starter ring failure twice in 3 weeks. HELP!!
 

Hi everyone. I'm looking for some trouble shooting advise. I installed a 3.6 VRAM in my SC this winter. I replaced everything except the starter (SACHS power clutch kit, starter ring, flywheel). Right from the beginning there was a banging noise when starting. After 2 weeks the banging got worse and suddenly the starter just spun on it's own. I took the starter out and noticed 10+ teeth missing on the ring. Searching here, I came to the conclusion that the old starter was the culprit. So, I ordered a new high torque starter and ring from our host. This weekend the same thing happened again. What am I doing wrong? Am I supposed to shim the starter and if so what is the procedure? Am I just getting a bad batch of starter rings? Do I need a starter with support on the back side to handle the extra compression of this engine?
Suggestions anyone?

This happened to me. It was that the ring gear was not seating on the Sachs power clutch. I had to tap it down with a small brass hammer(you could use a piece of wood and tap with hammer). Never had a problem untill I installed power pressure plate or I was just lucky before.
Also, use OEM starter ring.

When I installed the ring, I first put it in the oven and it slipped right over. I then made sure it was bottomed out on the pressure plate. I'll definitely take some measurements when I drop the drive-train again. Here's a pic of my disaster.

http://forums.pelicanparts.com/uploa...1339451190.jpg

http://forums.pelicanparts.com/uploa...1339451226.jpg

6 mm I guess. 3.6 ring gear sits 36 mm from engine 3..2 front. Rg surface is only 30 mm. Dan.

Mixing the different starters, ring gears and transmission isn,t simple, so many fifferent sizes. Measure carefully.
Dan

Many years ago ('92), I put a 964 3.6 motor in my '80SC. Back then there weren't conversion flywheels available. I used an '89 Carrera4 flywheel and redrilled it to take a 915 pressure plate and clutch. Has worked perfect lo these 20 years! Could the dimensions of the conversion flywheel be enough different to contribute to your problem? Two years ago, my starter solenoid began to fail, so I replaced it with the mini hi torque starter w/no shim (the $125 or so Ebay one) and everything is still working perfectly. Just my $.02

This is the flywheel I redrilled for a 915 PP. Back then, seemed to be my only option.
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=964-102-239-00-M260&catalog_description=Flywheel%2C%20%39%31%31%2 0Carrera%20%34%20%28%31%39%38%39%2D%39%30%29%2C%20 Each%20

If I recall there is a step in the ring gear Could you have installed it backwards??

Ignoring the electrical / grounds angle for a minute, I think due to your engine swap, you should verify with some measurements like i did in my post #7 and 8 over on my post that you replied to. http://forums.pelicanparts.com/porsche-911-technical-forum/683035-grinding-starter-still-could-use-some-guesses.html#post6800598

Use a vernier caliper and verify the depth of the ring from the starter mounting face versus how far your starter extends when it's energized on the floor with jumper cables from a battery.
My condolences for having to perform another drop...

I agree, I was talking to Brett at Kennedy and he said to verify run out as well as your suggestions. He also had another valid point about timing. Once it's running again I should check start up timing. Too much advance can cause kick back. Another possibility that my friend/mechanic suggested was using too much heat when installing the ring may have caused the teeth to go brittle. I put the ring in my oven at 400 deg. He seems to think no more than 250deg. He also noted that when teeth get ground off they usually don't completely shear off like mine did. This brings me back to my original theory that we're dealing with a bad batch of starter rings.

http://forums.pelicanparts.com/uploa...1339547387.jpg
http://forums.pelicanparts.com/uploa...1339547420.jpg

My $.02.. I've installed many a ring gear on many different vehicles over the years(30+), including P-cars.. I've always laid the new ring gear on the flywheel and heated it with a torch until it drops into place.. I have never 'helped' into place with a hammer, a block of wood or whatever.. By doing this you will distort the ring gear and cause all kinds of problems.. I have seen bad runs of ring gears. Also take your measurements as referred to previously. When you start 'mixing/matching' parts anything can happen..I hope this helps.. When your problem is resolved, please share the results with us, I'm sure this is not the first time this has happened.. I don't think timing is a contributing factor..

UPDATED 11-16-2012 - (search my posts on other threads for more...)

- Kenedy Engineering (KEP) says that Bosch had a thin nose bearing & it breaks on engine kickbacks - then the pinion goes out of tolerance & chews

- I found that was exactly the problem - the Bosch hi-torq starter was the definite cause -

I am switching to an IMI HiTorque - on KEP's advice - from Pelican, number is 101N, and IMI says it does NOT require shims

meanwhile - the ring gear CAN BE REPLACED by RIMCO - $130 - just got mine back today


i had a nearly identical problem with an older style 901 flywheel in a 914-6

except the ring gear is machined as a part of the FW ($300-$450)- brand new from our host only 5K miles ago

- teeth sheared off like above

same thing happened to the previous new FW in about the same length of time

i am using a hi-torque 1.5hp Bosch starter i got from Stodddard some years back, which was new when it went together with the first new FW that it chewed up





.

I was told that a high torque starter is actually easier on the teeth since it will engage first before it starts spinning and it spins a little slower than the original style. My buddy has the same setup done 10 years ago with a high torque starter, etc. and has had no problem at all with the ring teeth.

I agree with the above poster. Do not force the ring in place I hang it from mechanics wire heat it with a mapp torch then using welders gloves drop it in place.

can't say i ever needed to heat a ring gear to install it on a pressure plate. a couple of light taps with a plastic hammer and they seated just fine.

John, have you ever run into this problem before? Maybe heating it up does make the metal more brittle. I did heat both rings up in the oven at 400+deg. What are your thoughts?

you can see the heat treated blue/brown area toward the teeth, so it's already been done a lot hotter than your oven @400 degrees. maybe there's just is a bad batch of them and they're brittle. i've never seen that particular problem and hope i never do. normal wear is the teeth get chewed on their sides and get more pointed. if the distributor belt breaks, the engine can fire and run backwards, fighting the starter.

If the distributor belt is broken would the engine run rough or not at all? The reason I ask is I was 3 hours away from home on Sunday when the teeth tore out. I managed to jump/push start it with help from strangers at the gas station. I then drove 3 hours on the highway with the engine running perfect.

When my 964 3.6 broke a dizzy belt, I didn't realize it for a couple of weeks! Finally noticed the engine had a knock/rattle under heavy load, kinda like a spark knock with low octane fuel. Under ordinary use, seemed to run almost normal. Just pop off your dizzy caps and check!

I just took the two distributor caps off and the belt is fine.

Well, I finally got around to removing the drive-train again. The second ring gear is torn apart just like the first one (see pics below). This ring was used with a new high torque starter, so obviously my old starter was just fine. Before the second ring gear failed everything sounded and ran perfectly. There was no abnormal sound or anything else that would concern me. I used a red marker to indicate where the ring gear is aligned with the bell housing. Then once I separated the tranny from the engine, I reattached the starter and energized it. The gear is lined up perfectly. With the explosive damage of the ring gears I can only come up with one conclusion, which is, the ring gears are brittle. Now I don`t know what to do. :confused:

Check out the pieces of teeth lying in the opening
http://forums.pelicanparts.com/uploa...1340072933.jpg


http://forums.pelicanparts.com/uploa...1340073213.jpg


http://forums.pelicanparts.com/uploa...1340073251.jpg


http://forums.pelicanparts.com/uploa...1340073286.jpg