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DRR Trophy
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I changed ring/pinion from 4.50 to 5.14 and have had nothing but trouble. At first I thought a tire was out of balance...then the driveshaft was rebalanced and still no relief. The d'shaft was out of round so I went ahead and had a NEW STEEL shaft built but the vibration is still there. It shows up from just after 330' and gets worse from there. Is it POSSIBLE that the NEW ring/pinion is causing this? Car runs 100 mph in eighth.
 
Posts: 73 | Location: Mooresville, nc | Registered: October 11, 2013Reply With QuoteReport This Post
DRR Top Comp
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quote:
Originally posted by 62Galaxie:
I changed ring/pinion from 4.50 to 5.14 and have had nothing but trouble. At first I thought a tire was out of balance...then the driveshaft was rebalanced and still no relief. The d'shaft was out of round so I went ahead and had a NEW STEEL shaft built but the vibration is still there. It shows up from just after 330' and gets worse from there. Is it POSSIBLE that the NEW ring/pinion is causing this? Car runs 100 mph in eighth.


8.8 am I right? Crush sleeve or solid pinion spacer?

Have you re-checked your pinion bearing pre-load after running it?
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
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How long is the driveshaft from center to center of u joints? A problem that most of us don't think about is called "critical speed". If your drive shaft is longer that 50" at hi rpm there could be a problem. Google drive shaft critical speed there are a few charts put out by Mark Williams and others that tell you what your limitations are, and what type of drive shafts may be needed if you are exceeding them.
 
Posts: 145 | Location: california | Registered: November 16, 2010Reply With QuoteReport This Post
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Don't know about solid spacer, bearing pre-load or crush sleeve. I will find out about those. It's a 9" with "N" case. RPM at stripe is 6000-6100. New d-shaft (steel) is 3.5 inch diameter and 48.5 " from center to center. I would bet that it's not anything to do with critical speed. All new U-joints too. Again, there was no issue with this until the 5.14 went in. Would a solid pinion spacer cause such vibration?
 
Posts: 73 | Location: Mooresville, nc | Registered: October 11, 2013Reply With QuoteReport This Post
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quote:
Originally posted by 62Galaxie:
Don't know about solid spacer, bearing pre-load or crush sleeve. I will find out about those. It's a 9" with "N" case. RPM at stripe is 6000-6100. New d-shaft (steel) is 3.5 inch diameter and 48.5 " from center to center. I would bet that it's not anything to do with critical speed. All new U-joints too. Again, there was no issue with this until the 5.14 went in. Would a solid pinion spacer cause such vibration?


If you have a crush sleeve or solid pinion spacer that somehow now has the pinion bearing preload loose after making hits on the car, you could have a vibration.

Best thing to do is climb under it take the driveshaft out, grab the pinion yoke and see if there's any slop.

I wouldn't race it again until I identified the problem in the pinion.
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
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Definitely in the pinion, if the vibration is related to the gear change Sir.
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
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Thank you gentlemen. I'll yank it out tomorrow.
 
Posts: 73 | Location: Mooresville, nc | Registered: October 11, 2013Reply With QuoteReport This Post



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Max RPM on your drive shaft @ 48" is 7200. You are Ok on critical speed and safe. Hope you find your prob.
 
Posts: 145 | Location: california | Registered: November 16, 2010Reply With QuoteReport This Post
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