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Geof136
Samba Member
Joined: May 08, 2019
Posts: 8
Location: Fairfield
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 Posted: Sun Dec 01, 2019 2:11 pm Post subject: RPM/torque |
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Hello fellows,
Can some please tell if my 1990 Vanagon Carat auto is running only at 60mph at 4000rpm? Is this normal? Am I losing some torque in the transmission? Any answers would be great appreciated. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Sun Dec 01, 2019 3:49 pm Post subject: Re: RPM/torque |
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| If memory serves me, you should be running 4000 rpms at 70mph or so. |
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jimf909 
Samba Member
Joined: April 03, 2014
Posts: 7466
Location: WA/ID
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| Posted: Sun Dec 01, 2019 4:01 pm Post subject: Re: RPM/torque |
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There are a good number of data points in the threads below. A key factor is your tire size (not wheel size as a number of folks mention).
Factors to consider:
- Is your speedo accurate (most read 3-5 mph above actual speed)? Confirm actual speed using a GPS.
- Tire size: stock tire sizes for 14” wheels are about 25.7” in diameter. If you have larger tires your rpm will decline for a given rpm.
- An unlikely scenario where your R&P or gearing was changed.
https://www.thesamba.com/vw/forum/viewtopic.php?t=371734
20 pages of various AT R&P considerations here too...
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
_________________
- Jim
| Abscate wrote: |
Do not get killed, do not kill others.
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Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.
Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
Last edited by jimf909 on Tue Dec 03, 2019 12:26 am; edited 1 time in total |
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Geof136
Samba Member
Joined: May 08, 2019
Posts: 8
Location: Fairfield
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| Posted: Sun Dec 01, 2019 6:09 pm Post subject: Re: RPM/torque |
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Thanks fellowships, I changed the size of my tires
and that explains the difference on speed in relation to the RPM. |
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Steve M.
Samba Member
Joined: July 30, 2013
Posts: 6829
Location: Fort Lauderdale, Fl.
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| Posted: Sun Dec 01, 2019 6:32 pm Post subject: Re: RPM/torque |
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Try using a GPS Speedometer App on a Smartphone to check your speedometer.
4000rpm gives me 69-70mph on 225/7- R-16's
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There are seven days in a week. Someday is not one of them. |
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E1
Samba Member
Joined: January 21, 2013
Posts: 6545
Location: Westfalia, Earth
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| Posted: Sun Dec 01, 2019 8:38 pm Post subject: Re: RPM/torque |
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| Geof136 wrote: |
Thanks fellowships, I changed the size of my tires
and that explains the difference on speed in relation to the RPM. |
To what size?
Both our vans were consistent in terms of intermittently using stock 25.6" tires and also 215/65R/16s which are 27".
Stock speedos read high by design, not by a given mph but by a given percentage. When we showed 55 on small tires we were going about 52.
The bigger tires make the speedo very close to accurate, but low by a mph or two when showing 55.
I use the "Your speed is" signs every time we pass one but have found them to have slight variances of 1-2 mph also. The faster you're going, the more accurate it is to use them as gauges to compare against.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman |
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