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PostPosted: Tue Aug 13, 2019 9:38 pm 
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Joined: Mon May 13, 2013 8:34 pm
Posts: 39
Car Model: Saab 99 Turbo
Hi All,

Recently completed a full engine rebuild on my 99t and its been run in for a good 700 miles so far going well, the gearbox was solid before I did the rebuild so didn't get much done to it while out other than new seals and a new indent spring. Starting to get a knocking noise coming from the primary housing at the front, which tends to be on tick over or mid-revs when hot but goes away on full acceleration. When I filled the gearbox oil I put 2.2 litres in the main box and 0.3 in the primary drive. Assuming the chain is slapping against casing and possibly the tensioners have an issue be interested to know if its a big issue I can live with for a bit or if it needs immediate attention and parts etc.

Any advice greatly appreciated.

Cheers


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PostPosted: Tue Aug 13, 2019 10:10 pm 
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Light Pressure Turbo

Joined: Fri Jun 16, 2006 9:26 pm
Posts: 579
I think the gearboxes hold a little more than 2.5 litres oil so suggest you check the level.
I doubt the primary drive chains are slapping the gearbox casing, they can be noisy when idling but this is usually due to uneven engine running.
4 or 5 speed?
What do you mean by indent spring?


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PostPosted: Wed Aug 14, 2019 9:55 am 
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Joined: Fri Aug 05, 2005 6:51 pm
Posts: 2654
Location: Cheshire
Car Model: Saab 900 and 99
devnet 99 Turbo wrote:
Hi All,

Recently completed a full engine rebuild on my 99t and its been run in for a good 700 miles so far going well, the gearbox was solid before I did the rebuild so didn't get much done to it while out other than new seals and a new indent spring. Starting to get a knocking noise coming from the primary housing at the front, which tends to be on tick over or mid-revs when hot but goes away on full acceleration. When I filled the gearbox oil I put 2.2 litres in the main box and 0.3 in the primary drive. Assuming the chain is slapping against casing and possibly the tensioners have an issue be interested to know if its a big issue I can live with for a bit or if it needs immediate attention and parts etc.

Any advice greatly appreciated.

Cheers


If it's a 4-speed it will take 2.5l, 5-speed is 3l.

When at idle and you press the clutch pedal, does the noise stop?

Nearly all of the 99/900 gearboxes are still sporting their original chains. What I have found over the years is whilst the 'stretch' specification given by Saab leaves some chains within specification, the actual 'stretch' specification of the chain itself is outside the tolerances. Just for clarification, chains do not actually 'stretch', the rollers/links actually wear.

_________________
900i '87
99 '83 Turbo Killer
99 EMS 77
Lancer EVO 6.5 TME '00 in red
Lancer EVO 6.5 TME '00 in black


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PostPosted: Wed Aug 14, 2019 9:59 am 
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Joined: Fri Aug 05, 2005 6:51 pm
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Location: Cheshire
Car Model: Saab 900 and 99
99 Pete wrote:
What do you mean by indent spring?


Probably the spring holding the ball bearing into the 'detents' on the selector shaft.

_________________
900i '87
99 '83 Turbo Killer
99 EMS 77
Lancer EVO 6.5 TME '00 in red
Lancer EVO 6.5 TME '00 in black


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PostPosted: Thu Aug 15, 2019 8:29 pm 
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Joined: Mon May 13, 2013 8:34 pm
Posts: 39
Car Model: Saab 99 Turbo
Yes its a 4 speed and yes I meant detent spring. The noise does stop when the clutch is pressed and it sounds OK at higher revs...


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PostPosted: Thu Aug 15, 2019 8:47 pm 
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Light Pressure Turbo

Joined: Fri Jun 16, 2006 9:26 pm
Posts: 579
[quote="99 EMS"

Nearly all of the 99/900 gearboxes are still sporting their original chains. What I have found over the years is whilst the 'stretch' specification given by Saab leaves some chains within specification, the actual 'stretch' specification of the chain itself is outside the tolerances. Just for clarification, chains do not actually 'stretch', the rollers/links actually wear.[/quote]

What method did Saab use to asses the chain wear? I should know but can't remember. How far out the tensioner is?
Do you use one of those gauges that measure the length over several links (or a similar method with some verniers)?

I did once strip a gearbox which had obviously had a problem in the chain casing as it was all smashed up. But never had to repair a gearbox which had failed for this reason.

I'll be interested to get all the chains I've got and measure them up properly and see how much variation there is. Having run a 900 T16 up to 375,000 miles on it's original chains and currently another one up to 280,000 I have to admit I've not worried about them too much other than giving them a quick 'bend' test when I've got a 'box in bits. Some gearboxes do seem a little more snatchy on and off the throttle than others, perhaps this is due to primary chain wear? Interested to know your thoughts. Do you source new chains or use good used ones?


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PostPosted: Fri Aug 16, 2019 10:13 am 
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Joined: Fri Aug 05, 2005 6:51 pm
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Location: Cheshire
Car Model: Saab 900 and 99
devnet 99 Turbo wrote:
Yes its a 4 speed and yes I meant detent spring. The noise does stop when the clutch is pressed and it sounds OK at higher revs...


It does appear you could have something worn in the primary casing, could be several things, worn chains, faulty tensioner, worn bearings. You either live with it or open it up and check the internals.

_________________
900i '87
99 '83 Turbo Killer
99 EMS 77
Lancer EVO 6.5 TME '00 in red
Lancer EVO 6.5 TME '00 in black


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PostPosted: Fri Aug 16, 2019 10:23 am 
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Joined: Fri Aug 05, 2005 6:51 pm
Posts: 2654
Location: Cheshire
Car Model: Saab 900 and 99
99 Pete wrote:
[quote="99 EMS"

Nearly all of the 99/900 gearboxes are still sporting their original chains. What I have found over the years is whilst the 'stretch' specification given by Saab leaves some chains within specification, the actual 'stretch' specification of the chain itself is outside the tolerances. Just for clarification, chains do not actually 'stretch', the rollers/links actually wear.


What method did Saab use to asses the chain wear? I should know but can't remember. How far out the tensioner is?
Do you use one of those gauges that measure the length over several links (or a similar method with some verniers)?

I'll be interested to get all the chains I've got and measure them up properly and see how much variation there is. Having run a 900 T16 up to 375,000 miles on it's original chains and currently another one up to 280,000 I have to admit I've not worried about them too much other than giving them a quick 'bend' test when I've got a 'box in bits. Some gearboxes do seem a little more snatchy on and off the throttle than others, perhaps this is due to primary chain wear? Interested to know your thoughts. Do you source new chains or use good used ones?[/quote]

Saab stated the clearance between the primary housing and the chain rubbing block should not be less than 10mm.

I no longer really measure chains, if the customer states he wants new chains I fit them, if he declines i put the old ones back in. Would you measure the timing chain on an old engine you are rebuilding, then fit it back in the engine?
I fit OEM chains.

_________________
900i '87
99 '83 Turbo Killer
99 EMS 77
Lancer EVO 6.5 TME '00 in red
Lancer EVO 6.5 TME '00 in black


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PostPosted: Mon Aug 19, 2019 1:37 pm 
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Joined: Mon May 13, 2013 8:34 pm
Posts: 39
Car Model: Saab 99 Turbo
I do wonder now when I replaced the primary housing gasket and briefly looked over the gearing and chain the tensioner, the tensioner itself seemed a bit loose in the sense it wasn't really tightly tensioning the chain but either side moved one way or the other, at the time not knowing much about gearboxes I assumed it was meant to be like that and it tensioned up when in motion....!?


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PostPosted: Mon Aug 19, 2019 2:39 pm 
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Joined: Wed Jul 30, 2014 6:57 am
Posts: 160
Location: The Netherlands
Car Model: 900 classic
It's not really a tensioner, it's more of a dampener. It stops the chains from flapping about.

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PostPosted: Mon Aug 19, 2019 3:18 pm 
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Joined: Mon May 13, 2013 8:34 pm
Posts: 39
Car Model: Saab 99 Turbo
Ah right that makes more sense then in how it was operating when manually manipulated it.


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