Ian C Posted April 27, 2003 Share Posted April 27, 2003 For an underdrive one. I haven't had a chance to test it yet, see if I notice anything, but the operation was easier than I expected. Would you guys like a write-up? I also cleaned out my -Ian Quote Link to comment Share on other sites More sharing options...
Alex Posted April 27, 2003 Share Posted April 27, 2003 I feel a bulk order of fine wire mesh coming on! Have you taken a piccy on the pulley??! Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 27, 2003 Share Posted April 27, 2003 IAN, what's an Underdrive Crank Pulley ? [ and, YES, if it's something blatantly obvious, you CAN call me 'thicky' ] Quote Link to comment Share on other sites More sharing options...
Adam W Posted April 27, 2003 Share Posted April 27, 2003 Apparently they're highly dangerous, can unbalance your crank, cause crankwalk, undampen your oscillations, or something. According to the yanks. Ian C is living on the edge . . . Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 27, 2003 Share Posted April 27, 2003 SO, they're all the BAD points... BUT, what's it DO ?... What's it FOR ?... WHAT IS IT ? ? Quote Link to comment Share on other sites More sharing options...
Alex Posted April 27, 2003 Share Posted April 27, 2003 It's the "fan belt" pulley on the crank. Using a lighter one should allow the car to rev quicker and reduce engine load. PLEASE NOTE THIS HAS NOT REPLACED THE DUAL MASS DAMPER Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 27, 2003 Share Posted April 27, 2003 Isn't the Crank Pulley a HEAVY weight for a particular reason.... ? ? I don't think it was designed extremely heavy just for a laugh ! Is it for increased inertia / to reduce shock loads / to 'balance' both ends of the crank a little ? ........or something ( and YES I know the pulley's got a damper in it for the Fan' belt - that's there for a reason too ! = water-pump / P'St' Pump / alt' etc.) Quote Link to comment Share on other sites More sharing options...
Ian C Posted April 28, 2003 Author Share Posted April 28, 2003 Originally posted by Alex Holdroyd It's the "fan belt" pulley on the crank. Using a lighter one should allow the car to rev quicker and reduce engine load. PLEASE NOTE THIS HAS NOT REPLACED THE DUAL MASS DAMPER Yes it has I'll show you it later. I have pictures too. Well, I think it is. From studying it close up. Anyway, the pulley does two things. One, reduces rotating mass. Two, it underdrives the accessories. Not enough to cause bad functioning, apparently the water pump, aircon, PAS, alternator etc should be unaffected but less power is taken from the engine to drive them. Now, Terry S and Leon have both used them for 30k+ miles and they both had their engines apart and found no problems with them, no abnormal wear etc.. So that's good enough for me, for now. If it causes me any problems I'll just swap back in the old one anyway. Perhaps the Americans see a problem with these the same way they see a problem with their crank oil seals? The oil seals give way due to crazy amounts of boost pressure on stock short blocks, therefore the problem is with the oil seals, hmmmm. Anyway, I've taken it for a shakedown, I didn't have any bolts left over, the ECU is relearning (I removed the battery) and the last of the cooling system airlocks are out so soon I can actually see if I feel a difference -Ian PS it's also anodised blue, that's why I really got it Quote Link to comment Share on other sites More sharing options...
GavinL Posted April 28, 2003 Share Posted April 28, 2003 Originally posted by Ian C Perhaps the Americans see a problem with these the same way they see a problem with their crank oil seals? The oil seals give way due to crazy amounts of boost pressure on stock short blocks, therefore the problem is with the oil seals, hmmmm. The front crank seal is located inside the oil pump itself and by all accounts the failure is caused by high oil pressure inside the pump. I know of three people on this BBS not including myself who have blown the FCS on stock twins, way off the sort of pressures a big single will produce. Quote Link to comment Share on other sites More sharing options...
Ian C Posted April 28, 2003 Author Share Posted April 28, 2003 That's me told Quote Link to comment Share on other sites More sharing options...
Steve W Posted April 28, 2003 Share Posted April 28, 2003 PS it's also anodised blue, that's why I really got it OH, as long as there's a GOOD reason I get what you mean about the 'under-driving' now Ian - just lower geared so everything's turned slower (alternator ? - no big boom-box then ? ?) Let us all know how it goes mate. (let me know how many mph it's worth on the Terminal Speed:sly: ) FatS. Quote Link to comment Share on other sites More sharing options...
dude Posted April 28, 2003 Share Posted April 28, 2003 Gavin , make that 4 mine went at leons on friday John:flame Dev Quote Link to comment Share on other sites More sharing options...
Digsy Posted April 29, 2003 Share Posted April 29, 2003 I have a "weepy" front crank seal too, but it hasn't gone yet (touch wood). Just to hijack the thread a little, a lot of oil pumps have a small hole just behind the seal that vents excess pressure to the oil pan. If this hole gets blocked then the seal can get pushed out. Anyone know if the 2JZ pump has this feature or not? Quote Link to comment Share on other sites More sharing options...
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