Diy Underdrive Pulley: RD Tib
02-11-2007, 08:28 AM
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Diy Underdrive Pulley: RD Tib
<u>Description</u>
This DIY is for the installation of the OBX underdrive pulley, but is applicable for any other underdrive pulley and replacing all the pullies wouldnt be too far of a jump from this DIY.
<u>Materials needed</u>
Underdrive pulley (obx)- ebay- ~$90
Ratchet set, (i used both metric and american)
-7/8, 9/16, 12mm(or 1/2)
-extensions
-breaker bar
phillips head screwdriver
tire iron
air wrench (not 100% neccessary but helps)
mechanic gloves if u are a whimp
3 shots captain morgan, can be consumed in coke solution ;-)
<u>Degree of difficulty</u>
5-6 out of 10
basic tools
<u>Time</u>
actual duration- 2days
actual working time ~3 hrs
ideal working time ~1.5-2hrs
<u>Procedure</u>
First we need to jack up the vehicle and remove the tire. Make sure you support your vehicle with at least one additional jack or jack stand just in case. After you do this you will need to remove the tire shroud which should be relatively self explanatory. after you remove the tire shroud you will be able to see one pulley which is the crank pulley; it should look something like this:
The first thing we need to do is to loosen the crank bolt. Trying to do this by hand with a ratchet is very difficult because you would need to have somebody hold the brakes while in gear to prevent the crank from turning, then you would need to be very very very strong to loosen it, i am a weightlifter and i still couldnt do it so its very difficult with a ratchet. I had access to an air wrench and tried to loosen it with that with no luck. The only option left for me was to use the blipping method. This method takes advantage of the motion of the pulley while in motion and uses your starter to muscle the bolt loose. To do this you need to take the biggest ratchet you can find and insert the handle into a breaker bar, then set it up so that when the engine turns, it will be unable to turn the breaker bar. The safest way i could think of doing this looks like this:
Use a 7/8" socket, set the ratchet to loosen, and make sure everything is secure. After getting to this step make sure you disconnect your spark-plug wires to prevent ignition. next position somebody infront of the breaker bar and have them move back about 20 feet for safety. have them watch the blip to make sure nothing goes wrong. briefly turn the key all the way to make the starter turn the pulley, repeat this step until the bolt is loose, checking after each blip. Make sure not to hold the ignition down for too long. Practicing blipping without the ratchet is reccomended, to make sure you know how much the pulley is going to turn each blip, (shoot for 1/4 turn of the pulley)
After the bolt is loose you need to remove the belts
To remove the outside belt on the crank pulley we need to loosen the tension on the belt by moving the alternator toward the engine (use 1/2" or 12mm sockets and follow directions in pic)
Remove front belt and now we need to work on removing the back belt. to remove the back belt we need to loosen the tension between the a/c pulley and the crank pulley. the tension pulley can be relaxed by loosening the 12mm bolt shown in picture (note: my bolt was VERY difficult to turn for some reason and yours may stick a little also, a good solid ratchet with a good fitting socket, some muscle, and some patience will take care of this problem)
After removing the last belt you can remove the crank bolt and remove the stock crank pulley, it may take some wiggling and some pulling but it will come off, the comparison between the stock pulley and the aftermarket pulley is remarkable, the OBX pulley weighed about 4 pounds less than the stock one and was a few inches smaller in diameter, the picture shows the difference:
now install the new pulley, this might take some effort. put anti-sieze on the threads of the crank bolt and reinstall the bolt, tighten to 125ft/lbs, prefferrably with an air-wrench.
Now we need to replace the belts with newer, smaller belts. For the OBX pulley the sizes i recomend are 34 inches for the front belt (alternator), and 31.5" or 32" for the back belt (A/C), reinstallation of the belts is pretty easy if you have the right size, just reverse your steps and tighten the adjustment bolts until you get the right tension on the belts, which should be <1/4" play. Obviously you need to install the back belt first. If you are having trouble reinstalling the belt for the A/C pulley, then u can remove the tension pulley, install the belt, then reinstall the tension pulley, this is what i had to do with the 31.5" belt. here is the finished product, looks nice dont it? too bad you can barely see it from the engine bay lol. This is definatly not a ricer mod...
Now u need to check it while its running to make sure it runs fine w.o any squeaking, give it some test revs and then test out your a/c, if this is all fine then go ahead and reinstall your tire shroud, and reinstall your tire, then go test her out. Keep an eye on your pullies for the next few days to make sure everything is running perfect.
When i started it up i noticed that it was alot easier to start and when i took it for a run i definatly noticed a difference, the biggest difference was felt between 2-4k rpms and gears 1-3 but it definatly helped in all gears and across the powerband. The engine now revs faster and accelerates quicker because of the smaller recipricating mass, and im sure the underdriving helped too, but i think the weight difference was the biggest change. Have fun guys!! ghead and post any questions...
Here is a pic of it running:
This DIY is for the installation of the OBX underdrive pulley, but is applicable for any other underdrive pulley and replacing all the pullies wouldnt be too far of a jump from this DIY.
<u>Materials needed</u>
Underdrive pulley (obx)- ebay- ~$90
Ratchet set, (i used both metric and american)
-7/8, 9/16, 12mm(or 1/2)
-extensions
-breaker bar
phillips head screwdriver
tire iron
air wrench (not 100% neccessary but helps)
mechanic gloves if u are a whimp
3 shots captain morgan, can be consumed in coke solution ;-)
<u>Degree of difficulty</u>
5-6 out of 10
basic tools
<u>Time</u>
actual duration- 2days
actual working time ~3 hrs
ideal working time ~1.5-2hrs
<u>Procedure</u>
First we need to jack up the vehicle and remove the tire. Make sure you support your vehicle with at least one additional jack or jack stand just in case. After you do this you will need to remove the tire shroud which should be relatively self explanatory. after you remove the tire shroud you will be able to see one pulley which is the crank pulley; it should look something like this:
The first thing we need to do is to loosen the crank bolt. Trying to do this by hand with a ratchet is very difficult because you would need to have somebody hold the brakes while in gear to prevent the crank from turning, then you would need to be very very very strong to loosen it, i am a weightlifter and i still couldnt do it so its very difficult with a ratchet. I had access to an air wrench and tried to loosen it with that with no luck. The only option left for me was to use the blipping method. This method takes advantage of the motion of the pulley while in motion and uses your starter to muscle the bolt loose. To do this you need to take the biggest ratchet you can find and insert the handle into a breaker bar, then set it up so that when the engine turns, it will be unable to turn the breaker bar. The safest way i could think of doing this looks like this:
Use a 7/8" socket, set the ratchet to loosen, and make sure everything is secure. After getting to this step make sure you disconnect your spark-plug wires to prevent ignition. next position somebody infront of the breaker bar and have them move back about 20 feet for safety. have them watch the blip to make sure nothing goes wrong. briefly turn the key all the way to make the starter turn the pulley, repeat this step until the bolt is loose, checking after each blip. Make sure not to hold the ignition down for too long. Practicing blipping without the ratchet is reccomended, to make sure you know how much the pulley is going to turn each blip, (shoot for 1/4 turn of the pulley)
After the bolt is loose you need to remove the belts
To remove the outside belt on the crank pulley we need to loosen the tension on the belt by moving the alternator toward the engine (use 1/2" or 12mm sockets and follow directions in pic)
Remove front belt and now we need to work on removing the back belt. to remove the back belt we need to loosen the tension between the a/c pulley and the crank pulley. the tension pulley can be relaxed by loosening the 12mm bolt shown in picture (note: my bolt was VERY difficult to turn for some reason and yours may stick a little also, a good solid ratchet with a good fitting socket, some muscle, and some patience will take care of this problem)
After removing the last belt you can remove the crank bolt and remove the stock crank pulley, it may take some wiggling and some pulling but it will come off, the comparison between the stock pulley and the aftermarket pulley is remarkable, the OBX pulley weighed about 4 pounds less than the stock one and was a few inches smaller in diameter, the picture shows the difference:
now install the new pulley, this might take some effort. put anti-sieze on the threads of the crank bolt and reinstall the bolt, tighten to 125ft/lbs, prefferrably with an air-wrench.
Now we need to replace the belts with newer, smaller belts. For the OBX pulley the sizes i recomend are 34 inches for the front belt (alternator), and 31.5" or 32" for the back belt (A/C), reinstallation of the belts is pretty easy if you have the right size, just reverse your steps and tighten the adjustment bolts until you get the right tension on the belts, which should be <1/4" play. Obviously you need to install the back belt first. If you are having trouble reinstalling the belt for the A/C pulley, then u can remove the tension pulley, install the belt, then reinstall the tension pulley, this is what i had to do with the 31.5" belt. here is the finished product, looks nice dont it? too bad you can barely see it from the engine bay lol. This is definatly not a ricer mod...
Now u need to check it while its running to make sure it runs fine w.o any squeaking, give it some test revs and then test out your a/c, if this is all fine then go ahead and reinstall your tire shroud, and reinstall your tire, then go test her out. Keep an eye on your pullies for the next few days to make sure everything is running perfect.
When i started it up i noticed that it was alot easier to start and when i took it for a run i definatly noticed a difference, the biggest difference was felt between 2-4k rpms and gears 1-3 but it definatly helped in all gears and across the powerband. The engine now revs faster and accelerates quicker because of the smaller recipricating mass, and im sure the underdriving helped too, but i think the weight difference was the biggest change. Have fun guys!! ghead and post any questions...
Here is a pic of it running:
