While researching Z-engineering supercharger i found very little information on these chargers, and alot of people saying you can't get parts for them any more. Z-engineering have been taken over by RUF and are not the most hopefully company, their Swedish, and speak limited English. But I found once taking the chargers apart some parts did have some kind of marking or model number on them. They were just sneaky when putting them together, and would put the bearing marking facing inwards so you can't see them until removed. Then measuring parts, researching more, looking in to different types of bearings. and how different bearings work. Working out different threads of nuts and bolts. Measuring belts with old length of string method. I also had two of theses chargers taken apart at same time. so I could cross reference the parts. I have both ZR1 (Ribbed pulleys) and ZR2 (Toothed pulleys). So I made a list of the parts I have found out while rebuilding it. plus some useful videos.     Contact Angle bearing video - Main Shaft Bearings http://youtu.be/etxk2gA9HUM   ZR1 Internal Main Shaft bearings: Quantity:3 (Same bearings that original came from Z-engineering) "7003 CD / P4A" or "7003 CDGA / P4A" - OD:35mm ID:17mm Width:10mm - Must always replace all three!!   ZR2 Internal Main Shaft bearings: Quantity:3 "7003 CXGA / P4A" - OD:35mm ID:17mm Width:10mm - Must always replace all three!!     Deep Grove bearings video - Large pulley Bearings: http://youtu.be/fNDRl9wXxYk   ZR2 Larger Pulley Bearing: Quantity:2 (Same bearings that original came from Z-engineering) "6203-2Z / C3GJN" - High temperature bearing - OD:40mm ID:17mm Width:12mm (upgrade for ZR1! more robust metal covers, over the ZR1 rubber/plastic covers)       ZR2 Aftermarket Toothed Belt:Quantity:1 "500 5M 25" - Length:500mm, 5mm teeth, Width:25mm. - TOO WIDE for small pulley - possibly cut down to 21mm. or "500 5M 12" or "500 5M 15" - Length:500mm, 5mm teeth Width:12mm / 15mm - Thinner belt but will work okay. (This will get belt walk where belt moves side to side and stretches the belt, meaning it need to be replaced quicker) Original Z-engineering belt - Length: 495mm, Width: 21mm Extra length on the aftermarket belt can be taken up on the tension of the pulleys.   ZR1 Aftermarket Ribbed Belt:Quantity:1 "Poly-V 190J/483PJ" or "Goodyear 06905" - Length:483mm, Ribs:12. - or use two 6Rib belts Original Z-engineering belt - Length: 483mm, Ribs:12     ZR1 & ZR2 - Engine / PAS / Water pump / Z-engineering tensioner / Supercharger pulley / Belt:Quantity:1 Off the Self Belt that fit are "6DPK1697" or "7DPK1697" Double sided! Make sure to get the double sided version, as they also make a single sided version. The 6 ribbed belt will work but May belt walk, 7 ribbed belt is much better. (6 rib belt is from the BMW E90 series.) Original Z-engineering Belt - Length:67" or 1701.8mm, Width:25mm 7 ribs, Double sided belt. Contact Brammer or other belt manufacturers for custom made belts - give them "7DPK1697" and tell them you need it double sided, it's already the correct length belt, but it is only single sided. And a double sided belt is required. or you could try the original VW part number and ask them to make it longer.   Original VW Engine belt part number: "021 145 933 H" Length:1360mm, Width:25mm 7 rib - Original VW double sided Air Con belt. Original belt TOO SHORT!! Pk number for this belt is 7DPK1360   How to figure out V-belt codes and numbers The 1st number is the amount of ribs on the belt. So 7 = 7ribs. 6 = 6ribs. And so on. PK is a single sided V-belt or DPK is the Double sided V-belt. And the last 4 number are the length of the belt. So 1697 = 1697mm length. To recap 6DPK1697 = 6ribs, double sided, 1697mm length.   Oil for inside charger Fully synthetic 0-40 change every 2000-2500 miles   Rear oil housing (bath) seal: Quantity:1 of each ID:80mm O-ring Width:2mm - Bottom O-ring ID:78mm O-ring Width:2mm - Top O-ring   Front and rear Oil Seal for Main Shaft need to be custom made, there are a few companies who could possible make them.    Grease for large pulley bearings - Not needed if buying new bearings, only if refurbishing old ones. "SKF LGHP2" - High Performance High Temperature Bearing Grease.       All Nuts and bolts are the same for ZR1 and ZR2. Tensioner Nut and Bolts: Quantity: 2 M10 - 60mm : Allen Key High Tensile Grade 12.9 bolt. M10 Nyloc Nut. Quantity: 2     Larger Pulley Front Shaft Bolt: Quantity: 1 M8 - 17mm : COUNTER SUNK allen key High Tensile Grade 12.9 Bolt. Use original countersunk washer, it's the same size as the internal bearing ring, and gives nice even pressure. (new allen key head left, original countersunk washer middle, original phillips head right.)     Larger Pulley Rear Shaft Bolt: Quantity:1 M10 - 20mm: Allen key head, or normal Hex head High Tensile Grade 12.9 Bolt.   Super Charger Main Snail Housing Bolts: Quantity:12 M6 - 16mm : Allen Key Head. Normal tensile should be fine, can go high tensile if wanted   Alternator bracket, with z-engineering tensioner. M8 100mm Quantity:2 Allen key head. 12.9 high tensile. The original bolts will be to short once the new tensioner bracket is fitted. Originals are 80mm.   Oil bath grub screws M8 - 8mm grub screw Quantity:2 Allen key head.   Pipe work Air filter (or MAF) to impellar intake 3" (76mm) to 3.5" (90mm) - 90 degree silicone elbow. Alloy elbow are usally a wider radius courner and touch the inner wing and don't fit.   Air filter Any 3" (76mm) will work, so pick your preferred preference. (Usally the oringal carbon / emmiosns canister needs to be removed or relocated) The one or two with ??? are parts I'm not 100% sure on. but I will update as and when I find out..     Difference between ZR1 and ZR2 Pulleys:   ZR1 Small Ribbed Pulley: 44mm??? x 12ribs = 6psi 34mm??? x 12ribs = 8psi   ZR2 Small Toothed Pulley: 27 teeth = 6psi approx. 24 teeth = 8psi approx. (any other number of teeth on the small pulley are custom made)   ZR1 large pulley 12 ribs - supercharger pulley, 6 ribs - engine pulley.   ZR2 Large pulley 73 teeth - supercharger toothed pulley, 6 ribs - engine pulley.     Rear Oil Housing Breather Hole: There are 2 small grub screws that sit horizontal in the oil bath. These are to change the oil within the supercharger. Although not in the easiest position to access once on the vehicle, it can be done with a length of small tubing, and a large syringe. Reason NOT to rotate the oil housing to make the grub screw easier to access is.... the breather hole would sit half way down, leaking oil as it's not pointing vertically up. Also this breather hole needs to be kept clear, as it only very small. as I have seen one or two pictures on the internet while doing research, where people have rotated the oil bath.     Impeller or Pulley Removal: To remove the impeller or small pulley from the main shaft, heat either the impeller or small pulley depending on which you are removing with a blow torch. A heat gun will not get it hot enough. Try to heat the whole pulley or impeller evenly constantly moving the blow torch. This will make the metal expand and slightly loosen it's self from the main shaft. Try not to heat the main shaft. As you want the pulley or impeller to expand not the main shaft. They can then be prise off genteelly making sure not to bend or misshape. Also be careful because they will be boiling hot. I wear thick welding gloves. You will need to do this to gain access to the main shaft bearings. If removing the impeller make sure not to lose any of the very thin spacing washers. And make sure to re-fit them when re-assembling. Re-heat on re-assembling, don't uses a press or anything like that. Very light taps with a hammer and some wood, once heated will be okay. You shouldn't need to smash it on. If it still to tight and won't go on with a soft tap, heat it more. Always use wood in between, so not to mark or dent the parts. Make sure they a fitted straight and true. I use a micro meter and measure the gap all the way around in between the impeller and housing once fitted, making minor adjustments if needed, also re-heat, if it started to cool. Once finally cool, the impeller or pulley will have a very tight fit to the main shaft and will not come lose.     Other Info: SKF are a huge world wide bearing manufacture, you can go direct to them, or you can find quite a few vendors on Google. You can even find SKF bearings for sale on eBay. Brammer are a large UK company who make and supply bearings and belts. They have quite a few branches throughout the UK. Or you can contact them via there website. There are also many other belt manufacturers who can make and supply custom made belts.     Original Z-engineering VR6 Fitting Guide: http://philhalbasch.com/charger/MK3_VR6_FITTING.pdf