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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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Discussion Starter · #1 · (Edited)
Two questions:

On looking in the 164 workshop manual, mechanical gearbox section, the end of the chapter diagnostic section, there is the noise troubleshooting section describing a noise heard on acceleration, heard mostly in 4th and 5th, 75 mph and above. This pretty much is the noise I hear at higher speeds. I think it has always done it since new as far as I can tell. Referring to the test section for that specific noise, the manual says to check the 'spur' gears for faults or excess clearances of some sort.

1. What are the 'spur' gears? I might assume they are the spider (side pinions) as described in the manual, but there is no definition anywhere for the 'spur' gears vs the side pinions in the diagrams.

However, I don't know why there would be noise from those gears or the other parts of the spider gear setup, since when driving in a straight line, theoretically none of those gears rotate, just the large ring gear. The gears inside the spider cage rotate only when the car is turning.

2. I may have asked this before, but can the differential casing be removed from the transmission without removing the transmission from the engine? Is there room? I must admit I haven't peered under that part of the car looking specifically for that, but boy, it would sure make life simpler if it could be, to inspect the differential cage and parts.

thanks,
 

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I removed the trannsmission and differential and clutch housing as a unit in my garage and it was a two man job. The younger man was not me.

The only way to get some room aft of the differential was by removing the steering rack.

Economy of effort would dictate taking the whole unit out, I don't think just by removing the Steering Rack you will have enough room.

If your condidering the gearbox and differential as a unit maybe that would work?

Frank
 

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Two questions:

On looking in the 164 workshop manual, mechanical gearbox section, the end of the chapter diagnostic section, there is the noise troubleshooting section describing a noise heard on acceleration, heard mostly in 4th and 5th, 75 mph and above. This pretty much is the noise I hear at higher speeds. I think it has always done it since new as far as I can tell. Referring to the test section for that specific noise, the manual says to check the 'spur' gears for faults or excess clearances of some sort.

1. What are the 'spur' gears? I might assume they are the spider (side pinions) as described in the manual, but there is no definition anywhere for the 'spur' gears vs the side pinions in the diagrams.

However, I don't know why there would be noise from those gears or the other parts of the spider gear setup, since when driving in a straight line, theoretically none of those gears rotate, just the large ring gear. The gears inside the spider cage rotate only when the car is turning.

2. I may have asked this before, but can the differential casing be removed from the transmission without removing the transmission from the engine? Is there room? I must admit I haven't peered under that part of the car looking specifically for that, but boy, it would sure make life simpler if it could be, to inspect the differential cage and parts.

thanks,
Check this out Del. http://www.alfabb.com/bb/forums/164-168-1991-1995/153764-fitting-alfa-romeo-q2-differential.html
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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Discussion Starter · #4 · (Edited)
" What are the 'spur' gears?"

No one knows the answer? Are they the spider gears (side pinions), or the other gears (crown wheels) in the spider cage? And, why should they make noise if one is driving in a straight line, when no gears in the spider cage should be rotating, if that is what Alfa means by the spur gears? The manual doesn't say that the car is turning for this specific case.

The only other thing I can think of is that the tapered bearing on the right hand side of the diff housing is not shimmed (lhs not shimmed) properly and so the big ring gear assy moves slightly out of alignment to the right with the transmission pinion gear, thus it or the tapered bearings making a little noise which increases in loudness as the vehicle speed increases.

At least that can be checked (I think) without removing the transmission/diff, just the rhs axle.

Maybe Carlo will recommend a different lube instead of the ATF. Always a possibility.
 

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Side pinion gears.
 

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Discussion Starter · #6 · (Edited)
That's what I suspect as well (either funny, or typical that they would change the name), except I don't understand why they would be making a noise when the car is going straight, as no gears in the spider cage are rotating (this is of course provided that the two front tires are the same diameter). So, why would the manual would say to check their clearances, or look for damage.

Makes no sense. That's why I'm speculating about the shimming of the rhs tapered roller bearing, only other adjustment in play when driving straight ahead.
 

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You can really smooth out and quiet down these transmissions with new diff L and R side tapered bearings and races in my experience. I would switch to GL4 MTF 75W-85 as well. After doing those two things, I have never had a better transmission in my car in every respect. When the diff is out for any reason, inspect the tightness of the roll pin that holds in the diff pin. I know you are aware of that issue, which can make a noise as well, though when the diff pin is loose, the noise will/can start in the lower numerical gears, not high speed so much. I'm thinking more diff bearings, which is of course related to what you are saying with the shim. Maybe your bearings have worn a bit and the shim is no longer thick enough? New bearings and the same shim and you would probably be good.
Charles
 

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The differential can only be serviced if you strip the gearbox as I understand it.

The pinion gear in these transverse gearboxes would be technically a spur gear if it isn't helical cut. I'm pretty sure it is helical cut though. There is no right angle spiral bevel ring and pinion in these transmissions, the pinion and crown gear are just regular helical cut gears like the speed change gears.

The spider gears (two) and the axle drive gears (two) are the only bevel gears in the transaxle. These are not spur cut either. They are bevel cut. If even one spider gear breaks the transmission cannot drive the car.
 

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Discussion Starter · #9 · (Edited)
" I'm pretty sure it is helical cut though"

Oh, yes, you wouldn't want to drive a car with straight cut ring and pinion gears, as the noise is really something. Decades ago, back in the early days of sports car racing, sometimes straight cut gears were used. Really noisy.

Still haven't figured out why the manual says to check the diff spider gears if there is noise usually heard in 4th and 5th if the car is going straight, as there are no rotating gears in the spider cage at that time.

I suspect that the noise is from the potentially mis-shimmed tapered bearings instead, as Charles suggests.
 
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