Pulley Upgrade?

TJ Wrangler

New member
Joined
Mar 31, 2014
Location
Nor Cal
TDI
Duramax LBZ
Lightened pulleys/sprockets will do absolutely squat, compared to reducing the weight of the flywheel by the same amount because 1) moment of inertia is related to the square of the diameter, I=mr², and a sprocket/pulley is of a much smaller diameter than the flywheel; 2) the kinetic energy required to rotate a sprocket/pulley is related to the square of the angular velocity, T=0.5*I*omega², and the camshaft/injection pump sprockets turn at half engine speed.

The best bang for the buck in terms of reducing rotational inertia in order to improve vehicle acceleration is to reduce weight at the wheels, because the moment of inertia is multiplied by the square of the overall gear multiplication ratio, multiplied by the fact that you have 4 of them.
Im reading this subject while doing research for a lighter injection pulley for my ALH motor. I have to disagree with this statement...a lighter injection pump pulley should do wonders for timing belt life compared to running a TDI with a heavyweight VE pump pulley if your using high RPMs. That is my reason for the search. I just wish I could find someone in the UK who would like to work with a Yank on getting some UK/Euro parts shipped to me for my build.
 

DPM

Top Post Dawg
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Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
think about the springs in the pump head and what is continually happening to the pump's torque requirement.
 

bhodgkiss

Veteran Member
Joined
Sep 11, 2006
Location
Banbury, UK
TDI
AFN Passat Wagon
....to drag up an old thread, is there actually any issue running the lightweight ALH pulley with an 11mm pump? Some people mentioning the lightweight pulley bad for intermediate shaft life?
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
No hard data from me, but I think it's one of the reasons they went to longer timing belt intervals. Damping the shock load on the belt from the injection events.

It might go either way for the cross piece in the pump, as the pulley is on the other side from the cam plate and pump head, and might make the shock loading on that piece greater because it reduces the amount the belt will give. But then, it could reduce the snap of the belt on the IP internals, because as the roller comes to the top of the ramp (or the control collar port opens) the tension in the stretched belt will let go and skip the rollers over the cam lobe.

Lots of rambling from a nobody.
Interested to see others' take on it. Putting some thought into the IP drive, myself.
 

turbovan+tdi

Top Post Dawg
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Mar 23, 2014
Location
Abbotsford, BC.
TDI
2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
I think its heavy for a reason. Take a small output 4 cylinder and put a lighter flywheel on and what happens?
 

bhodgkiss

Veteran Member
Joined
Sep 11, 2006
Location
Banbury, UK
TDI
AFN Passat Wagon
Thanks
But the ALH auto 11mm pump has the lightweight pulley as standard (and the AHH longitudinal version) so why did VW choose to make these light for a reason? Something to do with the auto?
I don't see why VW did both specs? Its not like one was phased out due to issueS?
 

turbovan+tdi

Top Post Dawg
Joined
Mar 23, 2014
Location
Abbotsford, BC.
TDI
2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
Thanks
But the ALH auto 11mm pump has the lightweight pulley as standard (and the AHH longitudinal version) so why did VW choose to make these light for a reason? Something to do with the auto?
I don't see why VW did both specs? Its not like one was phased out due to issueS?
Sure about that, I've done both ALH pumps and never seen a lightweight 11mm pulley?
 

p0wer

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May 21, 2009
Location
Jyvaskyla, Finland
TDI
Golf 3 -94 1Z 377hp, Golf 3 Cabrio 4-Motion 1.8T 620hp, Golf 3 Syncro 2.9 VR6 HX52, Bora AJM 4-Motion 2260vk +120% Firad, Passat 3B Syncro AFN 2260vk
But the ALH auto 11mm pump has the lightweight pulley as standard (and the AHH longitudinal version)
ALH Automatic has always 1.8kg pulley (038130111B) like others. AHH has lighter 0.6kg pulley (028130111J).
 

bhodgkiss

Veteran Member
Joined
Sep 11, 2006
Location
Banbury, UK
TDI
AFN Passat Wagon
I bought my alh pump second hand and it came with lighter pulley I think, I might be wrong

Ok so the ahh, that survives with a light pulley? Why is this the lightweight version as standard? Longitudinal engine can cope?
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
@p0wer, there's also a 038130111A. Do you know what that's for and its weight?

Geez, some people want the lighter pulley, I want the heaviest one!
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
@p0wer, there's also a 038130111A. Do you know what that's for and its weight?

Geez, some people want the lighter pulley, I want the heaviest one!
ikr, I'm thinking about making one out of brass for the increased density.

Then the real reason for making one when they're available on the shelf, make it with a shear pin in it on a running fit (maybe a ball bearing sorta like an A/C pulley), so that any kind of injection pump failure will not take the timing belt with it.
 

-zamppa-

Well-known member
Joined
Jan 13, 2010
Location
Finland
TDI
Audi Allroad 4BH V6 TDI/6M, Compound charged Golf 3 AHU, Passat 3B5 TDi 4motion, Typ1 & 636B
@p0wer, there's also a 038130111A. Do you know what that's for and its weight?
According to ETKA it is used some 2001 and earlier model G4/Bora and it is replaced with 038130111B afterwards(10/2000). I think it is heavier pulley also, atleast it looks the same.

Then the real reason for making one when they're available on the shelf, make it with a shear pin in it on a running fit (maybe a ball bearing sorta like an A/C pulley), so that any kind of injection pump failure will not take the timing belt with it.
I've had many IP failures, and never got problem with timing belt. I had many (atleast 5) broken crosscube, couple broken camplate pins, and when every other part survived, of course stucked & cracked plunger(11mm & 12mm) was next on the list.

Your idea is good, but maybe it is not necessary because something will give up inside the IP anyway and keeps timing belt unharmed?
 
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TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Fueling/HP levels in and of themselves do not cause problems with respect to requiring a heavier pulley. Bigger plunger diameters and more aggressive camplate profiles (higher hydraulic and inertial forces) increase torque fluctuations on the sprocket that are then taken up by the belt. This is why the North American automatic transmission ALHs (11mm pump, DE143 camplate) have the heavier pulley as standard and originally specified a 40k mile TB change interval instead of 60k miles for the manual transmission cars before there were superceded at least twice with longer-life TB P/Ns, when they were increased first to 80k miles then 100k miles for both manual and auto.

It's simply a timing belt life issue, not a performance issue. My car has a 12mm plunger in an otherwise stock 10mm pump. I don't want any surprises when the TB approaches close to the replacement interval.
 
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[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
I've had many IP failures, and never got problem with timing belt. I had many (atleast 5) broken crosscube, couple broken camplate pins, and when every other part survived, of course stucked & cracked plunger(11mm & 12mm) was next on the list.

Your idea is good, but maybe it is not necessary because something will give up inside the IP anyway and keeps timing belt unharmed?
Thank you for the information before I went out and spent many hours making a part that wouldn't really do what I wanted of it.

I can definitely see the t-belt being stronger than the ears on the end of the injection pump's shaft. Once those are sheared the pump input shaft will more or less freewheel as the engine coasts to a stop. Even if something were to catch in the transfer pump, the key would shear.
My car has a 12mm plunger in an otherwise stock 10mm pump. I don't want any surprises when the TB approaches close to the replacement interval.
Got a part number for the plunger return springs? They're the last bit I'm looking for for the 12mm pump head I've got laying around, got the same plans with the gentler 10mm pump camplate.
 

-zamppa-

Well-known member
Joined
Jan 13, 2010
Location
Finland
TDI
Audi Allroad 4BH V6 TDI/6M, Compound charged Golf 3 AHU, Passat 3B5 TDi 4motion, Typ1 & 636B
Thank you for the information before I went out and spent many hours making a part that wouldn't really do what I wanted of it.

I can definitely see the t-belt being stronger than the ears on the end of the injection pump's shaft. Once those are sheared the pump input shaft will more or less freewheel as the engine coasts to a stop. Even if something were to catch in the transfer pump, the key would shear.
The shaft and those ears are quite strong. Definitely something else will give up than them. I am still using the same shaft that was used during those all "experiments" which I mentioned before.



This 11mm gave up smoothly somewhere around 5000rpm with 5th gear. I saved it at this condition so I can remember afterwards those times when IP-build up was one of my daily routines as bacon & eggs at the morning. :D

If the timing belt is tightened correctly and checked once in a while it will survive from IP failure.
 
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