Hampton

My '93 RSA suffered a failure of the dual mass flywheel. This topic has generated interest before, and some questions about engine numbers and build dates. I would like to share my experience.

I was at a DE and was on the pit-in road and, without any prior warning, I heard a loud clanking from my drivetrain/engine. It sounded like two metal hammers in a metal bucket, shaken vigorously. The answer: catastrophic dual mass flywheel failure. I put my car on the trailer and went home, as it was not drivable.

My '93 RSA is May 92 build date, engine number is 62N07081. The old flywheel was one of the early 'Frudenberg ' design.

After much debate and research, I decided to replace it with latest version of dual mass FW and a new clutch. I did not go with a lightweight flywheel because I am considering Club Racing and the single mass FW results in a class upgrade and I want my car to stay in D Stock.

Regards,
Hampton

Randall G.

Very interesting. Arjan B. had information indicating that the LUK DMF wasn't introduced until engine #62N07138, May '92. Your engine build date with failed Freudenberg is consistent with his information.

Missed the LUK by 57 engines ... bummer .

Bill Wagner

Hampton:

Here's a "cut-n-paste" I have about the replacement of the DMF from Freudenberg to LUK:

Engine serial numbers where the LUK dual mass flywheel was used instead of the Freudenberg flywheel began with engine number 62 N 01738. The change took place on May 13, 1992.

Serial number for the early LUK flywheels (maybe even later) is:

964 114 012 02

The information is out of Bruce Anderson's 911 Performance Handbook.

I know nothing about how Porsche numbers their engines, but I would think it would be sequential. With this in mind, it seems odd that the number of your engine has last four digits being 5343 units higher than the change number identified above, and yet it's build date is roughly at the same time the change took place. Also, does the full serial number of the car indicate it's a '93 model??

Be sure and check with your parts supplier that the DMF IS a Luk and not a Freudenberg. A lot of independent suppliers are still selling the Freudenbergs, which I think either Porsche or Freudenberg may have had a "fire sale" on.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Adrian

Dear Bill,
Actually Porsche do not build their engines pass the short stage in sequence. An engine is allocated to a chassis number at this time. Now if that engine happens to be allocated to a Porsche which say ends up at "spezial werks" the engine may not be completed for some months and may get the newest parts. A later engine serial number may continue down the line and get earlier parts.
Now the RSA was a special case. The first RSAs were fitted with 1992 engines despite the fact that were "officially" 1993 VINs (P). They all had M718 applied. RSA production was started in Jan 1992. The engines that were allocated to this production would have been made earlier. There is actuall yno hard data available from Porsche which tracks such things by the way. It is almost impossible to follow anything like this wth any degree of certainty. Remember Porsche delivered the last 1989 Turbo in 1991. I know of at least one 964 which was finally delivered in 1995.
One other thing, "economics". When Porsche introduced a new improved product this did not mean the instant end of the old one. We know that for the ROW 964s that they continued to receive the old DMF and not the new ones. The C4 never received the LUK on the line. Same thing happened with DMEs a few years earlier. The USA versions tended to be given the new stuff first.
Moral of this story: Whilst guides such as TSB engine or VIN number data is useful it is not always accurate. I might point out that what happens at Porsche is pretty standard. We have exactly the same problem with our aircraft. A later aircraft serial number has earlier components serial numbers or mods not installed etc.
Ciao,
Adrian
911C4

Randall G.

Even Bruce Anderson now suspects engine number 62N01738, given on the U.S. bulletin for LUK implementation, is incorrect. The European bulletin (which Arjan B. dug up and supplied to Bruce A.) lists engine number 62N07138. This appears to be the correct number, based on several examples of cars being produced in May of '92 with engine numbers &gt;&gt;62N01738.

It appears there was a typo on the U.S. bulletin (the 7 & 1 being reversed).

Adrian

Dear Randall,
I concur, on all the European language versions I have seen it says 7138. I remember we had a debate on this some time ago. However in the end Porsche admitted that they really did not know 100% either. Arjan sent me some stuff but I also got them from Norway, Germany, Switzerland (AMAG) and a French one if I remember correctly. The European versions I have are all dealer letter headed not TSBs directly like they are in the USA. All the same stuff though,
Ciao,
Adrian
911C4

Bill Wagner

Hmmmmmmmmmm. Looks like someone at Porsche was typing just a little too fast

I think I'll change my cut-n-paste so it says 7138 instead of 1738, but does anyone know if the changeover date (May 13, 1992) is accurate? Based on Hampton's production date and number, I'd be inclined to think it is, but can anyone confirm this???

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Bill Wagner

Hmmmmmmmmmm. Looks like someone at Porsche was typing just a little too fast

I think I'll change my cut-n-paste so it says 7138 instead of 1738, but does anyone know if the changeover date (May 13, 1992) is accurate? Based on Hampton's production date and number, I'd be inclined to think it is, but can anyone confirm this???

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Adrian

Dear Bill,
Changeover dates are from Engineering. Basically this is when the new part is approved for use and installed onto the drawing. Production line implementation dates are something very different. Porsche have and had a policy of using up the old parts first. As I also said many of the 964s leave the production line for different parts all the time. I have to be honest and say I have yet to receive data that anyone received a LUK DMF off the production. The Maint Manual was not updated until 1994. The date of May 13th 1992 is a date I associate with the RS America actually.
However to answer your question, we will never truly know unless we get data from owners who just happen to find a LUK installed and then supply their 964s plate data. Due to the fact that the LUK are quite reliable we could be waiting a long time,
Ciao,
Adrian
911C4

Jim Michaels

The build date on my RSA is May 12, 1992, so I'll try to remember to check the engine # when I get home. Based on information I got several years ago, I had concluded that my RSA (#146) didn't have the LUK DMF. Now I learn that it might have missed having good LUK by only one day. At least it's too late for my car to have *early* flywheel failure.

Hampton

Follow-up to my original post:

Mileage was 40,000 miles.

There were no warning signs that I noted. Although my exhaust system is 'loud', I do listen to my engine/drivetrain and I think I would have noticed. The car has been very reliable and up until this, I considered it bullet-proof. It has been a pleasure to drive/own and can be seen at the <a href="http://www.rsamerica.net" target="_blank">www.rsamerica.net</a> gallery.

I was aware of the potential for the FW to fail, and I was not too surprised. My mechanic considers the FW/clutch a wear item - so be prepared. The replacement flywheel is much more substantial and, a better design according to my mechanic.

The pressure plate was intact and did not have to be replaced.

Cost for parts ( FW, clutch, throw out bearing, guides, bolts, seals, fluids, ......$1365. Labor 17 hours. Plug in your own total cost. Whew! It did hurt!

Regards

Randall G.

Hi Hampton,

FWIW, 17 hours is extremely stiff for replacing the clutch and flywheel .... unless other (substantial) work was performed. For example, my clutch was replaced last year for only $420 labor. That's on the low side, but around 8 hours is a fair number for a C2. The job can be turned around in a single day by a professional shop, so I don't see how they get off charging you 17 hours.

Sorry .... don't mean to be critical or ruin your day, just making a point. <img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" />

Rich W

Very interesting. My RSA is a March 92 build, and when I upgraded to a LWF last year found the original flywheel was a LUK.

Don't know my engine number off the top of my head. I'll poke around and get back.

FWIW, I bought the car with 23k on it, and no record of flywheel replacement prior to my purchase.

Jim Michaels

A LUK DMF in a March '92 RSA is surprizing; unless that was a replacement for an early failure. In a previous post I indicated that my RSA had a May 12, '92 completion date (LUKs were said to have been installed beginning May 13). Thus, my engine number should be somewhere around the beginning LUK install engine #7138 (or 1738). My engine number is 7121. That's 17 before the LUKs were installed with engine # 7138 (if prior info is correct). So the 7138 figure is more likely correct for the LUK install.

Rich W

My engine serial number is 6273. It is certainly possible the Freudenberg flywheel was replaced by the previous owner - I just don't have any record of it. Anyone know if Porsche USA keeps records on that kind of replacement? It would have likely been done under warranty.