High RPMs

[Theo]

I'm a proud first-time Saab owner of a 87 900S 5spd 16val with 134k. When traveling in fifth gear at 70-75 mph the tach reads near 3500 rpm, in third going 35 mph it's near 3000 (similar for all gears and speeds). I admit I haven't have a four banger in awhile, the last was a Neon 5spd with DOHC, very smooth and quick car, but I don't remember the rpms being so high. I've never owned a Euro car. Also, the shift indicator is always telling me to shift up, I think the car would have me drive in 5th in town. Is this normal? If not, has anyone else had this experience? If so, what is the fix?

Theo

[cdaly]

My 92 5spd does 22mph/1000rpm in 5th. That comes out at about 3000rpm at 70mph. At 3500rpm you should be up to 80mph.

Is the clutch slipping? It'll feel a bit like an auto if you floor it in 3rd or so (engine revs up before speed picks up). Test the clutch like this:

Engage 1st gear.
Right foot hard on brake and throttle up to 3000-4000rpm
Slowly lift clutch

This will stall the engine. If the engine keeps running when the clutch is fully up, it's slipping.

[DeLorean]

sounds about right to me. with my SPG, 38 mph in 5th is 2000 RPM's. I shift around 3000 most of the time. the shift light just likes to spout crap. I say remove it

[900t]

When the shift up light tells you to shift, there is little reason to disobey it unless your current mood / traffic conditions disallow it.

Runs off vacuum. Essentially you are pressing the gas too hard and should shift up and therefore use less throttle (thereby increasing vacuum and turning the light off)

[ejenner]

Shift light must be a US thing - My car has no shift light??

[Zelandeth]

Think you'll find the light is there. (Next to the main beam indicator), and if that light's on, a little light will spill into it. Not sure if it's wired in though.

[Theo]

Thanks for the replies; however, I'm more concerned with what I believe to be high RPMs rather than the little light. I just thought some how the two were a result of the same issue.

[GearHead]

Ive gone 25 in first with no shift up light ops:

[Vermont Saab]

Originally Posted by ejenner

Shift light must be a US thing - My car has no shift light??

I think the shift up light was a US thing.

I usually pull the bulb 'cause the shift up light sucks!

[Matthew]

The difference between engine speeds at a specific vehicle speed and gear is principally due to different primary gearing. The gearbox is driven by three parallel chains from the clutch input shaft (effectively coupled to the crankshaft when the clutch is engaged).

Inside the primary gear housing are two sets of sprockets IIRC. The gear ratio of these determine that one car will see 3000RPM at 70MPH, while another will see 3250RPM at 70MPH.

My T16 has Type 6 primaries, which is short gearing (good for 130MPH peak). Alex's T16S has a Type 8 set, which is very long gearing (good for 140MPH+). Most common is a Type 7, but there's also a Type 5 on earlier cars IIRC.

Primary gear sets can be swapped from car to car.

http://www.saabcentral.com/forums/viewtopic.php?p=36008

Originally Posted by Keith

You need to change the primary drive sprockets in the gearbox. You can do this with the gearbox in the car if you remove the front bumper and radiator, and work through the hole between the headlamps. You need to get the front cover off the gearbox that has the front mount attached so you will obviously need to support the whole lot from underneath.
And a decent puller to get the sprockets out of their bearings.

You can tell what primary set is currently in yours from the gearbox number.

GMxx5xx 30:27 ~ 21mph/1krpm in 5th

GMxx6xx 31:26 ~ 23mph/1krpm in 5th

GMxx7xx 32:25 ~ 25mph/1krpm in 5th

GMxx8xx 33:24 ~ 27mph/1krpm in 5th

Those are just very rough indications of speeds, depends on tyre sizes etc.

[Abbott 900]

My T16 must have type 8 as well then, as my car does about 83mph in 5th gear at 3000rpm.

I personally prefer this as a lot of my trips are motorway miles...

[cdaly]

There's also two options for auto boxes. Question there is, what is the benefit of the higher gearing? My 900i auto does 20mph/1krpm in third. Will it pull effectively with the higher ratio? Mind you, it'd be only an extra 2mph/1krpm so it might not be worth the effort...

[MonkeyMan]

Dayum...I don't even hit 3000 until 74-75 in 5th gear!

BEN

[Theo]

Thanks everyone. Sounds like mine is just about right given the age and miles. My wife calls it a beater, I call it vintage (I wanted to make sure I was right).

Theo