SactownP31

Well I finally got around to having the UPD underdrive pulley as well as the UPD idlers installed. Well, where do I begin. Products are well made and Installation went relatively smooth. Fit and finish is great. So for the performance part. Idlers offer no real performance but should be used more as preventive measure to the plastic stock pulleys. Now on to the underdrive. The car, as expected revs faster and smoother. Breaks traction even easier, that light blinks much more often now. The power gains are quite noticeble. Throttle response is much improved. If I were to guess about the whp gains I'd say 8-15. In all honesty I'd have to say the magic spacers perf gain was more noticeble. But nonetheless I am very happy with the UD pulley mod. Disclaimer, the reason for this thread is more to report on reliability of the underdrive aspect of this pulley not so much on how much gains there are. So with that in mind. I drove the car for about 100 miles today. Mix of highway, city, agressive and just cruising and can report that there were no electrical or power steering or ac issues. ECU didnt go ape shyt or anything. So far so good. Oh, and once again want to give a big shout out and a thank you to Shardul for these great products at great prices.

SactownP31

Crya

iTrader: (1)

SactownP31

Not dificult but then again I didnt do it myself. Pull the underside covers off, take off the fan shroud and air tubes and you got plenty of access. The underdrive pulley is the reason i had an amg tech do the install for me. Its one of those mods where there is no room for error. Just a side note for anyone who is wondering the ud pulley has no timing marks. Flywheel is locked at 40 deg with special tool thru bell housing. So keep your old pulley to be able to time it in the future.

SactownP31

While I'm at it I want to give a shout out to MB Motor-Werkes out of Camron Park Ca for doing the install. They are AMG specialist and one of the very few who were willing to do the install. Like I said no room for error on this mod.

Crya

iTrader: (1)

Celicasaur

Nice. How long have you had the crank pulley fitted for? 100 miles or more?

If you could, perhaps chime in every thousand or few thousand miles or so to update and keep this as a long-term thread to speak of how it performs over time. I'm sure it will be fine tbh hopefully anyway as this is not a solid pulley and will therefore still help to cancel out a lot of the engine harmonics/vibrations.

It's just a pity that there aren't dyno numbers to go by.

skratch77

Keep an eye on the seals to see if they start leaking oil also.

I'm sure there are gains to this mod but I personally would not touch a crank pulley on this motor.

not sure why companies dont make under drive accessories pulleys and leave the crank as is.

BLKROKT

SactownP31

Exactly. These 2 are rather unconventional mods and a lot of people dont agree with them.

SactownP31

That was the the plan. I'll drive it all weekend and give a progressive review, then check in every few thousand miles. It will be hard to do a real longevity review as I usually only drive it on sunday because its my only day off.

SactownP31

Yes and you can feel the 1lb saved on your driveshaft right. But I'm not supposed to feel 2+lbs saved on my crankshaft. Well thats not fair.

SactownP31

I will say this, the stock crank pulley is very well thought out and made. It looks exactly like the lightweight pulley I put on my clk550. And the stock clk pulley looks like the UPD pulley but weighs twice as much. Ive had it on the clk for 4 years now i believe and no problems. But that was just a lightweight not an underdrive.

SactownP31

I think its because the underdrive aspect is only part of the whp gains. Most of the gains come from csp being lighter. Off the top of my head I believe the clk gained 13 whp when I dynoed it 4 years ago, and that was just a lightweight pulley (4-6lbs saved) not an underdrive.

bentz69

I always love these claims lol. I can see the tach get to 6500 .3 seconds faster so it must a gain in whp

SactownP31

A Guess is not a claim. The only claim was from a dyno done 4 years ago on my clk. Car does rev faster and is a bit more jerky. I see a bill for my mich 275's coming sooner rather than later.

SactownP31

Ok I drove the car some more today and noticed a few things. For starters the gains in power and respose are down low, we're talking idle to 4k. So for city driving and a dig you're golden. Here's the problem, the pedal. This pulley drastically changes the throttle feel. Its very touchy now, too sensitive. And the more I drive the more I'm having mixed feelings about it. Its getting a bit too jerky and while driving on freeway its damn near impossible to keep at a steady speed. Lots of up and down on speedometer. You have to barely touch pedal. Think of it like a sprintbooster on roids. Im thinking the underdrive is doing exactly what it was meant to do, steal early hp from accesories and help deliver it to the wheels. But its doing something that i wanted to avoid, its erasing the middle ground. Meaning Its turning the driving experience into *****foot or ballstothewall only. This is the reason I tried for a while to find one of those old eurocharged lightweight pulleys that were stock diameter just lighter. I'll report back every so often just for updates.

chrisridebike8

I would think that is more a function of the ecu adapting to you "testing out the new parts" rather than the actual pulley being that drastically different. I've gone from a 48 lb flywheel on a car to a 12 lb flywheel and didn't have as drastic a reaction as you seem to be having with this pulley. Enjoy it, but realize what is actually happening with you car and also give us some objective data. seat of the pants feel and placebo effect doesn't fly with a lot of us.

Celicasaur

Without wanting to sound like we're trying to knock you down or anything, the gains surely can't be that pronounced on the car. Hell, if the throttle response really opens up that much down low, then this would be a superb mod for most of us on here. I'm surprised that you don't like this...most people usually want more of this when they get a box tune...

also....for what it's worth, the gains should be all over the powerband but mostly felt in gears 1 and 2, with a taper off in third and then nothing meaningful in 4th.

shardul

iTrader: (1)

Thanks for the review!

SactownP31

Its not so much as too much power or gains or nothing like that. I'm saying that when you barely touch the pedal the car goes. Im talking minuscule, barely putting tip of your toes and curling with the slightest pressure and it goes, not rockets down road but just goes, slightest pressure off and your completely off the throttle. Which is awsome for city/spirited driving. On highway driving I try to keep it at a steady 80. 10-20 seconds later it creeps up 5-7 mph. Tried to slow down and pulled back slightly and I was completely off the throttle. And it did this the entire trip yesterday. Cruise controll will be used a lot more from now on, thats for sure. All I'm saying is I've never had pedal/throttle control problems and ive had this car for almost a year. I'll do a reset this morning and see how that goes.

skratch77

Sounds like the ECU is trying to compensate for the rpm difference and is raising the TPS on you.

what is your TPS % at idle in park fully warmed up and what is it in drive with the foot on the brake?

SactownP31

Not at all man its all good. When I drive cars or use equipment I get a good feel of how it runs and then develop muscle memory to it. What im saying is on this car to keep it at steady speeds, before this mod, whether it be 35, 55 or 80 I would have to apply about 15% throttle, maybe more maybe less. Now its more like 5%, so the margin of error has shrunk down drastically. Which is why the car is feeling very jerky and somewhat unpleasant during that short time frame when I'm NOT trying to tear up the roads, mostly when wife and kids are with me.

SactownP31

Thats what seems like. As far as giving you an exact number. If I knew how I'd tell you.

SactownP31

live data says tp% 13.3 at idle.