What is your RPMs at 65 MPH? [Archive] - SaabCentral Forums

: What is your RPMs at 65 MPH?


gruberoliver
31-07-08, 10:38 PM
I have an 88 900 manual...and I recently got a 93 900S with an automatic. Here's my question. It seems the RPMs are high for the automatic. At 65 MPH I am running about 3200 to 3400 rpms. It is shifting through all the gears just fine.

Is this the normal rpms for this speed?

Thanks for the help

TheRedBaron
31-07-08, 11:24 PM
Well, I can't tell you exactly, but the c900 autobox is a three speed, and not geared super long, so that sounds about right.

Matt88S
01-08-08, 01:09 AM
I have an 88 900 manual...and I recently got a 93 900S with an automatic. Here's my question. It seems the RPMs are high for the automatic. At 65 MPH I am running about 3200 to 3400 rpms. It is shifting through all the gears just fine.

Is this the normal rpms for this speed?

Thanks for the help

It's a three (3) speed transmission with no overdrive and is geared for days of old when the national speed limit was 55mph. Your RPM's are normal. They make great city runabouts but not so great for the highway.

Cheers!

TooMany2cvs
01-08-08, 02:29 AM
It's a three (3) speed transmission with no overdrive and is geared for days of old when the national speed limit was 55mph.

Ummm, the autobox c900 wasn't designed solely for the US - it was sold in many other countries with much higher limits than that. My ol' CX automatic was geared roughly the same, and wasn't even sold in Leftpondia.

Cutshaw
01-08-08, 08:13 AM
Ummm, the autobox c900 wasn't designed solely for the US - it was sold in many other countries with much higher limits than that. My ol' CX automatic was geared roughly the same, and wasn't even sold in Leftpondia.
Yeah, from what I've read the AT was only 3 speed because of space constraints due to the 900 being basically an updated 99.

jetman
01-08-08, 08:41 AM
Other than the fuel consumption, the engine can take the RPM's quite well though.

TooMany2cvs
01-08-08, 12:25 PM
Yeah, from what I've read the AT was only 3 speed because of space constraints due to the 900 being basically an updated 99.

I think it's more a case of there just weren't 4-speeders available back then. 3spd was the standard in the late '70s, early '80s. Certainly the autobox Citroen chose to put into the CX in '82 was a ZF 3spd.

16saabs
01-08-08, 03:37 PM
there is'nt room for a 4 th gear auto with the front wheel drive, as mentioned above due to the lack of space in the box with all the other parts involved,
3rd in auto is basically equivalent to 4 th in a manual and then you have the 5 th gear which gives extra top end mph and mpg. you will be about 5mls a uk gallon worse off with the auto, but they all rev to 6000 before sensor trips it out, so revs do not hurt it, it's just doing a bit more revs than a manual for same speeds.
some might say( here goes an answer session??:cheesy: ) that a auto that has done a 100,000 miles has done more engine revolutions/miles than a manual, but it probably is hardly anything over all, as the auto does not go through the change up 1-3 as an manual 1-5??. answers please on a post card to, Issac Hunt at Richard Head Road, ScuntHORPE WI1,lIE:) :)

900t
01-08-08, 07:40 PM
Ummm, the autobox c900 wasn't designed solely for the US - it was sold in many other countries with much higher limits than that. My ol' CX automatic was geared roughly the same, and wasn't even sold in Leftpondia.

As well as some American muscle-cars of the time were being geared even worse, like 80 miles per hour at redline of 5500-6000 r/min :lol: Of course that was when you bought the "drag racer" axle ratio, something like a 4,56 :lol:

TooMany there were many CX's sold in the US, they were imported unofficially but PSA HATED it because they were trying to sell 505's that nobody wanted and there were people lining up to pay more than double that for Cx's.

In other words my point is "supra-tall" overdrive type gearings that give you 2000 or less r/min at a cruising speed around 70 mi/h is a very recent phenomenon starting in the early Eighties from US automakers, also spurred on by the widespread adoption of 5-speed manual boxes around the world around the era.

The only real penalty with the C900 autobox is fuel economy... I've actually just bought one of these, I haven't driven it but I am curious to see how it is. Then I will swap :D

I don't see why there is no room in the C900 autobox, remember the great thing about autobox is they are planetary, so we can just invent gears out of nothing by braking it here and spinning it there :lol:

Matt88S
01-08-08, 08:47 PM
Ummm, the autobox c900 wasn't designed solely for the US - it was sold in many other countries with much higher limits than that. My ol' CX automatic was geared roughly the same, and wasn't even sold in Leftpondia.

And where did I say it was? ;)

gruberoliver
01-08-08, 10:05 PM
Thanks for all the responses...I guess you guys are right. You get use to more modern transmissions with overdrive and such and kind of forget that just a few short years a 3 speed auto was about all there was. Way back in the day tachometers were rare on big Detroit V-8s so I guess you really had no idea what the rpms were. You just put in the 8-track and cruised paying 65 cents a gallon for gas.