Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)
Lyn

Dual Mass Flywheel versus Lightweight Flywheel

Recommended Posts

Have any of you tried a lightweight flywheel in your 3.6 or 3.8 997s? I know that the change causes transmission "rattle" noise at idle speeds, but I'm interested on the effect on drivability. Does the lighter flywheel make it more difficult to drive smoothly at low speeds, or does the quicker throttle response offset the negatives??

Share this post


Link to post
Share on other sites

Have any of you tried a lightweight flywheel in your 3.6 or 3.8 997s? I know that the change causes transmission "rattle" noise at idle speeds, but I'm interested on the effect on drivability. Does the lighter flywheel make it more difficult to drive smoothly at low speeds, or does the quicker throttle response offset the negatives??

You also need to do a search on problems associated with the use of single mass flywheels on these engines. Porsche even release a tech bulletin about not using them due to loss of torsional and harmonic dampening, which is what the dual mass is there for. Some engine builders will not use them unless the engine is first properly rebalanced. I know someone will chime in and tell you that they have had one for years and not had problems, but I can assure you that is not always the case, and the results can be disasterous.

This is what happened to a 3.6 X51 engine that was not rebalanced before using a light weight single mass flywheel, if you want to read more about it, start here:

http://www.flat6innovations.com/index.php/broken-crank

dscf4881.jpg

  • Upvote 1

Share this post


Link to post
Share on other sites

JFP is spot on. Do not replace your dual mass flywheel. The harmonic dampening it provides is key....and a potential recipe for a very expensive disaster if you remove it.

Also, I previously owned a 3.6L manual transmission and never noticed a rattle at idle. Are you sure this is the dual mass flywheel causing the noise?

Share this post


Link to post
Share on other sites

JFP is spot on. Do not replace your dual mass flywheel. The harmonic dampening it provides is key....and a potential recipe for a very expensive disaster if you remove it.

Also, I previously owned a 3.6L manual transmission and never noticed a rattle at idle. Are you sure this is the dual mass flywheel causing the noise?

I think he is referring to the rattle and noise you get after switching to a single mass lightweight flywheel, which is a common complaint, and an indication of the loss of dampening.

Share this post


Link to post
Share on other sites

Thx to all for stepping in with your knowlege and comments. That's what the Forum is for and I really appreciate the collective input.

Share this post


Link to post
Share on other sites

Continuing from JFP's post above...

"...Due to this I feel that adding a lightweight flywheel to any existing engine is not a wise decision, and that they should only be added when the entire rotating mass can be balanced and indexed to accomodate the lightweight unit. This means engine disassembly, so I'd only add one of these when doing one of our performance upgrades so the entire assembly can be precisely balanced." - Jake Raby from http://www.flat6innovations.com/index.php/broken-crank

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.