Huh. How about where the trunnion attaches to the differential? If things were relocated by welding, you’re going to want to make sure everything is squared up. Those dimensions are critical.
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Originally posted by Nader393 View PostHuh. How about where the trunnion attaches to the differential? If things were relocated by welding, you’re going to want to make sure everything is squared up. Those dimensions are critical.
Will'59 Alfa Romeo 101.02 Giulietta Sprint
'69 Alfa Romeo 105.51 1750 GTV (R.I.P)
'69 Datsun 2000 roadster Vintage race car
'88 BMW M3
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Originally posted by LateFan View PostI must have missed something - did you swap in a 105 rear end and trunnion? How different are they?
As Nader says, misalignment there can mess up the way it tracks through corners and make it a handful. What say the gurus of AlfaBB about this?
The upper point of the A mounts to the differential, the bottom attaches to the body.
I'd think the trailing arms would be more prone to causing things to sit crooked, but they look identical, and are both the same length. Perhaps its something stupid that I'm over looking, but I'm not sure.
Will'59 Alfa Romeo 101.02 Giulietta Sprint
'69 Alfa Romeo 105.51 1750 GTV (R.I.P)
'69 Datsun 2000 roadster Vintage race car
'88 BMW M3
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If anyone is tuning in and hasn't seen one, this is the 105 rear axle "trunnion." It's a smart system - that lightweight aluminum arm (OEM is steel) serves as the short trailing arm and the lateral locator for the rear axle assembly. Long trailing arms mount to the bottom of the tubes and carry the spring perches. So the axle is perfectly located and can't rotate or tramp. It's an evolution of the design in the 750/101 rear suspension.
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Oh, I didn't know you were adapting a 105 axle/diff to a 101 chassis.
If you're confident that the trailing arms and A-arm mounts to the body are square, then the differential mounting adapter would be suspect. Looks like you needed a ball mount on top of the diff. How was that done?
If you were going through that much trouble, this would have been a good time to ditch all that and go with other locating systems like a Watts, Panhard, or my favorite, the sliding block.
These systems lower the rear roll center, allowing the car to corner flatter. My adaptation of the sliding block deletes the bar going across the chassis where the trunnion bar would have lived. Instead, I have a titanium bar reaching from the diff to the rear bulkhead sheetmetal (reinforced, of course) to prevent differential tilt fore and aft, while still allowing it to pivot and oscillate with suspension movements.
'91 325i
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A number of years ago, there was a Sprint race car running with us in SOVREN, red with yellow accents, that had a sliding block rear end. This was early in my vintage racing, before I had one, didn't know what it was, and I used to follow this thing on the race track, staring at that yoke peeking out from under the rear apron. What was that?! Mesmerizing to me, and definitely an inspiration for my own later adaptation.'91 325i
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Originally posted by Nader393 View PostOh, I didn't know you were adapting a 105 axle/diff to a 101 chassis.
If you're confident that the trailing arms and A-arm mounts to the body are square, then the differential mounting adapter would be suspect. Looks like you needed a ball mount on top of the diff. How was that done?
If you were going through that much trouble, this would have been a good time to ditch all that and go with other locating systems like a Watts, Panhard, or my favorite, the sliding block.
These systems lower the rear roll center, allowing the car to corner flatter. My adaptation of the sliding block deletes the bar going across the chassis where the trunnion bar would have lived. Instead, I have a titanium bar reaching from the diff to the rear bulkhead sheetmetal (reinforced, of course) to prevent differential tilt fore and aft, while still allowing it to pivot and oscillate with suspension movements.
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As far as I know, there is nothing bent. It was all straight when I pulled the old rear end off, and was still straight when I repainted everything. There were some big washers that came with the poly bushings I installed, but there was no way in hell the parts were going to fit with the washers in place. I was in a hurry to get the car back on the ground so I could move it to a safer location as the fires got close to St Helena. I do need to go back and look more closely at everything.
Will'59 Alfa Romeo 101.02 Giulietta Sprint
'69 Alfa Romeo 105.51 1750 GTV (R.I.P)
'69 Datsun 2000 roadster Vintage race car
'88 BMW M3
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