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-   -   trans. angle /pinion angle adjustments ? (http://www.hotrodders.com/forum/trans-angle-pinion-angle-adjustments-205906.html)

rf9763 09-21-2011 08:37 PM

trans. angle /pinion angle adjustments ?
 
hello all, i under stand how to adjust pinion angle. i have a 4 link rear back halved ford 9 in setup.my question is ,my trans at the end of tail housing is 5 degrees down .do i set pinion angle at 5 degrees up for center to center and then lower pinion down 2-3 degrees? is that to much down on trans to make this work?i have driven car 50 60 mph and got small vibration from rear of car with this set up. this is my first 4 link and not sure about the trans angle. not much i can do to raise trans cause this is a vega. NO ROOM. lol. any advise or input would be great. thanks for your time and help.also motor plate in front and poly trans mount.

cobalt327 09-22-2011 05:03 PM

Quote:

Originally Posted by rf9763
hello all, i under stand how to adjust pinion angle. i have a 4 link rear back halved ford 9 in setup.my question is ,my trans at the end of tail housing is 5 degrees down .do i set pinion angle at 5 degrees up for center to center and then lower pinion down 2-3 degrees? is that to much down on trans to make this work?i have driven car 50 60 mph and got small vibration from rear of car with this set up. this is my first 4 link and not sure about the trans angle. not much i can do to raise trans cause this is a vega. NO ROOM. lol. any advise or input would be great. thanks for your time and help.also motor plate in front and poly trans mount.

The idea is to have a 0 angle with the vehicle under power and the exact amount of drivetrain deflection will be different for every vehicle. That said, if you end up with -2 degrees static pinion angle, you should be OK due to the tendancy for the pinion to 'climb' the ring gear under acceleration.

prostreet6t9 09-22-2011 05:17 PM

Keep in mind.... The 4-link will hold your pinion angle better than a stock set up.

user151 09-23-2011 10:29 AM

What Cobalt said may be correct "under acceleration" but considering you have a 4 link and sound like you are not a racer or dragger, I would set the rear pinion up the same as the trans is down... 5 degrees.

Centerline 09-23-2011 04:54 PM

Quote:

Originally Posted by user151
What Cobalt said may be correct "under acceleration" but considering you have a 4 link and sound like you are not a racer or dragger, I would set the rear pinion up the same as the trans is down... 5 degrees.

X2
The ONLY time you want a negative pinion angle is if its a strip car. A four link wouldn't need negative anyway as the pinion angle won't appreciably change during acceleration like it does with leaf springs. For street driving you want to match the trans angle in reverse. Trans 5* down - pinion 4-5* up.

Centerline
HotRodsAndHemis.com

The most important things you learn are those things you learn AFTER you know it all. -- Chip Foose

cobalt327 09-23-2011 07:27 PM

Billy Shope’s site on suspension- http://www.racetec.cc/shope/

Whether or not there will be pinion rise on acceleration depends on a hoard of things, the basic rule of thumb still applies: Under acceleration you want there to be as close to a zero angle as possible. If that means a degree or two difference between the trans and rear end, then so be it. But there's no correct answer w/o testing, anyway.

There is going to be some deflection unless the links, chassis and all the pick up points are 100% rigid. In a street driven 4-link I'd expect there to be more not less deflection (urethane or rubber bushings instead of solid rod ends, for example) and if that's the case, there's more possibility of some angle being needed as opposed to no angle at all.

I don't know how anyone could discern the OP's intentions were to not drag race it by his post, but then I assumed anyone doing a back-halved Vega w/a front plate and 4-link w/a 9" rear end planned on using it, not just profiling w/it. It will help if the OP would elaborate on the chassis, power train, the 4-link and how it will be used.

SSedan64 09-24-2011 02:02 AM

Pinion Angle tips from Rossler's site >> http://www.rosslertrans.com/Pinion%20angle.htm

4-Links do have much less deflection than Leaf & Ladder type suspensions.
As 'Cobalt327' said, Bushing type affects the amount, OEM Rubber, Polyurethane & Aluminum.


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