Birth of a Rally Car: Tech9 Ruf SCR

[pht9]

First of all thank you to John for his decision to let this thread continue, I hope that everyone enjoys my experience with the build and it could hopefully inspire others in some of the areas that are covered. Oh, and my post count will increase as people get to know me and our work

 

Its a very interesting debate reference the track of the car. I will freely admit to having limited rally experience. I hope to learn from the other experienced members here in their experience and knowledge, and likewise, sure some of my technical ability will bring some fresh ideas to the project.

 

The rally car build stemmed from my personal desire to do something different. I have raced on circuit in lots of fantastic machinery since the early nineties, I now have some time on my hands, and felt the need for a challenge. I love the older vintage 911's, we look after quite a few in the business, and this was a chance to start something new. I originally started looking at cars already built, but was quite shocked at both the level of preparation and nothing really got me fired up in terms of specification...... so my thinking was.....

 

weight less than 1000kg

power as close to 300bhp and in excess of 250 ft/lbs torque

HTP/FIA papers

Tarmac specification

 

The build would encompass lots of historically important parts, that I would find interesting to source and learn about, and lets face it, a lot of these parts are either NLA, or a chance to fabricate or produce high quality replacement items, keeping the historic design visual and technical aspects.

 

So, why a 3062 homologation narrow body car ?

 

Again, I may be wrong, but the limited rally experience that I have has taught me that my 'slicks and wings' experience and technique is not the fastest in rallying. I have considered that a car has to be neutral, able to be driven at the edge of the traction circle of the tyre to enable either the front or rear to slide into a corner to get the correct attitude for a successful entry and exit. I felt that had I opted for a RSR or an RS body with 9J or 11J wheels, then maybe a driver with higher ability than me could drive the car at the limit, but in my opinion, yes that ultimate grip level is higher, but I felt that I would not have the control like I would with smaller rubber, completely opposite to my instincts as a circuit racer, and I guess that factor also contributed to my decision.

 

So, I guess only time will tell , but lots to do before it turns a wheel !

[World Citizen]

Any ideas how far can you push the chassis spec. before you are either chucked out before you start or other competitiors start to whine and complain its 'so unfair' when your car get scrutineered at the first event.

 

Are you allowed to move the engine forward if it doesn't involve cutting the chassis or changing mounting points? Any restriction on using materials other than your basic steels and aluminiums for fabricated parts? What panels can you replace with composite ones? What brake spec. do you have to run, Porsche production parts or is it free?

 

I tend to agree with you on your reasons for going the narrow bodied route. In my mind having to throw wider tyres, wider track width and harder rollbars at one end of the car to make it go round corners is all about fixing a fundamental tyre grip problem not about adding speed to your build spec. Get the corner weights, centre of gravity, tyre contact patch, suspension geometry and brake balance right and the speed will come. Get it not quite right then you will have to lose some overall perfromance by slowing down the stronger end of the car to match the weaker end of the car so you have confidence it will go in the direction you want it to when you want it to. With your circuit racing experience I'm sure I'm not saying anything you don't already know.

 

One other advantage you have probably thought of already is with a narrow car is you can squeeze through tighter gaps between trees and fence posts without ripping a corner off

 

Can you post a link to the rules as I'd be interested to see what holes the FIA have left when writing them. I'm a poacher but have also been a gamekeeper with motorsport rules and would be interested in reading them.

 

Dom, shouldn't you also add long wheel based cars are for high speed corners, a LWB narrow bodied car will be quicker on high speed corners than a SWB wide bodied car due to the reduction in aero drag and the stability from the wheel base. Sounds like a debate for down the pub as with more drink I'm sure it would become clearer.

Edited April 27, 2011 by World Citizen

[pht9]

Any ideas how far can you push the chassis spec. before you are either chucked out before you start or other competitiors start to whine and complain its 'so unfair' when your car get scrutineered at the first event.

 

It is always prudent to get the MSA scrutineer to inspect the chassis at some point, before the car enters competition. I intend to get mine inspected prior to painting

 

Are you allowed to move the engine forward if it doesn't involve cutting the chassis or changing mounting points? Any restriction on using materials other than your basic steels and aluminiums for fabricated parts? What panels can you replace with composite ones? What brake spec. do you have to run, Porsche production parts or is it free?

 

I guess that this depends upon the series you intend to prepare for. In my instance, as I will obtain FIA and HTP papers, then I have to adhere to the homologation documents, in this case 3062. This document is not available online, would be more than happy to scan and email to you this particular set if you are interested in a similair build ?, although the quality is not great, it may not reproduce.

As an aside Homologation documents can be ordered from the MSA, IIRC they are about £50 per set.

In 3062 for instance, we have to run original bodywork with a ducktail, alu bumpers, mountings, bellows etc all have to be retained, no fibreglass front wings or bonnet.

I will run 930 four piston calipers all round, with cross drilled discs, I am deleting the servo assistance and will have a pedal box with twin master cylinders.

[pht9]

some more pictures of the cage installation

 

 

 

 

 

I hope this is the only time I see the underside !!

 

[pht9]

Just need to get Jonny Mowlem out there now Phil as well, maybe he could co drive for you, I seem to remember you both getting on well

 

I thought rallying was a non-contact sport ?!!

[World Citizen]

I guess that this depends upon the series you intend to prepare for. In my instance, as I will obtain FIA and HTP papers, then I have to adhere to the homologation documents, in this case 3062. This document is not available online, would be more than happy to scan and email to you this particular set if you are interested in a similair build ?, although the quality is not great, it may not reproduce.

As an aside Homologation documents can be ordered from the MSA, IIRC they are about £50 per set.

In 3062 for instance, we have to run original bodywork with a ducktail, alu bumpers, mountings, bellows etc all have to be retained, no fibreglass front wings or bonnet.

I will run 930 four piston calipers all round, with cross drilled discs, I am deleting the servo assistance and will have a pedal box with twin master cylinders.

 

No need to scan the homologation docs, just interested in how much room there is to maneuver. Sounds like not much which is good as it levels up the playing field to hopefully allow the best man to win not the one with the biggest wedge in his back pocket.

 

Dom, thanks for the insight to rally car set up, I know very little about rally cars and forget how many different types of terrain they have to run on so it must make it a right bun fight in finding the optimum set up. I bet over the years you were kept well busy by indecisive engineers not knowing what they wanted.

 

The shell looks in really good condition, its the total opposite to what I'm starting from I shall watch this build with interest, thanks for posting the pics.

[pht9]

the scuttle area proved very time consuming, I want the bulkhead area to be free from all the standard holes used for the heating system and loom routing. As we will use a bespoke wiring harness and no heating system, the area can be cleaned up.

 

We also fabricated a scuttle brace which is fully welded, as this area can flex, it replaces the factory bolt-in version.

 

[hukent]

Loads there Steve, I nearly added the long wheel base bit but that was opening up another can of worms:-) Rallying by it`s very nature is not actually relatively high speed, it is for the terrain but absolute speeds are lower than circuit racing.

 

As Dom rightly points out, the differences in Rally terrain are huge, so there is no finite setting,

also remember you are restricted by tyre size and in most championships by one make tyre.

This weekend we are doing the Pirelli Rally, vastly different to the previous two rallies of the year,which were in Wales with it's fast flowing stages.

The stages this weekend are Mega long straights with haipins and 90 degree corners after them. We run a different gearbox for this event, with better ratio's for the high speeds, it is in fact the 'Tarmac' gearbox, we also fit the Tarmac spec. brakes!

 

Any ideas how far can you push the chassis spec. before you are either chucked out before you start or other competitiors start to whine and complain its 'so unfair' when your car get scrutineered at the first event.

Are you allowed to move the engine forward if it doesn't involve cutting the chassis or changing mounting points? Any restriction on using materials other than your basic steels and aluminiums for fabricated parts? What panels can you replace with composite ones? What brake spec. do you have to run, Porsche production parts or is it free?

 

Very difficult to adapt anything on 'Historic' Spec. cars, as basically, if it wasn't used then, you can't use it now!

Although European regs. are a bit more relaxed.

Edited April 28, 2011 by hukent

[Richard Bernau]

Wide track cars are for fast high speed corners, by their very nature they are stable, twisty smaller roads require cars that are inherently unstable, narrow body cars are far less stable, hence they are much quicker at direction changes,

 

stand with your feet together, how stable are you? not very. stand with your feet, 2 foot apart, suddenly you become more stable.

 

OK - I am not going to argue with you about rally cars in general (not an argument I have a hope of winning ). I kind of get your analogy in that instability can be useful (maybe critical on some surfaces), drivers deliberately unsettling the car prior to corner entry aka Scandinavian flick etc. To take your analogy a step further though lets think about how the stance of a professional ski racer has changed from a skis together stance to a wide skis 18+ inches apart - be that in slalom, Super-G etc. I feel the wider stance lets you press off the outside ski and change direction more rapidly and that is exactly what I feel with the wider front track. Forget the racetrack, I am thinking of hooning around little French country roads peppered with roundabouts around CLM last summer. When I turn the car in now, I get more immediate response and at the risk of a cliche the car feels more kart like and pointy and square. What I don't have is that moment of classic 911 understeer where the front feels like pushing on until the tail comes into play. Remember, I am running narrow geo with wide tracks, and the same size tyres as before so almost nothing has changed other than track width. The increased pointiness at the front has been the biggeset revelation and delight for me going to wide tracks. I am not saying you cannot achieve this other ways - less front sway bar, smidge of front toe out, more rear sway bar/torsion bar etc.

 

At the risk of getting shot down in flames (and the risk of hijacking the build story with something that is impossible for an FIA spec SC anyway), I would suggest that the best tarmac rally spec 911 might be the ST shape with 9 inch flares all round. This is what Ryan has done in Oz - from a 2.7RS spec tarmac car he now has evolved to a similar spec but ST shape and it seems to be working very well for him.

 

 

In my mind at least, I think I would want a stable front end that I can lean on and which resists understeer to the maximum extent possible and an unstable rear that will help me rotate.

[Al_W]

V interesting discussion, chaps.

I can see both points of view, but it's interesting Porsche ended up widebody for rallying on SC and SC/RS

 

 

Maybe I'll put the rivet gun and Almeras flares back in the garage for now (I wish....)

[Fred]

I used to rally some years ago and I too deleted the heating system... I wish I hadnt though because a misty screen is a nightmare especially when darkness decends.

 

can't you use heated windscreen?

 

motorcyclist use a special spray on their visors which seems to work very well against mist.

[pht9]

yes, a heated screen will be used, combined with a blower system that will vent air across the surface of the screen, which should assist with any misting issues.

 

again, as part of the design specification, this car will be used only for tarmac events, so the worst conditions that this car will encounter is driving rain, I guess a combination of helmet visor demister and rain-ex will assist this aspect, as non of our circuit race cars had heating systems, and in inclement weather, this usually prevented any serious visibility issues

[hukent]

as part of the design specification, this car will be used only for tarmac events,

 

Oh, I see, SISSY rallying!!!!!!

In that case you're probably better off with a wide track system, as you need the car to be stable at all times, as I'm sure you're used to, being a track star!

Tarmac = wide track, go where you point it,

Loose = narrow track, more chuckable.

By the way, I'm always looking for an exciting ride.

Edited April 28, 2011 by hukent

[pht9]

Oh, I see, SISSY rallying!!!!!!

 

just dont like getting dirty

 

In that case you're probably better off with a wide track system, as you need the car to be stable at all times, as I'm sure you're used to, being a track star!

Tarmac = wide track, go where you point it,

Loose = narrow track, more chuckable.

By the way, I'm always looking for an exciting ride.

 

I guess the debate continues !!

[pht9]

Can you post a link to the rules as I'd be interested to see what holes the FIA have left when writing them. I'm a poacher but have also been a gamekeeper with motorsport rules and would be interested in reading them.

 

Here is a link that you may find interesting for reference, appendix J for each period

 

FIA appendix J historic period

[pht9]

This picture shows the mounting brackets for the plumbed-in fire extinguisher that will be fitted.

 

 

The seat mounting rails have been welded in to accept a pair of Recaro race seats. I got the mountings as low as possible into the chassis, the seat side mount brackets, then bolt directly onto the rails, this gives a good rigid mounting, seat can be moved fore and aft but will require unbolting.

For competition use, I prefer this method, as seat runners offer too much flex, and when I drive I get more 'feel' in terms of what the car is doing with a rigid seat mount.

 

The front strut brace has the mountings welded into the turrets, with a bolt-in bar.

 

[pht9]

It is planned to run coilover suspension so the rear suspension turrets require modification. This is required to give clearance of the increased diameter of the rear damper with the coil spring fitted. The upper area is also strengthened, as the loadings on this part of the chassis will increase due to the new suspension layout.

 

I wanted to keep the modifications to the correct 'period' style like the RSR, with 100mm turrets, so first step is to graft in the complete turret housing into the rear chassis beam

 

Here is a picture that shows the bare turrets before installation

 

 

Here, the completed installation

 

 

[Kroggers]

Nice stuff...

[Northy]

Do you own Tech 9 then? I can't imagine how much a build like this costs, otherwise?!

[MrPerkles]

Do you own Tech 9 then? I can't imagine how much a build like this costs, otherwise?!

"Current 911: 2005 Carrera GT , 1976 3.0 Turbo , 2008 997 GT3 Cup S , 1974 2.7 carrera , 1978 3.0SC rally"

 

he may just about have enough cash either way Northy

great build following with interest

[Fred]

"Current 911: 2005 Carrera GT , 1976 3.0 Turbo , 2008 997 GT3 Cup S , 1974 2.7 carrera , 1978 3.0SC rally"

 

he may just about have enough cash either way Northy

great build following with interest

 

When I first saw the cars phill earned, I nearly drop my cup of tea on my legs!

 

I just feel a bit embarrassed with my £4500 3.2...

 

but good on you Tech 9, you make guys like me dream of better days!!!!

[pht9]

Do you own Tech 9 then? I can't imagine how much a build like this costs, otherwise?!

 

I guess the build cost is relative to the end result, when you see what top spec historic escorts are selling for, then a quality build 911 will certainly be in the same league. I initially looked at buying a car that was already built and prepared as a rally car, but each time I viewed a car, I felt that it wasn't what I wanted and decided to build a car that I had control over all aspects. Sure the budget to build these cars is top-end, but I consider the investment to be safe in terms of the final value of the car, and also the use of some rare genuine and replicated historic parts makes the build very special both now and for years to come.

 

 

"Current 911: 2005 Carrera GT , 1976 3.0 Turbo , 2008 997 GT3 Cup S , 1974 2.7 carrera , 1978 3.0SC rally"

 

he may just about have enough cash either way Northy

great build following with interest

 

the way this build is going, something may have to go

[pht9]

Detail shot of the strengthening to the engine mounting location

 

 

Torsion bar reinforcement

 

[pht9]

With all the chassis modifications completed, the shell is delivered back to SPL to complete the treatment process.

 

After the initial dipping process was conducted earlier in the year, there is obviously a few weeks delay, whilst all the fabrication is completed. During this time, a small amount of surface corrosion can form, so a very important aspect of the bodyshell treatment, is the following stage.

 

The chassis returns for a 'quick-dip', then it is processed through the e-coat plant.

 

This ensures that the surface preparation is at its best, and gives the e-coat a fully prepared surface in which to adhere, and prevent further corrosion.

 

It is a good chance for the e-coat to penetrate the box section areas of the chassis, and also the rollcage itself, as fill and drainage holes are located strategically throughout the chassis to ensure full coverage.

 

Here are some pictures of the chassis awaiting the process

 

 

 

[

[pht9]

A bit more progress !

 

The chassis has returned from a redip and e-coating. It looks incredible, like turning back the clock to 1978 when the chassis was first produced. I am very happy with the current results, and we should have a really good base now for the final preparation into paint.

 

There were a few very small areas not covered by the e-coat process, due to air locks as the shell is dipped, but these were minor, and we covered them immediately with some epoxy two pack primer to protect, if you look carefully at the pictures you can see some small patches.

 

Thanks for looking