Installing the Underdrive Pulley

[Jack B]

I installed the JTS underdrive pulley tonight, here are the details:

1. Flatout directed me to JTS or IPsco, he had installed them before on his G4.

2.The Ipsco unit was on back order this week, so I went with the JTS product. Both companies tried hard to please.

3. The JTS website indicated their unit was a two piece design, it was not, it was single billet product.


4. On a lift, the job takes less than an hour, all work is done from below:

A. Remove the front belly pan.

B. The idler pulley has a 19mm bolt, use a long handled socket wrench and turn the bolt CCW, hold it as far CCW as possible, this allows you to slide the oem belt off the pulley system. Do not remove it from the car, leave it in place, but, off the pulleys. I took a picture of the serpentine belt route, it makes it easier when you re-install the belt.

C. Remove the six 13mm oem bolts that hold the pulley on to the damper.

D. You will need new bolts. I used stainless flange head bolts (M8 X 25mm X 1.25 (10.9 strength)). The reason for the new bolts is that the hub on the JTS damper is 1/2" thick, the oem is 1/8", therefore, the oem bolts will not work, too short. The bolts furnished by JTS are for a G3 and they will not work either.

E. Torque the bolts to 20 ft lbs and use Loctite blue and reuse/re-install the oem belt, put the front belly pan back on and you are done.

Here are some pics:
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Here is a comparison of the oem (1.2 lb/5-7/8" Dia) and JTS (1.1 lb/4-5/8") pulley

DSC01897.JPG


Damper with pulley removed

Pulley Removed.JPG


The JTS pulley installed and the belt reinstalled

Pulley Installed.JPG

[FLATOUT]

Awesome I'm doing mine today! Jack we saw 10-12rwhp on these on gen IV's. Great post.

[Dman]

Great post. Thanks for sharing. Nice to see more and more mod posts.

So you can reuse the stock belt?

[FLATOUT]

Great post. Thanks for sharing. Nice to see more and more mod posts.

So you can reuse the stock belt?

Yes you can reuse the stock belt.

[05Commemorative]

can you feel the difference? How would you describe it?

[FLATOUT]

Just got my IPSCO installed. Much easier from underneath on the gen V's. Did from the top on my ACR.

Didn't get a chance to drive it yet, but fired it up and everything is working fine!

Thanks Jack for the install tips it saved me some time.

[mnc2886]

Just got my IPSCO installed. Much easier from underneath on the gen V's. Did from the top on my ACR.

Didn't get a chance to drive it yet, but fired it up and everything is working fine!

Thanks Jack for the install tips it saved me some time.

Any before and after dyno?

[FLATOUT]

Any before and after dyno?

Negative. I did that with my gen IV (every mod I made more pulls) it got old, and expensive lol. I will dyno it before and after the race ECU and before and after headers.

[Jack B]

At best it is 1%-2% hp increase, I doubt you are going to feel the diff. I put about 20 miles on the car and it just seemed normal. It was a little wet today, therefore, hard to test the car.

can you feel the difference? How would you describe it?

[FLATOUT]

At best it is 1%-2% hp increase, I doubt you are going to feel the diff. I put about 20 miles on the car and it just seemed normal. It was a little wet today, therefore, hard to test the car.

I know a local gen IV that did a before and after and saw 12rwhp same dyno same SAE correction factor. That's the only one I know of.

[ViperSmith]

What's the benefit of this mod? Drawbacks?

[Nine Ball]

What's the benefit of this mod? Drawbacks?

It spins the belt-driven accessories a little slower, freeing up some hp losses attributed to those accessories (power steering, a/c, alternator, water pump). The negatives aren't proven yet, since Jack might be the first one with it installed on a Gen V. Some other cars see lower alternator readings, slower charging A/C temp. For the most part, underdrive pulleys have always been an easy 5-10 hp mod.

[Simms]

Just got my IPSCO installed. Much easier from underneath on the gen V's. Did from the top on my ACR.

Didn't get a chance to drive it yet, but fired it up and everything is working fine!

Thanks Jack for the install tips it saved me some time.

Did the IPSCO come with the correct Gen V bolts?

[BAD BOYZZ GARAGE]

Did the IPSCO come with the correct Gen V bolts?

Just received my IPSCO billet under drive pulley and installed on my personal ACR. IPSCO ships with correct M8 x 1.25 x 25 large flange bolts for G4 / G5 applications.. Beautiful set-up, precision machined with zero run-out, I'll post a photo in bit..

Bad Boyzz Garage

=DISTRIBUTORS OF POWER=

[FrgMstr]

I got the bolts for a Gen III with my pulley. The III and IV are DIFFERENT BOLTS. Make sure you can thread those in a few turns before you put a wrench on it.

[FLATOUT]

Did the IPSCO come with the correct Gen V bolts?

Yes, and mine went on with no problems.

[Simms]

Awesome, thanks guys!

[BAD BOYZZ GARAGE]

Here's a few photos of my installation..











Bad Boyzz Garage

[Viperbob]

is there a weight differance beteween the pully's?

[Voice of Reason]

is there a weight differance beteween the pully's?

I'll report back the IPSCO weight difference in about 2-3 shipping days, I ordered one yesterday at noon.

[Jack B]

The jts pully was 1/10 lb lighter, but, the rotational weight is far less since the most of the weight is in the hub.

I'll report back the IPSCO weight difference in about 2-3 shipping days, I ordered one yesterday at noon.

[FrgMstr]

I weighed mine a couple weeks ago and IIRC it was a pound or so lighter than stock. Fairly significant difference.

Also, I read that the lower RPMs on accessories might be an issue. I have see no difference in alternator voltages, and the AC blows as cold as it always has.

[Voice of Reason]

Also, I read that the lower RPMs on accessories might be an issue. I have see no difference in alternator voltages, and the AC blows as cold as it always has.

In all past cars that I've done this only at idle could I ever notice a difference. If the AC was on full blast at night with the headlights on the blower would slow and the lights would dim slightly. As soon as I accelerated everything was back to normal. The "sacrifice" was so small I really never noticed it, but I did notice how the engine seemed to rev just slightly easier/quicker with it. Well worth it IMO.

[FrgMstr]

In all past cars that I've done this only at idle could I ever notice a difference. If the AC was on full blast at night with the headlights on the blower would slow and the lights would dim slightly. As soon as I accelerated everything was back to normal. The "sacrifice" was so small I really never noticed it, but I did notice how the engine seemed to rev just slightly easier/quicker with it. Well worth it IMO.

I rarely drive the car in the dark, so I have not seen this. There is surely a bit more punch though. I wanted to get it on the dyno this week and see what the power changes are specific to this change only, but there is a big runway race here this week and all the dyno slots are booked for tuning.

[sharmut]

Wow, gorgeous. Would do it just for the bling effect.