JSpec

Is it possible to use the pulleys from the Underdrive pulley set (just the alternator and water pump pulleys) with the stock belt or another belt? I want to use the pulley set, but I don't want to eliminate my smog pump - being that I don't have a midpipe yet.

rynberg

If you haven't already bought the Greddy pulleys, Rotary Performance (rx7.com) sells some main drive pulleys that still use the airpump.

http://www.rx7.com/cgi-local/3catalog.cgi?cat=3&part=1

JSpec

Yeah, I just bought the alternator and water pump pulleys and planned on picking up one of SR's bolt on main drive pulleys.

martini

you can eliminate the smog pump without having a midpipe...

GsrSol

Call www.M2Performance.com , they have the same kit as Greddy and they offer the longer belt so they will know the size you need.

the_saint

Anybody using RX7.com underdrive pulley (main crank) and the Greddy underdrive pulley kit?

Any concerns about spinning the water pump and alternator too slow? what size belt do you need on the waterpump/alternator side?

Just curious.

Thanx

thesaint

GsrSol

I have a belt here for the wp, alt kit w/out smog pump. Heres the numbers : 5Pk780
With a tape measure it is approx. 32"

JSpec

I didn't want to eliminate the smog pump without a midpipe due to degradation to the stock cat. They have enough issues failing as it is..

artowar2

Let us know what you find out. I want to do the same thing.

twinturborx7pete

iTrader: (3)

i was looking for this, and see the part #, but who do you get the belt from? anywhere? universal belt part #? just need to replace mine and i want to make sure i pick up the right belt.

Jason

iTrader: (5)

You can use the the Greddy pulley kit with the airpump. You will need a longer belt. Not sure of the size. Just take yours off and go to a autoparts store. They should have one.

Jason
www.rx7store.net

Scrub

iTrader: (25)

We just put the Greddy pulley kit on MakoDhardie's car the other day without removing the air pump. It took a little measuring, and a copule trips to Pep-boys but we got it. In the next couple of days we are going to do my pulleys as well. The size belt you need is 140.9 cm's long. So the closest sized belt to that. In the morning I will check the exact size we got. We used a 4 rib belt instead of a 5 though. It still works fine.

twinturborx7pete

iTrader: (3)

i just want to make sure to get the right belt is all, its no fun running back and forth

MakoDHardie

Yeah, running back and forth does suck and the return transactions still have not gone though on my debit card, so I almost started sweating when I thought I'd lost $60 somewhere. I'm not sure I remember the exact number of the belt we used, but it was something like a KO560K4. Its a 4-rib belt but it works ok, and if for no other reason, saves weight.....well, at least that's how we justified not returning it for a different belt again after I had put everything back together. This belt did not get too tight until we had the belt tensioner preloaded almost all the way out. It still has a reasonable amount of room, but if it needs to be retightened in the future, there won't be as much room to tighten it. I would either suggest this belt, or maybe trying something one size smaller. The belt was easy to get on the pulleys as it wasn't near as tight as the stock belt. I actually had to take the waterpump pulley off in order to get the stock belt off because it was so tight that backing the tensioner screw al the way back out didn't relieve it enough to get it off. The only other thing to keep in mind is that the belts cost between $14 and $20, so don't go nuts buying a bunch of different sizes to see which fits best or you'll kick your own *** for not doing the math earlier. Scrub posted the exact metric length of the belt that I came up with mathematically, using 1/2 circumference of each pulley as the distance that the belt is in contact with the pulley for.