UKSaabs

Hi guys, just looking for a second opinion on this one please, my speedo failed on the way from York to London the other day, and already I have the symptoms of trying to stall when coming to a halt, and a decrease in boost.
Fortunately kept some tools in my boot, so have managed to get the drive gear out, my findings are as follows:
Transducer is fine, speedo registers both with and without drive gear on
Drive gear looks in depressingly good nick. No obvious signs of wear, missing teeth etc. Has anyone got a pic of either a new one or a knackered one for comparison?
Although the diff is full of oil and I couldn't see in the hole that the drive gear came out of, I stuck my finger in and it doesn't feel all that good. In fact it felt kinda mangled in there.

Now I know that MY96 cars were supposed to be weak in that respect, and although mine was registered in Oct96, I noticed an M97 label on the inner wing yesterday. Whether that has any bearing on this I don't know.

One final point to note, my diff has always been a bit grumbly when accelerating hard, is it possible that diff wear could have led to the demise of the metal speedo drive?

Cheers
Andy

I'm wondering if you have two issues here ... stalling = possible idle control valve problem. Speedo failure and decrease in boost - possibly an ABS controller fault, I think the speedo is fed from one of the wheel sensors on the later models (yours being a MY97 would be in this category)

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'98 9000 2.3T CSE, stage 3
'04 9-5 Aero manual, stage 3
'08 Jaguar XFR

Its an internal gearbox failure, common on the 1996 model year for some reason. Requires a complete gearbox and removal to fix it. Easier to just get another gearbox and swap it out. The teeth on the transducer should be square topped and not sharp and pointy for reference.

Car will only give you restricted boost as it thinks you are in 1st gear and the stalling will get progressively worse for a while then it should get over it. Dipping the clutch a bit earlier than usual to disengage the gearbox should help you, if it does stall you can just rolling bump it again.

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2005 Ford Fucos 1.5TDCi Wagon
2005 9-5 Aero with all the options.

Stalling when coming to a stop is a classic symptom of speedo failure on the 9000. The speed signal is generated by the speed sensor in the gearbox on all 9000s. The 9000 never used the ABS system for the main speed signal like later models did.

As Paul says, if the driven gear looks OK (and is not slipping on the spindle) and spinning it by hand generates a speed signal then the drive-gear on the diff is at fault. At this stage it doesn't matter much whether or not the diff itself is knackered or whether that caused the problem. The diff has to come out to replace either part and this requires complete disassembly of the gearbox - diff removal is just about the final step of dismantling the gearbox, unfortunately.

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That's fine guys, just as expected, info on drive gear teeth was excellent, mine are indeed still square topped. Now all I need is a good 3.81 box and some slightly warmer weather....

Thanks

There is a working 3.61 box in my back garden but its unlikely I will have another 9000 so its surplus to my requirements.

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2005 Ford Fucos 1.5TDCi Wagon
2005 9-5 Aero with all the options.

You are unlikely to find a 3.81 gearbox for a 9000. I had one some years ago, having had a 3.81:1 final drive fitted during a gearbox rebuild when the 4.05:1 FD I had fitted previously exploded. The 3.81:1 was quite a nice compromise between 4.05:1 and 3.61:1 for track driving on a Stage 3 Aero but when that exploded too I ended up back at 3.61:1, which I quite liked in the Aero.

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This happened to me.
When I stripped the gearbox I never found a trace of the drive gear - must have got mashed up by rest of the gears

Rebuild was going OK until the garage roof leaked above it.....

The gearbox in mine was, I think a 4,05:1. been replaced by a previous owner. No wonder I thought it was rapid out of the blocks!

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Vita est difficile et tum vobiscum morietur

Oops, must have misread the label!
3.61 it shall be then, certainly wasn't looking for anything other than what I already have (apart maybe from one that is able to be changed quicker than at present!)

Same thing has just happened to me with all the same symptoms at 230,000 miles - two gearbox oil changes between 160,000 and now. Very annoyed. Before I start cruising Ebay and talking to the specialists - has anyone got a spare FM57 gearbox lying around that I could buy from them? I would plan to send what I buy off to Hardy Engineering in Leatherhead for a refurb before swapping the boxes out. Whilst I have the skills to get the box in and out, fiddling around with the inside of a gearbox is way too complicated...

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9000 Aero Pxxx BBC - lovingly restoring to perfect condition...

Depending on year of vehicle might be worth trying new drive on the sender as this was problem with mine. Cheap fix as well before stripping box.

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9-5 Aero Estate 2005 in grey
9000 Aero 1995 in black
1994 GM 900
1987 9000 16V S Turbo

Its only the 1996 models that suffer the drive ring failure. The wiring from the sender runs very close to the shift linkage too, if the box has been out in the past the wiring can easily be routed so that the shift linkage rubs and snags on it until it breaks so check the wiring first, then try the sender and the shaft after that. If they dont fix it then its gearbox change time.

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2005 Ford Fucos 1.5TDCi Wagon
2005 9-5 Aero with all the options.

While there was a specific quality issue with some of the 1996 gearboxes, the same fault can affect other years too. The previous owner of my 1994 (MY95) CSE had to have the gearbox rebuilt after the drive ring failed.

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Thanks for your replies gentlemen - I had the transducer out and the shaft looked unbroken, put it on a drill and the speedo worked, so can only assume that it's the box. I might look closer to home for repair service before schlepping round the M25!

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9000 Aero Pxxx BBC - lovingly restoring to perfect condition...

Very true Bill but with a 1996 car its a case of 'when' rather than 'if'. The only 9000 box I have ever had fail on me is for this reason (and it was an M96) and im not known to be particularly sympathetic when im driving.

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2005 Ford Fucos 1.5TDCi Wagon
2005 9-5 Aero with all the options.

I'm now going to think what I can do to change the arrangements a bit - something which can take a feed off the ABS sensor and convert it to a signal that the ECU can understand is going to be a whole load easier - just tap a hole into the hub carrier and fit 'something' that monitors how fast the rotors go round and feeds it back either as volatage or resistance to the ECU. I've just been quoted £500 for a strip and build so could easily throw £150 at a basic home-made circuit board that can conevrt an ABS signal...

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9000 Aero Pxxx BBC - lovingly restoring to perfect condition...

Somebody figured out a way of taking a feed from the Vauxhall ABS system to feed the speed input for the T5 ECU. Might be worth browsing the saabconversions forum and see what they do about this and adapting their ideas. Its been an ongoing problem for many years and people have looked into it on the forum but dont remember anybody coming up with a definitive answer for it.

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2005 Ford Fucos 1.5TDCi Wagon
2005 9-5 Aero with all the options.

Should not be too difficult. The abs ring produces 46 pulses per rev. The speedo needs 2458 pulses per km. A tire size 195/65/15 has a circumference of 1.99m, so 502 revs per km, times 46 abs pulses equals 23080 pulses per km from the abs sensor.

So all you need a a small circuit that will divide the abs signal by 9.4 to get the correct frequency. Even a simple division by 9 or 10 would probably do, a 50 pence 4017 IC is all you need for that.

If I am correct the mk IV abs ecu has buffered outputs from all wheel sensor signals on pins 9-10-11-12 (used for TCS) that you can use as input signal.

I would say it's worth a try

90000006, where do you find all this information? Thanks ever so much. whilst I am mechanically very competent, beyond wiring up an LPG kit in my golf, my microelectronics skills are poor and I don't want to overload the ABS sensor. even if it costs a couple of hundred quid, it's a whole load cheaper and simpler to get someone to design and make one than ever it were to get a gearbox rebuilt. If we get a working prototpye then maybe its something that BillJ can market along with his other ingenious fixed for old saabs.

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9000 Aero Pxxx BBC - lovingly restoring to perfect condition...

the 2458 pulses per km is something I once found on another saab forum, the 46 pulses per rev are from my workshop manual. To be honest, don't know for sure if those number are correct, would be a good idea to verify them first.
I must have a 9000 speedometer lying around, will dig it up. I have a pulse generator and frequency counter so I can measure the needed number of pulses with very good accuracy.
Unfortunately I do not have a spare hub or abs ring available, if anyone does please take a minute, count the number of teeth on the ring and post the magic number here?

Next step would be to verify the output signals on the abs ecu (pin 9-12), for that I need to hook up the scope to my abs and spin a wheel. If that won't work we need some additional amplifier to tap directly into the sensor signal without disturbing the ABS system. No big deal either.

If all numbers match up I can design a simple circuit.