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Removing & Installing Crank Gears. AIR-TECH

Removing & Installing Crank Gears

In this article I will explain removing and installing the cam gear and the distributor gear on the crankshaft. If I had a dollar for every crank gear that I have thrown away due to someone taking them off with a hammer and punch I would be writing this article from a sandy beach in the mediterranean instead of from my cluttered desk. Please don’t take the gears off with a hammer and a punch. You will ruin them.

 

Here are a couple of correct ways to take them off. The easiest way is with a vw crank gear puller. You can usually buy one from you favorite vw shop or online. They are not cheap, but work really well. This is what I use.

The other way you can do it is in a press if you have one. You will use a set of jaws around the cam gear then press on the snout of the crank. Make sure you or someone else  is going to catch the crank so that it doesn’t crash down to the floor.

 

If you have a crank stand, great; If you don’t, you can mount your flywheel in a vice and bolt the crank to that. Mount the crank in the flywheel so that  the keyways are straight up. Use a hammer and small punch and drive out the small keyway on the end of the crank. Next, remove the oil deflector. That’s the concave washer behind the keyway. Using a set of spreader pliers, remove the snap ring that holds the gears on. Keep in mind the gears are a press fit. They will not slide off just because you took the snap ring off. This is where I see guys use a hammer and punch to get the gears off. Don’t be one of those people. If you have the VW gear puller, put it on so that you’re pulling on the cam gear. In other words, the jaw of the puller will be between the cam gear and the first large main bearing. You will be pulling both gears off at once. Before you start tightening the puller put some oil on the treads. Now tighten the puller bolt and the gears will pull off without ruining them. If you’re going to use the press then install your press jaws under the cam gear, tighten the jaws just snug. Now walk over to your press and set it up to press on the snout. Make sure that your crank is not going to hit any part of the press as you start pushing on the snout. Again, have your buddy get ready to catch the crank as it pushes through.

 

Now let’s talk about how to put them back on without ruining them. First and foremost, clean everything well. Inspect the teeth of the gears. If you see punch marks or chisel marks on the cam gear then just throw it away. What happens here is it mushrooms one or two of the teeth on the edge. It will not mesh well with the aluminum gear on the cam, causing a bind. Not good. Also look at your brass gear. If the teeth are chewed up that is from guys cramming the dist drive gear in. Also look to see if any of the teeth are folded over. It only makes sense to replace it if it is. Now that everything is clean and ready to go, place your crank back in your crank stand again with the keyways straight up. If your large keyway isn’t installed then install it. Make sure that it’s all the way in and that it’s level. That way the gears will go on easier. Now put oil on the main jurnal for the big main bearing under the gears. Put oil on the inside of that bearing. Gently put that bearing on with the dowel pin hole towards the flywheel.

 

Now let’s set up to put the gears on. I use a hot plate to heat the gears. Go to your tool box and find a large set of pliers big enough to grab the gear. You will be picking up the gears with these pliers to slide onto the crank. You can also grab a brass punch and small hammer (brass not steel). Turn your hot plate on high. Place the cam gear with the bevel towards the hot plate. This is the side we'll be putting towards the bearing you just put on. Now a trick I use is to squirt a couple of drops of oil on the top of the gear. Watch the oil. When the gear is hot enough it will thin out the oil and it will start to spread out over the gear. If you think you’re ready, grab the gear with your pliers and slide it onto the crank. It should slide right on. If it doesn’t, your gear is not hot enough. Place it back on the hot plate. If you get it half way on and it’s starting to grab the crank you can use your brass punch and gently tap it into place. If it doesn’t go gently then stop. Pull the gear back off with your puller and start over. If you have turned the gear blue, you overheated it and yeah, throw it in the trash (once it’s cooled down). Try again with another gear. Once that gear is on then install your gear spacer. There are no sides to this so you can’t screw up here. The opening goes with the key way.

 

Now the brass distributor gear. It’s brass so it does not take much time to heat up. I use the same method with the drops of oil. This gear should just slide on. Try not to use a punch on this gear as its really easy to fold over the teeth. If you find it won’t go on and you know it’s hot enough, you have overheated it and it is now egg shaped. There is no fixing it or making it round again. You can let it cool down and place it with the blue gear, in the trash.

 

Once both gears are on, install your snap ring. Make sure it goes into the groove. I also put the opening of the ring opposite the key way. Not that it matters, I just do. Now you can install you oil deflector. The cone faces the pulley. You do not need to heat this at all. After that, install your small nose main bearing again with the down pin towards the flywheel. Now the small pulley keyway. That’s it, you’ve done it. The first time is a little nerve racking, but once you get the hang of it it's not a big deal.

 

Things to look for while putting your block together that pertain to the crank gear:

You have your crank in the case half and you install your cam, lining up the timing marks. First, you should feel the backlash. You should have just a little. Rotate the crank with your hand and watch your cam. If it jumps out of the case, you might not have any backlash. Let’s say it turns fine but it comes around and gets tight or the cam wants to jump out in a certain spot. That is because someone has taken the gear off with a punch and has mushroomed some teeth and you didn’t spot it. If this happens to you, take the crank out and replace the gear. It will not wear in, it will wear out. Fix the problem. If you find you have no lash on your cam then first try changing the aluminum cam gear if it is a bolt on gear. If not, you will have to change the cam and or the crank gear. Yeah, I know it’s a hassle and costs money. Welcome to engine building.

Published on Friday, June 29, 2018 in Air Tech Articles, Tech-Tips. Comments: 0

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