How to change your cam follower inside. (Now with debate about failures and their cause.)

[GolfRS]

Quote, originally posted by shortydub »

just my .02 but the relation seems to be that the deformation is occuring at the point of pivot. The APR pump having the wider piston with the same contact area and then tapering off causing possible "cupping" on the follower. Where as the other pump pictured not having the tapered edge is "punching" into the follower, giving it a more definate point of pivot, yet possibly wearing through faster...

What you also fail to understand, is that if the follower is rigid and both pump pistons have the same contact area (green area in my pics), then NO pivoting can make it larger.
Again, PIVOTING is a circular motion around an axis (the piston in our case) and if there is no SIDE MOTION allowed (which is the RULE for this pump to function properly), it ALWAYS should leave the same radius footprint...

[magilson]

Quote, originally posted by Arin »

Not sure if any of this information can help at all, but here is patent information related to our pump:

It can't help at all. There is no help for any of us. It's deformation and we're all going to die.

[GolfRS]

Quote, originally posted by magilson »

It can't help at all. There is no help for any of us. It's deformation and we're all going to die.

Or maybe its PIVOTING going wild inside the cam follower !!!

Now that would be a disaster...no ??

[magilson]

Quote, originally posted by GolfRS »

Again, PIVOTING is a circular motion around an axis (the piston in our case) and if there is no SIDE MOTION allowed (which is the RULE for this pump to function properly), it ALWAYS should leave the same radius footprint...

READ THE FREAKING PATENT! Side motion is accounted for given the shape of the end piston shaft! It's not the piston that is pivoting! I don't know how many ways I can say this! It's the follower pivoting against the pump shaft!

[GolfRS]

Quote, originally posted by magilson »

READ THE FREAKING PATENT! Side motion is accounted for given the shape of the end piston shaft! It's not the piston that is pivoting! I don't know how many ways I can say this! It's the follower pivoting against the pump shaft!

Man...you are all confused.Maybe you are reading too many patents....

Of course the follower is pivoting.It is free to move, as i've already explained to you.

What you seem to keep ignoring though, is that there SHOULDN'T be ANY side motion happening, as that would seriously damage the pump, which needs to be moving in a constant vertical direction.

What exactly aren't you getting ???? FFS !!!

[Arin]

GolfRS, we may have a language barrier.

Pivot can mean to spin around in a circle on a single point, as you are stating it. I mean rocking back and forth on a point or fulcrum. A seesaw pivots on a fulcrum.

[GolfRS]

Quote, originally posted by Arin »

GolfRS, we may have a language barrier. Pivot can mean to spin around in a circle on a single point, as you are stating it. I mean rocking back and forth on a point or fulcrum. A seesaw pivots on a fulcrum.

Really ??Oh ok....
So what kind of movement would that explain when referring to the
pump again??

[shortydub]

Quote, originally posted by Arin »

GolfRS, we may have a language barrier. Pivot can mean to spin around in a circle on a single point, as you are stating it. I mean rocking back and forth on a point or fulcrum. A seesaw pivots on a fulcrum.

I was referring to it pivoting on a fulcrum, acting like a english wheel that is used in body shops. could this be possible?

[jeff2.0t]

OMG we will die!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!

Wil I give my car to my poor widow wife or should I ask to be buried in my car to prevent a cataclysm

[iThread]

[GolfRS]

Quote, originally posted by shortydub »

I was referring to it pivoting on a fulcrum, acting like a english wheel that is used in body shops. could this be possible?

Well i have no clue how that is, but the way i see it, the only 2 movements
that should be "allowed" in the pump in order for it to have the most endured stress on
the piston (vertically) is,

1)the up and down movement of the piston (completely vertically), and

2)the rotation, pivoting, dancing round itself (or whatever you wanna call it) of the follower, which is to be expected, since it not attached to anything and its free to move (up down+pivot around the piston axis).

ANY other movement could put more stress on the piston, causing it to break, with all the known consequences.

[magilson]

Quote, originally posted by GolfRS »

2)the rotation, pivoting, dancing round itself (or whatever you wanna call it) of the follower, which is to be expected, since it not attached to anything and its free to move (up down+pivot around the piston axis).

[rbradleymedmd]

Out of curiosity...why (if possible, most likely not) don't we find a way to make the follower and piston all one sturdy piece? Would this not alleviate all these problems? Or would this lead to issues with the cam lobe then?

[shortydub]

Quote, originally posted by GolfRS »

Well i have no clue how that is

Power hammer:
http://www.youtube.com/watch?v...lated

English wheel:
http://www.youtube.com/watch?v=APmSjzBvYd0

I think the contact area of the piston and the camshaft is acting like a mix of these two on our cam followers....

[GolfRS]

Quote, originally posted by shortydub »

I think the contact area of the piston and the camshaft is acting like a mix of these two on our cam followers....

Its a good analogy, since the forces on the follower are

1)impact from the piston/tip (its just now starting to show that maybe increased rpm for prolonged periods might actually cause disruption of the piston follower contact, acting like a hammer on return)

2)frictional/rotational forces in the inside as the follower pivots around the piston axis.

3)"normal" friction/wear form the contact of the follower with the camshaft on the outside.

[TypeR #126]

There does seem to be some confusion around terms and definitions. Here is a crude drawing that represents the type of pivoting I was referring to.

Here the cam follower is pivoting within the vertical plane of it's bore as the came lobe sweeps through it's arc, with the pump plunger acting as the pivot point. I've over simplified and exaggerated for effect.

[NoRegrets78]

Just ordered myself a follower. I know how the stock looked before I installed my APR pump...so I have a good basis for comparison. If it doesn't look right after 5k...we'll see. I have a feeling its fine.

[Arin]

Quote, originally posted by TypeR #126 »

There does seem to be some confusion around terms and definitions. Here is a crude drawing that represents the type of pivoting I was referring to. Here the cam follower is pivoting within the vertical plane of it's bore as the came lobe sweeps through it's arc, with the pump plunger acting as the pivot point. I've over simplified and exaggerated for effect.

Thank you for this image. This is what I tried to describe long ago.

[GolfRS]

Quote, originally posted by TypeR #126 »

There does seem to be some confusion around terms and definitions. Here is a crude drawing that represents the type of pivoting I was referring to. Here the cam follower is pivoting within the vertical plane of it's bore as the came lobe sweeps through it's arc, with the pump plunger acting as the pivot point. I've over simplified and exaggerated for effect.

Right..Now this is the thing i was also trying to explain SHOULDN'T be happening.

To begin with, the follower can't move in the direction you have positioned it, simply because its movement is directed by the the hole in which it moves, which is only up and down.Also, if you pic was the case, you would also find wear marks on the lips of the follower, and that just isn't the case....

Second, IF it were to move like that, the force acting upon the piston would not be a vertical one, and since the piston CAN'T move sideways, the whole of the force would be translated to stress.

The above are just a few of what would be happening if your drawing was actually what is happening.I'm pretty sure i can think of some more...

[csih]

Totally agree with GolfRS to the above
The main reason of cam premature wear except the extra force it takes from aftermarket hpfp's is the driving style. Especially when raping the car all the time by changing gears to redline


Modified by csih at 3:40 PM 3-25-2008

[magilson]

Surprise me and take some time to read the patent for the pump. Or don't and keep speculating when there is an explanation readily available... Either way...

[Arin]

Quote, originally posted by csih »

Totally agree with GolfRS to the above The main reason of cam premature wear except the extra force it takes from aftermarket hpfp's is the driving style. Especially when raping the car all the time by changing gears to redline

Is that why yours cracked in half? Were you goign much past redline?

[csih]

every single time, yes and 4 more cases i know from first hand all did to their cars the same thing. Imagine that the last case was on a Golf GTI 08 Model with 7000kms STOCK!

[Arin]

Quote, originally posted by csih »

every single time, yes and 4 more cases i know from first hand all did to their cars the same thing. Imagine that the last case was on a Golf GTI 08 Model with 7000kms STOCK!

How far above redline were you pushing it each time?
Were you running at 150 bar with that tune too?

[NoRegrets78]

I would imagine the DSG owners have less to worry about as the car shifts before even hitting where the rev limiter is set.

[csih]

Quote, originally posted by Arin »

How far above redline were you pushing it each time? Were you running at 150 bar with that tune too?

I have never run 150 bar. Its way far saying i will kill you from actually doing that,,,

[csih]

Quote, originally posted by NoRegrets78 »

I would imagine the DSG owners have less to worry about as the car shifts before even hitting where the rev limiter is set.

I was thinking the same thing too

[Arin]

Quote, originally posted by csih »

I have never run 150 bar. Its way far saying i will kill you from actually doing that,,,

Not really sure what that means. Only reason I asked if you ran 150 bar was because you asked about it in the past and said you, or someone you knew was going to do it. No one ever cleared that one up.

[GolfRS]

Quote, originally posted by magilson »

Surprise me and take some time to read the patent for the pump. Or don't and keep speculating when there is an explanation readily available... Either way...

Dude...you are starting to get on my nerves why your retarded "read the patent"
repetition.

Since you are "trying" to look smart, please enlighten us with your... "patent wisdom" or quit saying.Its not like it matters anyway.....

[csih]

Dimitri btw have you checked you cf?

[GolfRS]

Quote, originally posted by csih »

Dimitri btw have you checked you cf?

No but i am willing to bet its as good as new.

I don't push the car to the limit that frequently, and i check my pressure deviation every time i log.

I was going to check it though, just to make sure.

In contrast to what others seem to believe, i don't think follower failures are about to destroy the world.Its just another "fuel cut" hysteria, all over again.....

But we'll see pretty soon.

[csih]

Quote, originally posted by GolfRS »

No but i am willing to bet its as good as new. I don't push the car to the limit that frequently, and i check my pressure deviation every time i log. I was going to check it though, just to make sure. In contrast to what others seem to believe, i don't think follower failures are about to destroy the world.Its just another "fuel cut" hysteria, all over again..... But we'll see pretty soon.

I mostly agree but with fuel cuts you didnt had any hardware failures..if cf brakes then you begin talking from 1000$-++++ for repairs. So better prevent things than repair and pay a **** load of money later

[NoRegrets78]

I have to agree with csih...you really need to prevent the issue from the start before it bites you in the rear.

GolfRS: What do you mean we'll see pretty soon?

[magilson]

Quote, originally posted by GolfRS »

Dude...you are starting to get on my nerves why your retarded "read the patent" repetition. Since you are "trying" to look smart, please enlighten us with your... "patent wisdom" or quit saying.Its not like it matters anyway.....

ditto?

[GolfRS]

Quote, originally posted by csih »

I mostly agree but with fuel cuts you didnt had any hardware failures..if cf brakes then you begin talking from 1000$-++++ for repairs. So better prevent things than repair and pay a **** load of money later

Well that not exactly right.

A fuel cut is caused by a rather sudden drop in fuel pressure reaching as low as 80 bar.

Indications that the pumping mechanism is failing could be as subtle as a more than 3% standard deviation from requested, which is within the acceptable limits.This means that if you log your rail pressure and you see areas where the rail difference is more like 5 to 10 bar, then you should start getting suspicious.....