In the first and second parts of our R33 build-up series, Mark bought this imported turbocharged 2 door and fitted up a monster 3½ inch exhaust system to it. Now, in the third installment, we follow him getting it ready to take part as a course car for a competition tarmac rally. And it's transformed into a monster!
Firstly, why did you end up entering the Skyline in the Classic Adelaide Rally?
Probably for more durability than anything else, I mean the Datsun (1600 powered by a SR20 turbo engine) is still a pretty old-school sort of car, plus it needed an engine rebuild before I could use it again. So the Skyline was a good option. Plus, you know, that's really where the market's going and that's the sort of car I want to work on - so I'll promote that one, I reckon.
The organisers were happy for you to run such a more modern car than the 1600, since it is a classic rally?
Yes - it was just put down as a course car.
So what was the role of the Skyline over the four days of competition?
It was different from day to day. Two days we were leading the competition group - Thursday and Friday - and Saturday/Sunday we had to push some of the old tourers.... some old shitbox Hillman or something like that. We just had to push him along a bit. But there were two good days though.
Why was a cage needed in your car if it wasn't competing?
Just for safety.
So why only a half cage?
We simply did it to comply as a course car. They like you to have one on the competition stages, and it's in there simply for roll-overs. It's not there for chassis strength - it's just to keep the scrutineers happy. And also, one advantage of the half cage is when I take it back to standard, there's no welding marks or anything inside. It's a nice hoop - it's very practical.
So I guess you'll be taking it out fairly soon?
Oh yeah. I'll sell it to a Drift King or something like that. (Drift Kings are the local drive sideways guys!)
Was it a requirement that the cage complies to any recognised regulations?
Yeah, it complies to the FIA rules and CAMS.
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So what are the roll cage specifications for the Skyline in this application, you ask? According to the 1999 CAMS Manual of Motorsport, it has to feature "sound construction, be designed to suit the vehicle, adequate mountings and a close fit to the body shell". A main roll bar ("hoop") is mandatory and must be one piece with absolutely no joins. It should also be smoothly bent, reach close to the bodywork and stand as close as possible to vertical. The driver's shoulder (when viewed from above) must be protected by the hoop, and it must also never get within 150mm of the driver's head. Backstays are compulsory and these are attached near the roofline at the outer ends of the hoop and make an angle of over 30 degrees against the hoop. These too must run back as close as possible to the body. One straight diagonal member is also necessary to brace the hoop, and it must be joined to the hoop no further than 100mm from the hoop/backstay junction. Mark's car uses two of these diagonal supports.
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What material was it made from?
I used cold drawn seamless steel (with a minimum tensile strength of 350kpa) and the hoop size was 45 by 2.5 and the back runners were 38 by 2.5mm. Just as it says in the CAMS book.
And were high tensile bolts used throughout?
Yeah, we used 8.8 M8 bolts and high tensile hexagon head fasteners (to AS2465). And it's using some CAMS spec bolt-through bracket system on the hoop. It works nice and it's all as it says in the CAMS book.
Where were the mounting points?
There are four in the hoop, I think, and four in the backstay and diagonal members. And we've used all the original seat belt mounts and seat brackets to bolt it up.
Was it assembled mainly outside the car?
A lot of it was in - about three-quarters of it. But the most rewarding bit is the last bit when you can see it on the ground and you can work all the way around it. The only welding inside was only ever tacking and we were really careful.
Did the trim and the back of the car have to come out to fit it?
No, it'll still go in with the trim in, but I've pulled all the trim out of it just so I don't mark it. There won't be any sign of it once it gets pulled out.
How much does it weigh?
Probably not as much as the interior that came out. I'd have to estimate 15-20 kilos.
How long did it take to complete?
About 15 to a long 20 hours.
And the new seats you've had installed - were they required from a safety point of view?
No I just thought with the suspension and tyres and everything that I'd need something that'd hold my arse better than the factory seat. I don't like when you've gotta brace yourself. It makes a really big difference. And since there's not much padding there underneath you, you can really feel what the car's doing - it's wicked.
What type are they?
They're Momo Rookies - that's because they're so uncomfortable you wouldn't even complain about them.
Is there any bracket thickness requirement or any other regs in regard to the brackets?
Nah, if anything its way too much. The guy who did them just lost the plot and it got stronger and stronger - you could probably jack the car up one of these. They're way heavy. There like they're out of a Touring Car or something.
Was there any other safety equipment that had to go in?
There's the fire extinguisher, they wanted that. And a first aid kit and a couple of triangles.
And the Terra Trip system?
Yeah, that actually shit itself not long after we started, so a lot of it was off the speedo. It was very effective actually. Very effective because the pace notes that we were given were all so long and most of the roads you can read - so, I don't know, those Haldas (Terra Trips) just make you more paranoid I reckon. Maybe they're good if you go and get lost, but not on tarmac rallies.
And we hear you got chased along the special stages by Aussie racing legend Sir Jack Brabham?
Yeah - that funny old man. He's a deaf as a doornail I reckon. The navigator was sayin' he was hitting him with a book telling him to turn left. He's fuckin' fast though.
He was after you on the stages was he?
Yeah - and he's a quick man. He caught right up. You're not allowed to do ten-tenths out there - but he's showed he was a clever old man. He just doesn't like trees.
You mentioned that the cage in the Skyline wasn't designed to give any extra chassis stiffness, but did it make a difference?
I don't know. We'll wait until I pull it out. Because I've never really played hard with those rims and tyres either. It definitely cuts back some oversteer - it doesn't oversteer anymore. At least when you had it tank slapping you could chuck the bum out in it.
And how did the Skyline compare to the 1600 in the course car role?
Much sweeter. And it's a lot quicker, safer car - you don't have to be on it all the time. It's much, much more forgiving than the Datsun. Like, you can come in mid-corner and hit the brakes and it just understeers a bit - if you did that in the old digger it'd just chuck you off the road, you know. Twenty five years up in suspension technology is just amazing. But we were limited (by the factory computer) at 180 (km/h).
So you hit that limiter a couple of times did you?
A couple of times we got close. That was the biggest advantage about the navi looking over at the clock. You know, he can tell me when we're getting close - it's wicked.
Is it a harsh cut-out on the Skyline?
I've only ever done it once and that was bad enough. I don't remember exactly what it's like but it's a fright. It's like hardcore detonation - but it's not a damaging thing. It's awful - you drive it up and its bdd bdd bdd. Not good...
If anyone wants to further discuss the Skyline's half cage, contact Mark of Exhaust Technology on +61 8 8272 7500 or via
www.exhausttechnology.com.au
Mark's Monster, Part 1
Mark's Monster, Part 2 - The Exhaust System
Mark's Monster Part 4 - The Wheels, Tyres and Suspension
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