Two oddities

[WOODPIE]

While replacing rear sway bar bushings on our '73 2.0, I discovered two strange things.
1. The right outside pivot point for the trailing arm has been shimmed up with two plates and some standard size nuts placed between the pivot assembly and the mounting point of the frame, for a total of about 3/4 inch of shim. The left side is bolted,as far as I can tell, normally,as is the inside mounting points of both trailing arms. I am almost certain the PO would not know about this, as most of the work done during this car's most recent "restoration" was done by the previous PO. Any thoughts on why someone would find it necessary to do this? Rust damage or accident repair, maybe?

2. While tightening up some fuel line clamps in the engine compartment, I found a hole in the top of the intake manifold with no apparent purpose. It is about 1/4 to 3/8 diameter, and almost directly below the throttle arm. As a matter of fact, that's how I found it; playing with the throttle arm, the solid end of the cable flopped down and wedged in the hole. My research shows a hose marked 'Not Used' on page 40 diagram in my old Haynes. Should I simply find a suitable rubber plug for this orifice? The other air hose type lines seem to be correctly hooked up.

We have had this car for only a couple months, but also I have owned a '75 for 4 or 5 years. The purchase of the '73 has caused me to re-educate myself, so that I can more properly take care of both. Although I am new here, and haven't posted much, I regularly check this board. Thanks in advance for any of your comments!

[Dave at Pelican Parts]

The camber is generally set with shims between the outer trailing arm pivot mount and the body. It sounds like a TON of shimming was needed on the right side.

Best guess as to why: Rust repair done without careful measurements. If the suspension console was replaced, and it was welded on 1/2" or so too far down, you'd need a whole lot of shimming on the outer end to keep the camber angle from going very far into the negative.

The hole in the manifold isn't really a hole. It is the top of a "column" inside the manifold. This column helps support the manifold, and keeps it from getting squashed. There's another one on the other side of the throttle body, I do believe. Sometimes the manifold leaks around the top or bottom of these supports. Welding is a permanent cure, RTV is a temporary one, for this.

Ditto on the seam around the outside of the manifold--it can start leaking. Welding is a permanent cure, RTV a temporary one.

--DD

[WOODPIE]

Thanks Dave

Indeed , I detect a vacuum leak on said "hole". I get a feeling I should know what RTV is, but sorry I don't.

As for the trailing arm, what you said is the most likely answer I guess. I will take a closer look this weekend to detect welding repairs. I know the remedy would be a very extensive operation. At the very least, I would have to remove the aluminum foil wrapped around my fuel pump. The car is a daily driver, no race car, and I am happy with it's handling as is. I am thinking I should have the rear alignment checked out, though.
Happy driving!

[Conrad W Peden]

Maybe the trailing arm is bent?


------------------
CWP/VIR
72 914 L20E in rusto.
73 914 L20E 2.0L in resto.
http://members.rennlist.com/a914lover

[HMeeder]

Oooh, Oooh! I know this one!

RTV is a silicone sealer or gasket maker that comes in squeeze tubes. You can get it at any Kragen/Chief/Autozone for just a couple of bucks. It comes in several different colors/applications and I go for the black stuff.

RTV is excellent for sealing all those minute leaks and pinhole vacuum problems that plague our little cars that rely so much on solid seals to run properly. Some guys have quite a bit of the stuff in their engine bays! Another spot I use it is to seal the valve cover gaskets to the covers. Use it sparingly. You don't want the excess to get sucked into the motor our oil lines.

I favor Permatex Black. Withstands higher temps and gas and oil better and it's more difficult to see in the engine compartment. I know one guy who used liberal amounts of RTV red and it looked like he had glued his engine together!

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Herb
'72 1.7 Tangerine 'Teen
'74 2.0 Red Rustmobile

[sammyg2]

Room temperature vulcanizing, RTV, mostly known as silicon sealer, or instant gasket. Great stuff when used properly, worst stuff in the world in the hands of a DAPO.

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Gerald Gore II (Sam)
73 914 350 small block

[Doug914]

Okay, I'll bite...what's a DAPO?

[Doug914]

Oh, on reflection I figured it out myself...dumba** previous owner!!

[Dave at Pelican Parts]

I should'a thought of the bent trailing arm, Conrad. Thanks for pointing it out!

Yes, if the trailing arm has twisted in the direction that the wheel would lean in at the top, then a lot of shimming would be needed to get the wheel back to straight up and down. Replacing the arm would solve that. You should be able to make some measurements to see if the pivot of the left side arm is at a different angle than the pivot on the right side arm. You'll need a level and a ruler, and some confidence that the car itself is stitting level.

--DD

[WOODPIE]

Well, OK......I have a good 4 ft. level, and a tape measure. I can check the level side to side if needed with a water level. What should I try to measure? The angle of the pivot? Clue me in on this, Dave.

I am thinking here that I will be measuring the action or angle of an assumed correct trailing arm to the action or angle of an assumed corrected trailing arm. If the two sets of measurements fall within an acceptable tolerance range of each other, that means the shimmed arm is twisted. Am I close, or am I the Weakest Link?

[Dave at Pelican Parts]

Sorry, I wrote that one in a hurry.

You can measure the angle of the trailing arm pivot from horizontal. Put one end of the level on one end of the trailing arm pivot. (That's the tube that makes up the front end of the arm.) Make a mark on the level most of the way out toward the other end of the trailing arm pivot. Now move the higher end downward until the level is level. Measure down from the pivot to the level.

Compare those measurements for the one side, to the same measurements on the other side. If they aren't very close, one of the trailing arms is probably bent.

If you want to correct for the differing camber angles of the wheels, you'll have to take similar measurements of the wheels, and do some math.

Measure outward from the wheel lips to the level when the level is perfectly vertical. (I'm assuming the level also does "plumb", straight up and down--most do.) Divide the distance "out" by the distance "up" (along the level). This will give you the sine of the camber angle. Hit the arc-sin button on your calculator (or on the calculator program on your PC) to find the angle.

Simlarly, divide the small "up" distance you first measured on the trailing arm pivot by the "along" distance. That gives you the sine angle of the pivot to horizontal. The arc-sin button comes in handy again, here... The difference between the camber angle you figured in the previous paragraph is the angle of the wheel (and therefore the angle of the brake rotor, the hub, and the bearing races) to the trailing arm pivot. If you get a difference between one arm and the other, then one of your arms is bent.

Haynes has an illustration of the trailing arm out of the car and on a bench vise, with a straight line drawn. That's a way to figure out if one is bent or twisted without using all of the math--but it is more work to R&R the trailing arm than punch the numbers in on a calculator, IMHO.

I hope this helped at least some.

--DD

[WOODPIE]

I think I understand. If the wheel angle is different from the pivot arm angle, that would indicate some twist in the trailing arm. If the angles are similar, that would indicate that the aforementioned gross shimming job was made to compensate for a poorly replaced frame segment. I'll take a look next week--I sort of hope I have a twisted arm--this weekend it is new brake line hoses and speed bleeders on the '75. Thanks again to all for your input!

[Dave at Pelican Parts]

Wheel, the angles should be different--after all, the wheel is nearly straight up and down, while the trailing arm pivot is nearly horizontal.

You'd be looking for differences between the two trailing arms.

--DD