Re: freewheeling - Saab Vintage Models Bulletin Board - Saabnet.com
The banner above is an advertisment - if it asks you to download software, please ignore.
Site News -

[General | Members | C900 | 9000 | NG900 & OG93 | 93 | 95 | NG95 | 99 | Sonett | Vintage Models | Clubs | Other Cars | FAQs | Gifts | Member Photo Galleries | Member Directory | Classifieds | Manuals | *Buddy Registry | *Mileage Registry | Polls | What's New | Raffle | Photo of the Month | Sponsors]

Vintage Models Bulletin Board
1950-1966 [Subscribe to Daily Digest]
(Search Author's Posts: e.g. Keyword:username)*Members Only


[Main Vintage Models Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: freewheeling
Like This Post: - Subscribe to Daily Digest for this Bulletin Board
Posted by spiv (more from spiv) on Sat, 16 Oct 2004 19:56:24 Share Post by Email
In Reply to: freewheeling, jpNH, Sat, 16 Oct 2004 15:26:17
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup

When freewheeling is active, it allows car speed to exceed engine speed. With most cars, if you take your foot off the accelerator while going down a hill, engine braking will hold down car speed. In a vintage Saab with the freewheel active, the engine speed will drop off to idle, while the car coasts along freely.

If that's not clear, think about riding a bicycle. When you're going up a hill, you turn the pedals and the drive wheel turns in step with them. But when you go downhill, you can hold the pedals still and the drive wheel can still turn without moving the pedals. This is because there's a freewheel mechanism in the wheel hub, and it does basically the same as the freewheel hub in your Saab's transaxle.

What are the advantages? Well, freewheel originated when Saabs were powered by two-stroke engines that were lubricated by oil mixed with the gasoline. Without freewheel, descending a steep hill with your foot off the accelerator could cause the engine to turn at fairly high speed with the throttle closed. No throttle = no fuel = no lubricating oil = seized engine. So, Saab incorporated the freewheel mechanism, allowing the engine to slow down to idle while the car rolled freely.

Freewheel wasn't really necessary on the later V4-powered cars, but Saab kept it anyway (it was even on the first 99 models, in fact.) Why? Well, it does have a few other advantages:

-- Fuel economy is improved a bit because you can coast whenever you want, simply by lifting your foot off the accelerator.

-- The interior is quieter because the engine drops off to idle whenever it isn't actually working.

-- You can downshift without using the clutch: Just lift your foot off the accelerator and, as the car's speed drops, move the lever into the next lower gear. This is a big convenience in around-town driving, and can be a real plus in competition driving as well -- no fancy heel-and-toeing required to match revs on downshifts!

So if freewheel had these advantages, why did Saab drop it? Several possible reasons:

-- It could be damaged if the driver didn't understand how to use it. You have to bring the car to a complete stop before engaging or disengaging it; if you fail to do so, the teeth in the locking sleeve can be sheared off.

-- It's a bit fragile if abused: the older 6-roller hub is supposedly pretty robust, but the later 10-roller hub can break if the driver brings up engine speed too abruptly and slams it into engagement.

-- It could create a scary situation for a driver unfamiliar with it, because there's no engine braking as with a normal car. This doesn't affect just timid novice drivers, either! I belong to a track-driving club, and when I was passing the exam for membership, my instructor offered to take a few laps in my Sonett with me riding along, so he could "show me how to drive better." There was one corner where, in his race-prepared VW Rabbit, he liked to lift off at the apex and let engine braking take the car onto the proper line to exit the turn. When he tried the same thing in my Sonett, of course there was no engine braking, and he found himself barely able to escape going off! I was impressed that he didn't scream, although his eyes got really big...

posted by 68.13.13...


Posts in this Thread:
Alert me when someone posts in this thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup
Post a Followup

No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.

Name: Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
E-Mail: (Optional)
Re-Enter E-Mail: (Confidential & Secure - Not revealed to other users!)
Note: Please check your spam folder for BB responses.

Subject:

Posting rules are simple - No for sale/wanted ads may be posted here - use the site classifieds.
You may not cross-post your message to multiple BBs.
Not permitted: political/religious topics and being disrespectful (personal attacks, insults, etc...).
Site Members do not see any red text, inline ad links, bottom of page anchor ads, box ads, or anti-spam check.

Message: (please no for sale/wanted classifieds - post those in the Saabnet.com Classifieds)
Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).


Links are now automatically made active, no need for any special code (or use the Option Link field below) - don't put links in () or end with a '.'
To add inline images to your post above, use [img]http://www.domain.com/img.jpg[endimg] (or use the Optional Image Link field below).

Optional Link: (e.g. http://www.saabnet.com/)
Link Title: (Optional)
Optional Photo/Image Link: (e.g. http://www.saabnet.com/img.jpg)
Photo/Image to Upload: (Please be patient while file uploads)





StateOfNine.com
SaabClub.com
Jak Stoll Performance
M Car Covers
Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2024 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]

Random Saabnet.com Member Gallery Photos (Click Image)

This is a moderated bulletin board - Posting is a privilege, not a right. Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY. Classifieds are to be listed in The Saab Network Classifieds pages. This is a problem solving forum for over 250,000 Saab owners, so expect to see problems discussed here even though our cars are generally very reliable. This is not an anything goes type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the Saabnet.com Mission and Purpose Page. Please remember that you are not anonymous. Site Contact | Site Donations | Other Sites by SP - Poverty2Prosperity.org | Run Club Menlo Park | ScreenBot



Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all the Site Membership Benefits!