on a ZS I have driven and better than the big brembo's on my daily drive...
No fade, cooking overheating or any of that nonsense, even with cheap EBC Bluestuff pads...
The pedal/brake modulation was fantastic...for me this is the most important thing assuming the brakes work in the first place and something you rarely ever here people mention, why?
There are better brakes out there, for sure, but this is budget stuff, yet the modulation was the best I have experienced.

DIFFERENTIAL/LSD
Oddly enough, the car does not have one. I wouldn't waste my time fitting a type B or a quaife, just can't be bothered, if I was to fit one, it would be a carbon plate diff setup properly.
Anyway, shock horror, there is no diff in this car, yet it barely spins a wheel even pulling out of the hairpins in 2nd gear. (did spin in the rain early on) how/why...suspension!

SUSPENSION
If you've got this far and realised a car with no diff that doesn't spin its wheels, you've probably sussed the suspension works well!
The car corners flat, to the point that I could possibly loose 50lb of spring rate, it doesn't appear to lift a wheel and considering its crappy old GAZ dampers with little damping, if any, it is rather good considering! (not a patch on high end dampers tho)

ENGINE.
Boy, its no V6!!! It revs to 7400 (just over) but it feels quicker changing at 7k rather than revving it out, the data logger will show more info.
It is linear, it does rev, but compared to a V6, it also feels gutless by comparison.
The V6 is loads quicker than a VVC (a v6 with a close ratio gearset), don't let anyone tell you otherwise.
IF, it had the quaife ultra low ratio gearset, it may be a different matter, but it doesn't!

VVC vs V6.
forgetting the torque difference...
Totally different cars, the V6 is heavy upfront and shows it in the corners, especially the low speed twisties whereas the VVC is light up front and is more fruity in the low speeds thanks to it being 80kg lighter up front, the handling is like day and night between the two.


CONCLUSION.
An interesting little project.

You can build a great track ZS for little money if you think about what your doing and ignore the crowd

You don't need expensive fancy brakes, the modulation on this setup is fantastic, and its a bolt on kit!

You don't always need a diff as long as the chassis works. (again, not what the crowd would say!)


As a track car, this is great, it corners at over 1.2g which makes up for its lack of straight line speed, proving that power is NOT everything.

If you have found this interesting and educational, please add some rep.

THE END.

[talkingcars]

What is brake modulation?

[Mark S]

Originally Posted by talkingcars

What is brake modulation?

the progressiveness of the brakes and the pedal.

Most modern cars are over assisted, so kissing the pedal results in surgical removal of your face from the windscreen.

Some cars are just solid, the pedal doesn't appear to have any feel and sometimes you feel like your standing on it to stop the damn thing.

This setup has great feel, the harder you press, the further the pedal travels and the harder the car brakes/slows, not just going onto the brakes, but easy off them too, its very progressive, just the right amount.

[ZS Phil]

Awesome post, thanks for sharing Rep added.

As you know, I'm a newbie MG track goer but a long time MG enthusiast however some of the stuff here is new to me. Got a few questions...

Where you talk about a V6 with close ratio gearset, what ratios are we talking and where are the components from? I've heard of people making a hybrid box using 1.8 gearing in a v6 box, is that what we are talking about here? I did find the gears to be very long on the v6.

What other chassis mods have you done other than the GAZ coilovers?

Can you suggest some spring rates for the V6? I am waiting for some GAZ coilovers to arrive however they need refurb and valving/ spring rates setting up for track and would really appreciate your thoughts on this as you obviously speak from experience... I know you advised against GAZ but they really were too cheap to pass up on.

The brakes you are running, are they the Honda two pots? If so do they use the standard 282mm discs?

[talkingcars]

The closest ratio PG1 gearset is in the 2.0 EFi maestro 8 valve but that is too close, even for a T16 tubby, you don't need 1st to pull away it's that low.

[Mark S]

the twin pot accord type R brakes (300mm) and I use a 300mm disc I get machined up.

The suspension bushing is also key to exceptionally good brakes, the two do work hand in hand.

-

Yes, a hybrid box using any available gears, there's lots of PG1 gearset data to sift through and using a gearspeed calculator you can usually find the gears you want based upon tyre radius, speed and purpose. (I just use the lowest 3,4,5 with final avail on a V6)

Spring rates are dependant upon the rest of the car/chassis. Many of the components used in this build are custom made where we can't get good quality parts of the shelf, sadly most decent parts need importing, there is little available off the shelf in the UK that I would recommend.
Spring rates go hand in hand with the rest of the build, the spring rates on this would not work on most other ZS's.


Through the journey of the ZS, - in the early years - I like most asked and valued the opinion of people in the track and race field, looking back, the copy and paste method is not one I would recommend.
I once measured the dynamic changes that happen on the rear suspension, this is really interesting, remove the shock so you can move up and down the hub and see what happens (you will need steel rulers and measuring implements). There are many more things that happen under load that you can't see, but this item does much more than just go up and down! There is a reason for most things on a Honda/MG, and when you look at some of the bushes and understand them, you realise that most of the polybush manufacturers are clueless.
Basic research on forces will educate you on where the stress forces are and this type of suspension, this will help you in choosing where to restrict movement in suspension and as a bi-product you will laugh at why people brace up the cars where they do!

Then it all comes back to driver ability, I can't stress this enough. I couldn't do the job of a trackday instructor, I would go mad and be climbing out of the window whilst on circuit with the 'typical driver', 'they are all like it' I was told by an ARDS instructor I know at Oulton.

Seriously, drive it until you can't drive it any faster and any smoother.

Whilst you are going through the silky smooth driver journey, what you learn about what happens with the vehicle dynamics will help you in the driver skills journey, its a bit like a jigsaw, it will all come together, the understanding of what the chassis is doing through the corners and under braking, and very importantly, weight transfer, as you try to muscle around a circuit a ton of metal with nothing more than a couple of pedals and a steering wheel.

[Mark S]

Originally Posted by talkingcars

The closest ratio PG1 gearset is in the 2.0 EFi maestro 8 valve but that is too close, even for a T16 tubby, you don't need 1st to pull away it's that low.

some of the early monty/meastro stuff uses different shaft diameters that are not interchangable with the later pg1's.
The diesel and poss the X box was a puny shaft and a std later pg1 shaft which again bought its own issues in that gearsets would not easily interchange.

To play safe for building a hybrid box that can withstand some torque, look at gearsets from brm era onwards

[MG ZS STE]

Awesome post, tried to rep but it just says i need to spread it around before repping you again. must have been the panel filter brah

anyway, if i ever get into track days (which i would love to do) theres plently of good info here