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 Post subject: Setting Pinion Angle
 Post Posted: Thu May 11, 2006 9:03 am 
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Location: Ft. Worth, Tx
I am installing a equal length 4 link rear. I need to know what the best pinion angle setting should be. The car is going to be setting fairly low so the rear will be setting up in the car quite a bit. Any suggestions would be appreciated.

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 Post subject: Re: Setting Pinion Angle
 Post Posted: Thu May 11, 2006 9:06 am 
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Duswill wrote:
I am installing a equal length 4 link rear. I need to know what the best pinion angle setting should be. The car is going to be setting fairly low so the rear will be setting up in the car quite a bit. Any suggestions would be appreciated.



1* is all thats needed for a four link


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 Post Posted: Thu May 11, 2006 5:14 pm 
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I usually put 1 to 3 degrees in a four link car. Of course the pinion is angled down.

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 Post Posted: Thu May 11, 2006 6:21 pm 
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gearhead1011 wrote:
I usually put 1 to 3 degrees in a four link car. Of course the pinion is angled down.


How do you decide on how much pinion angle your going to use ?


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 Post Posted: Thu May 11, 2006 6:27 pm 
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Hello
I noticed you said the car was sitting very low, so the rear end is up in the car quite a bit
Have you raised the rear of the tranny, or is there quite an angle upwards for the driveshaft to the rear??
I lowered the front of motor and raised the rear of the tranny to get things inline. The top carb mt flange is now machined flat and now is paralell with the ground.
I am not sure if this is your scenario,? I just wondered on how you worded it
take care
Tom


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 Post Posted: Thu May 11, 2006 6:50 pm 
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DCarr wrote:
gearhead1011 wrote:
I usually put 1 to 3 degrees in a four link car. Of course the pinion is angled down.


How do you decide on how much pinion angle your going to use ?


The 1-3 is a range I use, it doesn't make any difference as long as it falls within those numbers.

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 Post Posted: Thu May 11, 2006 7:05 pm 
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I've always been told that you shoulld move your rear threw it's travel and it shouldn't have more tha 13* at any position on either joint. But the 1to 3 is good. I did read an artical a while back, that said a joint is more efficent with at least 1* angle. THey did a chassis dyno and saw a loss with perfectly lined up joint. Now I would say they was trying to sell joints, but they was selling rear ends, and a brand joint wasn't mentioned. But it was like 5 to 10 h/p. THey must have been playing to get the best results for their ball bearing straight cut rear and found that. Think that was tiger quick change , if you'd like to search. If I can find it I'll post the addy.

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 Post Posted: Thu May 11, 2006 8:07 pm 
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I have always reasoned that when under load the rear housing is trying to rotate up in front. If you start with the pinion pointed slightly down, when everything flexes with full load that the u-joint ends up lined up straight.

When I set up a ledder bar car I usually go 3-5 degree but the housing rotates as the suspension travels on a ladder bar. This is due to the single pivot point.

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 Post subject:
 Post Posted: Thu May 11, 2006 8:49 pm 
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Location: Tell City, IN
I would play this one a little careful because I had too much negetive...
BOOM there went the back u-joint at 94mph, (twisting the driveshaft out and busting the transmission) then I got another case paid to have it all switched over checking everything and put it back in with a new driveshaft also...2nd pass later BOOM again same thing, this time I didn't even have to take out the bell housing bolts it came right out as soon as I pulled the cross member out, this time breaking the trans-brake in half and took out the pump with it. So I done some reasearch and got the pinion lined up at about +1 Degree because my tranny is up high in the chassis and put in a new brake and got a deal on a JW ultra pump and got it back together. Runs without breaking now!! ..Still got a slight vibration on the high end though just not near as bad as right before it broke before. So I'd go by the book on this by checking your transmission tailshaft angle vs your pinion angle to get it right..
this applies to I think everything except for leaf spring cars because they have alot more movement..
here is a link to some good info on this..
http://www.streetissuecustoms.com/pinionangle.html
I hopes this helps.

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6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post subject:
 Post Posted: Thu May 11, 2006 9:04 pm 
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Location: Wodonga, Australia
Hey US,
If you broke a uni joint because of angle it must have been way out cause uni joints can work and a pretty big angle.
Production cars can have up to 20 or more degrees of uni joint angle.

The only reason we drag racers try to get thye pinion angle down to zero degrees is to reduce the load on the uni joint and as BUBSTR stated, to make more HP.

This is only my opinion but if most of us had our pinion angles anywhere from say 5 degrees to zero then we would be fine.

Trev

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 Post subject:
 Post Posted: Thu May 11, 2006 9:26 pm 
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yea the first time it was way out the 2nd time not as bad but still too negetive probably (I'm guessing) 7-10 degrees. After I found out there was a differance between the old leaf spring style and the coil over set-up
I realized there was waaay too much and I corrected it. it's about -1 or 0 now total pinion/driveline angle. I do still have a vibration...not sure where it's coming from, been worried about it for a long time but it hasn't broken anything..Luckily. Any idea's?

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6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post subject:
 Post Posted: Thu May 11, 2006 11:05 pm 
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Location: Western Illinois
us7race wrote:
I would play this one a little careful because I had too much negetive...
BOOM there went the back u-joint at 94mph, (twisting the driveshaft out and busting the transmission) then I got another case paid to have it all switched over checking everything and put it back in with a new driveshaft also...2nd pass later BOOM again same thing, this time I didn't even have to take out the bell housing bolts it came right out as soon as I pulled the cross member out, this time breaking the trans-brake in half and took out the pump with it. So I done some reasearch and got the pinion lined up at about +1 Degree because my tranny is up high in the chassis and put in a new brake and got a deal on a JW ultra pump and got it back together. Runs without breaking now!! ..Still got a slight vibration on the high end though just not near as bad as right before it broke before. So I'd go by the book on this by checking your transmission tailshaft angle vs your pinion angle to get it right..
this applies to I think everything except for leaf spring cars because they have alot more movement..
here is a link to some good info on this..
http://www.streetissuecustoms.com/pinionangle.html
I hopes this helps.
Jody If this is a good heavy duty U joint you may want to check your driveshaft ballance or a loose pinion bearing. I assume the tailshaft bearing was replaced with tranny. A U joint shouldn't vibrate on it's own. I've broken dana 60 axels one after another and still had the same u joints, not even worn. The axel problem got so bad I put straight die line on them and checked inbetween rounds. !/4 turn and out they came. That car hit extremely hard.

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 Post subject:
 Post Posted: Fri May 12, 2006 6:28 am 
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the u-joint's are new, all the bearings in the rear-end are new,including the crush sleeve in the rear-end, the driveshaft is new and balanced by a driveline shop, and like you said the trans everything is new including the tail shaft bushing. Now the only thing I can think of is a bent-input or out put shaft..because of the 2 times it broke the tranny. I don't know what else to do with it beside's that.

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6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post subject:
 Post Posted: Fri May 12, 2006 6:56 am 
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us7race wrote:
the u-joint's are new, all the bearings in the rear-end are new,including the crush sleeve in the rear-end, the driveshaft is new and balanced by a driveline shop, and like you said the trans everything is new including the tail shaft bushing. Now the only thing I can think of is a bent-input or out put shaft..because of the 2 times it broke the tranny. I don't know what else to do with it beside's that.
You have a couple good places to check. may want to get your dial indicator out and spinn these for run out. Check for a bent or loose spline on yoke too. I'm not sure what would be aceptable for run out. I do know if you can see it or feel it, it's not good.

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 Post subject:
 Post Posted: Fri May 12, 2006 7:51 am 
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Location: Beaverton Ontario Canada
Hello
I am a little nervous about a driveshaft letting go, since my corvette is quite narrow in that area and I am right there
I had a friend once who would not believe me that his motor needed to be tied down for for/aft movement
He was breaking the tranny off at the bellhousing, and once the driveshaft went tight, it was getting all bent. He did that for a few weekends , blamed it on the automatic and then went back to a standard
Many years ago, I helped a guy who had put a stick into a Mustang that was an auto car( just bought it around late 70's). When he got to the line and dropped the clutch real hard w/ a big slick it broke badly( a few times)_The last time he did not have ladder bars, only trac bars, so it folded the spring perches over on the rear end housing, so the pinion was pointing straight up into the trunk( track bars gone as well)
It also tore the side of the tranny off at the tailstock on the drivers side, so the driveshaft had the rear shaft of the tranny still stuck in it
We made ladder bars /fixed the car and it was OK. That was a long time ago. It was a 68 Mustang that had ran in the stock class, had 11 street miles on the speedo, guy sold it the weekend after it went down the track OK for $43- $4,600 Cdn, since he was scared of it now........it would be worth 30 times that now......he still cries about that one(only had the car long enough to break it, fix it and sell it)
.....A tad off track now with this story, but I did not have any good jokes for the other post, and I was starting to feel left out......LOL
off to go welding now
Tom
just make sure you get the driveshaft set up right


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