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Old 03-20-2018, 07:05 AM   #1 (permalink)
Hic
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VW 1.6TD Engine Off Coasting

The service manual for my MK2 1.6TD VW states that damage may occur if towing on the drive wheels at speeds greater than 80kph/50mph. Does this mean engine off coasting above 80kph is harmful for the transmission? I thought only automatic transmissions see damage from engine off coasting. Is this transmission in particular incompatible with high speed engine off coasting? Or is engine off coasting normally not used at these speeds? I've pulsed and glided regularly between 70~110kph on this car for almost 2 years now...should I be concerned about transmission damage?

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Old 03-20-2018, 03:00 PM   #2 (permalink)
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My guess is that the manual is in error, or didn't differentiate between the manual and automatic. However, don't hold me responsible for any damage that occurs.
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Old 03-20-2018, 04:05 PM   #3 (permalink)
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i think it's rather for the safety of towing a car, as towing a car is generally more unstable at higher speeds. A manual box shouldnt give a damn
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Old 03-20-2018, 04:20 PM   #4 (permalink)
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Or maybe it means that towing has not been tested above 80kph, so VW only ensures the safety up to that speed?
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Old 03-21-2018, 10:13 PM   #5 (permalink)
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Mmm they specifically say it could cause damage to the gearbox. They also mentioned that automatics should not be towed on the drive wheels at all, so the advice for towing at 50mph/80kph+ is intended for manual gearboxes.

There is no restriction of towing speed mentioned when towing on the rear wheels, so this is related to the longevity of the gearbox, rather than the safety of towing at highway speeds (or whether they've tested it to ensure).
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Old 03-22-2018, 02:35 AM   #6 (permalink)
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I would be more concerned about shutting off your turbo engine hot, with the turbo spinning wild after your pulse
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Old 03-22-2018, 10:37 AM   #7 (permalink)
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Quote:
Originally Posted by iikhod View Post
I would be more concerned about shutting off your turbo engine hot, with the turbo spinning wild after your pulse
X2. With my diesel Golf I only E-On coast (which I do a lot). With the key off you lose not only oil circulation to the turbo but also airbags, ABS, power steering and eventually brake boost, and it messes up my ScanGuage. In my experience you will not hurt your transmission from coasting briefly, even at higher speeds. Towing a car could conceivably be done over great distances and time, which may eventually do damage.
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The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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Old 03-22-2018, 11:23 PM   #8 (permalink)
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Quote:
Originally Posted by COcyclist View Post
X2. With my diesel Golf I only E-On coast (which I do a lot). With the key off you lose not only oil circulation to the turbo but also airbags, ABS, power steering and eventually brake boost, and it messes up my ScanGuage. In my experience you will not hurt your transmission from coasting briefly, even at higher speeds. Towing a car could conceivably be done over great distances and time, which may eventually do damage.
Hmm, I want to keep this thread on topic to the question of whether the transmission will see harm.
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Old 03-23-2018, 09:38 AM   #9 (permalink)
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If EOC at those speeds would harm your gearbox, probably would have broken something by now.
How much you save fuel with EOC compared to coasting with the engine running? Just out of curiosity.
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Old 03-23-2018, 09:53 AM   #10 (permalink)
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Quote:
Originally Posted by iikhod View Post
If EOC at those speeds would harm your gearbox, probably would have broken something by now.
How much you save fuel with EOC compared to coasting with the engine running? Just out of curiosity.
The damage may be insignificant over the short term. It's like saying shutting off after a pulse doesn't hurt the turbo because my turbo is still fine.

I'm not sure how much the savings are.


Last edited by Hic; 03-23-2018 at 10:02 AM..
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