Rear shocks

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Topic originally created by Mike Meehan on July 29, 2005 12:20 AM and viewed 3534 times in the old forum.

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Originally posted by Mike Meehan on July 29, 2005 12:20 AM
I know that this subject is old news to some but does anyone know if the Koni replacements for the self leveling units are the same for US and EURO cars. Also interested in peoples experience with fuel pumps.

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Originally posted by JeffLit on July 29, 2005 1:16 AM
I do not know if there are differences between Euro and US rear shocks (I suspect not). Attached below is an old e-mail thread on these units, just to get it into the durable (and searchable) record for future members: The front half of the rear shocks is simple. You can send them to Koni or any other Koni repair center for rebuild and dyno. Same with the fronts. I had mine done by ProParts (they advertise in some Ferrari pubs) www.tripointengineering.com/Koni/koniCenter.htm but any Koni center will do. The "load levelers" on the rear half of the car are another issue altogether. These were not used on Daytonas but they were used on 400s for a number of years (and 356 GT2+2s I think?). The following is just my opinion and experience. Koni won't touch them. No one seems to want to accept blame for their design. They're strange beasts, and probably never worked the way they were intended. In fact, I've had them completely apart and I can't see how anyone could have ever expected them to level anything. Every Ferrari expert I've ever talked to says that they didn't level. Also, anyone with a basic understanding of physics can see that having two shock/spring support assemblies of differing spring rate and dampening characteristics, all mounted to a single control arm in single shear is a really bad idea. They torque the heck out of the control arm and bushings. I've had as much weight in the back of my car as you're ever going to successfully manage -- my wife and one daughter, along with me and my other daughter up front and some fold-up chairs and cleaning supplies in the trunk. The ride height and quality (with the coilover units described later) never changed perceptibly. Other than originality, the load levelers hold no allure to me. When you talk to people about having the load levelers rebuilt you will undoubtedly end up pointed to Jeff LeBlond in Arizona. I heard only negative opinions of his work so I visited his home/shop when I was racing at PIR once a few years ago. Personally, I wouldn't let him touch anything I cared about but, hey, your mileage may vary. I ended up rebuilding mine myself but this was no simple task and the end result was not perfect. I had to mill a new internal plate to accept a standard o-ring since the original seals are unobtanium. I also had to weld in bungs to accept Schrader valves from Penske race shocks in order to be able to charge them up when finished because Koni originally used a special "gasifying" tool for filling these, something I don't own. I was fortunate that my internal bladders where in good shape so I could attempt my own rebuild. If yours are damaged then you're in worse shape than me. Even so, I'm not happy with mine. They hold a charge (how much they should be charged to is something I'm not sure of but it seems like about 170 psi (memory here) gave the same spring rate as the front shock/coilover when I tested them both in a press) but they don't work on the car as well as I would like. The good news is that I can adjust the pressure via the valves (kinda like air shocks) but the bad news is that they aren't as consistent as I would like and you need a portable nitrogen bottle to fill them because you can't get enough psi from a compressor. Instead, I ended up buying a setup from T. Rutlands that Ted supposedly had configured by a guy from Koni for use on his own car. They consist of a Koni shock with a threaded adjustable spring perch welded on, and an Eibach spring to go with it (I'd have to look up the spring rate). Supposedly, the Koni guy spent two days testing different springs and shock valving configurations to come up with this setup. All I know is that it works really well, and allows ride-height adjustability via the spring perches. You can buy this from T. Rutlands (I get no commission ;-). These were on my car at Monterey 04 and I won platinum in the Concours so either no one noticed or no one cared or the points loss was inconsequential. I've heard rumor that some Land Rover service shops should be able to rebuild the original load levelers because they are similar to units used on their trucks but I have not been able to verify that. The picture below shows the internals. In that picture, the shiny aluminum piece is the piece we milled up to accept an inner o-ring, as well as the outer o-ring. Compare it to the piece to its left, which was designed to accept a seal that sat in that recess, instead of in the groove in the inner bore that we created in the new piece. Oh, and preemptively... no, I will not rebuild yours, nor can I provide additional copies of that milled plate -- it was not CNCed, it was done by hand in the lathe. If someone finds a reputable rebuild shop I am still interested. Long windedly yours, Jeff Aaron then wrote: Regarding the Levelers - I pretty much went the same course as Jeff - although I did have LeBlond put new seals in my units - One of my units has leaked down since, and because LeBlond did not have a clear understanding of how the bladders worked, He put the charge shrader valves on the Oil side of the bladder. Live and learn - I wrote this up in a post on one of the chat/talk sites a while back - bottom line, regardless of intent - the Levelers really work more like an air shock than an actual leveling device. So far everyone I know with leveler problems has eventually ended up with "spring overs" in the back, usually adjustable. In my evaluation, the leveler needed to support about 350 lbs each at the correct ride height. After some experimentation I ended up with 80lb/inch springs on a QA1 shock compressed a bit over 4 inches at the correct ride height. If I recall I think the Koni coil over has about a 90lb/inch spring rate compressed about 6 inches to carry the other half of the 950 Lbs. Also, the Levelers contributed very little damping to the system, so I needed to adjust the QA1 damping way down. As Jeff points out, the correct way to do this is balance both the load and the damping between the set of shocks. The shop manual has the "shock dyno" graph of what the damping rate should be. Aaron Mike Mo. also confirmed: The self adjusting Konis, as expected, didn´t last one year past their last rebuild. I opted for an additional set of Konis and coil overs but never got them installed. Suggest you don´t waste you money on LeBlond or these units. Mike Mo.

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Originally posted by Zanny1 on July 30, 2005 8:21 PM
Everyone I have ever talked to, including Tom Shaunessy, has said "don´t waste your time or money on these shocks or Jeff Leblond". I personally believe the most distracting feature of the C4´s look is the way it squats in the rear with malfunctioning load levelers. Jeff, does T. Rutlands stock the shock kits you describe or are they special order? I´ve often wondered why one counldn´t replace the LL shocks with the same units used on the other side of the a-arm. I believe the 512 BB´s are set up this way.

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Originally posted by dbone on August 9, 2005 12:12 PM
I bought the second to the last set of koni-made coilovers specific for the C-4. They are koni's with an adjustable ring for height adjustment. I have not put them on yet, because I have other work being done at this time. I'll keep you advised if these work well. But from the looks, it is completely adjustable, so one can raise that sinking rear end. There are some posts on Ferrarichat.com- check it out you will get the part number and the distributor's name and phone number--- (I have, but not with me at the time of this post) Although, they have sold the last set. But They only made 10 to begin with to see if there was any interest-- apparently there is, so I would think they would make more on request.

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Originally posted by dbone on August 9, 2005 12:20 PM
By the way, Before I bought the replacements, after long search, I use 308 springs as a replacement for the c4 springs on that forward shock, and in place of the self leveller, i used a new set of rear konis(same as the forward rear shock- now i have an extra set). This worked. the 308 springs are beefier and keep the car up and "new konis" in place of the self levellers were for show--not a car show, but for my person viewing- and I figured they added some additional support.

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Originally posted by Michael Bayer on August 17, 2005 10:31 PM
Shaugnessy swears the way to go is cheep Pep Boys supplied Monroe load leveler shocks with Koni orange paint and proper stickers from Parker Hall. In other Forums there seems support for this fix as well, it would take a dedecated concours judge to even get into the position to notice them.............. Michael Bayer GTC/4 #14947

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Originally posted by Mike Meehan on August 19, 2005 2:19 AM
I might be willing to anger the Ferrari gods and use the PEP BOYS / NAPA fix for the rear shocks. Does anyone know the Monroe part # . Perhaps Ill just have to spend some time in purgatory and not go directly to hell .

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Originally posted by Aaron on November 15, 2011 1:00 PM
It has been a number of years - but I got back to the levelers-
Thanks John and Jack for the advice on how to get these back together, also the technical detail that Jeff
has put on the site under Details helped immensely to understand the working principle.
I had the leveler seals replaced again by Jeff Leblond in Arizona. The latest seals he sent me which fit in a
machined (not stock) hole, are Large "really killer" and I have high hopes that they will last this time.
I removed the shrader valve Jeff put in the top of the Leveler and had the hole welded up. I filled the
Oil side of the bladder on the insert and then placed the housing over it, then proceed to fill in the unit while apart.
John - I agree with your amount - about 550 ml of oil total. I did a bunch of pressure/volume calculation and believe that
under 400 psi pressure and while extended - the nitrogen side of the unit wil contain about 190 cubic centimeters of
Nitrogen. This should all work ?? we shall see. I fabricated a little gadget to pressurize the units to 400 PSI. It is time to
put them on the car.

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Originally posted by JBishop on November 16, 2011 7:10 AM
Aaron
I like your custom filler unit. I was going to build one myself but the local Koni guys in Melbourne are good guys and are only 20kms from me, so I use them. I can also use their dyno rig to test the units after repairing them. When I come over in Feb you will have to show it to me. Let us know how your car goes with the levellers back on. To other people, the seals Aaron has used will NOT fit a standard unit. Aaron's levellers were modified years ago by the guy in Arizona. Just to be clear, I have seals that fit the factory, non-modified units.
Well done Aaron.
John