TAP Tech GC8 2 Door Wide Body Tarmac Rally Car
 

Hello

Feel free to chip in with ideas, comments and suggestions. there is no such thing as a bad idea so dont be shy

As a bit of background, I rallied for a few months, in that time i entered 7 events and finished 1. in the last event i did we were second overall when we retired, in front of some ex works cars. i decided at that point that i had to build a proper car as reliability was killing morality
the failures included 3 gearbox linkage breakages, 4 rear driveshafts snapped, electrical gremlins and i crashed on one event. box was stock 6 speed, shafts were R180, electrics was down to being untidy behind the dash and the crash was down to me trying to be a hero, so we know a few of the things that need to be improved, but there were a lot more issues that got overlooked that needed attention

So, the mission is: To build a competitive and reliable rally car, by using modern technology, help from the right people, aero advancements and some 'outside the box' thinking. And along the way maybe make some friends, have some fun and learn something :luxhello:

The basic plan:
A '99 Type R chassis, caged, seam welded, tubed, arched, lightened
aerosim bodykit as the starting point
widetrack suspension with long travel dampers
sequential DCCD box
built high comp motor
proper ECU, transmission controller and dash
good cooling systems
better brakes with better ducting
but most importantly for me, the car has to feel right when it's driven hard, so this is where i will be concentrating a lot of my effort

I bought the initial car blind, off eBay, cheap, running, taxed n tested. So first things first let get her naked and see what we got.
https://cimg8.ibsrv.net/gimg/www.sco...cddc5b2a2f.jpg
Oh happy days :D

body panels in place, suspension set to 'stupid low' so set about sorting the inner arches, the car goes about 20mm lower than in the pic and still rolls, there is an issue with the back of the front inner arches which is preventing full lock at full compression but that should be sorted later
https://cimg5.ibsrv.net/gimg/www.sco...20b3dd0ae3.jpg

while i am in metal work mode the holes in the bulkhead and floor got 'patched' up. no idea where or how many holes i'll need so i did all of them apart from the steering rack
https://cimg9.ibsrv.net/gimg/www.sco...e236f3562a.jpg

cage in the process of being installed, got annoyed with my welder cos one minute the gas work the next it doesnt, so i'll either leave it for someone else to finish installing or buy a better welder, done most of the hard work and i know where all the tubes go so i can move on and it can be finished later
https://cimg7.ibsrv.net/gimg/www.sco...c6fc1fa19c.jpg

so now time to start thinking.
long travel dampers. this is not an issue on the back as they are long enough. the issue is on the front and it's the distance between the lower and upper mount that limits the length of damper. so i modelled up some strut tops which sit above the turrets and raise the top of the damper by about 30mm (still need to mock this up with a proper bonnet, but it works with the bonnet skin i have to hand).
the reason i did not raise or weld on different turrets is due to rules, 'standard suspension mounts' must be retained, however they do need to be strengthened to prevent the bolts from pulling through, so i added a few holes and increased the size of the bolts too, I have lost a bit of camber/castor adjustment but that can be sorted other ways. each top mount weighs 700g. old ones were 200g's (but bent often so needed strengthening anyways). Nuts, i just added 1kg to the car! anyways, here's a pic of them
https://cimg7.ibsrv.net/gimg/www.sco...6e5d754263.jpg

now how do we achieve a wider track
on the front the options are: use standard arms but move the inner pivot points outwards - awkward at the rear due to chassis rail, subframe can easily be modified but 'standard suspension mounts' must be retained so it's a non starter unless i do something like use eccentric bushes but that only moves the points a few cm's
use longer arms - standard arms offer no adjustment or easy way to extend so a custom set will be needed
modify the hubs - so i took a look at the hubs, the first thing that struck me was the weight of them, so i took them apart as they are the bolt on bearing type. the hubs themselves look like nice little things, but weigh in at over 5kg's each! well they're not going on the car unless they diet. I also wanted to look in to modifying the geometry at the hubs as the roll center is effected negatively by lowering the car beyond a certain point and there is an issue with inducing bump steer due to the angle of the steering arm. it's not easy to apply those changes to the existing hub to the extent that i want to, so i got on my computer and started modelling some
here's the models i made of the original hub assembly, mainly so i had reference points to start from
https://cimg2.ibsrv.net/gimg/www.sco...3bd50b38bc.jpg

subscribed! this sounds interesting, love a good project thread please keep updating as you go along with it. there are quite a few guys with proper knowledge still around i think who hopefully will pitch in with advice and ideas etc. good luck with it.

looking forward to seeing this one progress, nice drawings too!

Those Carbon/Kevlar wings look tough as hell.

Nice project. Subscribed!

Great your on here will follow

Thanks guys :) sounds like you're intrigued so i'll go into a bit of detail

Jonny Cut Corners, the kevlar wings are not very 'tough' really, they're single ply, you can see through them if you hold them up to the light, you probably noticed i'm a bit anal about the weight of things, the wings weigh a shade under 1kg each :norty: but maybe you were commenting on their appearance! :lol1:

I found a coded welder locally to do the cage and other bits so that's a relief, thought i was going to have to buy a better welder and learn to weld proper!

Wiring is well under way, my old man is doing it for me, he is as anal about wiring as i am about weights so should be a nice loom. Still havnt made a decision on ECU as the one i want is still being developed so he can't really do much more than the engine loom and basic interior stuff. Plan is to have a main bulkhead connector to make removal of engine quick and easy

Below is a pic of the hubs, adjustable steering arm, caliper mount and brake duct I have designed. Prototypes will be made shortly to see if it all works as designed, fingers crossed.

Summary of what i've done with the hubs
Lower ball joint location lowered 32mm, maintaining existing axis of rotation
Steering arm now uses a spherical bearing, adjustable from stock location (0) to -60mm, maintaining the existing axis of rotation - this enables me to use the longer bottom ball joints that are on the market to drop the pivot point a further 25mm if necessary and still maintain ideal steering arm geometry.
Wheels I chose 17x8 team dynamics pro race. Cant go any wider due to rules. Can use 18" but I don't want to mess up the geometry by doing that. And 17's are quite a bit lighter. There are lighter wheels out there but i need about 16 of them and when rallying you have to view them as consumables so the price was a major factor when choosing. Plus they have huge inner clearance and a great rep for being robust
Brake bells are custom
Brake rotors are 366mm diameter
Clearance between caliper and wheel is tight (2.5mm as designed) but I designed in some flexibility in case of issues, so i can go to a smaller rotor with minor hassle
Hubs have stock brake mounts in case I ever swap calipers I can use some 'generic' brackets and just bolt a different brake kit on. They also use standard '114x5 bearing pack's' and the wheel sits centrally to the bearing to avoid premature failure
Caliper mount bolts are now in double shear so the main load path goes 'straight' into them rather than being offset and the bolts being in single shear. This will limit flex which is a concern due to the tight clearance
Standard speed sensor retained, now located vertically, from above, in the centre (can't see it in the pic)
Duct will probably be fiberglass and is symmetrical so i only have to make 1 mould
These should bolt straight on to any 5x114 so i can pt them on a car and go test them prior to putting them on the rally car

Hub, caliper mount and steering arms weigh 3.4kg's (0.5kg of that is the caliper bracket) so the hub and adjustable arm is 2kg lighter than a stock hub

The whole assembly (hub assy, brake assy) excluding the wheel is predicted to weigh 16.5kg's. 6.5kg's of that is the rotor!

sorry if that bored you guys to tears, but i'm well into this project :thumb:

https://cimg6.ibsrv.net/gimg/www.sco...2f7449a1f8.jpg

I love a bit of detailed cad design being an engineer myself. Great work. Love this!

How on earth have you got 366mm discs inside a 17" wheel?!
Those rims must be wafer thin?

Cant get more than 330mm in a stock 17" wheel!

Ps, I was refering to the look of the wings. I have noticed your weight obsession lol.
It pretty hard to save weight from a GC8 I think, so you need to be a bit crazy about it to get a decent improvement.

How much go you think polycarb windows would save over stock?

You said your going to be running 17" 8j wheels but in the pic they look like ROTA GTR-D's at least 9j how will that wide look body work with smaller wheels or is that where the wide track comes in to play ?

I also think you'll struggle to fit 366mm discs under 17" wheels , My WRC car had 365mm discs and AP 6 pots that only just fitted under 18" wheels , and I had some Team Dynamics
Cheers Ian

Are you using the 100 pcd bolt-on bearing (legacy and wrx hatch)? Or, the STI 114.3 bolt-on bearing? Or, the 114.3 STI bolt-on bearing, then re-drill the pcd to 100, and turn-down the flange? Or, dual pcd wheels?

Normally, you'd use spacers on the driveshafts. Are you doing something different? Does your hub design accommodate the stock shafts?

Now, I know what all the girls say but an inch really isnt that big :lol1:

Have some faith Iain :D Your old car was designed 20 odd years ago :p

If it doesnt work out i'll skim a bit off the brake mount so the caliper can move further in and skim a bit off the OD of the rotors, no biggy as got a bit of room on the inside of the rotor to play with. It's half the reason i'm getting prototypes of all this stuff made.
I got no idea how thick the rims are, TD would only give me the data for the inside in case i copied them :wonder: at least they gave me the bit i need to work with

Rims in the pic just so i can set the thing up, 18x9.5 with stupid tyres, it's the only set I have at the moment apart from space savers :lol1:

Windows i'll let you know. got quoted £900 for a heated screen and set of poly windows from demon tweak, i told them they could keep them for that price :cuckoo: i'll make my own cheers! Heated screen i'll have to buy tho, but not bad for about 225, saves me having to have a heater and the pipework, so cost effective weight save and simplifies things too. we'll deal with the cold by switching the anti lag on :luxhello:

Keeping bearings simple. 114.3, they're easy to replace, cheap enough and seam to last on abused cars, wheels spec'd to suit so no need to bother messing with PCD. centre of wheel aligns with centre of bearing to minimise loading on them too
I dont like the idea of spacers, i assume you put them at the hub end, between the contacting faces of the outer CV and the bearing? If you do that then it moves the CV joint away from the pivot point, they're designed to pivot on the same axis as the hub (outside) or bottom arm (inside) so moving that joint could cause issues with binding and premature failure. Or is there another way to shim them about?
I'm looking to make some 60mm longer bottom arms and 60mm longer and stronger shafts and CV's
These hubs accommodate standard CV's and should work on a standard car

Great thread, loving all the tech talk. Just wish I understood it all lol.
Keep up the good work and keep the thread updated. :thumb:

AS performance make the spacers, but you loose the ABS on a classic, when using the bolt-on bearings/oem STI hubs.

LIC do a spacer to keep the tone ring http://www.licmotorsports.com/sites/...structions.pdf

Maybe you could make the tone ring and spacer in one? Unless your speed sensor set-up works differently?

Might be something useful in this?:
http://bbs.22b.com/forums/showthread...rack-use/page2

Don't know if this might give you some duct ideas:
http://rooducts.com/rooduct-intermed...-2002-to-2007/
http://rooducts.com/

some good info in there thanks :thumb: