RR Pulley = BAD MOJO

[yeasure]

i still can't understand why your pully went on so easy, it almost killed me to get mine on, nothing easy about it.
Sorry i didn't mean to come off like an ass but understand this isn't the first time i've bought something for the cobra then come to find out it's 100% sh*t.
I've spent more money replacing the same mods over and over because i listen to people on forums(not just this one).
I can make a list of all the things i had to rebuy because people would say, "oh it's the best or it's great save money"

 

[cobra101]

I am going to go try that test asap. I will mark the pulley and shaft, then go drive around a bit. My boost drops off from 14.7 to 12.7 after 4500rpm too. I have the 2.75RR, 100mm idler with bracket and a 74 gates belt. I don't think their should be any slip. If my test proves that the RR is NOT slipping on the shaft, I will buy a smaller belt (possibly a gatorback). I hear people do run gatorbacks with the RR and it works fine.

 

[AmazonTuning]

it is not the pulley..it is the tolerance of the blower shaft..they are slightly varied just enough to have a pulley spin on the shaft.

 

[Fang]

Originally posted by cobra101
I am going to go try that test asap. I will mark the pulley and shaft, then go drive around a bit. My boost drops off from 14.7 to 12.7 after 4500rpm too. I have the 2.75RR, 100mm idler with bracket and a 74 gates belt. I don't think their should be any slip. If my test proves that the RR is NOT slipping on the shaft, I will buy a smaller belt (possibly a gatorback). I hear people do run gatorbacks with the RR and it works fine.

I was running a 73.5 Gatorback on the 2.8 RR and didn't see any problems except the belt dust. Never gave it a chance to seat though. First impressions were great.

 

[JKD COBRA]

cobra101 - just remember that you will probably always have some boost drop off. Its not only because of belt slip or pulley slip, the eatons will drop boost. A tighter belt is not the answer. Your already running a tight belt, I wouldn't go any tighter.

 

[Friendchicken]

Would it be possible the pulley or the shaft had lubricant on it of some kind? Anti seize or something?

 

[Pyro]

I have the SFPHQ interchangeable set up with the steel hub so I'm sure mine is ok BUT I think it's time to put marks on the pulley and snout just to be sure.

 

[Pyro]

I have an idea....Why not just weld the pulley onto the snout? :bash:

 

[flyn high again]

Originally posted by Linn@AmazonRacing
it is not the pulley..it is the tolerance of the blower shaft..they are slightly varied just enough to have a pulley spin on the shaft.

An easy test is to install a different brand pulley and see if it spins, too.

 

[SVTADVISOR]

I think c/a glue would work better!

 

[BuffDigits]

@flyn yup thats exactly why im doing. I think what should come out of this is for people to do what was suggested here a few times, mark the pulley/shaft do some high rpm shifts (go around the block, all i did was jump on 2nd up to 6k a couple times)

and just double check that if your not getting the hp you were expecting check to see if the marks stay aligned.

might be that some people that think they have belt slip actually have pulley slip.

simple test, doesnt cost anything and will tell you pretty quickly if anything is happening.

 

[stevenscamaross]

ROFL... lots of people on this board are running RR pullies. I run a 2.75RR without any idlers with a 73.5 gatorback belt. I received a little belt dust for the first 100 miles break in on the belt, but now I see none. Every Eaton car drops boost. Something is fishy.

 

[dougwg]

Originally posted by Linn@AmazonRacing
it is not the pulley..it is the tolerance of the blower shaft..they are slightly varied just enough to have a pulley spin on the shaft.

Linn is right!

Let me ask you guys something

Do you think RR's pulley was out of spec?

OR

Do you think the (MASS PRODUCED by the thousands) Eaton may have been out of spec?

From what I have seen, I would believe the later!

 

[cobra101]

JKD Cobra, Thanks for the info. I will keep the same size belt than. I could of sworn I heard of several eatons making around 14lbs and holding it til redline?

How about a similiar size belt but switching to a gatorback? (74 inch)?

Ohh, and I just marked the pulley and shaft and drove around. No slipping of the pulley on the shaft at all. I will keep my eye on it.

 

[Mackie]

Edited

 

[yeasure]

Ok i'm getting somewhat confused......are you saying it's not the pully but the eaton itself?
I understand it could be that RR did a one size fits all perfect deals and didn't think about them being different sizes/shafts but this still doesn't make much since......reason, what pully marker has done test on 03/04's to see if the shafts are different sizes(if i'm off base here please correct me, i'm trying to understand this) i know pully makers/resellers will now start saying they have tested for this but i don't buy that either.
Seems like to me they all use the same specs other then some are steel, some are alumium.

 

[yeasure]

ttt

 

[BuffDigits]

well the fact is the RR pulley I got (which looks practically hand made on a drill press) was in fact spinning around the shaft.

whether that is because the shaft had a variation in it or the pulley is not known, however a steel steeda pulley seems to fit just fine. so someones spec is varying somewhere.

@steven, indeed eatons loose boost but not at 4k and yes something was fishy, the pulley center hole size was too big and so the pulley was spinning around the shaft. (or the eaton shaft was too small depending on your perspective)

 

[Hicompression]

Why RR Pullies are a Bad Design!

Aluminum Linear Coefficient of Thermal Expansion = 25x10-6 cm/cm.C

Steel Linear Coefficient of Thermal Expansion = 12x10-6 cm/cm.C

An aluminum pulley expands at two times the rate of the steel shaft it is riding on! The hole in the middle of the pulley expands based on this rate which can lead to slip! This is simple physics.

Aluminum pulleys on a steel shaft where the heat soak temperature of the S/C can reach 200+ degrees F is a bad design, period.

<--M.S. Materials/Metallurgical Engineering

 

[hmwave]

Originally posted by BuffDigits
@steven, indeed eatons loose boost but not at 4k and yes something was fishy, the pulley center hole size was too big and so the pulley was spinning around the shaft. (or the eaton shaft was too small depending on your perspective)

Probably too late to try but do you have the means to measure both with accurate calipers and post the results?

Would be great to compare that with some other snouts/pulleys sizes from other cars to help resolve this.