Underdrive Pulley Install Guide

[backman_z]

Great write up. Easy to follow instructions. I did it in the wee small hours of the morning today.

The only thing I did differently was to use a screw driver head instead of his leverage contraption. I put the screw head through a hole in the stock pulley, and into the boss (see pics). This held the stock pulley in place while I loosened it.

http://www.flickr.com/photos/backman_z/4845265417/
http://www.flickr.com/photos/backman_z/4845884042/

Thanks again sd/boxster!

[Johnny Danger]

You will quickly notice that the new under drive pulley is dollar for dollar the best bump in performance one can do for their boxster. Good luck.

[Boxster586]

Originally Posted by Adam

Did you happen to take a picture of the new and old pulley next to each other or weigh them? Is there a reduction in size, weight or both? Why only change the crank pulley and not all the accessary pullies, seems like there would be a more profound effect and free up some more hp?

I realize this is an old post but wanted to add a little information for those who may later come across this thread like I did.

I installed my RSS pulley last night. I weighed the factory crank pulley - 327 grams. The RSS under drive pulley on the right is smaller but weighed more at 376 grams.

[MikenOH]

Originally Posted by Boxster586

I realize this is an old post but wanted to add a little information for those who may later come across this thread like I did.

I installed my RSS pulley last night. I weighed the factory crank pulley - 327 grams. The RSS under drive pulley on the right is smaller but weighed more at 376 grams.

Had a chance to drive it yet and notice any difference?

[Boxster586]

Originally Posted by MikenOH

Had a chance to drive it yet and notice any difference?

Hello Mike-

I did take it out for a short drive. I believe it IS the best $219 (includes new shorter belt, pulley tool, and shipping) I've spent on this car. Peppier in the lower rpms. Can't really tell above 5500 rpms. I need to get back on the track to confirm as I have zero access to a dyno.

Have a good week.

[notworthy]

I just completed my installation of the updated Mantis Sport underdrive pulley. The engine feels a bit more free and when I say a bit, I really mean just a bit. Good value mod though. The hardest part was cutting the boss, everything else was really straight forward. I actually got the pulley for free, and got the belt for $52, so a nice inexpensive mod.

Thanks for all the technical data and installation steps, they made the job really easy for me.

[rokketdawg]

I just bought a TRS underdrive pulley and just wanted to know how the hell you got any of the tools in there to do this. Does anyone have pics of the crankshaft removal tool...specifically the tool that uses the threaded bolt to push against the crank to force the pulley off of the tip? I'm sure this must be a shorter threaded bolt than the average kit you can find in any auto parts store, but pictures would go a lot further to explain that part of this process. Thanks!

[Supermini]

Hey guys, great guide here with pictures and everything!

you dont need a special tool to remove the factory crankshaft pulley, i found an old bolt that was the correct width to push through (dont need to thread it) one of the holes on the pulley into the boss (which later you have to cut off). this will stop the pulley from turning allowing you to undo the nut.

then removing the pulley is a case of gently levering it off with a long screwdriver.

i bought this one


Crankshaft Pulley Kit (For cars with AC)


I can feel the difference, it is a small gain, but its worth it.

[ilikeching]

Originally Posted by Boxster586

Hello Mike-

I did take it out for a short drive. I believe it IS the best $219 (includes new shorter belt, pulley tool, and shipping) I've spent on this car. Peppier in the lower rpms. Can't really tell above 5500 rpms. I need to get back on the track to confirm as I have zero access to a dyno.

Have a good week.

Lighter rims & wheels will definitely feel the difference too, much more peppier at low rpms.

[jb92563]

Someone had said that there would be no AC at idle with a 4" UDP, so I thought I'd post my results to clarify.

I installed my Tarret 4" under drive pulley and all went well and better than predicted.

Particularly, I am happy to report that a 2001 S with the 4" under drive pulley still allows full operation of the air conditioning at idle!

Here is the Proof below:

With the Tarret UDP installed and the engine up to full operating temperature,
Ambient temperature 70 F as shown on the guage, and ~750 rpm at idle for over 5 minutes, airconditioning set at full the temperature of the air leaving the vent is ~38 F.


Tarret UDP and Original

[rokketdawg]

Can anyone explain how they torqued the new bolt down without having a hole in the pulley to lock it in place?

[jb92563]

You need a pulley that has at least one hole in it so you can use a bolt, but if no hole then you will need to clamp it with a vise grip and some pieces of wood to protect the pulley.

Having driven my Tarret 4" UDP for a few days now I'm very pleased with what feels like extra torque and power.

It also seems like the engine sounds smother and quieter.

The extra torque in first gear needs a bit of getting used to, as it was raining this morning and I have been getting a bit of tire spin using my old familiar technique.

A little slower application of throttle in the wet is required.

Overall, I have to say it was a much easier install than I thought it would be, although grinding off the casting protrusion was a pain because I did not have a right angle grinder that would fit in that tight area so I had to use an airtool saw and file to get at it and tidy it up.

A 90 degree die grinder air tool with cutoff wheel would have been the perfect tool to get in there and get it done quickly without fuss.

No problem getting the old pulley off either as the shaft is not tapered so simply prying it off with a long screw driver is all that is required.

You also need a cheap 24 mm socket and cut it down to the minimum to go over the bolt head with a grinder as its a tight space in there and not much room for the socket and wrench.

Well worth the ~$200 and perhaps the most HP bang for your buck of any mod you can do to a Boxster.

[Quadcammer]

about to do this mod and well I'm a bit confused by something.

The crank pulley looks like it slides over a keyway. If you leave the car on the ground and you put it in 5th gear with the parking brake on, the crank shouldn't turn, hence there should be no issue with removing or tightening the bolt.

Am I missing something?

Thanks

[JFP in PA]

Originally Posted by Quadcammer

about to do this mod and well I'm a bit confused by something.

The crank pulley looks like it slides over a keyway. If you leave the car on the ground and you put it in 5th gear with the parking brake on, the crank shouldn't turn, hence there should be no issue with removing or tightening the bolt.

Am I missing something?

Thanks

Tightening the crank bolt is not the issue, but if and when you go in for an IMS swap, or some repairs involving resetting the cam timing, be prepared for a significant up charge as the shop is going to have to remove the under drive pulley and reinstall a factory unit in order to lock the crank at TDC, that is assuming you have not removed too much of the pin boss from the engine cases when you installed the pulley. If you did, the trans will have to be pulled so that the engine can be locked at TDC from the flywheel. Oh, and the latter adds roughly $3K to the bill of whatever else is being done.

[Quadcammer]

Originally Posted by JFP in PA

Tightening the crank bolt is not the issue, but if and when you go in for an IMS swap, or some repairs involving resetting the cam timing, be prepared for a significant up charge as the shop is going to have to remove the under drive pulley and reinstall a factory unit in order to lock the crank at TDC, that is assuming you have not removed too much of the pin boss from the engine cases when you installed the pulley. If you did, the trans will have to be pulled so that the engine can be locked at TDC from the flywheel. Oh, and the latter adds roughly $3K to the bill of whatever else is being done.

Thanks for the tip. Pretty sure I will have enough of the boss remaining the crank at tdc.

That doesn't answer the question of why the crank is turning during this job...it shouldn't be

[geetee]

you seriously cannot remove too much of that boss. It's pretty deep. The center hole extends in deeper than what you can cut off.

[JFP in PA]

Originally Posted by geetee

you seriously cannot remove too much of that boss. It's pretty deep. The center hole extends in deeper than what you can cut off.

Don't bet on it. We have had cars come into the shop with the entire boss hacked off, which allows enough slop in how the pin holds the pulley to make it all but useless.

[jsceash]

Originally Posted by rokketdawg

Can anyone explain how they torqued the new bolt down without having a hole in the pulley to lock it in place?

RSS supplied a wrench with the pulley kit. Kit included a belt pulley and a pin type wrench.

[jsceash]

I had to remove 1/4" of the boss Plenty of hole depth left.

[Quadcammer]

I hacked off a decent amount of the boss, but there is definitely plenty left, even with excellent clearance to the pulley. Not too concerned about that.