Mk1 race car (Ex slick 50) and Mk2 daily.

I thought I would introduce my Car. A few people will know it, and I have a blog (www.fishontrack.co.uk), but a thread is good because it can lead to discussion/help.

I just did my first race meeting at Brands in the VAG Trophy. The car was great, I am learning! I borrowed through my teeth to get to this point, but it is worth EVERY penny when the red lights go off.
My best Brands lap time from the day was 58.5'ish.
I was hitting 7000rpm in 4th gear at the end of the straight which is just over 110mph with my ratio's. I was usually braking too early for paddock
I somehow managed to win Class B in race 2, 12th overall I would loose alot of places in the first lap (inexperiance, and having my mirrors pointing too far in!) but could then fight my way back through - 'Fun' is the word.

The car is set-up to be very balanced. We have it to be very very slightly leaning toward understeer in the fast corners because it keeps my confidence while learning. And towards the end of the race, all the tyres have gone off and the brake bias tend to be more rearward, and the chassis more oversteer'y. I'm not allowed to adjust the bias valve during the race - it has to be out of reach.



Here is the Spec;
Engine;
1800 8v
comp ratio: 11.25:1
12.2 lift cam
Cam Timing 4.2mm lift TDC inlet / 4.0mm lift TDC exhaust
41mm inlet valves
35mm exhaust
Standard Induction
Gas flowed cast manifold.
Large downpipe not sure of VAG origin.
Single exhaust box 2.5 pipework.

Gearbox;
FM / FD code. Close ratio box.

Suspension;
Leda Coilovers.
28mm Rear anti Roll bar
Reduced Standard front anti roll bar.
Super Pro Bushes.
700-950 rear springs
250-450 front springs.
Polybushed standard top mounts (for now)

Interior;
Corbeau Revenge Race seat
Luke 6-point Harness
Passenger seat for trackdays.
Fire Extinguisher.
SPA laptimer.
Window net, not the granny sort.
Safety Devices 6-point cage.
MSA rain light.
Sometimes ME!

Brakes;
G60 Girling 54? 280mm front calipers
280 x 22 vented discs
Front caliper conversion brackets from EPYTEC Germany.
Mk2 rear disc conversion Scirocco 16v handbrake cables.
Mk2 22mm Master Cylinder and servo.
AP Brake Bias adjuster located in the car (out of reach of driver, as per regs)
Ferodo DS3000 front brake pads.

Wheels;
BBS 157 ET24
Originally from the BMW E30s. you will need different wheel nuts to run these.

Tyres;
DRY Dunlop Direzza 195/55/15
WET Toyo R1-R 195/50/15


There are still things I want to sort on the car:

I am 910kg (with me in it), so 60kg over my lowest limit. A LSD will raise my limit by 65kg, so I'll only have to add 5kg to my current set-up.
The exhaust manifold is not flowed very far.
I need to devide the hot/cool air in the engine bay.
The car is pretty high, but wont go lower because of travel issues!
I want some caster, and solid top mounts - will mount them ontop of the turret with a spacer to increase suspension travel.
The 280 discs are warping
The wiring is still a total mess!
The shell could do with being painted inside.

I dont think I will be able to make Combe, so the next race is mid August at Brands GP!





Rear disc conversion:



Front set-up







Gearbox rebuild:







Interesting lower airbox - Slick 50 trick



Tyres for wet races. I scrubbed them in the dry, and they are CRAZY soft. Almost as soft as a competition wet. they wouldnt last long when pushed in the heat!















I am sure if I was a more practiced/commited driver, the car would go round brands indy circuit in 57.2 seconds... probrably better. I am currently changing gear (when trying to overtake anyway! Otherwise a little before) at 7000 rpm, but there is a redline sticker at 7500 - I just dont want to risk it!

 

very nice good to see some pics of the mk1

 

nice build, quick little car then!

 

Thanks.
It took alot of work to get it from a well-used old race car to something that is hopefully reliable. The only thing that wasnt rebuilt was the engine.

It's tempting to spray the interior, but I'm convinced I would crash it immediately after!

 

....good luck.

 

Photo i took of Sam at Brands. Real nice chap and i wish him the best in his future racing.

 

Very nice, best of luck with it

 

Thanks for the thread Sam.

A typical Slick 50 car showing its lineage there with the six point cage, the spring rates for a non-LSD'd car, Pack D head I would guess on those valve sizes, the reduced front ARB, and stock / Bonrath centered top mounts.

How did the rear discs work out - ok on rear bias or on the margins? I forget whether the Slick 50 cars were piped diagonally.

 

Thanks
Thanks Mike. Same to you. Just had a look at your Audi build, epic! Shame it had to go.

Hi Chris, yeah the bias worked out great - just about! The AP bias valve is wound all the way to the front and seems perfect like that. The rears do seem to be doing a fair bit of braking, as they get pretty hot. But the balance is good. Cheapo pads in there.
I have it piped partly diagonally. Worst case scenario - I would have one front brake.. And the handbrake/gearbox!

What is a 'Pack D' head Chris?

We have played around and tried different front spring rates, and have gone a little stiffer on the front. I felt it needed it with the larger tyres and more grip. It seems to be better.
Considering trying a different front anti roll bar, as the one fitted does NOTHING. Its interesting reading the different thoughts on Front ARB's, so fancy trying it out.

I had to fit my spare dampers (as one of the originals blew), and it turns out they are much better, although steel and heavy. They are also much stiffer than the originals, I have them 4 clicks from softest, instead of 14 on the others.

The Dunlops work best on slightly lower-than-normal pressures. I could be imagining it, but they may last longer (before going-off) than the Toyo's.....
How many laps roughly do the Toyo's last before going off?
I reckon i got 8 good/hard laps out of the Dunlops.

 

Pack D is TSR Speak for bigger inlet & exhaust valves + lots of porting. Different tuners use different terminology for their heads, so it's hard to correlate. Most/all of the Slick 50 engines started out as TSR / Man-In-The-Shed heads I believe. Some were then modded further by other tuners - names escape me at the minute.

Nice build! Any idea what sort of power it's producing? 140ish if you're running a properly lairy cam?

I run 280 fronts / rear discs on the scirocco, and the willwood bias valve in that works well enough - Wound most of the way to the front to keep the back end under control. I'm running a single pipe to the rear brakes.

Those spring rates are scary

 

Thanks Mike.
I was told 150bhp. But I really have no idea, only guesses. I could pull past the 16v class cars although they are 120kg'ish heavier. What BHP are they running usually?
Power to weight for class B should be around 170bhp per tonne.

When I took the old manifold off (cracked to pieces! It was wildly ported), I had a look at the head exhaust porting... Its wasnt huge. I should have measured!

The rear springs are very stiff, but it's not wild to drive - even when the rear tyre pressure rise. I think most 'hot hatches' need to be pretty solid on the back, to remove the inherant understeer. Although it depends on the rear toe angles doesnt it. But the golf isn't adjustable - without the use of a barrier.

 

So have you got dual bias adjusters fitted or the OEM one on the rear axle still?

It'd be worth testing in the wet unless you already have

JP Rose. Macclesfield.

My old Slick 50 motor, one of the better 3 in the field I'm since told, was 165@ Stealth and I am told some nudged the 170s. Of course Dyno Lottery caveat applies, but hopefully higher than 140.

Those rears are interesting, in combo with the front. They must somehow be the only thing holding it on the road! Experimentation with soft-ish front springs, no front ARB and normal rear springs pitches these Golfs into oversteer, time and again. I assume the mild front rates are all focused on getting some grip from the Slick 50 List 1A front tyres, 13" or 14" max, generating some turn, but using the back to do the rest.

If you have spare hacksaw blades or a Coke can, then your rear toe and camber is adjustable subject to regulations

 

Chris, Great point about checking the bias in the wet!! I need to check that!
The standard rear compensator is gone, I'm only using the AP one.... It would be good to reduce it further so I have room to adjust.

Really jumping up and down in the back only gives the tyre sidewalls something to do!
what rear springs are others using? It feels great in mine, so surely others have similar springs? What are your 'Ex-slick 50' springs roughly Chris?
Im not getting much oversteer, unless I do something stupid. It is nicely balanced and will float out of a corner with full throttle instead of dragging the front sidewall along the ground.

 

I don't have the rates (and no longer have the car). It was just very common to have a relatively light front spring, like the ones you quote, and then an apparently ludicrous rear rate - it stands out a mile. It must all revolve around the limited front grip on baggy 13" or 14" 1A road tyres.

Now you're using Direzzas, front grip is up significantly, so you should be able to up the front springs or ARB to control the extra roll you will generate.

 

Spot-on. Yeah, I uprated the fronts, but only slightly. The ARB wil have to be experimented with.

 

I guess that's a properly lairy cam then - where does the powerband come in? Do you drive it on the road much, if at all?

I rev my 2.0 8v to 7200 (limiter is set there) and it's shown no problems so far. I reckon you should be ok with a 7500 limit with the shorter 1800 crank, provided it's been balanced.

 

Not sure what the exact cam spec is Mike, but it sounds very lairy.
again, not 100% sure if its balanced, but I guess it is..... 0.5mm oversized pistons etc.

It tends to really pull from 4800'ish but comes alive around 6000rpm and is still pulling when I change gear at 7000. There is a nice amount of torque though.
I should really get it on the rolling road, but no time or $$$$ after that race!

There isn't much for me to update for a few weeks, but looking to make some changes for the next race soon

 

Is it not best to run a stiffer ARB and damping settings on the rear and drop your spring rates down. Surely if you hit a curb at the moment your just hopping about.

Very nice car though and best of luck with the season !

 

Thanks
Hmmm, I dont know, maybe.
.....although I dont think I can get a stiffer rear anti roll bar (28mm), and the dampers are very stiff too - all round solid'ness at the rear. And only around 150kg over each rear wheel (with me in it) - although not quite that well balanced!

It is pretty unsettled if the rear touches a kerb, although thats expected really. Otherwise it isn't launching itself off the kerbs.

I now realise those rear springrates sound a bit high for a mk1, but I am only a novice and find it handles very predictably - although my driving is probrably unpredictable

If you go around the race paddock bouncing the rear of the FWD hatches, I am sure you will find they are simlarly as stiff..... I have done it.... From Mini's (old/new) to clio cup cars and fiesta cup cars - All of them are SOLID, even when jumping up and down inside (owners permission), I promise.

 

Another trick they did was bin the 1.8 metering head & replace it with a 1.6 version for more fuel which is probably on yours.

I take it the other usual filter goes inside that or just as it is?

Can you get these from anywhere now a days?

mike