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Pressure Plates. AIR-TECH

Pressure Plates

    Let’s talk about pressure plates; there are all kinds out there. In this article I would like to describe the different types, and styles. One of the biggest problems I see with the air-cooled VW cars is that everything is so interchangeable. Now that is a good thing in most cases, but when you go and buy a part it might not be the right one for the year of the car because someone has put a different year part on the car. An example; You might have bought a pressure plate for a 69 bug only to find out when you installed it, now the clutch doesn’t work and every time you push on the clutch pedal the car makes a horrible sound. That might be because someone has put a 73 trans in the bug and it takes a different pressure plate. It’s a good thing DMV doesn’t make us put down every year part that is on the car, because the title would weigh 3 pounds. So let's look at the types.

 

180mm: These all have a collar in the middle and I see three styles here, 6 spring, 9 spring and full diaphragm.

 

200mm: There are some with collars and some without. There are three styles here, 9 spring, full diaphragm, and three finger diaphragm.

 

210,215,228mm: These are all for the 1972 on busses. These all come without the collar in the middle, and as far as I know are all full diaphragm.

 

Ok, now the important part. You have to match the pressure plate with your flywheel and transmission. There are two types of throwout bearings. Why is this important? Well the type of throw out bearing has to match the type of pressure plate.

 

Let's look at the two different throw out bearings. I will give you the years but as I said in the beginning, you can’t trust that is what you actually have.

 

Early: This is up to 1970. It does not have a guide to ride on. If you have this style then you have to have a pressure plate that has a collar in the middle.

 

Late: This is 1971 and on. It has a guide around the main shaft that the throwout bearing  rides on. This style takes the pressure plate without a collar. If you mismatch here you will have problems.

 

Displaying throwout bearings.png

 

Now you know what to match up. What pressure plate is the best? Well that depends on what you have and are wanting to do with the car. I will list the different ones and share my opinion.

 

6 Spring: Bone stock motor, 36hp or 40hp, bug or ghia. If you have a choice use either the 9 spring or a full diaphragm.

 

9 Spring: Bone stock motor, 36hp, 40hp, 1300, 1500, bug, ghia, bus. Can work on 1600 but would not be my first choice. I prefer the full diaphragm or the three finger diaphragm.

 

Full Diaphragm: Stock motor, or daily driver motor with up to 70hp.

 

3 Finger Diaphragm: Stock motor, or a daily driver big motor with up to 90hp.

 

Aftermarket pressure plates: Most of these are full diaphragm now days. They range from 1700 to 3200. I would use these on a Friday/Saturday night car that is making 150+ horsepower.

 

“So why not just go with the aftermarket one on a motor that makes less then 90hp? It won’t slip and bigger is better right?” You can, but keep this in mind: With more holding load it is harder to push in. In other words, your clutch pedal will be a lot stiffer. “So what? I have a strong leg”. Ok fine, but do you like replacing clutch cables and the hook that is on the pedal assembly? Have you thought about the clutch tube in the tunnel breaking? Have you thought about your wife or girlfriend driving the car? What about the clutch arm in the trans? If you have late model stamp steel clutch pedal, awh yeah, that’s going to break. So think about what you're doing with this car and pick the pressure plate that best suits your needs.

 

Here are a few things that I have seen:

 

Big pressure plate, stock disc- Well you can rip the center out of the stock disc.

 

Big pressure plate, puck style disc- You better have a beefed up trans. If the clutch doesn’t slip you will break the weak link in the trans.

 

Big pressure plate starts slipping soon after installing- It’s usually the “shoe” of the pressure plate is warped now that it has seen a few heat cycles. The fix: Have it reground and not replaced.

 

Guys with hydraulic clutches- Make sure you're not overextending the plate. In other words, going way over it’s breaking over point to release the disc.

 

Installing the pressure plate wrong- You might think, “Really, how the hell can you do that? It can only go on one way. You would have to go way out of your way to screw that up”. Not so true. On 200mm+ flywheels you will notice a step in it where the pressure plate sits. Make sure when you tighten down your pressure plate that it sits down into that step. If you don’t you will cock the pressure plate and have problems.

 

The best way to install a pressure plate is to tighten it down in a star pattern evenly, a little at a time and make sure it is going into the step evenly. Once down, tighten the bolts to 22ftlbs, again in a star pattern. Please use spring washers and not lock washers under the head of the bolts. For those of you wanting to use the mega pressure plates it’s also not a bad idea to upgrade the bolts to 10.9 instead of the 8.8 bolts.


So that’s it. I hope you learned something. Quiz on Tuesday, no pressure.

Published on Wednesday, March 29, 2017 in Air Tech Articles, Tech-Tips. Comments: 0

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