911 flywheel question

futuresoptions · 07-19-2007, 03:20 PM

Just a quick question in reference to a 77' 911 2.7. I have never dropped my engine before, but sometime in the near future I will need to in order to replace the flywheel. Now on everyother vehicle I have owned the ring gear which I believe are the teeth that the starter engages on the flywheel to turn the engine are located on the outside edge of the flywheel no? I was looking into buying a new flywheel for the change out but the person that I am trying to order from is telling me that these teeth "ring gear are bolted to the pressure plate on a 911 and then the pressure plate is bolted to the flywheel. Does this even sound right? I have never heard of a flywheel that didn't have the teeth mounted to it.

Thanks in advance

9elf · 07-19-2007, 05:42 PM

Yes mate, that's right.

The ring gear is not part of the flywheel. It's bolted on.

Here is the flywheel with the pressure plate and ring gear removed.

Walt Fricke · 07-19-2007, 07:45 PM

Right - bolts go through the ring gear piece, through the pressure plate, and end up in the 9 holes you see in the nice picture.

What makes you think you need to replace the flywheel? Because the clutch is slipping? If you are cheap and not risk averse and do the work yourself the odds aren't too bad that you can get by for at least a reasonable length of time with just replacing the clutch disk - that is, if you haven't been driving the car for too long with a slipping disk. Otherwise you are in for replacing the flywheel, the clutch disk, and the pressure plate. And at that point, the throwout bearing as well for good measure.

The only thing you should not have to replace is the ring gear, which really does look just like a ring with teeth.

Walt Fricke

9elf · 07-19-2007, 08:05 PM

If, as Walt Fricke says, you don't need to remove and then replace the 6 flywheel bolts, then that is the way to go.

The flywheel bolts are a one use item that are probably loctited in. They have a very shallow head so you need to keep the socket straight. The 6 bolt crank bolts need a lot of torque and can be a challenge to remove. Obviously not impossible, but a potential mini project within a project.

Also you may be surprised at how much 6 bolts can cost.

You will need something like this for the bolts.

barney911rs · barney911rs's Garage

Walt gives very good advice. I just had to recently replace my flywheel, pressure plate and clutch disc. If you need to do this, PM me and I'll get you the info for the place I bought them from. I was very happy with the products when they arrived and the prices. I told them what I was looking for, and they put together a package that met my needs. I'm sure they can do the same for you.

futuresoptions · 07-20-2007, 01:19 AM

Great guys thanks alot. I will probably need to replace ring gear soon,
PO stripped the teeth in mine, the new high torque starter I put in is catching fine, but I figure with time it will wear the teeth down on the new starter if I don't change out ring gear. Once again thanks.

futuresoptions · 07-20-2007, 01:22 AM

One question though. I have seen some flywheels on evil bay that have the teeth on the fly wheel and are shown for this year model. Is this a conversion flywheel that I have seen around?

Walt Fricke · 07-20-2007, 11:28 AM

Futures

The flywheel you want for your 2.7 looks just like the one in the picture. So if your problem is the ring gear, pull the engine, replace the ring gear, put a little tiny dab of grease in the pilot bearing and on the mainshaft splines, and put the engine back in. You can do it all in one weekend. One day if you hustle and are all prepared, especially if you have a strong friend or two to assist. With experience you can do something like this in 4 hours or so by yourself.

You might consider removing the starter from time to time to see how its teeth are doing before going in there. The partial stripping of the ring gear may do as you fear, but it may not. I assume that only the tips of the ring's teeth are damaged, and you don't have full teeth missing in action. And that you inspected the ring gear while you had the starter out for replacing.

Forget about e-bay as a source of technical information - it has just led you astray. You don't need a "conversion" flywheel for a 2.7 engine. If you want to run a 901 gear box (and you should not want to do that) with a 2.7, you just install the 901 flywheel (which does have the ring gear cut into it) and clutch assembly. Both have the same 6 bolt pattern you see in the picture. If a guy wanted to run the 901 with a 3.0 or 3.2 engine, then he might be getting into "conversion flywheel" territory, since those have 9 bolt flywheels to match their 9 bolt crankshafts, and you can't just put the early flywheel on.

Walt Fricke

p.s. to 9Elf - I torque my 6 bolt flywheels to 150 lbs/ft. You need to do that with an 8,000 rpm race engine to keep them from backing out, though it is overkill for a stock motor. I used to use a jack stand to steady the head of the torque wrench so the long 12 point socket doesn't wobble around. (After a while I went and bought a much shorter socket tool to make this easier). So far I have avoided the project within a project, but it sure is on my mind every time I touch these things.

Superman · 07-20-2007, 11:57 AM

I'm a notorious cheapskate, and I do not replace items that don't need replacing. Having said that, I look clutch parts over carefully each time I have the engine out. I sometimes show them to JW, and I listen CAREFULLY to his advice.

He says that certain parts are more stressed when the disk is a bit worn. I recently had my engine out and wanted to replace the flywheel (it was either not balanced or not straight), so I showed him parts like the TOB fork. He said it was not worn too much and not cracking, but he suggested I install a new disk. He said the new disk will cause the for to work much less hard. He was right. My clutch pedal is MUCH lighter now, even though the old disk was not entirely worn out. I did not replace the TOB. It was working fine and rotating smoothly. I did not replace the pressure plate. John says Sachs pressure plates tend to be reliably balanced. More so than flywheels. I also replaced the cable. Just because. I removed, cleaned and regreased the pilot bearing.

futuresoptions · 07-20-2007, 03:12 PM

Thanks for the Perfect post Walt. You have helped me out more than you know.... I just never heard of a ring gear not attached to the flywheel. You have laid my doubt to rest and thank you. I will order a new ring gear and if wear on the flywheel is too bad then I will also replace it. I will probably as good measure replace the pilot bearing, throw out bearing and clutch disc if I have to bother with removing the engine. Thanks Superman, and thanks guys for the help it is appreciated.