Lime Rock Thrash: The Reassembly

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The aluminum trailing arm project is complete. . . WHAT a thrash it was, two twelve-hour days this weekend.

First of all, the parts count for this job was outrageous. Once you get into replacing all the parking brake stuff, the number of little things you need to make it all work increases dramatically. As it was, despite my detailed inventory of what was needed (see Lime Rock Thrash: The Diassembly) I still ended up with a few extra parts and short of a few others, which fortunately were the same part numbers as the '71.


The first step was monoball installation. This is very simple: I heated the trailing arm ends with a propane torch for about five minutes and slid the cartridges in. Be sure to have the circlips on the OUTSIDE of the car (why I don't know, maybe Chuck Moreland can explain) and be sure the red dots on the circlips are on the outside. Note to self: purchase a $2 pair of circlip pliers.



Next, and I had no idea this was going to be such a multidisciplinary project, I had to fabricate a new brake line to replace the one I sawed through. Fortunately the FLAPS had a 12" or so metric line, ISO, AKA "Bubble" flare, with the correct 10mm x 1.0 fittings. This, coupled with a $5 tubing bender from the FLAPS, made installation of the line a breeze, I made it a little longer than the factory line so it would clear the arm.

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Installing the Elephant Racing bushings on the Sway-a-way spring plates was a breeze. Chuck has engineered a terrific product, with easy-to follow installation instructions that even a simian like me could follow. The only fitting issues were that the adjustable plates are wider than the factory plates, and so needed to be spaced out away from the body to fit. It took a couple trials with spacers to allow the spring plate to freely move up and down with no stiction, while the spring plate cover bolts were at clamp load (I forget the correct torque, but it's listed in the Carrera manuals, I'll dig up the page next time.)



As you can see, it's a fairly simple job. The challenging part of assembly is getting the order correct: Install banana arm and torque bolts to 72 ft/lb (100 NM). Then install torsion bar. Then, using a jack to support the trailing arm, carefully mount the CV axle to the hub, don't forget the gasket and the grease. This turned out to be the most time-consuming aspect, as the gasket kept slipping out.

As a brief aside on the CV bolts, I had been using some M10x50mm bolts from McMaster-Carr. These were property class 10.9, made by Cam-Car, a subsidiary of Textron. Too long! While the greater length is OK for the 901 flanges, the extra length, even with a belleville/schnorr washer and moon plate, interfered with the aluminum trailing arm.

Fortunately I am Mr. CV joint bolt. I had a bag of about 48 from my axle job. But then, couldn't find my 12-point XZN 10mm driver! Fortunately, I had two bags of the correct SIX-point Porsche bolts, these are property class 12.9, made by KAMAX, 10x48mm, and they fit perfectly. Motto: never throw anything out. Correct torque is 60 ft/lb for the 10mm bolts.



Behold, the right side assembled. You can see that the spring plate droops fully. At the laden ride height, there wouldn't be any air between the adjuster screw and the block.

And what a ride height! I reset the torsion bars so the outer spring plate (the one connected to the bar) was at exactly 11 degrees, just like it was before. If anything, this should have resulted in a higher ride height, becasuse I set the height without the trailing arm and CV attached. But it's close enough, I think, to avoid having to have Dan Jacobs re-index the torsion bars to set the ride height. In any case, even if the torsion bars have to come out, it's a breeze with the Elephant Racing bushings- the springplate cover just slides right off.



Now, a rant about the Weltmeister sway bar. I hooked up one side, and I have to tell you, I have a hard time visualizing how this thing can work and not bind the suspension up. Also, the replacement toe eccentric that they supply, to which the bar is hooked, has SAE threads! According to Performance Products, this is to "make replacement of hardware easier." To which I say, why not design something that doesn't break in the first place, and if it does, metric fasteners are pretty common! As it stands now, the only freaking SAE bolt in the ENTIRE car is the one on the spring plate, I don't want to carry around a 9/16 wrench, getting it confused with my metric stuff, just to adjust the ONE toe eccentric! Smart Racing bars are in my near future I think.

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Interestingly, the bottom shock mount on this car was NOT a 12mm bolt like everyone said, it was a 14mm x 85 10.9 KAMAX. I think a prior owner may have changed to that to use the Bilstein Rallye shocks, I'll check PET to be sure. I ran the suspension through its entire range of motion with the torsion bars removed and shocks attached, there was NO interference between the larger shock tubes and the heat exchangers, which was a plus.

Now, about installing the parking brakes. Once everything was installed and torqued, this was the last hurdle. The trouble is, the PET diagram doesn't explain what you need, the factory manual has NO information about installing the parking brakes (only adjusting them) So, for posterity, here it is. The parking brake shoes have circular lugs on ONE end only, toward the front of the car. There are TWO expanders, separated by a double-inverted conical spring. One expander mounts INSIDE the hub, the other one outside, so that the notches in the expanders engage the lugs on the brake shoes. The cable should have the two 17mm lock nuts backed off all the way to the end (the end toward the front of the car), and then is threaded through the guide tube, through the "inside" expander, through the expander spring, through the "outside" expander, through a washer, then the castle nut with cotter pin are put on. That happens FIRST.

Then the springs. There are two springs, a long one and a short one. The long one has these strange backward hooks on it, there's no way you could bend the spring to install this once the shoes were on. So the procedure is: install the long spring inside of the expander, with the coils at top and bottom. Hook the hole in the bottom shoe through the spring, and the hole in the top shoe through the spring. Then install the shoes by sticking the spring retaining pin through the hole in the center of the shoe. Then install the conical springs on the retaining pin by fitting them over the end of the pin. Finally, the washers fit over the pin, you push them on with your thumb, and then holding the pin with your other hand, just rotate your thumb and lock the washer into place. Do the same for the bottom shoe. Then finally, you can fit the short spring to the opposide side, this goes on fairly easily One the short spring is on, you can stretch the upper shoe in order to fit the adjuster. NONE of these parts, springs, expander, shoes, pin, conical spring or washer were different than on the '71, by the way, but I wanted to replace everything with new stuff.

Now to the bumper. Peter at Rennspeed makes a nice product, unlike the experiences of some here, I had no problem fitting it up. With the old bumper removed, I clamped it into position on the quarters, and then installed the brackets which are separate. These needed to be ground down to fit-- once they were fit in place, I mixed up some fiberglass resin and glassed the brackets into place using some standard weave cloth. Not pretty, but it got the job done. Once the resin set up, I took the bumper off and reinforced the brackets with some more glass and resin. Finally, I put the bumper back on, bolted it up, and then mounted the "horns" to the tubular L- shaped pieces that stick out of the car with some 10mm bolts. Simple enough. The fit could use some refinement, but total time in fitting was about 1 hour.

When I have more time I'll work on the gaps, and also paint the bumper Light Ivory to match the car.

The thrash is DONE! I'm beat, and the budget took a major hit. It's off to Dan Jacobs for a corner balance and align. I also obtained a triangulated Strut Brace from Chuck Moreland at Elephant Racing, but this will go on after front alignment is set.

[jluetjen]

Great Job John!

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Thanks fellas. Noah, I recalled your bad experience with the SAW plates when I tried to insert the torsion bar through the splines, rather than fitting the splines over the torsion bar. After cursing the SAW people for making parts that were incompatible I remembered that the spline count was different!

The car needs the brakes bled also, I managed to run the reservoir dry during the bleeding process. Doh!

It makes you appreciate the value of experience. If I had to do it over, I could do it in half the time, which would be still be a full weekend, if you had all the parts to begin with. Not having to drop the engine was a HUGE time-saver.

[Britain Smith]

Here is a pic of my e-brake after I figured out how to put it back together. I also could not find any diagrams or instructions anywhere.

-Britain

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Britain, that's an excellent picture. The rectangular metal things at the top are the expanders, one ouside the backing plate, the other inside, separated by a spring. The back of the expander has a circular protrusion on it, that goes inside of the expander spring.

You can also clearly see the long spring, and the bizarre attachment points for the ends. The end of the spring is actually shaped like an "S" and you are supposed to hook the upper bend of the "S" through the hole. Which is impossible with the shoe in place, so you have to move the shoe around the spring. Also clear is the short spring, with its much easier attachment, and the adjuster, which is actually two pieces. Properly assembled, the short spring holds the adjuster, and to change the position of the shoes you stick a screwdriver through the hole in the brake rotor and turn the adjuster left or right-- the spring acts like a detent to only allow you to turn it click by click.

Finally visible are the conical springs, pins and lock washers. These look harder to work with than they are.

Nice arms, BTW. I was considering polishing mine like Gunnar Racing, until I realized that the aluminum is VERY easily dented, and that it's probably over-engineered against any "stress risers."