Pinion Angle Test

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John_Heard
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Pinion Angle Test

#1 Post by John_Heard » Sun Jun 04, 2006 5:58 pm

Next time out with the Nova I want to try and measure pinon angle going down track to determine if I have it set where it needs to be. Some say 7 deg, some say 4 (down)... the question is what's really right for a leaf spring car?? I don't know for sure either.

So first I need to figure out how to measure it. I have a data logger on the car and the ability to video tape under the car, so I'm going to try and devise something that will let me see how many degrees of change there is. Suggustions are welcome :-)

Next ... what is perfect angle? What uses the least hp in the u-joints? Does anyone have experience with solid axle dragsters or something? What do they set those at?

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#2 Post by Craig W. » Mon Jun 05, 2006 12:10 am

Travis at Calvert suggested 3-4 degrees down to me, so I set it at 3.5. So far so good.
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#3 Post by John_Heard » Mon Jun 05, 2006 8:18 am

If I remember right mine's about 4 now. Question I have is how do we know that is correct? I wonder how Calvert arrived at that angle?

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CoMax Racing
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Pinion Angle

#4 Post by CoMax Racing » Mon Jun 05, 2006 9:47 am

I build 2 deg negative pinion angle into all my rear ends and set all the engines at 2 deg positive. Naturally this yeilds 0 deg variance with 4 deg total offset. Most chassis builders I have talked to use this basic spec.

I'm not sure how you would mearsure pinion angle as the car is going down track (easily that is).

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#5 Post by John_Heard » Mon Jun 05, 2006 10:00 am

Is that on a Hardtail?

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CoMax Racing
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Pinion Angle

#6 Post by CoMax Racing » Mon Jun 05, 2006 12:45 pm

Thats on all sprug cars. On hard tail dragsters and altereds you use solid shafts and couplers. These have to be set perfectly in line within .001-.002".

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Re: Pinion Angle

#7 Post by Mike Peters » Mon Jun 05, 2006 12:55 pm

CoMax Racing wrote:I build 2 deg negative pinion angle into all my rear ends and set all the engines at 2 deg positive. Naturally this yeilds 0 deg variance with 4 deg total offset. Most chassis builders I have talked to use this basic spec.

I'm not sure how you would mearsure pinion angle as the car is going down track (easily that is).
Yes, that would keep the driveshaft in phase but, on a stock framed car, it's danged hard to acheive 2 degrees positive in the transmission tailshaft. Most engine's crankshaft C/L are around 4 degrees negative. As far as what you're looking for under power, I would say 0 degrees is what you're looking for. I think Calvert determined that 4 degrees is probably the typical amount the leaf springs flex under power.

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#8 Post by John_Heard » Mon Jun 05, 2006 12:57 pm

Duh, Should have known that. Guess I've been looking at too many 4 link dragsters lately. So on the sprung cars are you talking about 4 link cars, ladder bar or leaf?

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#9 Post by Mike Peters » Mon Jun 05, 2006 1:09 pm

Beyond wrote:Duh, Should have known that. Guess I've been looking at too many 4 link dragsters lately. So on the sprung cars are you talking about 4 link cars, ladder bar or leaf?
I'd say 4-6 degrees for leaf spring cars but, I would think the Cal-Tracs would control a lot of the spring wrap-up so, 4 degrees as Calvert suggests is probably a good bet. Even a fabbed 4-link car seems to do well with 1-2 degrees pinion angle as CoMax Racing suggested as they have the flexability to mount the engine at the angle needed to keep the driveshaft in phase. Have you measured your tailshaft angle John? If you can acquire the data to find your pinion angle under power, that would be awesome!!! You'd know exactly where to set your static pinion angle.

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#10 Post by John_Heard » Mon Jun 05, 2006 1:23 pm

Yes, I've measured it, don't remember what it was off hand - I believe it was 3 or 4 down though (OEM). That's what I want to do, figure out a way to measure it under power.. It's one of those nagging questions that I'd like to learn the answer to.

Plus, I'm currently using some shims to set the angle and I'd like to get rid of them and put new mounts in the "correct" position on the rear.

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Pinion Angle

#11 Post by CoMax Racing » Mon Jun 05, 2006 1:42 pm

I guess I should have included the statement (in a perfect world). Yes, changing engine angles in a stock vehicle is very hard to do, and most of the time not worth the effort. Maybe I'm just getting a little spoiled with the scratch built stuff.

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Re: Pinion Angle

#12 Post by Mike Peters » Mon Jun 05, 2006 2:11 pm

CoMax Racing wrote:I guess I should have included the statement (in a perfect world). Yes, changing engine angles in a stock vehicle is very hard to do, and most of the time not worth the effort. Maybe I'm just getting a little spoiled with the scratch built stuff.
Yeah, I knew you had tube chassis cars on your mind. If you were getting that with stock-framed, stock floor-panned cars, I was going to beg for your secret. LOL!!!

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#13 Post by sc racing » Sun Jun 11, 2006 3:07 pm

I ran everything from 4 to 7 degrees and found 5 to work the best never figured out how to measure it going down the track. 0 is what you want under acceleration. 6-7 used to bind the ujoint and never 60 ft any better. I ran modified Comp Eng traction bars they didnt make Cal Tracs at the time . The best advice I got was from the guys who run the C stock and D stock camaros If you can get them to give you info.

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#14 Post by John_Heard » Sun Jun 11, 2006 5:07 pm

What type of car was that? How fast & heavy?

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#15 Post by sc racing » Sun Jun 11, 2006 5:31 pm

1980 camaro 3400# 10.33 @130 best 1.44 60 ft w/ bbc and 3200# 10.32@ 129 1.43 60ft w/sbc

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