Idler Pulley Debate

Black Gold 380R

Multiple SVT Collector
Established Member
Joined
Feb 28, 2008
Messages
5,585
Location
El Paso, TX
Hello All,

I seen these posts in another thread and wanted people to give their opinions on this issue.

Nice work please tell me you're replacing the stock idlers as well?

Haha yeah I'm replacing the idlers. They actually come in today. I'm going with the 4 piece Metco kit. Dual ball bearing idlers.

Good deal.

Okay maybe someone can explain this to me. "IF" the stock idlers are so bad (yes I have seen pictures of pulleys going bad and shredding belts. However, parts go bad and need to be replaced from time to time), then why do the kits (Billet flow, Metco, LFP) only come with 3 replacement pulleys and 1 to push the belt closer to the blower pulley? There are stock idlers on the inner belt belt as well. Why doesn't the kit come with pulleys to replace "ALL" the idlers?

Seems to me this is more of a marketing ploy. Yes, the new pulleys look way better than stock, but I really do not see replacing the stock pulleys as a "MUST" since the kits do not replace "ALL" idler pulleys.

Now, to be honest, I just ordered a set of LFP pulleys for my coupe, but only because I like the way they look over the stock ones. However, in my Vert all I did was replace the bearings in "ALL" my pulleys (Idlers and tensioners). So, instead of replacing the bearings in the idlers on my coupe, I wanted the "look" of the LFP pulleys. However, all the other pulleys (inner idlers and tensioners) will get their bearings replaced.

Please give me your thoughts on this as I do not see the "NEED" to replace the pulleys unless you like the look better, as I do, or to get more tension on the blower belt to reduce slippage.

Other than those two factors (upgraded looks or reduce belt slippage) I do "NOT" see the need to replace the pulleys.
 

cj428mach

Well-Known Member
Established Member
Joined
Sep 21, 2012
Messages
7,609
Location
Kansas
The stamped steel ones can crack, break, and come apart. The tighter the belt tension the more likely it is to happen.

For some idlers are just a bling mod, for others its a precaution.
 

roy_1031

roy1031
Established Member
Joined
Apr 20, 2011
Messages
4,796
Location
Rancho Cucamonga, CA
I upgraded mine to Metco ones because the stock one peeled open and took out the belt and hood blanket. Only had like 20k miles when it happened.


Sent from my iPhone using Tapatalk
 

03cobra#694

Good Guy
Super Moderator
Joined
Nov 12, 2003
Messages
62,080
Location
SW FL.
The stamped steel ones can crack, break, and come apart. The tighter the belt tension the more likely it is to happen.

For some idlers are just a bling mod, for others its a precaution.

What Mike said, and I did it for both reasons.
 

ITSTOCK

Well-Known Member
Established Member
Joined
Sep 9, 2004
Messages
1,782
Location
wv
It's not really a debate, it's been known since 2003 that the stock idlers will break and "explode", best case leaving you without a belt, worst case damaging your hood among other things. It has happened to plenty of us (yes, including me in 2004).
 
Last edited:

Black Gold 380R

Multiple SVT Collector
Established Member
Joined
Feb 28, 2008
Messages
5,585
Location
El Paso, TX
It has happened to plenty of us (yes, including me in 2004).

Plenty of us is a relative term when compared to all the Cobras made in 03/04. And if this is true I go back to my original question and ask "Why doesn't the idler kit come with "ALL" the pulleys" to replace the inner idlers as well? Are the external/supercharge pulleys the only ones susceptible to this breakage or exploding?

Was it a bad batch that is prone to this failure? My coupe has 45K miles and my Vert has 75K miles. I know this has never happened to my coupe and from my understanding it has never happened to my Vert.

And yes, I think it's a debate as this is not a recall issue. So, is it necessary or is it a precaution? I'm just trying to get some insight here as a lot of people say replace them, but is it really necessary?
 

GTCobraClone

Member
Established Member
Joined
Jun 16, 2009
Messages
623
Location
West Palm Beach, FL
Because they are only replacing the pulleys that are more prone to or have been documented to have a catastrophic failure.

Plenty of us is a relative term when compared to all the Cobras made in 03/04. And if this is true I go back to my original question and ask "Why doesn't the idler kit come with "ALL" the pulleys" to replace the inner idlers as well? Are the external/supercharge pulleys the only ones susceptible to this breakage or exploding?

Was it a bad batch that is prone to this failure? My coupe has 45K miles and my Vert has 75K miles. I know this has never happened to my coupe and from my understanding it has never happened to my Vert.

And yes, I think it's a debate as this is not a recall issue. So, is it necessary or is it a precaution? I'm just trying to get some insight here as a lot of people say replace them, but is it really necessary?
 

ITSTOCK

Well-Known Member
Established Member
Joined
Sep 9, 2004
Messages
1,782
Location
wv
Plenty of us is a relative term when compared to all the Cobras made in 03/04. And if this is true I go back to my original question and ask "Why doesn't the idler kit come with "ALL" the pulleys" to replace the inner idlers as well? Are the external/supercharge pulleys the only ones susceptible to this breakage or exploding?

Was it a bad batch that is prone to this failure? My coupe has 45K miles and my Vert has 75K miles. I know this has never happened to my coupe and from my understanding it has never happened to my Vert.

And yes, I think it's a debate as this is not a recall issue. So, is it necessary or is it a precaution? I'm just trying to get some insight here as a lot of people say replace them, but is it really necessary?

I think you are overthinking this. I'm sure it has to do with the size and location of the pulley and having different loads causing some to be more prone to failure than others.

The bottom line is that is your car and nobody is forcing you to replace them, so either take good advice or don't.
 

Black Gold 380R

Multiple SVT Collector
Established Member
Joined
Feb 28, 2008
Messages
5,585
Location
El Paso, TX
^^^ I guess I'll have to do more research as I would want to replace them all, not just 2 or 3. So, I will need to find out what the sizes are of the inner idlers and replace them if I can find the pulleys for sale individually or as a kit designed for the inner idlers as well.

Thanks for the comments thus far.
 

whitedevil95

@the03cobro
Established Member
Joined
Feb 12, 2012
Messages
3,353
Location
Temecula, CA
The inner belt doesnt have the same extreme tension that the outer belt has. Two of my friends literally exploded stock idlers which tore up their belts and left them stranded.
 

Rich'sTRsvt

Active Member
Established Member
Joined
Oct 28, 2012
Messages
798
Location
Madison, WI
Because it takes a lot more power to turn a blower when it is compressing lots of air then it does to run some accessories. Think about guys breaking off lower pulleys with big twin screws, how often do you see people breaking off lowers with their accessory pulleys?
 

Black Gold 380R

Multiple SVT Collector
Established Member
Joined
Feb 28, 2008
Messages
5,585
Location
El Paso, TX
Because it takes a lot more power to turn a blower when it is compressing lots of air then it does to run some accessories. Think about guys breaking off lower pulleys with big twin screws, how often do you see people breaking off lowers with their accessory pulleys?

I can see that. Makes sense. That's probably another reason why the outer set up is 8 rib vs. the inner set up which is 6 rib. I'm probably going to replace as many pulley's as I can. Once I figure out the sizes and see where I can buy them individually. Then I'll need to figure out type as some are smooth, while others have the ribs. Wish someone just offered a complete kit. Would make this venture a little easier.
 

c6zhombre

E85 NutSwinger
Established Member
Joined
Sep 14, 2008
Messages
5,430
Location
League City, TX
The tension difference between outer and inner belts are in several different zip codes IF you are running aftermarket crank lower and/or aftermarket upper blower. I have not seen you post your blower and pulley config....if you are 100% stock you might be fine for thousands of miles.

If you are running aftermarket, replace all the outer pulleys you can afford to do. Period. And if you come across a sliding whipple adjustable tensioner pulley....you have found shangrila
 

Black Gold 380R

Multiple SVT Collector
Established Member
Joined
Feb 28, 2008
Messages
5,585
Location
El Paso, TX
^^^ Yeah, I'm more of an appearance guy rather than a performance one. Don't get me wrong, I like performance, but with my Cobra's I'm very happy with the stock output levels. I've upgraded my clutch and exhaust and have done a CAI, but as far as blower set up I'm 100% stock on both my coupe and vert.

So, I bought my LFP pulleys for looks, not performance. However, it seems I may have stumbled on to some insurance by going with aftermarket pulley's. My inner set up will probably stay stock with new bearings, but my outer set up will be upgraded.

Thanks for all the comments guys. I appreciate it.
 

broke7

Stock IRS Guru
Established Member
Joined
May 4, 2003
Messages
4,249
Location
Alaska
Guys snap the end off cranks with larger blowers and devastate whole motors. That is how much forces at play here, let that sink in.

I had the same set of billetflow idlers on my car for close to 10 years with no issues. I just recently upgraded to Metco Double Ball bearings for the aesthetic qualities.
 
Last edited:

03 Indy Cobra

Well-Known Member
Established Member
Joined
May 30, 2005
Messages
2,734
Location
Indiana
I can see that. Makes sense. That's probably another reason why the outer set up is 8 rib vs. the inner set up which is 6 rib. I'm probably going to replace as many pulley's as I can. Once I figure out the sizes and see where I can buy them individually. Then I'll need to figure out type as some are smooth, while others have the ribs. Wish someone just offered a complete kit. Would make this venture a little easier.

Metco makes a complete set of idlers for the 6 rib accessory drive. Here's the link

http://www.metcomotorsports.com/proddetail.asp?prod=MCI-AD
 

Wicked46

Under Pressure
Established Member
Joined
Nov 6, 2006
Messages
3,174
Location
Palm Bay, FL
METCO is the way to go. I have them on my racecar/streetcar and there great. I have a set of 6-rib pulleys as well but haven't gotten around to install them just yet.
 

cj428mach

Well-Known Member
Established Member
Joined
Sep 21, 2012
Messages
7,609
Location
Kansas
Unless you really have nothing better to spend your money on, I'd put new INNER idler pulleys very low on my priority list.
 

Users who are viewing this thread



Top