S2 with A8 transplant

[skinthespin]

I have taken the first steps to a V8 conersion too, I have done the mad track car thing with a 300bhp/tonne MR2 Turbo and fancy a fast road car so have embarked on this project. I bought a crashed A8, took the parts I wanted, ie, engine, brakes, wheels, recaros and broke the rest, bizarelly by doing this I have funded the whole project so far, including buying the A8 AND the Coupe!

I plan on keeping mine a manual, but with custom tubular exhausts and individual throttle bodies, I looked at supercharging but decided against it as it would have a serious bulge in the bonnet and I want it to look (reasonably!) standard.

I don't get much time to work on mine with the family and the 60 hour a week job so decided not to post progress (as there isnt much!) but if anyone wants any info feel free to ask.

Pics so far:

[Gazjen]

I'm going to fit a centrifugal charger to mine, in keeping with the sleeper look

[PeteUr]

love the mr2 picture

[Ryss]

Nothing much has changed except that I stripped a 2000 A4 1.8t and have decide to use its steering wheel, rack, pump and front struts as the top mounts, cover a smaller area and will be an easier fit into the S2 and the steering wheel is smaller.

I can also cut out the shock mountings from the A4 and weld them, being steel, into the S2. From what I have been able to establish so far is that the distance between mounting points of the sub-frames will be manageable but the relative heights of the mounting points is going to be an issue and will require some modification.

Managed to get 8 throttle bodies (180 quid), all ali radiator (200 quid) and twin fan set from an 1994 Audi 500sel.

[Tommy200rs]

You could try to use the ABY 6 Gang and it fits to the V8 but the flywheel/clutch needs to be from S8. That box should need smaller tunnel than gigantic tipbox. The car will be also faster with manual box and better fuel economy. Those tip boxes go borken allways.

[Jamo]

You could try to use the ABY 6 Gang and it fits to the V8 but the flywheel/clutch needs to be from S8. That box should need smaller tunnel than gigantic tipbox. The car will be also faster with manual box and better fuel economy. Those tip boxes go borken allways.

He can't use the OEM ecu if he did that as it talks to the tip gearbox he'd have to go VEMS instead

[Gazjen]

You can if you can put the codes in the ecu for the manual version.

[Ryss]

I am in South Africa, Manual boxes from AAN motors are like hens teeth. V8 manual boxes are even worse to get.

I managed to acquire a used A8 auto for a good price. Will sell if I find a buyer or keep for a spare. See Pic

All I can say is its long .. close to 2 meters and very heavy. Can hardly lift it on my own, but then this is aggravated by its bulk. (and my age!!). From the pic one will see the external drive to the front diff. The Front diff drives is thru the bell housing, because the front output shafts have been moved forward closer to the engine, compared to older Audi's. This give less front overhang.

This, with a long gearbox all helps to improve weight distribution, ... I hope.

As some people have pointed out this big gearbox will most likely not fit in the S2's tunnel. As the project is just a bare body on 4 wheels, I will cut out the existing tunnel and fit a new one to cover the gearbox and weld it in place once all done. The A8's prop shaft will be made shorter to fit .

[Ryss]

Ok so time for an update. The body is still in Bloem but has now been sand blasted and primed with my special undercoat, which is not an automotive under coat but used in the shipping industry and ex Jotum. Have used it before and it is brilliant. Good anti-rust qualities but hard as nails, so lots of elbow grease to flatten

Looks a lot better now and not too many dent that could have been hidden by body putty.

My idea of a V8 track car was declined, so now its a question of seeing if I can register the chassis and get the final converted car, road legal. Other wise I need to fit a standard engine and gearbox and race it in Clubmans.

Here are some pics, of the sand blasted body.




Also started some serious planning on the front suspension parts that I want to use for the conversion to see how the mix and match pans out.

Parts list as follows.
Ex A8

Front strut
Twin pot brake callipers
Front lower control arm (taper of the ball joint is larger than the A4's)

Ex A4 (2000 B5)

Front cut (complete front)
Sub-frame
Top control arms and top shock mounting plate
Rear lower control arm
Shock

My reasoning for going this route as a starting point is that it utilizes the A8 front strut with the A8's brake calipers, wheel hub which will accept the A8's CV joints and drive shafts.
A8 caliper:-


The A8's front strut top mounts are much bigger than the A4's with a longer rear top control arm, so using the front strut top mounts of an A4 are preferred. The front body section of an A4 has been used to establish the correct orientation of mounting points. The caster and camber should be within tolerances. The current mounting points of the S2 , will end up almost in the middle of the top shock mount. The actual width of the set up will be matched to provide the same track as the A8.

Top of shock mounting:-


The A4 body allows me to cut and weld parts into the S2. As the A8 is all aluminum, this would not be possible. The A8's sub-frame would require major modifications due to the differences in the mounting point heights and width.

Front Cut Mock Up:-


The track width of the 1996 A8 is 1591mm
The track width of the 2000 A4 is 1528mm difference = 63mm
The track width of the 1991 S2 is 1445mm difference = 146mm
Sourced from http://www.carfolio.com/specifications/models/?man=557

OK so this means that the track on the modified S2 will be 73mm wider on each side. Sounds a lot but its just over 1/3 of a 235 wide tyre.

The bulk of the A4's shock tower is to the inside of the of the existing S2 shock mounting position. By making a bigger shock tower to the centre of the vehicle, it will clash with the position of the existing Brake Booster. As the car is currently a LHD , a steering column form an A4 will be used and the brake booster and master cylinder from either an A4 or the A8 will be used, which are positioned further to the centre of the vehicle than the S2's Brake Booster.

The A4 springs and shocks may well have to be changed to accommodate the weight, ride height and handling required once the car is completed and actual weights can be determined. After market A4 shocks will be easier to source than for the A8. Although the A8 front strut is a little longer than the A4 strut, final set up will will include new purpose made bump stops, if required, to ensure that the strut does not impact on the top mounting point or inside of wheel well.

I will continue to plan with this mock up for a while before starting to cut and weld on the S2.

[Ryss]

Towed the body to Cape Town on an a-frame and started work removing the rear suspension. Whipped out the rear suspension from the S2 and the A8.

Here is the comparison.

S2 suspension



A8 in comparison to S2




So as will be seen the A8 in much bigger and wider.

Did a rough test fit and liked the looks. Expected wheels to stick out further on the sides. This pic with discs fitted.



With further planning, head scratching and option consideration ... started cutting. Cut all four of the A8 mounting points off the sub-frame in an attempt to use the existing S2 mounting points, so no welding on the chassis would be required.

Then checked if the ride height would be achievable. Ride height will be adjustable with the final suspension springs and shocks that I will need to get.


Was pleasantly surprised by the camber adjustment possible on the A8 suspension.

At this stage I had second thoughts and decided to remove the floor in the boot and extend the chassis to the back of the car. The rear sub frame can then be mounted to this new chassis members.

[andy10v]

That is some serious work, please keep this updated.

[my2000apb]

That is some serious work, please keep this updated.

yes please do, i have the coupe and b5 2000 shell ready to go!

[Ryss]

Looks I need to find a detailed chart of the S2's chassis dimensions.

In the process of fitting Audi A8 rear subframe I am getting measurements that just do not make sense and conflict with each other.

Current thinking is to mount subframe with temporary plates in stead of actual rubber mountings and take the car for wheel alignment. These plates must allow for adjustment in both left\right and front/back. When all is square then weld in the permanent mountings.

Any info or advice would be appreciated.

[Ryss]

Success at last. Managed to get everything lined up and tack welded the orignal A8 mountings back onto the A8 subframe, but in a different position, to match up to the two front S2 mounting points. (will post pic's soon).

I used two lengths of aluminum angle, clamped to the disc rotors to do left/right measurements. The mistake I made was not to check for zero toe in and zero camber before starting the alignment process. Also had to remove some of the chassis rails so that the top control arm had enough clearance.

In addition the existing chassis rails need to be extended to the rear, to pick up the rear mounting points of the A8 subframe.

As soon as the car can be moved again, I can turn it around and start fitting the front subframe from the A8 and the top shock mounts from the A4.

Still battling to find detailed chassis dimensions for the S2 as I will definitely need these to complete the work on the front of the car.

[caterpillar]

my goodness!!!! more pics please!!! keep up the big work.. but more pics