Dino DIY - Suspension springs and shocks - New or are old OK?

I'm doing some work on the Dino and I know the shocks and springs are at least 15 years old, since I've had the Dino that long.

I know the bushes are in need of replacement because I can see them and I've disassembled the whole group, but how do you know if the springs and shocks are in need of replacing?
Image Unavailable, Please Login

 

While you could get a new set of shocks/bushings/boots/etc from the standard sources (i.e. T Rutlands/Maranello Autoparts at $1095.00 http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220209698292 , etc)
do you really need them?

When is it time and how do you know?
I asked the same to an informed, local Vintage Racing Mechanic and he said "Do what the racers do - have them tested by Tony Garmey, purveyor at Horizon Racing & Performance".

I telephoned Tony and arranged a time to run the shocks and springs to him for Shock Dyno testing and static spring load testing along with my Dino workshop manual and parts book for his reference. Tony has very nice equipment and many of the local vintage and modern Ferrari racers use his setup to prove/improve their equipment. The second photo shows a typical output graph of shock travel vs force and he can accomodate vari-rate shocks so you can see how "tuning" the Konis will affect the output.

He does need to build a special collar/clevis adapter for the Dino Konis and I'll post more updates as he proceeds to evaluate my Konis and factory springs. Initial quote was for $14 per shock for testing but I've asked him to do other items such as spring rate testing so we'll see as work progresses.

This promisies to be a great source of informatiion.

Contact info:
Horizon Racing & PerFormance
Tony Garmey
[email protected]
425.413-0785


Regards,
Scott
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Scott,
Springs sag or break. If tires are not hitting on bumps then springs have sagged as much as they will ever sag and all is fine. If you like the looks of the ride height, put the springs back in. Shocks do go but those Konis seem to go forever as long as the top seal keeps the oil in and dirt out. They can be tested and adjusted when the springs are off and should be if there is any doubt. I replaced my front shocks at about 100,000 miles because I ran in fine gravel and bound up the upper pivots. The steel ring surrounding the rubber bushing failed when grit got between it and the mounting bracket. Shock itself was just fine. I ground a relief in the bracket, installed new shocks and all has been fine for almost another 100,000 miles. And I still run in gravel sometimes. Turns out that I could have just welded on a new steel ring but I found out that later. The rears are original with almost 200,000 miles and are still fine. Paint will do wonders. I think new or repro Koni labels can be gotten. Some powder coat the springs as Jon did. Looks like his springs might have grown. Don't know how high the oven was to cure the powder but it might have relaxed some stress and the springs grew a little. His car is now running high. I know that if springs are compressed and put in a 400F oven, you can shrink them. Good luck in getting it all back together and looking pretty.
John

 

You called it John, the springs came back from testing and measured well, but the shocks were a different story.
Shown below is what you get for your $14 from Tony, graphs of the Force vs Displacement for four settings (plus another page of the raw data used to draw the graphs).

The front left and right are graphed below in four settings from soft to hard and there seem to be a slight problem; Tony conjectures that it might be the internal valving of oil contamination, but we won't know until opening them up.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Similarly, the rear left and right are graphed below in four settings from soft to hard and they're not especially bad but there is some deviation in both; the left at full stiff on rebound and the right was sluggish at one turn
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Tony showed me an interesting fact, Koni stamps the dates into their shocks and these were manufactured in December 1972. This falls right in line with the Dino's production date of February 1973 - they were sure producing them as fast as vendors could supply parts!

I went ahead and bought a set of new Koni's from T Rutlands and I'll have Tony test those as a baseline.
More later....
Image Unavailable, Please Login

 

Scott,
Great graphs. Thanks for posting. Be interesting to see graphs of the new one. Does look like the rears have had a harder life.
John

 

I purchased a new set of Konis from Rutlands and had Tony Garmey run them on the shock Dyno with these results.
Looks like the new ones have a shallower range, so we'll run them at full stiff.
I may still have the old ones rebuilt by Koni, but in the meantime I'll use the new ones
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Testing prior to install/setup can help set a baseline.

 

The graphs show that the OEM NOS rteplacement shock is nearly a third less on the rebound than the original that was delivered on the car.

Buyer beware, just because the replacements are sold as new, does not mean they are identical. The later versions could probably be cranked down to be firmer but due to the weight I would start the rears out at the full deflection setting