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> ovaling of the rear suspention ear, +installation tips on rear susp bushings
ChrisFoley
post Feb 2 2003, 08:32 AM
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In order to get the bushing installation right, it is necessary to press the bushings into the arm. Then slide the shaft through until one end is flush with the end of the bushing. The difference from the end of the shaft to the end of the bushing at the other end is the total amount you have to trim off the bushings.
Usually the bushings don't fit well into the arm. They should require firm hand pressure to install. The shaft should slide through with little effort. Normally the bushing becomes out-of-round when it is pressed in the arm, and this causes the shaft to bind. Also the two ends are usually not on a common center, so even if the shaft doesn't bind in either bushing, it will when it is in both.
Monoballs eliminate the problem entirely, but require a lot of modification. Roller bearing kits are better than the Weltmeister polygraphite bushings, but they are expensive and have their own shortcomings. My Delrin bushing installation completely eliminates the binding problem. I also address the common problem of rust on the pivot shaft by grinding the shaft to a slightly smaller dimension.
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cha914
post Feb 2 2003, 01:49 PM
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I made the bushings fit like you describe...firm to press in, but where the center shaft slides in easily...and that did take a while...but I didn't know about them being too long and not allowing the shaft to bottom out...so I am going to yank them back off and trim down the faces. Glad I found this out before I went for an alignment...

Chris, I don't know anything about derlin...what is special about it itself...and what is so unique about your installation? not trying to attack, I am just curious...maybe a good option for me on the second time around doing this (which I expect will be at the end of this year).

Thanks for the help,

Tony
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ChrisFoley
post Feb 2 2003, 11:17 PM
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QUOTE(cha914 @ Feb 2 2003, 11:49 AM)


Chris, I don't know anything about derlin...what is special about it itself...and what is so unique about your installation?
Thanks for the help,

Tony

Delrin is a hard (usually black) plastic, much better suited for suspension bushing material than Teflon, Nylon, Poyurethane, etc. It is of a higher quality than the polygraphite bushing material and it will last longer. The polygraphite is molded, while the Delrin must be turned on a lathe.
I prepare the trailing arm by reaming the hole accurately, so my bushings press in with the right pressure and they are aligned to one another. That way the shaft, which I have ground slightly to provide a fresh smooth surface, fits without binding. I also add grease zerks to the trailing arm to lubricate the bushings, and trim the end of the bushings to fit the shaft precisely. I have seen some variation in length of the shaft, as well as the trailing arm, so there is no "one size fits all" solution.
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Brad Roberts
post Feb 5 2003, 10:31 PM
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I'm going to shoot two short video's tomorrow of the roller bearings installed on a FP car. I will "work" them by hand to show the lack of drag. Something insteresting that is being missed in this thread: Your plastic bushings can be reamed/trimmed/polished.. whatever and they can spin freely while testing them on the bench. The problem is: all this changes when the weight of the car is on the bushings. Today, Tony and I where taking a look at Bontempi's FP car trying to find a measuring point for the trailing arms....Tony pushed down on the left rear of the car (I had this apart less than 3months ago and it moved freely) the car took about 30+ seconds to rebound from his "jounce". NOW, our roller bearing cars move up and down with a "jounce". I promise a well installed and greased plastic bushing has more drag than any of the roller bearing cars. I know the roller bearings are not really designed for "Joe Blows" street car.

B
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Tony C
post Feb 5 2003, 10:38 PM
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Also another thing to remember is that when loaded (ie in a turn) delrin and Poly have HUGE amounts of stiction/friction. This is where roller bearing or spherical bearing REALLY come into play.

A side note on the spherical bearing set up, the link that someone posted to the PP board shows Armando's spherical bearing set-up, please be advised that this set up for me, or another fabricator to create will be $2000+. The roller bearing set-up that Mike M/Tony/Brad are working on will be less than $500 and WILL address the problem of lining up the shaft square with the innear pick-up point. Stay tuned for more information.

-Tony
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