I am installing my rebuilt engine and my new 200-4R. I am using the transmission side mount kit from Danchuk. With the engine and tranny installed, I added some shims to the tranny mounts to level the carb mount on the intake. I then did a check of the transmission shaft angle compared to the pinion angle. The tranny shaft points down at 3 degrees and the pinion angle is pointing up at 8 degrees. I know these are supposed to be the same. Once I am totally done with the engine and transmission work, I will do a final check of the angle and get some shims from Summit Racing and correct the angle. My question is this. Would this 5-degree mismatch cause a vibration? This car has had a mysterious vibration from the day we got it. I am hoping that I have just found the root cause.
And just to double check, make sure you're measuring the pinion angle with the rear springs loaded, i.e. the normal weight of the car on the rear springs, as the angle will change a little if they're extended. Three degrees sounds about right for the engine/trans. Eight degrees doesn't sound like an original rear axle measurement...
4 degrees pinion up is what you want, factory setting. I don't believe 5 degrees will cause any vibration, the u joints will take care of that, that's why their there. It's more important that the transmission and rear pinion are in alignment, if the transmission tailshaft is 4 degrees down, the pinion should be 4 degrees up. The 4 degrees is negotiable, as long as transmission and rear end match.
__________________ Greg Embury
Came home at 3 days old in a 55 210 2 door sedan-and I've been addicted ever since.
Strange to have a stock pinion angle up 8 degrees. Should be measured at the yoke with the car sitting as it drives/runs (ride height/load). I like a slight down angle on the pinion 1-2 degrees. Your loaded, ride height pinion angle should be 1-2 degrees up in my opinion. Summit and others sell wedge shaped shims to adjust pinion angle.
"Luck is the residue of hard work."
David, both of those links have to do with drive shaft to rear end angles for racing, off road, lift kits, etc.
That is not a consideration since tri-5's are stuck with 3 to 4 degree engine angle, due to transmission tunnel and crossmember clearance. The pinion needs to closely match that, to elimenate vibration.
It's possible to measure drive shaft to transmission and driveshaft to pinion, then add, subtract, get the square root, etc., but that involves way too much math to get an accurate measurement.
Unless your building a race car, 99.9% of your driving involves cruising the highway or city streets, where you don't want any vibration. Set it at that ride height and don't worry about the 15 seconds you spend at full throttle. You won't notice any vibration then.
I agree, if you have a stock rear end, 8 degrees seems out of wack.
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