Crankshaft pulley ideas

[BGA]

I have followed the discussion regarding crank pulley problems on this forum. IDI vs. TDI. Key vs. D shaped. I can only see one reason why D is better than key shaped. Once it comes loose D shape will work longer as the key will probably shear off or work up keyway in crankshaft.
D and key is only for indexing and are not supposed to take any torque load (I guess)
I have both engines apart in my shop. Crankshaft outer dia. is same, aprox. 32mm and thread is M14. IDI 1,6 had 10.9 bolt and TDI 12.9.
If the mating surfaces on crankshaft and pulley are completely flat the torque capacity should be exactly the same on both designs (if same bolt and bolt torque is used).
As torque is transmitted only by friction, flat surfaces are a bad design. One part should have a recess so the parts only mates close to the outer diameter 32mm. This would have avoided pulley to start work and wobble at high bending + torque forces.
Has the surface of pulley a small concave shape? If no has VW engineers made a mistake or are they afraid of the pulley cracking. Pulley is made of SMP and mfg. process is difficult to control. SMP parts can be very brittle.
Now to my problem. I will use a IDI 1,6 in my tractor. From front of crankshaft I need to run a hydraulic pump 4-5 times more capacity than a PS pump. If I machine the pulley face so it only has contact with crankshaft close to the 32mm dia. I will be able to transmit 240Nm if my calculations are correct.
Given.: Bolt M14 12.9 clamp force = 124kN
             Friction = 0,14
I would appreciate any comments on this and appologise for my “swenglishe”

[silentdub]

I recently tore down my 1.6 and the keyway on the crank is very similar to that of many other engines. Other engines however require the pulley to be forced on as the fit around the shaft is very tight. The same engines that I am referring to also require a puller to get the thing off. This engine design looks as though it only uses the key to keep it straight not to mention the center bolt at like 770ft lbs.


I didn't see any issues on mine, but on other engines, I have replaced the key with a slightly larger/thicker key for better fitment and never had a problem.

If you go to Sears Hardware, they have some keys that are hardened, you can file/grind them down to fit like a king.


I once had a pulley not only break the key, but sheer off part of the key way on the crank, I had to weld it up, grind it out and fit a new key.


BTW: I am not a 1.6 Expert.

[92EcoDiesel Jetta]

He's in Sweden, no Sears hardware there I don't think but you never know.

What you need to drive more load is a spline between the crankshaft and pulley.

[R.O.R-2.0]

I recently tore down my 1.6 and the keyway on the crank is very similar to that of many other engines. Other engines however require the pulley to be forced on as the fit around the shaft is very tight. The same engines that I am referring to also require a puller to get the thing off. This engine design looks as though it only uses the key to keep it straight not to mention the center bolt at like 770ft lbs.


I didn't see any issues on mine, but on other engines, I have replaced the key with a slightly larger/thicker key for better fitment and never had a problem.

If you go to Sears Hardware, they have some keys that are hardened, you can file/grind them down to fit like a king.


I once had a pulley not only break the key, but sheer off part of the key way on the crank, I had to weld it up, grind it out and fit a new key.


BTW: I am not a 1.6 Expert.

and you must have an ANCIENT 1.6 if it still has a key, and keyway.. those were only one the earliest of early engines.. and that design was better than the later design.. the crank nose actually went most of the way thru the sprocket..

[BGA]

Sorry for missinformation. "key" is not a separate part. It is integrated in pulley.

[silentdub]

Sorry for missinformation. "key" is not a separate part. It is integrated in pulley.

hmmm, interesting. The key for mine is actually on the crank or so I thought.


If it starts to slip, worse comes to worse, tack weld it.

[R.O.R-2.0]

Sorry for missinformation. "key" is not a separate part. It is integrated in pulley.

hmmm, interesting. The key for mine is actually on the crank or so I thought.


If it starts to slip, worse comes to worse, tack weld it.

tack weld pot metal to a forged crank? yea... good plan 

if it has an actual keyway, and key holding the crank sprocket, then its an ANCIENT 1.6..

you dont just tack weld the sprocket to the crank..

[bajacalal]

I could be wrong here, but I thought the problem with the AAZ engine crankshaft pulleys was not caused by the actual load on the crankshaft but by impulse, meaning that because the air conditioning pump (among other things) switches on and off, this creates a large, instantaneous difference in load which gives a shock or vibration to the crankshaft where it mates to the pulley.

This happens because the pulley suddenly encounters much more resistance but the rotating crankshaft continues to rotate at the same speed. I think the AAZ also used a flat (serpentine) belt which transmits all of the shock loading from the engine accessories. A V belt will slip a certain amount. 1.6 IDI engines used a V belt and as far as I know, did not experience the problem even though they had the same accessories on the engine.

As long as the hydraulic pump system builds pressure gradually, and does not shock the engine with an instant heavy load, I don't think it should cause any problems if you use a V belt because a V belt (I think) would slip before breaking anything on the crankshaft, if the load was simply too much for it.

If you are concerned about the crankshaft pulley becoming loose, I would drill and tap the crankshaft and pulley to accept a set screw, maybe 8 mm diameter which should keep the pulley fixed in place. That's what I would do. Pulleys on industrial machinery mostly seem to use a both a set screw and key.

I am not an automotive engineer or an expert with these engines, so take caution before following any of my advice.

[vanbcguy]

The big deal (supposedly) was actually the alternator.  Nothing to do with impulses from it, but merely the nature of a 4-cylinder 4-stroke engine.  Every time a cylinder fires the crank tries to accelerate, but the alternator resists.  Once the "power" part of the stroke is done, the opposite occurs - the crank slows while the alternator is still moving at its previous high speed.  The result is the forces on the crank pulley smashing back and forth, but due to the actual combustion of diesel more than anything.

The fix was to add an overrun clutch to the alternator (so the alt can continue at its current speed when the engine hits its next compression cycle) and to modify the crank pulley and the crank nose with a new 'D' shaped design rather than just a keyway.

[silentdub]

Sorry for missinformation. "key" is not a separate part. It is integrated in pulley.

hmmm, interesting. The key for mine is actually on the crank or so I thought.


If it starts to slip, worse comes to worse, tack weld it.

tack weld pot metal to a forged crank? yea... good plan 

if it has an actual keyway, and key holding the crank sprocket, then its an ANCIENT 1.6..

you dont just tack weld the sprocket to the crank..

If I had to, I would. The pulley I have is not pot metal, but whatever works.

[R.O.R-2.0]

Sorry for missinformation. "key" is not a separate part. It is integrated in pulley.

hmmm, interesting. The key for mine is actually on the crank or so I thought.


If it starts to slip, worse comes to worse, tack weld it.

tack weld pot metal to a forged crank? yea... good plan 

if it has an actual keyway, and key holding the crank sprocket, then its an ANCIENT 1.6..

you dont just tack weld the sprocket to the crank..

If I had to, I would. The pulley I have is not pot metal, but whatever works.

your PULLEY may not be pot metal, but the CRANK SPROCKET definitely is..

if you weld the crank sprocket to the crank, you can never take the crank out of the engine. ever. again..

[silentdub]

[/quote]

your PULLEY may not be pot metal, but the CRANK SPROCKET definitely is..

if you weld the crank sprocket to the crank, you can never take the crank out of the engine. ever. again..
[/quote]


I'm not talking a 1/4 inch beaded weld, just a tack, something that is easily removed. no big deal.

Same deal on the caddy SRX motors, the chain gear is part of the crank, they spin off, then you have to replace the crank, otherwise you can cross your fingers and tack that thing back in place.

I have to look at mine tonight, I think it is different from what you guys are talking about, not sure why, it came out of an 85, so maybe that is what you guys consider ancient.

[R.O.R-2.0]

your PULLEY may not be pot metal, but the CRANK SPROCKET definitely is..

if you weld the crank sprocket to the crank, you can never take the crank out of the engine. ever. again..
[/quote]


I'm not talking a 1/4 inch beaded weld, just a tack, something that is easily removed. no big deal.

Same deal on the caddy SRX motors, the chain gear is part of the crank, they spin off, then you have to replace the crank, otherwise you can cross your fingers and tack that thing back in place.

I have to look at mine tonight, I think it is different from what you guys are talking about, not sure why, it came out of an 85, so maybe that is what you guys consider ancient.
[/quote]

no, its got the flat crank nose with the small tang to drive the sprocket..

IDK how the hell you are going to get a welder tip in between the crank sprocket and the seal carrier tho...

its not like throwing a small tack on a caddy crank with the sprocket all the way around the crank.. the sprocket kinda rests on the end of the crank, not completely around the end of the crank like most balancers/sprockets..

[silentdub]

no, its got the flat crank nose with the small tang to drive the sprocket..

IDK how the hell you are going to get a welder tip in between the crank sprocket and the seal carrier tho...

its not like throwing a small tack on a caddy crank with the sprocket all the way around the crank.. the sprocket kinda rests on the end of the crank, not completely around the end of the crank like most balancers/sprockets..

I figured that there would be a way to get in there somehow. It sounds like a really F'd up part to break loose. Sometimes the most simplistic part can be a real pain in the balls.

I guess if you wanted, you could modify the crank to take a key and then the pulley to accept it. They sell hardened keys that can be ground down to the size you need.

[R.O.R-2.0]

no, its got the flat crank nose with the small tang to drive the sprocket..

IDK how the hell you are going to get a welder tip in between the crank sprocket and the seal carrier tho...

its not like throwing a small tack on a caddy crank with the sprocket all the way around the crank.. the sprocket kinda rests on the end of the crank, not completely around the end of the crank like most balancers/sprockets..

I figured that there would be a way to get in there somehow. It sounds like a really F'd up part to break loose. Sometimes the most simplistic part can be a real pain in the balls.

I guess if you wanted, you could modify the crank to take a key and then the pulley to accept it. They sell hardened keys that can be ground down to the size you need.

theres no room for a key or keyway dude..

the only other viable option ive seen for people fixing the crank sprocket is to drill the sprocket, and the crank nose, and PIN them in place..

you dont get it.. the sprocket doesnt sit OVER the crank. it sits ON THE END of the crank.. the crank might protrude about 1/4" into the sprocket, but thats PUSHING IT..

the only crank/sprocket that used an ACTUAL KEY AND KEYWAY, are from the oldest of old engines.. im only aware of that design on the 1.5L engines tho...

ill say it again, the sprocket does not slide over the whole crank snout. it just slips on the end, against the flat surface..