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Discussion Starter #1
Hi,
Have bought a set of adjustable dampers with lowered springs fitted, for a 24v 3.0 1994 164 manual Super. Front end is sitting a bit high as the rear springs are at least 30mm shorter than standard, so back goes down and fron, even though shortened springs, goes up.
My idea of a fix is 20cm to 1inch shorter rear springs to balance it out. What would the spec of such springs be though? With standard rear springs the rear is too high and the front sinks down.
 

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Woah there big fella. You can't play around with springs based on desired ride height. Dampers have to be matched to spring rate which is, technically, unrelated to spring length although in practice shorter means higher rate (stiffer). Spring rates have huge effects on safe handling. You just cannot choose rear spring rates in the way you intend. For fwd in particular this is safety critical.

Even damper rates can affect safe handling.

When we fit new OEM rear springs to our 164 with the very old OEM front springs my wife spun the car under severe winter conditions, which exacerbate any imbalance in front to rear roll rates. For a car as well engineered as our 164 even the difference between brand new fresh springs with the correct rates and old tired springs affects handling balance. I put 50 kg of sandbags in the trunk right over the rear axle to compensate for the new springs. It took two years for the new springs to settle in and behave correctly.

The basic rules that apply are that spring rates affect roll rates and you need to keep roll rates biased towards the front axle or you may be in for a BIG surprise around that roundabout in the rain.
 

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Not understanding how you have your super configured. You have lowered front and rear springs and where are adjustable struts front and rear?
 

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Hi,
Have bought a set of adjustable dampers with lowered springs fitted, for a 24v 3.0 1994 164 manual Super. Front end is sitting a bit high as the rear springs are at least 30mm shorter than standard, so back goes down and fron, even though shortened springs, goes up.
My idea of a fix is 20cm to 1inch shorter rear springs to balance it out. What would the spec of such springs be though? With standard rear springs the rear is too high and the front sinks down.
First off what is the brand of springs on front and rear? Lowering springs on front and not on rear or vise versa? Sounds like vise versa.

Take pictures please.
 
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If you have fitted a complete properly matched set of springs and dampers made by a reputable suspension maker then you should not be having this issue. Trying to fix an incorrectly made set of springs with your own ideas about how to do this would be foolhardy to the point of being dangerous.

Choosing correct spring and damper rates is an incredibly complex engineering problem. Just setting the damper specifications remains a black art even at the top levels of competition, let alone for road cars. Specifications for the dampers depend on the spring rates. Spring rates are interconnected front and rear and with the anti roll bar rates. Technically the tire specifications are also relevant but for our 164 the range of tires that will fit isn't that different across the range.
 

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Discussion Starter #6 (Edited)
Thanks for replies,
I bought a complete, lightly used set of front and rear struts with springs. The guy had obviously realised his mistake in rear spring rate/length as had fitted a couple of nylon spacers to increase the rear height. As these spaces showed signs of splitting I removed them on safety grounds.
Not sure of the spring brand but suspect Bilstein. Adjustable shocks front and back - Bilstein at the front, Koni at the rear. Put the fronts in first and found the nose was really down with standard rear springs/shocks in place. After putting the rears in the car now sits tail down, with the front up.
Not sure of spring rates compared to standard but had to use spring compressors to take load of nylon spacers when cutting them out and noticed the spring length without them only puts a light load on the strut ends - only about another quarter of an inch of extension if were free to extend fully. Hence my conclusion they are roughly an inch a bit (about 3cm) shorter than standard rear springs.
So then my logic was to find midway springs, about half inch shorter than standard to get the whole car to sit right again - assuming spring rates remain unchanged.

Will take pictures tomorrow, Jason.
 

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Those white nylon spacers come with my Koni rear struts to keep rears up higher. I ran Eibach springs and Konis front and rear on my S without the spacers so my S sat level.
 

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Discussion Starter #8
That's interesting. Never thought they might have come with the Konis. Does that mean the Koni struts have lower spring pans?

The spring numbers for those fitted are:
Front: 1533 04 498 0
Rear: 1533 04 497 0
Green powder coating finish.
 

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When I put Konis on my LS, I left the spacers in, thus ending up with the rear slightly higher than the front. When we do use the LS though, the trunk is usually full of luggage, and assorted other stuff, so that it is not bad at all. Plus, the nose down, rear higher attitude gives slightly better aerodynamics, ie, lower drag, according to what I read and studied in my aero classes and wind tunnel work years ago. Well, one likes to think so, anyway.
 
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Discussion Starter #10 (Edited)
Prefer a slightly nose down attitude too, Del. At moment have
1628425
rather the opposite, which could potentially cause a degree of front end lift.
Front end was sitting lower than this with original rear springs/shocks.
If those spacers are from Koni and designed for their shocks, had 2 fitted each side, why did my lower ones begin to split? Does anyone make tougher ones?
 

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1628455
 

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Alfa changed from nose up to nose down after their Bertone GTV era. The first Alfetta and related sedans were designed to ride nose down. Possibly the first ground effects racing cars influenced this but also growing interest in fuel efficiency helped. Nose down yields significant fuel efficiency gains particularly if a chin spoiler is also fitted. It's amazing how little forward rake is required to substantially improve aerodynamics even at standard road car ride heights.

No car designed for high speed should ride nose up. Pre 70's Alfas were never fast enough to worry about nose lift at high speeds. Many quite ordinary cars built after the early 70's were fast enough to start going light over the front axle. The 164 is certainly one of those.

Spring length and spring rate are not logically connected. Suspension travel and spring rate have to be correlated. Most definitely you do not want to be trying to correct ride height differences front to rear by fitting shorter springs to lower or longer springs to raise one end of the car relative to the other. The spring rates and lengths need to be engineered together so that the car behaves predictably (and unless you are Fangio reincarnated, safely) at all speeds and especially in fast bends and on poor grip road surfaces. Those spacers substituted for adjustable spring pans, one reason adjustable coilovers are common. Find replacements. Coilovers adjustable for ride height do not change behaviour with changes in ride height although you must be careful to match any changes at one axle to changes at the other. Spring length and suspension travel are not affected by ride height changes using adjustable coilovers. Your plan to fit longer springs even if the spring rate is not changed is not wise. The car will not perform in the same way as it would if fitting spacers instead.

When I changed the rear springs, dampers and front roll bar in my Subaru BRZ I was careful to buy a Whiteline roll bar and a set of MCA anti-squat reduction brackets from reputable Australian aftermarket manufacturers who thoroughly test everything they make. For rear springs I bought updated 2017 rear springs direct from Subaru after carefully investigating what Subaru did to change from pre to post 2017 suspension settings. I fit Bilstein HD (B6 in the EU) dampers relying on their expertise. Great results, producing the exact changes in handling I wanted and expected.

Only buy suspension bits from engineers, never DIY design your own system.
 

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I remember seeing quite a few years ago a study done by Alfa where they took a mid 60's GT and measured the front suspension and rear suspension lift at ~100 mph. Then they added a chin spoiler, similar to the old Bobcor spoiler, and a small spoiler to the rear end of the trunk lid. Without the spoilers, they measured ~250 lb lift at the front and ~100 at the rear. The with the spoilers attached, they were able to reduce those figures by somewhere around 1/3 or so. Do not remember those numbers now, but there was a significant reduction in vehicle lift. That body lift of course translated into additional drag added to the cross section base drag.

The front end design of the GT was probably the worst for drag, as it's shape caused more air to be rammed down under the front of the car, esp with the chassis being nose high anyway by design. Stylistically, it looked ok, but for aero efficiency, it was absolutely terrible.
 
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Discussion Starter #15
Steve, my rear shocks were fitted with two of those on each side - perhaps why the lower one on each side had begun to split.
Does anyone sell such things as separate items?
 

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Eibach makes a lot of springs for a lot of people (they make TRC parts for Toyota for example). You could try the part numbers with your local Eibach dealer.

One odd thing you said that the front dampers were by Bilstein whereas the rears were by Koni. Both sets are adjustable? Bilstein adjustable dampers are normally supplied with matching springs supplied also by Bilstein as part of a set (PSS systems for example) but I'm not sure they actually make the springs themselves. It is not usually a good idea to mix different types of damper on the same chassis. Koni are double tube while Bilstein are famous for their monotube deCarbon type dampers.

I find it hard to believe that you will be able to set these two very different types of dampers to work together on one chassis. I also wonder about the previous owner of this odd package, how and, more importantly, why he or she assembled mismatched damper types into one set for a 164. Pretty weird.
 
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