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348 suspension tuning bushings etc.

Discussion in 'Technical Q&A' started by fatbillybob, Dec 9, 2003.

  1. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
    16,627
    socal
    Hi guys,

    A long while back Rexrcr and I have had some discussions on suspension tuning. Finally, my parts are with Rexrcr (Rob S) for some shock tuning and spring work. I'll report here what is done and perhaps Rob can tell you more technical details. So we'll give you a report here the end of December/January on the shocks and springs. My guess is a heavier front end spring and softer rear ala 355C. I'm tracking the car only.

    To that end I started looking at the rubber bushings. MY car is a '91. All you guys with old cars would be amazed at how crappy your bushings are either by original rubber design or fatigue and age rotting. I don't think Italians can make rubber any better than they do electrical systems. After playing with these bushings it is a miricle my car can stay on the track at all.

    So I researched bushings here is what I found. 348C bushings have part numbers but no one can get them. They cost out at about $4,000 of you can get them. 355C bushings are available but no one can confirm if they will fit the 348. The 348 uses all the same kind of bushing but 3 different sizes. All 348 bushings are the same except the lower rear a-arms having two differnet sizes.

    Since I could not confirm if 355C bushings fit nor could I confirm the materials of either the 348C or 355C I decided to not bother with OEM Ferrari bushings. Additionally, Joe at Concours auto who is a racer was not impressed with 348C bushings but thought they were some kind of teflon. I looked into having someone custom make bushes for me but 2 guys chickened out.

    I took one bushing apart to find that the construction was really basic. I bought a lathe and researched materials to use as bushings. It seems that bushings are either rubber, poly urethane (energy suspension type), Delrin (acetyl), or bearing (Heim or monoball).
    This is also the order of worst to best regarding performance but ride quality degrades in reverse. I don't care because I'm a track car. For sake of simplicity I chose Delrin. Delrin is a mother of a hard plastic related to nylon but does not melt like nylon. It is teflon impregnated so the plastic is slippery. It is way better than PU for racing but PU is a better compromise for a street car. ..not interested. I lathe cut the bushings with about 0.003" interferrence fit so they would allow arm articulation. Rubber only allows the arm to articulate as the rubber gets twisted between inner and outer bush shell. It is important to have rotational ability so that you don't have stiction in the suspension. If you have stiction Rob S will get mad because it will upset your wheel rate and all that nice spring and shock work he does. :). The Delrin really makes nice hard bushings. Many racer consider thisto be a solid linke suspension. However, IMO I think that only metal can be a solid link so that means Heim or Monoball. Of course at the end of doing such a nice project I finished the last bushing only to get cocky.

    Now I'm going to make Monoball bushings for a truely solid suspension . This only because my lathe skills have gotten pretty good in a short time and "I feel lucky". For those who are interested the Heim joint is also called a rod end joint. To use this on your Ferrari would mean a cut and weld and some re-engineering of the arm ends. I don't want to be a guinnie pig so that is out. However, if you could find a pro to do such a conversion you would have an infinately adjustable suspension and very trick. The Monoball is basically and spherical bearing in-cased in the outer bushing shell with the control arm bolt running through the center of the monoball. This allows a range of articulation and little stiction in the suspension= happy Rob S. The monoball is the ultimate hard link using all OEM parts except the monoballs. So you can't get in trouble.

    If anyone needs the bushing dimensions sans the outer shells let me know. I think that we all ignor our rubber bushings too long. If you do nothing else put in new OEM rubber bushings to restore some lost handling. If you jsut got rid of all the rubber in the 348 suspension including the shock and spring rubber you would improve your handling. You will degrade your caddillac ride but if you want a caddy go buy one....
     
  2. jjstecher

    jjstecher Formula Junior

    Jan 21, 2002
    962
    Rochester Minnesota
    Full Name:
    John Stecher
    BillyBob hit me up with the bushing dimensions, I have been trying to get a set of Poly ones for a while now but havent had time to measure my own. I talked with Rob earlier about getting a set of the Challenge bushings but at 4k are a little expensive and provide to harsh a ride for the street and track time I put in. Have you contacted Engergy Suspension yet about if they can match what you need?
     
  3. ernie

    ernie Two Time F1 World Champ
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    Right on Billybob. Good work man. I bet even after you spent the dough on the lathe your are still saving thousands of bucks over buying the factory crap.
     
  4. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    Ernie,

    You crack me up. Remember what we have always agreed upon...its only a car. Are you running yet? Fun times are coming 1/17 at buttonwillow. There will be 3 Ferraris out there so far.
     
  5. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
    16,627
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    JJ,

    The dimensions I have are the finished bushing dimensions that go on the OEM inner sleeve and in the outter sleeve. I think you are thinking of pressing your old bushings out in total and pressing new ones in total. Also, I contact ES and they were not helpful at all. REmember the botched group buy??? They suck. Personally I would not buy anything for ES. I know they do not have bushes for the 348. The 348 bushes are a very specfic size and there are 3 of them. Not only do you need the overall length for example but the position of the inner sleeve relative to the outter sleeve is important. You can have or make a bushing with the overall length correct and it not work due to this problem needing length relative to inner sleeve position. This position is held constant by a flange of a specific thickness. I found when custom making these that the error was about 0.1mm. So you can't just measure them without calipers and think you are all right.

    I can't get you a critical dimension of the outer bush size since I never had to press out the outter sleeve. There was no reason to do it. You need the inner diameter of the A-arm of which there are three different sizes and obtain an exact dimension with a proper caliper and then build your bushing to 0.003" oversize for a proper press fit. Precision is very important here.

    If you just press out the inner sleeve and and reuse the OEM shell and washers my dimensions will be perfect. I used a 0.003" press fit on Delrin and may have to go to 0.001" if they do not wear in nicely. Poly urethane is spongier. I would think 0.003 or a tad bigger would be needed. But you will get squeaking! PU squeakes. Delrin does not. It depends on your definition of loss of ride quality. A bumpier ride or a squeaky one. Remember the 80's corvetts?
     
  6. jjstecher

    jjstecher Formula Junior

    Jan 21, 2002
    962
    Rochester Minnesota
    Full Name:
    John Stecher
    BillyBob,
    I started disassembling the front suspension last night and I am going to bust out the calipers when I get it done to get a measure on the bushing size that I need and order them one at a time. I talked to ES and they were a**clowns like before with the group buy. I thought maybe they had changed their tune but they still suck. Besides that I know that Norwood sells some bushing for the 348 so I am planning on talking to them when I get a chance here today. I know ploy squeaks like no other and that is the reason I have stayed away from it till this point. Now after thining about it I would rather have a harsh ride than a squeaky car...I dont think anyone would want an 80's Vette squeaky Ferrari. Anyway let me know how your progress goes along with your Delrin bushings, I would be interested in installing them if everything ended up in the correct price range for you.

    Thanks for the help as always BillyBob!

    John
     
  7. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,333
    As long as you are in there experimenting anyway; let me suggest that before you weld the newly machined bushings onto the a-arms, that you assemble the a-arms, install in the chassis, and work/play to make the a-arms move freely but without any slop. Then spot weld them in the car so that they remain low friction when the suspension is assembled for the final time. Lowering the friction will pay dividends in grip in bumpy conditions.
     
  8. 348paul

    348paul Formula 3

    Dec 27, 2002
    1,098
    Kent - UK
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    Paul Hill
    Billybob and all,

    If you need to make any of these in quantity, I would be more than happy to have a look at making a batch. Delrin (Acetal) is one of the easiest to machine so the parts would not be that expensive. :)

    All we would need is a dimensioned drawing.

    Paul
     
  9. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
    16,627
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    JJ,

    My bushingings are installed! I went with Delrin to increase the solid link feel. If racers are not using solid bearing joints like monoball or Heim they are using Delrin. Check with Norwood to see if he has Delrin. I never thought of checking with him. Anyway my project is done I;m just waiting for Rob S. to ship me springs and shocks. Actually, I'm making adjustable end links and Delrin sway bar bushings now. I'm going with Rod ends one left hand one right hand and then a hollow steel tube with nuts welded on the ends to act as a threaded tube. I could not find a threaded tube and I could not find the tooling to cut threads in a raw 12mm tube nor could I figure out an easy way to add flats to the tube to adjust it. So I figure it would be easier to weld nuts and then lock the rod ends down with a double nut kind of like the steering rod end. The reason for the adjustable end links is to take this out of the equation during "corner weighting" of the car and then so as to not ad back in an error during re-attachment of the end links. Since I suck as a driver I have to take every advantage I can get. I'm smarter than inately skilled so I have to capitalize on that. If you are dismantaling your bushings do not destroy the washer nor the inner or outer sleeve. You may find it cheaper to go my route and make the delrin bush. I also have a good way to get these out of the A-arms if you want me to post it.
     
  10. jjstecher

    jjstecher Formula Junior

    Jan 21, 2002
    962
    Rochester Minnesota
    Full Name:
    John Stecher
    Paul that would be very interesting if you can get these machine...I wonder who all on the board would be interested in putting up some cash to do a larger order for the 348 to minimize cost?
     
  11. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    Smart move. Try aluminum hex stock, drill and tap for your rod end, cut a line adjacent to the LH threaded one for reference, then make standoffs for the ARB and control arm. A 3/8" or 10mm rod end is plenty for ARB loads.

    This set-up is on 355 Challenge and should bolt on to 348. But as usual, I don't have part numbers and it'll probably be less expensive to DIY.

    Or, get metric rod ends that thread together and fit directly to the control arm and ARB end link. This will be large bearings, inelegant, less precise, but less machining.

    In the good old days of 348 Challenge, adjustable drop links were forbidden. I had to set up one chassis with tilt just to eliminate 200 lb of crossweight. Had that car on the scales at Road Atlanta for hours trying to work around the issue.

    You're gonna love this system.

    Rob
     
  12. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
    16,627
    socal
    JJ,

    I took my readings directly from my bushings and Chinese caliper FWIW. Therefore, it is possible that my numbers are off and if so the error needs to be in the neighborhood of 0.05mm for good function to remove stiction. Also, for all we know Ferrari has a supplier of these bushes and their requirement may have been overall length overall diameter and then flange thickness. If that is so then the inner sleeve could be any thickness and that would screw up a group machine project. When you get yours apart e-amil me the dimensions to the closest 0.1mm so we can compare. If both our numbers match there is a greater possiblity that you guys could do a group machine project. Go ahead and put out the feelers for such a project but there are some constraints like one end of all bushes has a delrin washer that needs to be made so the washer fits nicely. This extra delrin washer was where some rubber used to be. you xan see it protruding right now from your a-arms. The thickness of this delrin washer is dependent on the final resting place of the outer sleeve. That dimension may not be the same on all cars. The second contraint is the material itself. There are slight variations in delrin. You need to find one on the lowest end of the CF for more slipperyness and low water absorbing.
     
  13. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    Rexrcr,

    I can hardly wait for the spring/shock set-up. I love new toys! Thanks for the tip on the end links. I was going to use steel tube becasue the OEM links are thick Aluminium. It is hard to know how much such an item needs to be able to take. Thanks for the tip on the Aluminium hex rod stock diameter. I'm now on the hunt for that and the correct taps.
     
  14. jjstecher

    jjstecher Formula Junior

    Jan 21, 2002
    962
    Rochester Minnesota
    Full Name:
    John Stecher
    Billy,
    I hope to get around to the car this next week, I have to take care of some house issues this weekend but will be back in business soon. Thanks for all the input you have been extremely helpful.
     
  15. ernie

    ernie Two Time F1 World Champ
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    Hey billybob, unforutately NO I'm not done with my car. I went to the poweder coating shop last friday and they weren't even close to being done. They have had them over three weeks now. I did ask them to do some masking that is a bit of a pain in the butt, so I really didn't push the issue. Anyway next should be done next friday. If they aren't done then I'm really gonna be irritated. But I will finish this thing soon.
     
  16. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    Erine,

    Did you end up taking the lower part of the motor out to replace the timing gear bearings?
     
  17. ernie

    ernie Two Time F1 World Champ
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    Naw I'm gonna take my chances. I think it will last till the next 30K no problem.
     
  18. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    Thats ok. it is easy enough to get the engine out. You can do it again some time.
     
  19. No Doubt

    No Doubt Five Time F1 World Champ
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    Mr. Sideways
    Did this ever happen?? For street (rubber/teflon/polyur) or just for track (delrin)??
     
  20. evansp60

    evansp60 Formula Junior

    Nov 2, 2003
    383
    Ottawa, Ont. CANADA
    Paul,

    If you make up a batch, I'm in for a set.
    I'm sure others will line up!
     
  21. Ingenere

    Ingenere F1 Veteran
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    Dec 11, 2001
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    I would be up for a set of the Delran busings as well.

    Dino
     
  22. No Doubt

    No Doubt Five Time F1 World Champ
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    Mr. Sideways
    Our wait continues for new bushings!
     
  23. 348paul

    348paul Formula 3

    Dec 27, 2002
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    Paul Hill
    Believe it or not, these are still on the back burner waiting for a decision. I have done quite a bit of research on this subject over the last year and material specification is still nagging at me. Delrin does seem the most obvious & popular choice but I have a couple of other specs of material that are MoS2 filled as well and the advantages of these can not be overlooked!

    Paul
     
  24. PAP 348

    PAP 348 Moderator
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    Dec 10, 2005
    85,061
    Mount Isa, Australia
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    Pap
    I dont really want to start another thread about this,but i was just wondering,ive been looking at all the 348 pics on here,and most seem to have the rear wheels sitting a little further out than mine. Im assuming that they are wheel spacers? Do they really help that much?? Or do people put them in,for better handling because they race the car around a track,not so much for street use. Or is it for tuffness reasons?
     
  25. Ricambi America

    Ricambi America F1 World Champ
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    Dec 7, 2003
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    Daniel
    On my car (1990 348, s/n 86426), rear spacers made a HUGE difference the stability of the car around 110mph. Before the spacers, the car used to get very "light" and drifty at high speed. With the spacers, my car behaves more predictably and sits down properly.

    On late 348's, Ferrari actually increased the rear track of the cars because of this known handling problem. Early cars -- I think 1989-1992 -- simply had a rear track that was too narrow. All would agree that upon installing spacers, the car should be properly re-aligned.


    Most 348 brothers who install spacers use either the 15mm rear spacers with longer bolts, or 25mm rear spacers. Both sets are available from Hill Engineering (and of course Ricambi!)

    http://ferrarichat.com/forum/showthread.php?t=56851


    -Daniel
     

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