B3 conversion to AAN quattro

[Ryss]

Striping a URS4 and transplanting engine, gearbox and rear diff into a FWD 1991 4 door saloon. Yes I am nuts On a limited budget.

In sunny South Africa we do not have much choice in vehicles available and I just love the B3 shape so knowing it an impossible task, just makes it a better challenge.

Donor S2 available for same parts. Pedal set (car was an Auto) and rear subframe (complete)

Engine will be moved back in chassis to allow for a front mounted radiator and inter cooler with the help of an RS2 Style bumper. Posted this idea for comment previously on http://www.s2forum.com/forum/showthread.php?t=60018.

OK so here some pics.

The car





URS4 radiator fits in nicely in the space available. Viscous fan replaced with electric unit.



Position of Output shaft.



Final position of engine and drive shaft angles still needs to be done. Waiting to get hubs back with new bearings. Also upgrading from original pcd of 4 X 108 to 5 x 112.

Having discovered the AAN engine was fitted with RS2 turbo and manifold (factory fitted option) which I will run using our local management system (Gotech) and with this potential power will also raid the S2 for the big brake conversion.

Engine and gearbox mountings will need to be fabricated, as the existing URS4 gearbox mounting clash with the tunnel now that the engine and box have been moved back.
So this means mounting points for gearbox mounting on the subframe and engine mountings that point forward by 40 odd mm.

Plan with rear end is:

Had a look at the S4 rear suspension and as with anything ... pro and cons. (Heavier, shock mounts different, expensive OE parts etc) Decided to use the spare S2 subframe I have and mount the rear of the S4 diff to that. This will mean the S2 shocks, struts, hubs, brakes etc will all be an easy fit.

Distance between center line of side shafts and rear mounting of diff will fit inside the S2 subframe. Front of gearbox extends past the front of the subframe. May be a good idea to extent the subframe to the existing mounting points for the beam axle and have a cross member from the extension, to hold the front of the gearbox. But then front mounts maybe too far away from the control arms and result in flex of the subframe.

So the idea is to have six mounting points. The two mountings of the modified subframe, attached to the main mounting points for the beam axle, and four new mounting points will need to be fabricated for the standard mounting points of the S2 subframe. All these six mounting points will all be supported by a roll cage to provide the necessary strength.

Only problem with this plan is the track of the car will not be wider than standard, so that will have to be achieved with fabricated control arms and longer drive shafts. Also means a lot less work as I do not need to fiddle with body work (IMSA90 STYLE) to get the car mobile.

The fuel tank, although vertical behind the rear seat, has a bulbous bottom that will be in the way of the diff and prop shaft. So that has to come out. Will most likely end up cutting most of the boot floor out. Will also have to increase the height of the gearbox tunnel, so that there is enough room between the gearbox and the tunnel for the gear selector shafts.

OK thats all for starters. Sure lots of suggestions will be forth coming. Look forward to them.

[Greg_S]

Quite a bit of work to be getting on witht here Ryss. Sticking to the standard S2 suspension setup would be more straight forward but for the front yet it sounds like you will be doing alot of fab work anyway.

[Ryss]

Greg.. thanks for the input. Fab work is not too bad. Mainly new engine and gearbox mountings, mountings for rear subframe and boot floor.

Got the S4 rear suspension out yesterday and stripped out the diff. (Surprising lighter than I expected)





Here is a pic of the diff roughly positioned in teh S2 subframe.



Started stripping the 90 and see the shock towers are 93mm apart vs the S2 @ 1052 mm. Springs on the 90 are a smaller dia so will make for a very tight fit for the S2 springs even if they could be angled in that far. Lots of space to add new shock top outiside of the currents ones. Can also change the height so ride height is correct. So this willl need to be done. Dumped two shock towers a few months ago that I cut out the S2/v8 project.

Stripped the suspension out the 90 and removed all the cover plates (heat shields) and exhasut etc. Found some nice chassis members to which mounting points can be added, whcih I never saw before, but they are still too short to pick up the rear mounting points of the subframe. But not a major problem like I was expecting.

Front cross member of the diff extends past the mounting points of the old beam axle. Could use the same method of mounting this cross member as is the URS4. But still think it would be easier to mount the diff in the subframe and get the
orientation to the diff and subframe correct relative to each other and the fit this as one unit to the car. So S2 Subframe will need to be extended futher foward to a third set of mounting points.So dug out the spec measurements for the subframe. There is a 29mm difference in height between the front and back mounting points of the subframe. This can be used to get the subframe level. The diff much then be mounted in the subframe with its center line of the input shaft on the same plane (parallel) to the subframe. (if that makes sense.)

To mount the diff and subframe it will still require the car to be leveled, the subframe to be centered in the car and then positioned at the correct level in the car. Final check is to ensure input flange of diff is at right angles to the level line of the car and in the center.

Removed the petrol tank and tow bar.

The petrol tank.


The boot.


The tunnel running across the boot is to accommodate the beam axle and I think will be the new height of the floor, more or less. (Can somebody supply a pic of a B3 Quattro boot floor?? Would be appreciated.)

Next step is to drill a few holes thru the boot floor to mark the inside of the chassis members and cut the floor out the boot.

[andy10v]

You are a glutton for punishment!

Good luck with your latest project!

The 90q

[Ryss]

You are a glutton for punishment!

Andy10v . Tell me about it. After 6 hours today I was finished and looked like a coal miner.

Boot floor is out and sub frame with wheels attached, is roughly in position.

Photobucket is playing silly *uggers, so if you are desparate to see some pics of progress, see http://www.facebook.com/media/set/?s...4487553&type=1

[Ryss]

Made some progress.. On the rear , converting the chassis to a quattro system.

S2 sub frame rear diff mounts trimmed off and a flat plate has been welded on to the top of them, which will serve for the back mounting of the S4 diff. In this planning I will try and allow for the option to widen the track by 50mm a side, so if I ever decide to do the IMSA 90 replica I can do so, with a minimum of work. Managed to find some drive shafts that happen to be the correct length for the S2 sub frame and S4 diff combination.

The sub frame will be mounted to two fabricated cross members will be straight across, 76 x 38 rectangular tube, with a drop mounting spot of 50mm. This will match the sub frame mounting points and clear the rear S4 diff mounting.

Front Sub frame mounting points are 29mm lower than the rear. In order to simplify fitting of the sub frame and cross members, I decided to keep the tops of the two cross members on the same plane. The front cross member height will be 29mm higher than the rear cross member. This makes it easy to refit a floor and to ensure everything is level.

To provide additional strength to the front legs of the sub frame, a detachable cross brace will be fitted, which curves under the diff.


S4 prop shaft will have to be shortened by about 300mm or so and the section under the rear seat will have to be raised to the at least the same height or a shade higher than the tunnel. Lots of fuel pipes and brake lines under the floor pan in this area just complicates the issue.

Some pics....
Right chassis cut open to plan extension to rear cross member.



Rear cross member and rear diff mounting



Front cross member


My biggest headache at the moment is the rear shock towers, which will need a lot of modification. At least I found the shock towers I cut out of the S2.

[Ryss]

Shall we say progress is slow, but getting there. Just had to wait for shops to open after annual shut down. Want to send rear cross members for shot balsting before welding them in.

I the interim had an idea with regard to moving the engine and gearbox 40 mm back in the chassis, so that a front mounted radiator can be fitted.

Original plan was to re-fabricate the mounting arms off the engine to pick up the original engine mountings. Current idea is to fabricate a "double decker" mounting plate and use a universal engine mounting on the top deck. Will just give the 40mm required and retain the same overall height.

Also discovered that the AAN engine has a factory fitted with a RS2 turbo and manifold.

Will keep you posted with a host of pics in due course.

[Ryss]

Finally managed to get the engine and gearbox into the car. My double decker engine mounting needs some explanation.

Bottom aluminum plate bolts on in normal position.
Second aluminum spacer plate is shaped to fit on top of this first plate and allow a standard engine mounting that is to be fitted to clear the lips on the standard engine mounting brackets that are welded to the chassis.

The center of the round engine mounting is then drilled 40mm back from the original engine mounting, effectively moving the engine and gearbox back 40 mmm in the chassis.

Fitting the radiator is still going to be a tight fit. Another 10mm still available if required, but then space at the rear of the engine will be very tight, making it difficult to get to engine / gearbox mounting bolts and will require some fancy fabrication of the exhaust down pipe and exhaust.

ECU will be by a Local supplier called Spitronics, who will be making a special version to allow sequential injection and ignition on a 5 pot. This system will run without a MAF, based purely on engine RPM and inlet pressure, ambient temp, alititude etc.


Work on the rear of the car with mounting the S2 rear subframe etc. ground to halt due to pressure to work, and may or may not be affected by another projects involving an S2/ V8 conversion. and my type 85 track car.

Will post some pictures after the next session.

[JMLAudi]

Hello

Hi

Great project, i see your Audi 90, has the ski bag option.
I know is a daft question, why cant you use the radiator in the standard postion.
More pictures please.

Chat soon
cheers
john

[Ryss]

Two reasons for moving the engine back are for better weight distribution and secondly, being an AAN engine the intake manifold points right to where the radiator normally sits.

Radiators have been fitted in normal position with the AAN inlet. But long term plans for this car include track use, and therefore wanted the best cooling possible.

Pics are coming......

[simon20vq]

Excellent like you I love the B3 shape and cant wait to see the finished product. Keep posting pic's.

[pasbogdan]

Do you still have the b4 quattro chassis as a donor?
Use rear flor(for mounting subframe) and inner arches with towers from that.

[Ryss]

Do you still have the b4 quattro chassis as a donor?
Use rear flor(for mounting subframe) and inner arches with towers from that.

Thanks for the comment, but do not have a B4. Donor is a C4 URS4. S2 chassis\body that is also available could have been used but that is another project.

[GazzaG60]

interesting project. ill kep an eyeon this as my b3 will go aby-ish

[Ryss]

Slight change in plans.

Rear suspension will be fitted without dif and drive shafts. Will trim some old CV's to hold the bearings in place, as in the interim the car will be powered by a 7a (ex Track car) and 5spd FWD box.

Rear subframe cross members, That I fabricated, have been sent away for galvanizing and rear brake calibers ( EX S2) have been refurbished and ready to fit with new pads.

Pedal set has been fitted ( Car was an Auto). Front brakes will be a modified 320 mm x 30mm with 4 pot merc (brembo) calipers.