AirSpeed VW Community Forums

Technical => Engine Tech Forum => Topic started by: flat4 on July 22, 2006, 05:27:15 PM

Title: Crank Timing Gear
Post by: flat4 on July 22, 2006, 05:27:15 PM

so I was assembling my crank today, and couldn't get the timing gear on the crank.  I heated it in oil, no dice.  I stuck it directly on the BBQ, still no dice.  I was using a hammer and some spacers to get it moving (slowly mind you), and suddenly it moved quite a bit.  It cracked between 2 of the teeth.

so how does one get the crank timing gear on without breaking it?

does anyone have a straight cut crank timing gear for sale?

Title: Crank Timing Gear
Post by: dannyboy on July 22, 2006, 06:37:48 PM

been there done that... sorta  :unsure:
what brand gears and crank? what are the measurements?
you need ALOT of heat
like the surface on the gears should be bluing its so hot.  have the crank right beside you, take the gear as quickly as you can off the burner, and put it on the crank nice and straight and it should go on (you might need to hit it a COUPLE times but nothing more. if it goes on even slightly crooked your hooped, you will have to re heat, and try again.
when i built my motor I didnt know you were supposed to use heat... so i put it in a 10 ton press, it went on about half way and crack....
one of the many dumbass moves i made building my first motor...

Title: Crank Timing Gear
Post by: Bruce on July 22, 2006, 07:11:49 PM

You were lucky it broke.  If not, you might have never been able to get it off again in the future.

This problem has plagued the aftermarket crap manufacturers for years.  It is not that difficult, but some manufacturers can't seem to hit the ID correctly.  You must measure ALL aftermarket straight cut gears.  It is very common for the ID to be too small.  This is what was wrong with your gears.

Also, you should measure your crank.  Although not as common, on rare occasions the crank may be off.

To heat your gear, set it on a hot plate.  Smear a tiny bit of oil on the top surface.  When the oil is smoking(300-400

Title: Crank Timing Gear
Post by: GRK on July 22, 2006, 07:48:48 PM

Electric hot plate works Great, set it on and walk away for awile.
Gary

Title: Crank Timing Gear
Post by: flat4 on July 22, 2006, 08:30:45 PM

Thanks fo the input.

So 3 more questions then.

1. How do I get the woodruff key out of the crank?
2.  What sise shoud the crank be?
3. Anyone have an extra crank timing gear?

Title: Crank Timing Gear
Post by: Bruce on July 22, 2006, 08:45:37 PM

You don't normally have to remove the key from the crank.  Did you damage it?

I don't know the correct dia for the crank.  Do you have a stock crank you can measure?  Stock cranks are always correct.

Title: Crank Timing Gear
Post by: flat4 on July 22, 2006, 08:52:56 PM

No sir.  No damage to the key.  I figured it would be easiest to take the crank to a machine shop and have that surface ground/polished to get the distance I need for the timing gear clearance.  But now that the key is in, I don't think it will come back out.

I guess I'll order another set of gears and give it another try.

As a side note, I noticed that my spacer between the timing gear and distributor drive seemed to be just as snug as the crank timing gear when I was mocking it up.  From what I remember from the last assembly, it just slipped on.  Could this be an issue with the crank itself?  I'm using one of those racer spacers.

Unfortunatley I have no stock cranks here.  Anyone take the measurement for me?

   

Title: Crank Timing Gear
Post by: Bruce on July 22, 2006, 11:49:37 PM

Why not just use stock gears?

Title: Crank Timing Gear
Post by: flat4 on July 23, 2006, 10:02:32 AM

Is there any advantage/disadvantage of using stock gears vs. straight cut gears?  I thought the stock gears put a load on the bearings at high RPM.

Title: Crank Timing Gear
Post by: Bruce on July 23, 2006, 10:15:26 AM

Advantage: stock gears always fit
Advantage: stock gears are free
Advantage: stock gears are quiet
Disadvantage: Straight cut gears commonly fit poorly
Disadvantage: Straight cut gears cost you money and don't make you go faster
Disadvantage: Straight cut gears make a silly poser noise, the VW equivalent to a ricer part.

You only need straight cut gears if you are running BB Chevy type springs.  If you use VW size springs, HD singles or duals, stock gears will work fine for you.  Use the double thrust cam bearings.

Title: Crank Timing Gear
Post by: Cameron on July 23, 2006, 12:16:36 PM

flat4,

Never hammer, or press, the timing gear on to the crank. You can actually bend the crank, if you use enough effort. If the gear sticks half way, pull it off and reheat it.  Since you already beat the gear on to your crankshaft, I suggest you measure your crank, and make sure it is still straight.

There is no need to machine the crank to fit the gear. As Bruce mentioned, there have been issues with the aftermarket gears. The gear has the wrong inside diameter, rebore the gear. It should be .002\" smaller than the crank.

 

Title: Crank Timing Gear
Post by: Bruce on July 23, 2006, 01:15:13 PM

Quote

so i put it in a 10 ton press, it went on about half way and crack....
 

Quote

... or press, the timing gear on to the crank. You can actually bend the crank, if you use enough effort.

!!!

Title: Crank Timing Gear
Post by: flat4 on July 23, 2006, 04:25:03 PM

What about something like Erco triple springs?  Will the VW cam/timing gear be enough?  I'm a little worried that something is wrong with the crank, as the racer spacer doesn't fit either.

Title: Crank Timing Gear
Post by: Bruce on July 23, 2006, 11:52:43 PM

I'd say with ERCO triples, you probably should use straight cut gears.

At this point you should check out the crank.  You can lay it in the case with the #1 and #3 bearing supporting it. Then dial indicate the center main, and the pulley end.  Also you need to find out the correct dia of the seat for the gear.  I would use a micrometer, not calipers.

Title: Crank Timing Gear
Post by: flat4 on July 24, 2006, 12:04:46 AM

I'll have to get the old gear off, find a replacement, then do the measurements to find out if there is any damage.  I don't think I was whacking it terribly hard.  I'd hope that the crank would be a little tougher than the strain I may have put on it.

Title: Crank Timing Gear
Post by: Hansk on July 25, 2006, 11:27:49 PM

Quote

This problem has plagued the aftermarket crap manufacturers for years.  It is not that difficult, but some manufacturers can't seem to hit the ID correctly.  You must measure ALL aftermarket straight cut gears.  It is very common for the ID to be too small.  This is what was wrong with your gears.
 

I've seen so many various parts continuously made incorrectly for years. Not just a bad run , the same thing over and over. Why ? because we keep buying them without saying anything , without returning them , without demanding a better product.  Please , what ever you do , don't just buy another set and hope for the best or have them re bored to fit and forget about it. Demand satisfaction from the manufacturer for your original purchase. Hopefully your supplier can help you with this.
(my 2 cents)

Title: Crank Timing Gear
Post by: flat4 on July 26, 2006, 08:59:05 AM

The issue I have is that I bought a mismatched set of parts.  I bought an \"import\" crank, and a brand name gear set.  The last time I used both a brand name crank and gear set, it worked fine.  This time, not so much.  I wouldn't know who to address the issue with, and I'm sure if I added enough heat to the gear (which I probably didn't) it would have worked.  Even with heating the new gear up with a torch it required gentle persuation to slip on to the crank.

Title: Crank Timing Gear
Post by: John W. Kelly on August 01, 2006, 08:35:09 AM

A coffee heater works too. But like Bruce said, some of the aftermarket stuff leaves alot to be desired.