S2 with A8 transplant

[Ryss]

bear in mind the stock coupe has a fair bit of positive castor angle on the rear axle though
The position and angle of the strut tower is not vertically central over the wheel arch.

Which is why, using the A8 suspension the wheel needs to move back from the stock S2 position.

[Error404]

but surely you will then need to alter the angle of the turret since there will not be enough clearance to run with much misalignment in the vertical angle of the strut?

[WabTheKing]

Yep with you on the space frame idea, I'd just loose the s2 shocker tops and just use the outer body as a silloette keeping the same wheel location, have a look at some space frame designs for ideas, I managed to pull my rear arches out by bout 20mm to cover 10j's there's a guy in Sofia who has welded wider arches on that looks good aswell, think it might look odd if you extend the wheel base, the a8 suspension idea is good tho, another idea would be to look at s2 avant rear suspension as that's similar to A4 poss similar to A8 ?? The front would look good with a B5 A4 front end, or even RS4

I like the idea of the multi link suspension, will be a fantastic handling car if all goes to plan! Keep us posted with your ideas :-)

[Ryss]

Error404... I'm a bit (actualy very) slow to catch the point you are making which, I think is that there is not enough room inside the shock tower for the shock and spring to move from a positive camber to a zero camber.

I have tested with a front shock from an A4 B5, but without the spring on. So although I am sure there is enough room, you have a good point and I had better check.


WabTheKing.. bear in mind I am working on a very small budget. I have to use the parts I've got. I am using the A8 wide track, so that I do not have to shorten or lengthen the side shafts and also because its going to be a big WOW factor. Thats assuming my remodeling of fenders is done with a degree of artistic merit.

Thanks for the input chaps.

[Ryss]

This weekend spent two days on the project. First thing I did was test fit a rear shock with coil spring fitted, to see if the change in camber from original position to the new position, is possible. No problem there as there is plenty of room to play with.

Put some temporary braces in the back of the car before cutting out the rear fenders and turned the car round. Whipped out the front S2 suspension and started planning the fitting the front subframe.

Initially looks Ok but not as easy as I first thought.

Cut out the S2 engine and ABS mounts and cleaned out the engine bay.


The bottom of the rear mountings are level with floor of the car, as in the A8. Just need to cut the chassis open so that the subframe can move further back. This will be at the same level as the existing rear subframe mounts, extending them rearwards and to the centre of the car. These will then have to be reboxed and reinforced, something along the lines I have tried to show in the pic below.


As in the pic below, will reinforce the chassis where the S2 track rod reaches over the chassis and will have to build a box section welded to the chassis which will serve as the mounting points for the front of the subframe. Need to have a close look at this and work out the best method to make these mountings, bearing in mind that the mounting point still need to moved to the rear and will therefore be closer to the chassis leg.


Good news is that it looks like the steering rack will fit in the engine bay. Just need to make a shelf on which to mount it.
Also need to straighten up the front of the car as its slightly bent and twisted.


Here are some pics showing the wheel in position (sort of).

[Ryss]

I have had a few slow weeks lately, but got stuck in today. Previously I rechecked my previous thoughts and planning and decide that in order to get the rear mounting of the subframe to sit where they need to sit, would require cutting into the chassis of the S2. Not a good idea, so I made a jig for the rear mountings and cut off the rear mountings of the subframe. They will be rewelded to the subframe +- 35 mm closer to the centre of the car.

Also measured the height from the subframe mounting and to top of the gearbox where it goes into the tunnel and, as I had been told, a substantial increase in the size of the tunnel will be required. With the rear mountings removed, the subframe from the A8 fits nicely in the S2. Checked wheel location and wheel movement lock to lock and all looks cool.

Lots of time required to reweld the rear mountings onto the subframe in their new positions.

today I had a productive day. First fitted the new rear mounting plates for the front subframe using a bolt in the standard mounting position, to hold it in place. Fitted a down plate and welded that to the bootom plate. Still need to add another reinforcing piece on the side of the bottom plate, but need to weld this mounting in before doing so. Here's what it looks like.



Then put the subframe in position and fitted the front wheels to double check the position. Used a laser light and a camera tripod to see if everything was centered but the batteries I bought in the morning must be old because the light fades to nothing after a few minutes of use. So no sooner has the light been position correctly and it dies.

The idea is to position the light in front of the car and dead center. Then tilt the light up and down and all the critical center points should line up. i.e three center points marked on rear firewall, Rear diff and center of front subframe at the rear and in front. So thats on hold till I get some decent batteries.

Straightened the two chassis legs. Not perfect yet but good enough to start work on the two front mountings for the subframe, so started making the front mounting points. Here is a pic of the front mounting, before work started.


With the bottom plate (3mm) and front support (3mm) in place.


With the inside top plate (2mm) in position.


And with the last plate (2mm) on the inside in place. (sort of) One more plate will be required at the back(wheel well side) to box and seal the whole extension.


And that brings us up todate.

[s2_bo]

Looks like your coming along well.
Im looking forward to seeing what its like when its done. What engine management are you going to be using?

[Ryss]

s2_bo.. I plan to use the complete wiring loom, speedo, engine ecu, gearbox ecu, ABS etc from the A8. Some problems coming, I am sure, but hopefully not with engine and gearbox.

[WabTheKing]

Auto box's in the A8's aren't great, I believe you can still use the motronic someone has figured away to use the auto loom, sensors etc.... With a manual box, looks like you are making good progress, Keep the faith my friend! haha

[Ryss]

This project is on hold while I finish a S2 restoration for the road and get a 1985 Audi 90, four door Quattro ready for the track, which should keep me busy for the next three months.

The 90 has been fitted with a NA 7A 20v motor that has been ported, cams ground for longer duration, twin intakes, S2 injectors, stand alone engine management (Gotech) etc.

[Ryss]

Its been a while as I have been busy on other prodjects, but today decided to continue with the long overdue work on the front suspension.

As added explanation the S2 has a single lower wishbone, whereas the A8 has two lower and two upper control arms. so need to convert shock towers to different system.

Cut off the the shock towers , firewall and steering rack platform from the front of the A4 B5 front cut, that I had kept for the purpose. This was the complete front cut.


Idea is to then trim this down to fit the S2, The platform on which the steering rack mounts will be welded to the S2's firewall. Will attempt to make as many of the joints that are needed, along existing double seems, so that nice strong welds can be made. Current holes in inner fenders for steering will be closed as the steering track rods will now be further back and those openings come with the piece cut out of the A4.

Rechecked the differences between the A8 and A4 subframes and although the are different the distance between the control arms is the same. On that basis the distance between the upper control arms should also be the same. Also checked the length of the steering racks (end to end) and they are not the same length. Hmmm.. .

Checked the distance between the centre of the shock towers (A8 vs A4) and the A8 is 30mm wider at 850mm. The control arms of the A4 is about 15MM longer. Too many variables. Decided to proceed and fit and then see where we stand, so started cutting.


Here is the first test fit to determine where I needed to cut the S2.


Cut line on the inside of the shock tower of the S2.


Shock towers gone.


Section removed


First test fit.


Top view of the section as it joins the S2 firewall.


Looking good. Height is about right. Still need to move the new shock towers back a bit and have about 25mm to go before the S2 fire wall starts getting in the way. But will see whats up in the next session.

Will first just tack everything in place and then take the car for wheel alignment. If required I will change the position of the subframe or the top mountings to bring things into spec. Only then will the final and permanent welds be made. Well that's the plan. Worst case I can have adjustable upper control arms made to compensate for both camber and caster.

The plan for the front fenders is to make fibreglass moulds of the standard S2 front fender. I will make a replica and modify that to fit the wider track of the S2 with the A8 front subframe, which is about 7cm wider on each side.

This is involve widening and flaring the fenders, but could also maybe do a change so that alternative headlights could be fitted, otherwise will have to import two headlights.

Also had a brain wave as how to solve the rear fender flares. Thinking of fitting a side panel (blade) made from carbon fibre, like on the R8. This could be the easiest way on transitioning from the standard side to a wider fender and the modified B6 rear bumper.

Here are some pics of the bumper from way back.




Also the section between the exhausts will have a carbon fibre cover, which will also fit any A4 B6 with twin pipes. (140T)

Getting all stoked on this project again.

[andy10v]

Good to see you back at it!

[WabTheKing]

ooooooooooooo =D i want to B5 RS4 the front end of my coupe with the multi link suspension so will be taking notes lol

good work mate

[M_GORDON]

[donce]

how is it going on ? winter sleep?