Speedometer Drive Failure

[gratroweb]

Could someone give me an idea of the amount of work required to replace the nylon speedo drive wheel that is mounted on the differential (used to drive the speed sensor)

Are there any short cuts without removing the transmission and is it a job for an advanced DIY mechanic job.

(Saab 9000 CSE 2.0i LPT 1994)

Thanks

[ylee coyote]

sharp intake of breath...
not an easy job at all ...
It means taking the gearbox out and there is a dissasembly of the gearbox parts to get to the offending item
I have not done it but the local dealer saw me coming and charged £1200 for the job
A good independant will be considerably less

abbott charge £600 for a tear down and re-build
if nothing else is wrong that will be £600.50 to you !!

It is possible to do DIY but it will be a haynes 4 spanner job..
There has been some-one who has done it and has posted the procedure on here so its worth a search..

BTW welcome to the board !!

[gratroweb]

Thanks for the info.

Is it worth replacing any parts whilst am at it? (ie. is it worth replacing transmission parts - it's done 128k miles)

PS. Is there any more detailed info available than Haynes?

[wrighar]

The jobs a beast.

I've gone down as far as the diff, but not any further and it took 2 whole days from driveable to driveable. (1 day to remove and refit, one to strip and rebuild.

Add another 1-2 hrs to remove and refit the diff.

Other things that will need replacing very soon.

All 4 bearings for the input and output shaft (about £20 each)

Maybe 1 or 2 of the hubs at £80 each as the inernal splines wear badly (cheaper and softer than wearing the very expensive shaft...)

The crushable bushing (a must replace)

Possibly a circlip or two

Maybe the 5th gear cog, it's very small, takes lots of hard and wears it internal splines (seen as slop/slack

The top lock nut that holds the lot together

Think about chnaging all 4 synchro's, or at least check for wear.

Think about changing the gear box linkage bush (£20) and gearbox mount bush (£35) while the lots out.

That's probably it for starters..

Andrew

[gratroweb]

Thanks Andrew

I have heard it may be possible to get at the offending item by going in from the side of the diff ? is this really possible?

Can i get a non-nylon part as a replacement (i would rather it wear out the teeth on the sensor as it's much easier to replace.

[wrighar]

I wouldn't have thought you could do it through the inner driver exits as the diff is mounted firmly (very) by big bearing feom inside the gearbox casting.

The nylon wheel would be on the larger shiney ring at the bottom of the diff in the picture here:-



The inner driver for the dricers side is much smaller than the passenger side as it does not encompass the CV part as it just fits to the tranfer shaft.

Even these bits can get hare to get out...



Andrew

[saabz2000]

heres a thought,

what about an aftermarket device to generate the signal for the speedo??? i know these are available for aftermarket speedos, so i guess it is possible that they might drive the saab item.

[jp11]

Absolutely. That's just too much time and expense just get a working speedo on a vehicle with 126,000 miles. My 91 9000i also has an erratic (and sometimes non-working) speedo. It happened after a gearbox change. But I can tell you - the box isn't coming out again! How can you easily tell exactly what's wrong - i.e. is it the gear or the sender?

[wrighar]

The gear on the sender can be checked (see pic above), the sender and spedo head can be checked.

Also, an finger in the sender hole will inform the digit owner as to the state of the nylon drive cog

I did look into the possibility of building a replacement sender or using the ABS senders, but it all got too difficult (do a search of the 9000 archives and see....)

pulse rates per mile/km and repulse rates are mad.

ABS used 43? teeth per wheel rpm
Gearbox uses another for speedo and trionic speed feed (25 ish per turn)
SCC uses a repulsed signal from speedo head at about 43000 per mile (or Km)

What I do know is the Trionic T5 eventually goes a bit mad when it hasn't had a speedo feed for a while....

Andrew

[gratroweb]

I would be interested to know if anyone knows of an after market product that could reduce the cost (ie. no tranmission removal).I guess that is at least one of the reasons why it now comes from a sensor on the rear hub on 9-5s? (as i understand it).

[chucktv]

When mine went it turned out that the sensor had locked up and stripped the inside of the nylon gear that connects to the sensor (Scaero's pic). If the problem is with the sensor or any of the parts pictured you shouldn't need to remove the tranny; at least I didn't. Just a thought.

[gratroweb]

Following up from the failed speedo drive gear in the gearbox, I eventually got the job done by an independant.

The job cost a staggering £800 which included the cost of the replacement gear (£5) to get the speedo working again.

Moral of the story is that if you have a saab 9000 that is getting old and the speedo drive gear fails, think very very carefully before embarking on getting this job done. It may prove uneconomic.