Quote:
Originally Posted by mongocanfly
(" it's not apples-to-apples ")
True.....
I've got about 25-30 sites saved that relate to suspension setup and driveline angles..it can get confusing sometimes
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Exactly. The thing is, it's correct info for that application.
The most common phrase I've heard for the DIY builder is "match the angle of the pinion to the trans but opposite & be within a degree vs. exactly matching". They'll say 3° down @ the trans tailshaft (industry standard) & 2.5° up @ the pinion. The angles are .5° from being equal-but-opposite. The end result is a working angle of less that 1°. It might work for may apps, but not so much for extreme dropped cars/trucks. The 2.5° 'up' angle is subtracted from the 3° 'down' angle because it's below parallel @ the point of measurement for each. If the pinion is above that parallel point, the numbers are ADDED together which results in a 5.5° working angle.
What about an extreme drop application that has a ride height of about 5" off the ground??
The trans output shaft is just above the bottom of the frame rail (lets say @ 7.5").
The vehicle is using a 28-30" tall rear tire OD.... that puts the C/L of the differential @ around 14-15" above the ground.
So if the trans is pointing down & is @ approx 7.5" off the ground AND the rear pinion is approx. 15" off the ground (30/2 = 15; 15-7.5 = 7.5" slope). So it's a 7.5" slope over X-amount of inches running uphill (length of the combined shafts) from the trans to the differential. The scenario w/the trans output-to- main shaft angle getting added together typically equals a BIG working angle which is hard on joints. This is one reason why 2pc set-ups can be used to an advantage (more opportunities to minimize the angles). Most of these apps will have the pinion @ zero or slightly pointing down (more likely).
When I would explain my set-up, the usual response: "you need to raise the vehicle or raise the drivetrain within the vehicle".