Ok , who's installed underdrive pulley(s) on their A/T Coupe?
I'm going ahead and installing a crank pulley with the appropriate shorter belts and was wondering how anyone's install went.
I've got the 'install sheets' from the Unorthodox site and it seems straightforward altho a little cramped to get a pulley puller into if necessary.
I've read what I can, and talked to my dealer and am going ahead with it.
For about $230 USD (belts included), I figure it's worth a few hp's and ft lbs.
They say 80% of the gains come from the Crank Pulley alone, so I'm only installing that one, and I'm gambling that the engine is internally balanced well enough to not be adversely affected by a pulley change.
Any points from whomever has done the installation would be appreciated.



<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

I thought of doing this, but did not want an underdrive pully. I then spoke to Doug Stewart at Crawford's, and he advised against it, saying that in his opinion the crank pully should have a harmonic balancer on it. That was enough for me. This is one mod I wont be doing.

Lou

 

Lou, I wondered that myself with all the discussion lately on the subject. So I talked to my buddy who's a techie at my dealership. He says these VQ's are balanced internally at the crank to eliminate any harmonics, and won't be adversely affected by a lighter underdrive unit.
He said for any real problems to arise you'd have to be pushing the engine to it's limits over a prolonged period for anything to go bad.
For my style of driving there shouldn't be any problems at all.
I understand your hesitation tho. It took me months to decide to go ahead with it, but I just can't resist it.... wish me luck.[img]/w3timages/icons/smile.gif[/img]

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

Do you really understand what a pulley damper does? Yeah, some people like to call it a harmonic balancer also, but keep in mind that an engine never really "spins" smoothly. As each spark plug fires, it momentarily speeds up the crankshaft. If you could watch it in slow motion, it would be constantly "speeding up" and "slowing down" in quick pulses.

The damper on the crank pulley counteracts this pulsation, which will help prevent early bearing failure.

 

I appreciate the input Hitman, but I'm done worrying about it anymore. There's so many pros and cons on the subject, it's enough to make you dizzy. [img]/w3timages/icons/smile.gif[/img]
Since the mod is good enough for my dealership, though, it's good enough for me.
Like i said, wish me luck.

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

Okay then... good luck.

BTW, you probably won't have any problems unless you're planning on driving your car forever... or at least more than 100K miles.

 

I have had a UR crank pulley and WP pulley on my street and track driven G20 for almost 5 years now and have had no problems with the bearings or any weird engine noises after the installation. I know many others who have had them on track driven cars that spend most of their life at high RPMS and they have had zero issues as well. I wouldn't hesitate to get a set for a G35, as long as you don't have a supercharger, if you do it'll alter the boost due to the change in pulley size.

Justin McClanahan
Heavily Modified 95 Infiniti G20
Working on a G35 Project Coupe

 

Thanks for the input Justin. I'm going ahead with the mod after thinking about it for some time.
I've had this mod on other rides and liked both it's theory and effects so I'm a little familiar with it and like it.
The mod on this ride has gotten some bad press lately making many hesitant to go ahead with it, but from what I've learned, along with some positive feedback from our members,
I've got one on order. From what I can tell, the lightweight underdrive crank pulley will yield most of the benefits of underdriving and weight loss so I'm only switching out that one.
IMHO , I believe that this mod will have some effect on balance and harmonics, but will be so miniscule as to not cause any worries (I hope).
As I said previously, one of the technicians at my dealership gave the go-ahead for the mod, and has some experience with this on his own vehicles that are raced. I'm reasured that at least I have their support in the unlikely event of problems.
Thanks again for your input. It also gives me reasurance.

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

I had my dealer install it with my RT High Flow cats. I spoke with the engineer before doing so. He set my mind at ease. The dealer however needed a special tool to lock the flex plate to remove the bolt. They said there's broke. So it took longer.

 

Tluv, Thanks for the tip on securing the flex plate to loosen the c/p bolt. After looking, I find that the ESM covers this in detail in the timing chain removal section. That pulley bolt could be difficult to remove.
I'll have to talk to the tech rep at my dealership...
Thanks [img]/w3timages/icons/smile.gif[/img]

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

I had the dealer install the whole set (crank, water pump, and alt). No problems after 2 months. I still have the stock crank pulley and its not a 2 piece unit with a rubber dampener between the 2 pieces. It is solid steel with a little rubber ring in a groove on the outside (radiator side). I cant see how this design significantly dampens any crank resonance. Most of the crank and bearing failures that have occured with these pulleys have been on inline 6 motors due to the long crankshaft and the amount of twisting and snapback. The VQ has a very short crank and the amplitude of the resonance is minimal hence the minimal dampening on the stock pulley. Nothing to worry about on a street VQ. And they are good for some gains you can feel. More of a broad torquey gain from idle on up, not powerband gains like intakes give.

 

Yeh, I'm not so concerned now with bad resonances or vibration, but I am with getting the OEM pulley off. Might need a locking tool and a puller to accomplish that. Space in there is very tight.. Looks to me like the rad should come out too.
Thanks for the feedback... The pulley will be in soon and I'll post how my install goes.

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

The UR Pulley is probably the best bang for the buck for the G cars. We are running a UR Pulley on a 300ZX Twin Turbo for almost 5 years now, no problems. We have been selling them for almost 6 years now, and i haven't had any complaint from any customers. I have one on my 2001 Maxima also, and still no problems. For HP Gain, you don't need the other 2 pulleys, those are just for esthetics. The Main Pulley is where all your HP come from. The other two pulleys are the same size, but they are lighter, by a few onces..... There are no cons w/ the UR pulley kits, only Pros

Coz


www.czp.us

 

Sounds good bro, thanks.. I'm looking forward to doing the mod, but am a little apprehensive about getting the OEM pulley off......For a 'backyard mechanic' it could be an issue.

<font color=red>GSM</font color=red>
<font color=red>GSM</font color=red>
<font color=black>Silverstone Coupe</font color=black>

 

It's a brand new car, it'll slide right off It's not too hard, with the right tools, anybody could do it. I just use pry bars, cause usually on newer cars they just slide right off.

Coz


www.czp.us