Part Weights

Neil Haughey · Jan 2, 2012

Those that have raced these cars here extensively in the UK tell me that you don't want to much lock, it makes the car understeer to much. To elaborate on what I said earlier in the dry I have only desired to have an LSD when pushing right onto my limits under racing conditions, on a track day on dry conditions when your not risking it I just didn't need it TBH and if my car wasn't a race car I doubt I would bother with it personally.

Jonny944CS · Jan 2, 2012

ORIGINAL: Neil Haughey

Those that have raced these cars here extensively in the UK tell me that you don't want to much lock, it makes the car understeer to much. To elaborate on what I said earlier in the dry I have only desired to have an LSD when pushing right onto my limits under racing conditions, on a track day on dry conditions when your not risking it I just didn't need it TBH and if my car wasn't a race car I doubt I would bother with it personally.

+1
Based on my limited road/track day experiences.

40% is a bit too much for my car in most dry conditions. It just doesn't have enough power. In the wet the unit really earns its money - giving fantastic confidence during traction and braking.

333pg333 · Jan 3, 2012

ORIGINAL: Neil Haughey

ORIGINAL: 333pg333

It all sounds good Neil. Can you remind me what your car finished up weighing after ditching all the OEM parts listed?

Click to expand...

Hi Patrick, it weighed 1130 Kg with 4 gallons onboard. This includes btw fully working pop up headlights, electric windows and OEM exhaust. With me in it 1202 Kg which puts me 12Kg over the class 2 limit. With my new Dansk exhaust on the car could well be right on the limit. If I take the headlights and a few other things off the car I will have to stick some lead ballast in the passenger seat area.

Thanks Neil. I'm not sure what the S2 exhaust weighs but the turbo version is really quite heavy. I would assume that going to fixed lights, non steel doors, new exhaust, you would be well under your class weight limit. As you say though, you can re ballast lower in the car so that's something for the future. Makes me hopeful that mine might sneak in around the 1100kg mark without driver. Bigger wheels/tyres/brakes plus extra turbo stuff will count against me vs your car so should be about the same as yours I'm hoping. Also hoping to know that in a few weeks.

Re the OEM LSDs, I'm 95% sure they were a 40/40 plate type. My mechanic terms them as a good sports / trackday car setup but not up to the rigors of Motorsport. I had to have mine rebuilt a couple of times just doing trackdays. Having had the 50/80 Motorsport LSD setup in the old 951 (S2 r/p) I can't say I really noticed any noticeable understeer. Maybe in really slow hairpins but that could easily have been wheel/tyre, suspension geometry as well. Now going with 968 trans w KAAZ 6 plate setup 45/90. So many other changes though, so won't be able to truly compare.

Jonny944CS · Jan 3, 2012

The locking % needs to be carefully considered against the output characteristics of the particular engine and chassis. One size does not fit all.

For turbo cars with big power (>300 bhp), I'd guess the 80 and 90% traction ramps will be more occupied taming oversteer than inducing understeer [8D]

Locked diffs (100/100) and dragster style weight distribution were the norm at Le Mans during the 70's/80's turbo era. Though I'm not sure the drivers would describe them as the sweetest handling cars, more an exercise in patience until the next straight appeared perhaps???

Hilux · Jan 3, 2012

ORIGINAL: Neil Haughey

Those that have raced these cars here extensively in the UK tell me that you don't want to much lock, it makes the car understeer to much. To elaborate on what I said earlier in the dry I have only desired to have an LSD when pushing right onto my limits under racing conditions, on a track day on dry conditions when your not risking it I just didn't need it TBH and if my car wasn't a race car I doubt I would bother with it personally.

I bow to experience however would have thought that 80% would have only been an issue on long sweeping bends but better in the twisty`s.

Ho hum - we live and learn.

Definitely looking to fit one in my Golf - the torque steer is 'interesting' as is lift off oversteer [8|] so I`ll research a bit harder.

Neil Haughey · Jan 3, 2012

No Jonny got the point bang on, it comes down to power/torque really and on 245 wide rear cups the S2 just doesn't have enough to suffer from inherent traction problems except in very low speed 2nd gear corners. However the effect of causing a sudden instability in the car from an open diff is really not nice and of course its throwing away lap time. Of course once one can push even harder still hopefully the LSD will pay dividends as then just sheer speed causes its own traction problems.

Neil Haughey · Jan 3, 2012

ORIGINAL: 333pg333

ORIGINAL: Neil Haughey

ORIGINAL: 333pg333

It all sounds good Neil. Can you remind me what your car finished up weighing after ditching all the OEM parts listed?

Click to expand...

Hi Patrick, it weighed 1130 Kg with 4 gallons onboard. This includes btw fully working pop up headlights, electric windows and OEM exhaust. With me in it 1202 Kg which puts me 12Kg over the class 2 limit. With my new Dansk exhaust on the car could well be right on the limit. If I take the headlights and a few other things off the car I will have to stick some lead ballast in the passenger seat area.

Click to expand...

Thanks Neil. I'm not sure what the S2 exhaust weighs but the turbo version is really quite heavy. I would assume that going to fixed lights, non steel doors, new exhaust, you would be well under your class weight limit. As you say though, you can re ballast lower in the car so that's something for the future. Makes me hopeful that mine might sneak in around the 1100kg mark without driver. Bigger wheels/tyres/brakes plus extra turbo stuff will count against me vs your car so should be about the same as yours I'm hoping. Also hoping to know that in a few weeks.

Re the OEM LSDs, I'm 95% sure they were a 40/40 plate type. My mechanic terms them as a good sports / trackday car setup but not up to the rigors of Motorsport. I had to have mine rebuilt a couple of times just doing trackdays. Having had the 50/80 Motorsport LSD setup in the old 951 (S2 r/p) I can't say I really noticed any noticeable understeer. Maybe in really slow hairpins but that could easily have been wheel/tyre, suspension geometry as well. Now going with 968 trans w KAAZ 6 plate setup 45/90. So many other changes though, so won't be able to truly compare.

Hi Patrick, if I was to move away from PCGB class 2 spec I could get the car a hell of a lot lighter. One of the S2's I know of that raced in CSCC weighed 1050 Kg. On the lights I would just pull the whole lot and fit a fibreglass panel that patterns the badge panel and pop up headlights. This is what most race cars have here as it replaces the whole lot with a single panel weighing under 2 Kg. You can even drive on the road like this as the car is tested for MoT as is and would be classed as day time running only.

On the subject of the LSD I note that those other models only had much more lock on decelleration not on acceleration. Your car sounds awesome btw, we just don't have anything like it here.

Jonny944CS · Jan 3, 2012

ORIGINAL: Hilux

Definitely looking to fit one in my Golf - the torque steer is 'interesting' as is lift off oversteer [8|] so I`ll research a bit harder.

FWD is a different matter.

As you say, the rapid engagement of a plate based LSD can be a little agressive, tending to drag the steering around (not helped by the unequal length VW driveshafts).

I ran an ATB on a Mk1 2l 16v - a great improvement over an open diff for road and light track use, just watch out for the MOT man's break testing equipment!!!

On the flipside, an ATB won't help if you don't like lift-off oversteer as it reverts to pretty much a full open diff on deceleration.

On the subject of the LSD I note that those other models only had much more lock on decelleration not on acceleration. Your car sounds awesome btw, we just don't have anything like it here.

I'm not sure why you would ever want more lock on decel Neil.

My understanding was that both KAAZ and M/Sport diffs are step on in terms of functionality from the standard OEM 40/40; in that they have modifed cam shapes to reduce the locking effect under breaking, relative to a more agressive accel lock.

Neil Haughey · Jan 3, 2012

Yes but isn't the KAAZ unit effectively running back to front in a 968? In other words its designed for a G50 box like in a 964/993 but just happens to fit the 968 due to parts commonality. If you look on the net for example for KAAZ differentials for Porsche they only tend to list 911's and the newer models.

Lots of lock on decel is coming on 911's as it aids braking stability and in particular is supposedly very helpful for those banzai trail braking maneouvres modern 911 race cars seem so good at.

333pg333 · Jan 4, 2012

Gents

The KAAZ unit can be setup in a number of different ways. I left it to the guy who rebuilt the gearbox to decide on the one for me. Of course it can be changed. The Mondena that he refers to is the company that produces LSDs for Guard and Ferrari amongst others. I had mine at 50/80 so decided that 45/90 would be the closet to what I was used to.

"The KAAZ comes with 1.5 way asymmetric ramps meaning the decel side will be half that of the accel side. If the ramps are installed upside down/backward then it would reverse. The decel side would be twice that of the accel side. So the settings possible are (accel/decel) 90/45 (3 active frictions per side), 60/30 (2 active frictions per side), 30/15 (1 active friction per side). Or if the ramps are installed upside down, 45/90, 30/60, 15/30 is possible.
Modena's traditional ramp angles were 40/60, 50/80 and 80/80. And they are double adjustable"

1050kgs in a well sorted S2 would indeed be fun Neil. Perhaps one day for you. [

]

Neil Haughey · Mar 12, 2012

Just did an update guys to the OP. Took my headlights out on Sunday. Bit of background first, we built the car up such that it could be fully road legal and capable which included headlights. Well last year was the only year the car has actually been driven on the road. Like every other race S2 it also has Ring driving lamps fitted in the fog light aperture to meet the MSA regs. What I found last year was that with the headlights on dip beam it illuminated the road no more than with just the driving lamps on their own. To make matter worse I had some problems with the beam height adjusters making full beam not much better. Ultimately I came to the conclusion that in this country for a car that has a specific purpose the factory headlights are pretty much a chocolate frying pan job. It can be day time running only on the MoT which is no problem at all for me as its only run in the day either for a quick track 1/2 day or to do stuff like check that the ABS works OK etc. etc.

The headlights weighed less than I expected, the whole lot is about 7.5 Kg with the covers left out. These are going back on the car held in place with L brackets. Thing is though its 7.5 Kg saved which was all high up way in front of the front axle line so a bit of a no brainer mod. We also weighed the OEM exhaust and my brand new Dansk one back to back with both in their bare configuration. Only a 3.4 Kg difference (11.6 v 15) is a lot less than it feels but I get the feeling though that most of that is in the back box, again a useful saving from the opposite end of the vehicle.

Overall with my weight at 72 Kg and the all up weight previously at 1202 Kg this puts me more or less bang on the class 2 weight limit of 1190 Kg.

944 man · Mar 13, 2012

I can remember when I weighed 72 kilos, but only just..... [

]

Neil Haughey · Mar 13, 2012

11st 4lb dry [

].

My personal weight distribution is not great though due to my Gerry Marshall approach to race fitness, I even have the tweed jacket and have been known to like a cigar [

].

944 man · Mar 14, 2012

GM was a friend of my uncles (whos a professional racer, with a similar waistline and approach to race fitness). Certainly a larger than life character.

Simon

Neil Haughey · Mar 14, 2012

Well its extra padding in case of a crash, and helps to improve the cars CofG as 10 Kg in the gut is a foot lower than 10Kg in the arms/shoulders [

].

Hilux · Mar 14, 2012

Sorry for the OT post but I had to....................you`ll see why [

]

GM was a friend of my uncles (whos a professional racer, with a similar waistline and approach to race fitness). Certainly a larger than life character.

Oh yes , how true, one of the most succesful drivers in the UK bar none - won over 600 races.

When I was a little lad my best friends bigger brother (by a few years) was involved with DTV and we went everywhere (including Crystal Palace - yes there was a race track there once) and I have seen Baby Bertha and Big Bertha in action with the big man himself many times.

If you like that era try these.........................

Gerry Marshall at Crystal Palace part 1

part 2 - superb finish

Neil Haughey · Mar 14, 2012

I have a nice little dit about GM. A good mate of mine used to own a TVR and went on one of their clubs track/event day things at Brands Hatch a good few years back. My mate who had no idea who GM was described this guy as sounding and looking like a total geezer, waltzed about like he owned the place, big side burns etc, etc. Anyways he took my mate around the track in his own car, went about twice as fast and made the car dance around every corner whilst driving one handed and chatting. The way my mate describes it is that after the fear subsided the sheer amazement at what the car could do in talented hands was laugh out loud amazing. The best bit is my mate still had no idea who GM was until much later after the event. I think the fact that someone can generate such a huge impression in a person who had no idea who he was speaks volumes about what a legend the man was.

944 man · Mar 15, 2012

I had a book by Gerry Marshall, called 'How to Go Racing' or something similar. I couldnt believe it when a few years later, I saw GM walking out of my uncle Chris's transporter/coach in the paddock at Oulton Park, all smiles and 'see you later then'. It turned out that they were big mates.

I looked everywhere for the book when I got home because I wanted GM to sign it for me, but it had 'disappeared'. That was probably during the first year of the TVR Tuscan series, so 1989?