Bushings...why the 550 is awesome

In its day the 550 was the premier Ferrari. Has anyone ever seen a rotating rubber bushing? Not me. The 550 is the first car I have ever seen with quality rubber bushings designed to take the stichion out of your suspension so that your suspension can perform as designed. Most people have no idea what I am taking about. If you care read on. If not go to a new thread because this is going to bore you to tears.

OK, so in racing the goal is to have the a-arms freely moving about the attachment points with no friction. The best way to accomplish this is with bearings (aka monoballs), then delrin bushings, then rubber bushings. Rubber is for comfort and to prevent noise transmission to the chassis. Bearings make for the most accurate and reproducible suspension setting throughout the suspension travel. This makes for the best most consistent tire wear and control of the tire contact patch on the road. Hence high performance. Comfort and performance are inversely related...that is just life. So with a streetcar with attitude you have to compromise and that is what all high performance cars do.

In my quest for the hottest suspension on the ragged edge of streetable I have decided to make delrin bushings as I have for many racecars in the past. I like delrin because it is cheap and easy to machine and performs like bearings and has a similar life but takes much more time to hand fit and mill each bushing. That's where delrin makes no sense time vs. cost but I got time so that's what I am doing.

So back to the OEM ferrari fantastic rubber bushings. You can see in the picture of the bushing taken apart that it is not typical. What you have is a typical spool looking metal bearing inside a bearing shell and then a second spool with antiseize on it that rides on outter spool. Rubber is sandwiched and that allows the a-arm to freely rotate. At least one poster in the past has thought his inner bushing was ripped apart and bought new ones but really this is the way the 550 bushings work. All other cars I have seen use an inner spool married to the shell and when you place the a-arm there is massive stichion. Also on the OEM 550 bushing the thickness of the rubber is very small so there is not much movement of these spools. I believe that I'll get less improvement in performance with my delrin bushings because usually there is a mile of rubber in there. I also think that the oem 550 bushing will wear out faster than typical bushings because of this thin rubber. So replace your bushings and get back that OEM performance.
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Now this is a picture of the reject superformance bushing from ViVek's thread. The black lines point to one spool of the bushing. The red line point to the other spool of the bushing and they can freely rotate on each other. This reject bushing is fine as long as the rust does not rust the two parts together preventing free rotation.
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This is also from Vivek's thread. Notice how this smaller upper a-arm bushing does not have the double spool. This one is of the typical bad design. I think this is also from superformance. The OEM bushings in my 2000 550 have double spool bushings on both a-arms. So if you want maximum performance there are two questions to ask superformance. First is the durometer (rubber hardness) of the after market bushing same as OEM? Are all the aftermarket bushings for this application double spool? A bushing that fits is not adequate but might be better than blown out bushings but not by much. I use the term double spool bushing because I don't know what it is called. IF someone knows what the oem 550 bushing is called please post.
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I have completely removed my suspension right down to the pick-up points. I am impressed on how well the 550 is designed better than any Ferrari I have taken apart to date. I believe that more maintenance is needed than is typically given to suspensions. Too many people never change shocks and never change bushings. These are a wear item and wear faster in 550's because they were designed for performance not durability. My Chassis frequency calculations show that this car was not set up for comfort but to Ferrari's own compromise on the sporty side of streetcar. Complaints of porpoising are an indication of that and also an indication that shocks need attention.

 

Perhaps you had polyurethane bushings. Almost no one but racers use delrin and delrin bushings are always "hand" fit because the tolerances need to be a few thousands of a millimeter to take up the play but freely rotate. Delrin does not squeek as it is self lubricating and by design they freely rotate, but like bearings noise is transmitted to the chassis.

 

Yes I would replace but about the entire fleet runs bushings like your condition. I think that people just don't know what they are missing in performance. I'm a little weird in that I race so I have a different expectation out of my sportscars. The 550 is set-up to be a kinder GT car not like the 360 in the lineup. So if the 550 is used as a weekend car taking the wife to dinner and an occasional blast to 80mph replacing the bushings is an anal excercise. But if you demand all the engine to suspension performance you paid for and even seek to remove Ferrari's compromise to their level of streetable, it is going to cost you. When I'm not racing I'm thinking about racing. Every time I get in my 550 I wish I had a rollcage and 1000 less pounds in it. I got a disease. So please everyone has to understand my problem and only make "my problem your problem" if you are demanding.

 

Hi John,

Yes Flanblock. Ferrari has used this term since at least the 308 but the 308 never had freely rotating rubber bushings. I'd like to know what this type of rotating bushing is called. Someone else has to make them. I wonder why I have never seen them before or why a company like energy suspension claiming all kinds of great things from their poly U bushings that all users know is BS has not stepped up their game and gone to a rotating double spool design.

I stay away from p-bugs. I have a long history of pain from them but that's a personal problem.

As to our 550 bushing wear what you say makes sense but in reality my 12-13 year old bushings were toast. There are 13 years of 1000lbs of static corner weight. The saging of the bushing and the thin rubber washer ends squeeze out of the bushing and get pinched out until non-function. You can really feel the a-arm slop in your hand when you disassemble down to the a-arm and wiggle it with your hand! With your hand and I am weak! The rubber stays bonded. It took a torch to get it out easy. The primary wear is on the spool ends. If you think about it that makes sense. All the forces it sees are fore/aft and a blunderbust reaming out of the spool ends from the various lateral forces acting on the a-arm. If the rubber mass was greater they would last longer but then would not perform as well. The interior rubber is only about 3.5mm making for not a lot of movement. That is why I suspect that my delrin project not give me the huge differences I normally feel when I go to delrin suspensions on say my Corvette or BMW.

 

The unsprung weight on each corner is over 100lbs (I weighed them). Even your hand force is nothing compared to the static 100+ or the forces in motion. I suspect the new bushings will free up like the old ones with time except the upper which on the superformance site looks to be traditional non-double spool bushing. When you use new bearings or monoballs the light a-arms just flop down with gravity. When you use delrin you can wack them with hand pressure and they move wherever but don't freely droop until some wear sets in. Rubber and polyU twank like a rubber band. Wherever they are they stay and impart some preload to the suspension kinda like a swaybar without adjustable endlinks. So the double spool rubber bushings doing what you describe seems perfectly in the relm of normal and exactly what one would expect 1/2 way between a traditional rubber bushing and Delrin.

 

Yes they should because the bushing is pinched by its outter spool like a normal bush while the inner spool is free to rotate.

 

Yes you got it. Stiction really is not a streetcar issue. But it becomes real important when you try to manage tires with reproducible suspension results, precise corner weights, and precise timing on track where fuel loads make a difference even in a 3000lb car. It may seem like a rediculous excercise but even in SCCA clubracing our drivers get their undies in a bunch over a few millimeters of intake restrictors or 25lbs of ballast.

I guess what really got me to post about this is how impressed I am that Ferrari bothered to use good bushings. However, somehow they allowed designers to make 100lb doors and use 60lb seats! arghhh! It's like a 500lb woman wearing sexy stockings and Louboton pumps. What is up with that?

 

I would love to see pics of the project boxer racecar. Post them up! If you are starting with a shell my first reaction is tubeframe it and go with a hundred suspension designs where parts are plentiful and cheap. Stockcar suspension parts can be adapted to tubeframes and make killer fast cars light with excellent brakes that don't break the bank. A whole corner's monoballs can be had for the cost of one Ferrari rubber bushing and wheel spindles/ hubs can be had for the cost of Ferrari brake pads.

 

So in earlier posts I showed the bushing taken apart. I'm lathe cutting delrin pieces to replace the rubber. Fits are exact. Here is a sample of the front lower control arm bushing. The result will be no rubber slop, long bushing life, and free rotation. This should be very close to monoball suspension performance.
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assembled bushing out of a-arm. It is a lot of tedious work but the benefits are worth it IMO. I have done this on 3 race cars. Delrin suspension may be a bit rough for street drivers and can transmit some noise to the cabin. I don't think it is bad though not for everyone. Don't do this if you want comfort for all your senses.
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