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Ok guys, let's have a friendly debate about this. I am in the midst of setting my engine and tranny up and running into some serious confusion. I have read different things about setting the proper engine/pinion angle and ride height.

I have read that (atleast for our trifives) that you sould level the frame and set the 4* engine down relative to the frame (as the pinion has the 4* built into it due to the spring perches.) Then I have read and been told that you should set "ride height", then set the engine/pinion angle.

So what is "ride height"? Apparently this is affected by tire size and car weight. So, to get ride height, I would need to set the body on the frame (fenders, hood, deck lid, etc.), put all the seats and windows in, gas tank with gas, and know how many passengers I am gonna take since people have weight, any cargo, then buy tires and wheels, etc.

The pinion angle varies due to the weight compressing the leaf/coil springs, thus changing the frame relative to the axle, no? If this is true, then bumps in the road, acceleration, braking, turning, amount of gas, amount and size of passenger, cargo, etc., ALL change the pinion angle continuously, right??

So how can you set the engine/pinion angle this way?

Let's have a debate on this. What's right? What's wrong? I am VERY confused. Am I way off with my thinking? Who has ever put together a car completely then put the engine and tranny in last?
 

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That ride height bit makes no sense to me. So if I change to a larger diameter rear tire, all of a sudden my engine is at the wrong angle?
Setting the engine at an angle to match the rear is what's needed. And having a level frame from which to compare makes sense. It's what I plan on doing.
 

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The ride height has no bearing on the engine angle, but it does on the pinion angle with a live rearend. The factory angle on the engine is 4 degrees relative to the main frame rails. On a C4 installation where the differential doesn't move, I set the pinion up in front at the same angle as the engine sits or just slightly less to account for compression of pinion snubber cushions.

With a rearend that is atached with leaf springs, the pinion angle changes as the springs are compressed and relaxed. It's not so much about ride height as it is getting the spring in the proper location to set the pinion angle correctly. There is some debate about where exactly to set it, but in general you want the pinion at the same angle as the engine while driving the car.

Since you are using the stock tri5 rear housing, it seems to me that all you should be concerned with is setting the engine at 4 degrees and calling it good. I would check the pinion angle just to see where it is. One way to do that without loading up the car with weight is to use ratchet straps to pull the frame down to ride height. Then I'd check the angle and see where it is.
 

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Starting with engine/trans angle, it has nothing to do with ride height. The 4 degrees was set by GM years ago to establish body clearances. GM built a 4 degree slant to the manifold to keep the carb level. The frame only has to be level front to rear to check the measurement.
Engineers determined that the engine and rear pinion should be parallel to reduce vibration and increase U-joint life, so the rear should be at 4 degrees at ride height. The spring wrap will change pinion angle so it's set at ride height so it will change an equal amount in either acceleration or decellaration of the rear axle.
To establish ride height the rear springs can be compressed with a couple of ratchet straps and pull the rear down to the measurements in the assembly manual. ....http://www.trifive.com/garage/57%20Chevy%20Assembly%20Manual/3-3.gif That will give the correct amount of spring wrap.
 

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I recentley had my driveshaft cut and balanced by DRIVELINE in Irvine, CA. I asked them pretty much the same question as presented here. He had a simple answer. Install everything as you feel it should be, start the engine put 'er in drive (or first if running a stick) and hit the throttle. If she vibrates on take off, your angle is to much. If you have o angle you will wear out/seize the u-joints after a while.
 

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Long subject. But to start out let me set the stage of what I and
several highly skilled friends have done, some operate top Shops.

First, we are talking about a TRI-5 stock frame with a solid banjo
rear end. No independant rear ends or custom frames.

I'm just about to install a Dutchman's 9 inch rear end and Earles
custom cross member for my 6 speed. So I'm doing this for the
second time.

Let me back up to the LS1 install. We set the engine in place and
set the radiator and core support in place, temporarly. I needed to
verify that the engine front accesories cleared the fans and aluminum
shroud and steering drag link. We had previously cut out the center
section of the floor boards and made a removable floor board "Tunnell
Cover" This made setting the tranny angle easier.....

Once that was done We finished welding the front motor mounts with
the Tranny to rear end pinion angle at a total of 3 degress, 1 1/2 on
each end. We placed a bottle jack under the assembled cross member

The car was on a drive-on lift with all seats, fuel tank, and such in
the car. I set the car to the "Ride Height" that I drive it at. Not the
LOW LOW at Rod Meets.

After the front motors mounts were welded in then we recheched the
tranny to rear end angle and adjusted accordingly. We then bolted up
the cross member with the tranny mount installed with a few shims.

The next step was to Tack in the cross member frame brackets, remove
the cross member and re-check the angle. All was well so we welded
the frame brackets.

Now, to be clear, we did not set the engine to a 4 degree angle down
at the rear because the LS1 injection is not affected by excessive
down angles. The important item was a correct driveline installation.

Carbs can have sensitive float issues, hense this can be very important.
We allways installed engines to as close to a stock front motor height as
possable. I've never had an issue with excesive down angle on an engine
if the drive line was set properly. However, once you set the drive line
angle and you have an excessive down angle on the engine then I
would thing that a person would only have two alternatives.

The first would be to shim the rear end pinior angle, I never liked this
solution, but it is done and you can purchase the shims. Of cource
then you would have to change the cross member height.

I prefer to never use shims on the rear end. As mentioned above, I
install a few shims under the tranny prior to welding in cross member
frame brackets. JUST in case you ever need to lower the cross member !!

As far as an engine with excessive down angle If I every had to get a
better or perfect 4 degress I'd machine a few degrees off a Carb Spacer,
simpler for me....

I installed the LS1 & 6 speed three years ago. Now I ready to install
the Dutchmans 9 inch [with a stock 4 deg] and Earles cross member.

The two primary reasons are. First even with the current re-built rear
end it's still a 56 banjo assembly - Too much ,, and I'll shell it.

And second the exhaust is too close to the floor boards. Even with
two and three layers of Duro Mat they get pretty warm when stuck
in heavy traffic on a hot afternood.

Earles cross member has bends on both ends to allow the exhaust
pipes to fit much lower, and be removed easily.

All of the is based on my Street Rod and a Few Race cars. And
I've never had an issue with u-joints or drive line vibrations.

If you move your engine back everything changes. In the times that
I've completed engine set backs we only had the rear end pre-set
But Tack'd not welded to a stock 4 degrees setting as a base line.

Once the car was complete we then set the cross member and rear
end angle,, Then welded

Yes, you are correct, pinion angle do change change as the car
is driven, but not much in a Steet TRI-5. Thats why you should
always set your drive line angles at the ride height that you
drive your car !!!

The Higher the HP, the harder you Drive, The harder you shift,,
The more stress is on the drive line assembly. We take our time.

If you need a cross member, try a converstaion with Earle at
Williams Classic Chassis. Earle is very sharp and can provide the
parts you need. His welding and fabrication is outstanding.

If you would like afew pics, let me know...

http://www.williamsclassicchassis.com/new/


Michael
 

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He had a simple answer. Install everything as you feel it should be, start the engine put 'er in drive (or first if running a stick) and hit the throttle. If she vibrates on take off, your angle is to much. If you have o angle you will wear out/seize the u-joints after a while.
Excuse me, and no offense to you 57lair, but that's about the dumbest thing I've read on this board recently. :sign0020:

Where do these people come from anyhow? They obviuously don't understand what causes driveline vibration and how to eliminate it. :rolleyes:
 

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One more thought.

One thing I found out the hard way....if you've installed the pocket kit into your frame, the shackles will take all the movement out of your axle so there is A. no need to strap the rear end down to ride height and B. no need to compensate for axle rotation when you're welding your perches in place. I originally set my pinion angle without the body installed on my frame at about 3 degrees down because I was told when the weight of the car is back on the frame it will rotate up about 7 degrees (which would give you the 4 degrees UP that is needed). That works UNLESS you've got the pocket kit. JIM.
 

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Once that was done We finished welding the front motor mounts with
the Tranny to rear end pinion angle at a total of 3 degress, 1 1/2 on
each end.
This wording is how the confusion starts on this subject. It's sometimes difficult to discuss this without defining exactly what we're talking about. What is "tranny to rearend pinion angle" defined as? What does "1 1/2 on each end" mean?

The bottom line is that you measure the engine and pinion angle relative to the leveled frame. Carbed chevy engines are designed to have a 4 degree angle, down in back. This is supposedly for a few reasons, but primarily to fit the tranny and driveshaft under the body easily. Other reasons cited are to cause air in the cooling system to go to the front of the engine, and oil to drain to the rear of the engine better.

The Tri5 body and drivetrain was designed for a 4 degree angle on the engine. The radiator support slants back 4 degrees too. Much less angle, and you're going to be cutting the tranny or driveshaft tunnel out unless you lower the engine somehow.

The "u-joint angles" are something different but must also be examined. The are defined as the angle between the DRIVESHAFT and pinion, and between the DRIVESHAFT and tranny tailshaft. Front and rear U-joint angles should be kept EQUAL, and no more than about 3 degrees if possible.

The pinion and the engine/tailshaft should be kept parallel when the drivetrain is under a load. That's the simplest way to look at it.
 

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One thing I found out the hard way....if you've installed the pocket kit into your frame, the shackles will take all the movement out of your axle so there is A. no need to strap the rear end down to ride height and B. no need to compensate for axle rotation when you're welding your perches in place. I originally set my pinion angle without the body installed on my frame at about 3 degrees down because I was told when the weight of the car is back on the frame it will rotate up about 7 degrees (which would give you the 4 degrees UP that is needed). That works UNLESS you've got the pocket kit. JIM.
Jim, I don't see how a pocket kit changes anything. The spring PIVOTS in the front and the pinion angle does change as the suspension moves up and down. The only thing a pocket kit does is move the spring inboard.

If I were installing a leaf spring rearend I would pull the suspension down to ride height, and I would install the pinion at 1/2 to 1 degree less than the engine angle. So if the engine is at 4 degrees, I would install the pinion at 3 to 3 1/2 degrees to allow for some axle wrap, which IS going to happen unless you have something to constrain it.
 

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pocket kit

Hey Chevynut. With the pocket kit installed the rear eye on the spring isn't FORCED to flex the spring like when its stationary on the stock spring perch. The movement is transferred to the shackle (my picture is upside down). Since the spring isn't forced to flex, it doesn't move the angle. JIM.

 

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The shackles act the same way whether you have a pocket kit or not.

Correctly installed, the front spring eye is at the same vertical location, pocket kit or stock.

The spring and axle housing is not going to rotate several degrees as the springs compress, due to weight on them. However, there can be rotation due to the torque reaction of acceleration. This is much different.

Some of you guys make this too hard.

There should be no need for debate here either. If there are differences - then there's only two reasons for it. Reason one is confusion over definitions, wording, and reference points for measuring. Reason two is some of the answers are wrong.
 

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Not me.

Lord knows I'm not the guy to get into a debate with you guys over this--you've probably forgotten more than I'll ever know. What I DO know is that there was NO rotation in pinion angle with or without weight on the frame and all movement (maybe with the exception of an RCH or two:)) was in the shackle--NOT the rear end as I was told it would (by an artical in Classic Chevy by Irwin). I even wrote to him about the misinformation. Maybe my car is haunted.:scared0016: JIM.
 

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Lord knows I'm not the guy to get into a debate with you guys over this--you've probably forgotten more than I'll ever know. What I DO know is that there was NO rotation in pinion angle with or without weight on the frame and all movement (maybe with the exception of an RCH or two:)) was in the shackle--NOT the rear end as I was told it would (by an artical in Classic Chevy by Irwin). I even wrote to him about the misinformation. Maybe my car is haunted.:scared0016: JIM.
As a matter of interest Jim, when you performed this task, you did wait until all of the weight was applied prior to doing a final torque up on the fasteners, right?
 

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Not yet.

As a matter of interest Jim, when you performed this task, you did wait until all of the weight was applied prior to doing a final torque up on the fasteners, right?
Nick, I still don't have all the weight on the car--glass/seats/fuel tank/exhaust, so I haven't done final torques on many of the suspension components. Body is bolted down and I'm working toward the time when I can torque/check stuff. I hope I'm doing things in order--I believe I am. JIM.
 

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Excuse me, and no offense to you 57lair, but that's about the dumbest thing I've read on this board recently. :sign0020:

Where do these people come from anyhow? They obviuously don't understand what causes driveline vibration and how to eliminate it. :rolleyes:
No offense taken. Just a messenger on that line. Any rate, yes there is a 4 degree on the engine and that's where most guys/gals make a big mistake when measuring the level of their engine. I've see guys set a level on the valve covers and set the engine/trans alignment based on that and go from there...Wrong When the carb mount face on the intake manifold is level, you have 4 degrees rear down tilt. Take it from there on your pinion angle.
 

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I just get the chassis level then put a level on the carb mount face ,that gives 4 degrees down then turn the level around and make sure the engine doesnt lean to one side or the other. I then make some mounts to suit this location.
Then I put the diff housing in with weight on the springs to simulate loaded weight using u bolts and the perches not welded then centre the diff from side to side then rotate the diff so it has 3 degrees then tack the perches then remove the diff and weld the perchs on. I usually get a diff specialist to fully weld the perchs so they can make sure the housing is straight.
Don`t know if this is right but I have done it many times and never had a problem. No vibrations no worn universal joints and many street miles and low 10second 1/4 mile times.
 

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I just get the chassis level then put a level on the carb mount face ,that gives 4 degrees down then turn the level around and make sure the engine doesnt lean to one side or the other. I then make some mounts to suit this location.
Then I put the diff housing in with weight on the springs to simulate loaded weight using u bolts and the perches not welded then centre the diff from side to side then rotate the diff so it has 3 degrees then tack the perches then remove the diff and weld the perchs on. I usually get a diff specialist to fully weld the perchs so they can make sure the housing is straight. Don`t know if this is right but I have done it many times and never had a problem. No vibrations no worn universal joints and many street miles and low 10second 1/4 mile times.
Sounds like a good way to do it. One question though. Do you go with 3 deg. up instead of 4 on your axle to account for axle wrap under acceleration?
 
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