Underdrive Crank Pulley
- Thread starter Al Seim
- Start date
racer_tim
New member
Al, I had a lead on these, but it didn't work out. I sent him a "sample" of the one I have, and he said that it wouldn't work.
I use the one from the A/C drive belt, and use the long nose alternator pulley. I do have an alum intermediate shaft pulley that'll be my next "upgrade" but your right, there doesn't seem to be any good alternative for the 8v VW's from Unorthodox, or other standard "bling" type companies.
Want another Scirocco shell cheap?
With 6 point cage ?
1975 with 32/36 carb ?
I use the one from the A/C drive belt, and use the long nose alternator pulley. I do have an alum intermediate shaft pulley that'll be my next "upgrade" but your right, there doesn't seem to be any good alternative for the 8v VW's from Unorthodox, or other standard "bling" type companies.
Want another Scirocco shell cheap?
With 6 point cage ?
1975 with 32/36 carb ?
Eric Parham
New member
Unorthodox Racing (UR) used to carry at least one for the old style single V-belt on the 8V. They had one for the 16V too. The underdrive pulley for an 85 VW Scirocco 8V was part # 021410302 from UR (see UR 8V crank pulley), but it seems to be NLA. Not sure if that was for the AC or non-AC application. It might have had a 2nd groove for PS too. Sources worth checking include UR, Eurosport, ECS and Neuspeed.
Edit: Here's one for a 16V (part # 021410002), which might work on an 8V with the right shim: UR 16V crank pulley
I've used a smaller crank pulley that originally ran a belt to a power steering pump, but never found quite the right alternator pulley to line up. The needed waterpump pulley offset was about halfway between the late (smaller bolt circle) AC/non-PS size and the non-AC size, but that could be shimmed. I was able to rig something close with an old Motorolla alt, but the Bosch alt was a no-go no matter which combo I tried. Has anyone found a longer pulley for the Bosch alt? If so, what did it come from? The standard one is about 1-5/8 offset. I found an even shorter 1" offset on a diesel (I think). I needed something between 1-3/4 and 1-7/8 offset, though. The Bosch can't be shimmed out because there isn't enough thread.
I had to go back to a stock diam crank pulley on hot summer days using the Scirocco II (small grille), apparently due to insufficient water pump speed. I probably could have tried to get better cooling air flow with an airdam and kept the underdrive (that is, if I could have also solved the misalignment/belt-throwing issue).
There are plenty of underdrive pulleys currently available for the poly V-belts (e.g., 2L style), but not for the single V-belts. I was thinking of trying one of those. Reading the ITCS, I think it called for same "type" and gave examples of V-belt vs. cogged or toothed belt. Is a poly V the same "type" as a single V? They're both "V". I guess it's just referring to the belt itself (type of drive?), so I suppose the crank pulley could be a poly V turning a single V-belt and accessory pulleys, but I'm not sure how well that would actually work. I think the Golf3 2L pulley (at least the one from UR) has both poly V and a single V next to it for the PS, but only the poly V looks reduced. Anyway, here's the ITCS rule:
ITCS 9.1.3.D.1.n:
Alternate water pump,alternator,power steering,and
crankshaft pulleys of any diameter or material may be used.
Type of accessory drive (e.g.,V-belt,toothed belt,etc.)shall
remain as stock.
Edit: Another idea might be to get an aluminum pulley for a 93-98 Golf3 (they're relatively cheap for some reason), and then, if there's enough metal inside, machine off the poly V part to leave just the single V portion (that's there for PS) and a more appropriate amount of offset
Edit: Here's one for a 16V (part # 021410002), which might work on an 8V with the right shim: UR 16V crank pulley
I've used a smaller crank pulley that originally ran a belt to a power steering pump, but never found quite the right alternator pulley to line up. The needed waterpump pulley offset was about halfway between the late (smaller bolt circle) AC/non-PS size and the non-AC size, but that could be shimmed. I was able to rig something close with an old Motorolla alt, but the Bosch alt was a no-go no matter which combo I tried. Has anyone found a longer pulley for the Bosch alt? If so, what did it come from? The standard one is about 1-5/8 offset. I found an even shorter 1" offset on a diesel (I think). I needed something between 1-3/4 and 1-7/8 offset, though. The Bosch can't be shimmed out because there isn't enough thread.
I had to go back to a stock diam crank pulley on hot summer days using the Scirocco II (small grille), apparently due to insufficient water pump speed. I probably could have tried to get better cooling air flow with an airdam and kept the underdrive (that is, if I could have also solved the misalignment/belt-throwing issue).
There are plenty of underdrive pulleys currently available for the poly V-belts (e.g., 2L style), but not for the single V-belts. I was thinking of trying one of those. Reading the ITCS, I think it called for same "type" and gave examples of V-belt vs. cogged or toothed belt. Is a poly V the same "type" as a single V? They're both "V". I guess it's just referring to the belt itself (type of drive?), so I suppose the crank pulley could be a poly V turning a single V-belt and accessory pulleys, but I'm not sure how well that would actually work. I think the Golf3 2L pulley (at least the one from UR) has both poly V and a single V next to it for the PS, but only the poly V looks reduced. Anyway, here's the ITCS rule:
ITCS 9.1.3.D.1.n:
Alternate water pump,alternator,power steering,and
crankshaft pulleys of any diameter or material may be used.
Type of accessory drive (e.g.,V-belt,toothed belt,etc.)shall
remain as stock.
Edit: Another idea might be to get an aluminum pulley for a 93-98 Golf3 (they're relatively cheap for some reason), and then, if there's enough metal inside, machine off the poly V part to leave just the single V portion (that's there for PS) and a more appropriate amount of offset
Eric / Tim:
Thanks for the info. I'm surprised no one is making this. For "most" cars (for racing), an underdrive pulley cools as well or better, gives a few HP and adds reliability. Now that it's legal in IT, you'd think someone would make them.
Maybe I'll look into the A3 pulley.
Best Regards,
Al Seim
Thanks for the info. I'm surprised no one is making this. For "most" cars (for racing), an underdrive pulley cools as well or better, gives a few HP and adds reliability. Now that it's legal in IT, you'd think someone would make them.
Maybe I'll look into the A3 pulley.
Best Regards,
Al Seim
I use to race a VW Rabbitt in the old IMSA Champion Spark Plug Series....and have a ton of parts for the
8 valve Rabbit 1788/1800 motors....I have a many parts left....blocks, transmissiions, cams, ALfa cups, wheels, body parts and many hard core parts....but I had two underdrive pulleys machined out of billet aluminum.....for the two motors I ran....if you have an interest in any of these parts or anyone else e-mail me at [email protected] or call me 843-222-2897
8 valve Rabbit 1788/1800 motors....I have a many parts left....blocks, transmissiions, cams, ALfa cups, wheels, body parts and many hard core parts....but I had two underdrive pulleys machined out of billet aluminum.....for the two motors I ran....if you have an interest in any of these parts or anyone else e-mail me at [email protected] or call me 843-222-2897