4 link, driveshaft angle confusion

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finallyrunning
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4 link, driveshaft angle confusion

#1 Post by finallyrunning » Fri May 23, 2014 1:46 pm

I have 68 Camaro rear half with a 4 link that uses a ladder bar frame. 30" tall tires ( forgot who makes it). Built the car myself and just got it running. BB 482 700hp pump gas. Engine and Trans are in the factorylocation. Doing some pinion angle adjustment. This is what I got.
Trans 2 degrees down
Driveshaft is running up hill 5 degrees.....
Rear of driveshaft is 2.5 inchs higher at the rear

I was told that driveshaft so be running down hill to rearend. So at first I put rear pinion 3 degrees up to compensate for a -1 degree of pinion angle. Is this right?
Or should I put pinion 1 degree down regardless of Trans or driveshaft.
I don't know how it ended up like this car is almost stock ride height.
Need some true help. Thanks

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clutchdude
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Re: 4 link, driveshaft angle confusion

#2 Post by clutchdude » Wed May 28, 2014 5:35 pm

you don't want negative pinion. With a 4 link car i dont think you need much pinion angle 1-2 degrees?

Trans 2 degrees down, rearend 0 degrees would be 2 positive. My driveshaft also goes up from trans to rearend, depends how low the car is in the back as well as the rearend type. dana 60 / 12 bolt drive higher in the case than a 9 inch

finallyrunning
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Re: 4 link, driveshaft angle confusion

#3 Post by finallyrunning » Thu May 29, 2014 9:24 am

Thanks for the response

It's a 12 bolt. What I had was trans 3 degrees down and Pinion was 4° up. To give me a negative one degree pinion total. 3 - 4 = -1. But with the driveshaft running uphill at 5° , which would give me Universal joint angles over what I have read is to much. (Transmission yoke down 3° driveshaft up 5° universal articulation 8. (Right? I think.).
As far as the driveshaft running up to the rearend, from what I have tried to figure out is that even if you have the trans and pinion degrees the same, (but opposite), angles. The driveshaft running up to pinion is already passed the straight line your trying to get underload. ( pinion will not try to climb down ring gear, it climbs up to meet the straight line. This sounds a lot better in my head. Make any sense?

So what I have done is lowered the front of the engine about 1° which raised the trans mission tail shaft up 1° (which now the tail shaft is 2° pointing down) Then raised the ride height of the car 1 inch (which I don't like would like to keep the car lower) and reset my my pinion angle. So what I have now is trans tail shaft yoke 2° down, driveshaft at almost 0, pinion 3° up.

Need some reassurance does this sound good?
Thanks again any more info's always helpful

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clutchdude
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Re: 4 link, driveshaft angle confusion

#4 Post by clutchdude » Thu May 29, 2014 11:33 am

Lets forget the driveshaft angle for a min, driveshaft just connects the trans to rearend.

2 degrees down on trans, 0 degrees on rearend gives you the 2 degrees you are looking for.

Here is some good info also http://www.markwilliams.com/driveshafttech.aspx

finallyrunning
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Re: 4 link, driveshaft angle confusion

#5 Post by finallyrunning » Wed Jun 04, 2014 3:56 pm

Sorry to be a pan. But when you say 2 degrees down at Trans, 0 degrees at pinion , gives me the 2 degrees im looking for.....
That's ? 2 degrees positive up? or neg down?
I keep reading with 4 link I need 1 degree neg (pinion down). In relation to driveshaft.
Also. You said your driveshaft travels up to rear end as well? And this is ok?
I think maybe I'm trying to understand 2 different theories

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Bruce69Camaro
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Re: 4 link, driveshaft angle confusion

#6 Post by Bruce69Camaro » Thu Jun 05, 2014 6:34 am

Here is what I used to set mine up: http://www.swracecars.com/Files/pdf/10_300_400.pdf
Scroll down to page 6, Instructions for locating the rear housing under the car.
My pinion angle might, if I remember correctly is like 1 degree up, which is basically what clutchdude is stating.
Hookdaddy who worked for S&W is a member here, let me see if I can get ahold of him to give more details on what I posted a link too.
Those who think they know it all have no way of finding out they don't......... :scratch:

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Hookdaddy
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Re: 4 link, driveshaft angle confusion

#7 Post by Hookdaddy » Thu Jun 05, 2014 7:33 am

I'm still having problems visualizing a 4-link rear suspension on a ladder bar frame? Pinion angle on a 4-link is not nearly as important with as it was when early drag cars were using leaf springs and a pinion snubber. point the pinion at the rear of the trans and you're done.
Don Scholl
S&W Race Cars - retired
145H Super Comp
145Y Stock Eliminator & ET Brackets

finallyrunning
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Re: 4 link, driveshaft angle confusion

#8 Post by finallyrunning » Mon Jul 21, 2014 10:48 am

Thanks Don
What I have is a Alston pro street sub frame that has 4-link bars
(Ladder bar sub frame).
This is where I have it set.
Trans at 1.78 down. Pinion at 0.
What do you think?
Thanks.

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Hookdaddy
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Re: 4 link, driveshaft angle confusion

#9 Post by Hookdaddy » Mon Jul 21, 2014 12:48 pm

can you post a link to the Alston frame you are using?
Don Scholl
S&W Race Cars - retired
145H Super Comp
145Y Stock Eliminator & ET Brackets

finallyrunning
Posts: 12
Joined: Thu May 22, 2014 9:48 pm

Re: 4 link, driveshaft angle confusion

#10 Post by finallyrunning » Mon Aug 04, 2014 3:03 pm

https://www.cachassisworks.com/p-1551-p ... overs.aspx
I have one of the first versions of this 4link set up. It only has 4-5 holes on the front mounts and they are straight vertical.

Took the car to the track last week it ran 10:70 at 129 miles an hour off the trailer 1 time ever after building the car 20 yrs. car hooked pretty good little tired chatter on Hoosier QuickTime street tires. I thought that was pretty good for just your average gearhead building a car by himself from scratch need a little more preload. And loosen up the shocks a little bit.
Car was set up with the 1.75 down on the trans and the rear in Pinion angle set at zero.

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Hookdaddy
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Re: 4 link, driveshaft angle confusion

#11 Post by Hookdaddy » Fri Aug 08, 2014 3:35 pm

OK - now I'm with you. Forget that it once had a ladder bar frame in it. That's a true 4-link with equal length bars, it's just that the 4-link front brackets are mounted to the crossmember instead of to the frame rail. Sounds like the trans and pinion angle are ok. The limiting factor for now will be the adhesion of the street type tire. Start with some tire pressure adjustments and go from there. Keep us posted. 129 mph is big time for a 10.70 ET - that's showing me 10 teen potential
Don Scholl
S&W Race Cars - retired
145H Super Comp
145Y Stock Eliminator & ET Brackets

finallyrunning
Posts: 12
Joined: Thu May 22, 2014 9:48 pm

Re: 4 link, driveshaft angle confusion

#12 Post by finallyrunning » Fri Jul 17, 2015 9:14 am

Finally have a chance to get get back to ya.
Thanks for all your help. Gotta get it scaled and maybe move the IC alittle.
Car went 10.01 135mph. Pump gas ,exhaust, street tire. Then broke the gear. Still has a lot in it. Be spraying it with slicks soon.

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