Ideas for suspension mods on a Audi 80 B4 2.3e

[DeanG]

Ok, so I am looking for some ideas on what suspension mods to carry out on Shaun's old Audi 80. The idea is to sharpen up the handling by lowering the car by maybe 20-25mm and perhaps fitting a strut brace. Should I consider fitting S2 springs or will this lower it too much? Any ideas on where to source springs from? Any views on whether fitting a strut brace will be beneficial, as the 2.3e does not come fitted with a strut brace like my RS2. Any thoughts on where to source parts from would also be helpful.

Thanks in advance for any tips.

[Greg_S]

Dean, you may be able to fit a universal strut brace that you drill and fix to the turrets. As for springs it may be worth comparing the current with the S2 versions to see the difference, I wouldnt have thought the standard springs would lower it too much though as the S2 is still quite lofty on stock springs

[DeanG]

Thanks for your reply Greg, for some reason I didn't get an e-mail notification. In the meantime, I ordered the Eibach Pro-Kit springs that should lower the height by 30mm, these appear to have got really good reviews. They are also the most common combo with the Bilstein shocks and if they are coming off I might as well replace the shocks. The next question is whether a set of Bilstein B4 shocks will work well with these springs. My only concern is that they wouldn't provide sufficient dampening. I think the ideal combination would be a set of Bilstein B6 shocks, as these are 20% stiffer compared to the B4 Bilstein shocks, but unfortunately both the B6 and B8 shocks for the Audi 80 have been discontinued for the rear, but strangely enough the fronts are still available. I have tried to get hold of a Bilstein UK tech rep all day with no luck to discuss whether the B4 shocks would be a good combo and I have seen a couple of good comments. Thanks for your suggestion on the strut and I think I will see what the handling is like after the replacement of both the springs and the shocks.

[Mcstiff]

I wonder if the B6 or B8s are still available for the B5 saloon.

[DeanG]

I thought I would post an update on this, as the Eibach Pro-Kit springs and the Bilstein B4 shocks have now been fitted and what a difference this has made to the handling on the old girl. Ok, so it's not as good as the RS2, but this is a perfect combo for this car. It's sitting about 25 mm lower and I will be posting some pics. I am absolutely delighted.

[steve briance]

Strut brace added to my CQ was done y welding in a pair of factory brackets and using the brace. Not sure if it helped handling but it sure has made my top mounts last a lot longer. Yes, sounds odd but prior to fitting I was getting around 18 months, now I'm about 7 possibly more years out of the current set. I can only think that it is holding the turret geometry steady and the mounts have less flexing to tolerate. Who nows bt it's worth it for service interval extension alone on the mounts!

[Lago Blue]

Steve,

Sir, I've been thinking about your post for a while and thought someone might have by now responded to it as it begs one, at least to me it does. So here goes.

As this early failure issue being perhaps still the oldest continuous & most widely shared problem amongst all of us, better
understanding of this failure, its' consequences & possible prevention should be more widely known. Full disclosure I have widgets to
hawk, but beyond that I just think you ought to know (and certainly deserve to know) what I -think- I know; and I, your thoughts.

From a enthusiast's perspective, you've done some very worth-while work to your car by retro-fitting the factory bar and no doubt there are now sense-able changes to how the car feels to drive, or at least; there should be. After all, certainly the factory wouldn't have bothered with this; for nothing. However, as your premise above is that this mod may lengthen the service interval for strut-mounts; & as that contravenes my own understanding of why & how strut top-mounts fail (or not), I would like to discuss this further and invite you to possibly expand what you've said & help me see how, what you contend; can take place.

What I think is that, all a strut-bar can do here is aid in the precision with which the top-mounts' outer shells are held steady (an entirely valid purpose), but that is the extent of it's influence on both the mounts' behaviour & life-span (i.e.: essentially nothing). In my view, the reason for that is because of how the mount is a) constructed, b) held in place by the fender's mount receiver; and c) how it is acted upon by the damper shaft. What I hope to show with the following is that OEM mount function & service life can IMHO -only- be improved by helping it achieve its' original design intent; from within.

I'd like to briefly discuss some strut-mount function & failure as follows:

(As an aid to understanding some of these points, it may be helpful to imagine the early quattro versions with similar suspension front & rear; where the 4 mounts must bare the gross vehicle weight (2/3rds on the front axle, 1/3rd on the rear) and then some multiple thereof; during operation.)

- Loading:
Top-mounts must indeed carry at least the entire vehicle gross weight constantly, whereas they only bare lateral loads sporadically. They get very hot, soften & weaken in use. This contends that it is upward vertical shock loads and that energy through-put which begin the failure process, vertical loads are by far also the larger here; and work against where the mounts are most vulnerable to failure: along their vertical axis.

- Impact Protection & Transmission:
In stock form when brand new, the un-aided OEM strut top-mount is a most capable but sacrificial part which is progressively consumed, sometimes with a single impact, while lessening the blow to the car and occupants, and making far less likely any damage to that fender attachment point, but perhaps more importantly from a strictly steering feel & feed-back viewpoint, it protects the bearing in its' base.

While driving, significant object impacts against a tire, such as the far side of a pot-hole taken at speed, send a shock-wave up the main-spring to the strut attachment point that could theoretically otherwise break anything else less compliant along that path.

Similar to a crash helmet, top-mounts have impact protection to offer-up; only as long as they have significant resilience remaining that has not already been beaten out of them. It is this capacity that is lost as the mount collapses, reason enough to prevent same. The key to a long-lasting fix for these is that the mounts must always have -extra- capacity available, beyond any worst case impact, that cannot be removed; and it is this which enables the mount to recover, and to be ready for the next big one.

- Comfort & NVH:
One might ask, if it where really true that further suspension resilience was unnecessary above the main springs, perhaps we could also all do without seat-cushions too? That wouldn't be my choice. By design, like a recoil pad on the butt of a rifle against your shoulder, mounts receive those worst case explosive shock loads -not- contained by the main-spring & damper action alone; absorb them and pass them upwards (and outwards!) more gradually than would occur otherwise.

When new and struck violently, OEM mounts have that extra vertical capacity which serves to allow time for the distribution of some of each impact load to be sent outward more broadly and slowly, as well as vertically, into the inner fender's mount receiver cups entire circumferences, rather than all the force going just straight up. When new, this occurs more firmly and quietly because a fully resilient new mounts' entire exterior conical soft surface can be more fully employed to receive and transfer some of the vertical impact energy; re-directed side-ways, precisely because a mount with a fully intact and resilient inner core allows time for this force deflection to take place.

Spread across the progressive contact made between the mounts' exteriors, and the fenders' receiver cups interiors carefully tapered interface, a good deal of shock loads are thus dispersed more gently into the expanse of the whole hemi-spherical inner fender than would occur with a more collapsed OEM mount or a more solid connection. Frankly, it's a compact & brilliant if slightly flawed (or perhaps best described as incomplete?) design.

- Top of Steering Axis Locating:
Top-mounts fixture the strut tops laterally, a primary alignment and steering function dimension. After being disturbed both vertically and laterally, it is critical that the strut-shafts be predictably and quickly returned to exactly the same central home positions; as they were originally, each & every time, endlessly. Consider that the closer an axle's two top-mounts are to "as new" condition, the more likely the two are both in the same position and moving the same way, simultaneously. On an axle that should not actively "steer", the closer those mounts are to new, the more likely it is that those wheels are to -not- going to steer, either together, separately or inadvertently. Of note here is that even on mounts where the center metal core has been totally torn free from the rest of the mount, the circumference of the outer shell is entirely unchanged from a brand new one. So how could a strut bar possibly influence mount life-span? I don't see how the two might interact. Although it is precisely here where a strut-bar and top-mount can both concurrently aid steering precision, I don't see any direct connection between the two, no causality of longevity given to one from the other.

- Steering Axis Rotation:
As imprecise as OEM mounts' bearings necessarily are, the OEM mount bodies they inhabit provide resilient beds which certainly lengthens their life-spans. For many drivers, this is perhaps all the bearing they need, and for this discussion mute till one has prevented vertical mount collapse in any case.

- What is "Mount Failure":
A progressive process which afflicts all stock installations and which refers generally to the vertical collapse of the mount body although there are other characteristics lost on the way down. It can be immediate or much more gradual, whereby mount function is degraded from the "as new" condition to the point where it cannot lose any more height and both vertical and lateral resistance to its' center core being displaced; is weakest. As mounts collapse they are less and less able to resist being poked and stirred by the damper shafts. What this developing weakness allows is increasing amounts of slack in the mounts which must be first taken up by strut movement before the main-springs & dampers will even begin to compress or extend. That is why new mounts make the car briefly feel so taut when 1st driven on. When new, a mount offers up its' best strength and resiliency both vertically and radially. Only that newness can best keep the paired strut-tops most closely parallel, in plane, doing the same thing at the same time and remaining on center or getting right back there. Being new, they in turn force the main-springs and dampers to react immediately to inputs. Any weakening of that, the "as new" mount's ability to function as above, i.e.: without any loss of its' best ability to react most forcefully to load and immediately bounce right back, any loss of that resiliency, integrity or height; signals the beginning of that end process. Whether one recognizes that decline or not, upon 1st use, that hidden internal permanent damage has begun; and continues to take place.

- How to detect failure:
Always surprising to me is how oblivious &/or uncaring some are to this in my view, primary unserviceability (and particularly to its' possible prevention!). Residual height remaining less than new, hidden internal tearing visible only when mount pressed open vertically, & finally obvious external tearing, flattening or core detachment are the physical signs. Vibration may be felt and the steering will become increasingly vague with a lack of on-center feel. Know that stock, and all the joints kept "as new", these cars exhibit pin-sharp steering. How do you measure mount failure?

- Why mounts fail;
Because stock, when received, they lack any means to prevent their otherwise unrestrained vertical over-travel. They don't fail laterally because they can't over-travel laterally, at least not until they have 1st failed vertically, then all core displacement is over-travel. This is borne out by the fact that both NLA "Mount-Savers" & test "Strut-Stops" best prevent mount failure by providing only vertical restraint.

- When does failure begin:
When an un-aided mount is 1st installed; and the car is lowered onto it, the inevitable march towards complete failure has begun.

- How could your un-aided OEM mounts -not- be failing or failed?
Unless the car has not been driven, they cannot be, not degraded. Your current mounts are therefore most likely (despite an absence of symptoms?), not immune to failure's insidious beginnings, & have been made internally damaged to some degree. All that remains is the degree to which they are toasted.

What this contends is that:
a) Since OEM top-mounts are made hollow with obvious reliefs & voids in the top & bottom, clearly the design intent was for the mount center to be able to deflect vertically somewhat relative to its' outer shell with loading, and to then return to the un-loaded position; otherwise the void would have been more filled in than it is so that it couldn't move so much in the 1st place. However, also missing is any physical restraint on that movement to prevent over-travel of the central core -relative- to the shell, movement beyond the elastic limit of the mount's rubber core and its' several bonded interfaces. This over-travel is the fate of every mount installed un-aided, even the latest/greatest dealer sourced Boge ones. As a strut-bar does nothing to bridge the gap between the mounts' outer shells and the mounts' move-able inner cores; a strut bar cannot abate this;

b) Top-mounts fail primarily and most quickly due to severe vertical blows causing over-travel of the mounts' central metal core relative to the outer shell. While the inner fender cup or receiver holds the mount still, it is beat upon from below by the damper shaft which acts in concert with the main spring top like a hammer, the fender is the anvil which ensures the shaft's hammer-blows have purchase against the mount. This energy transfer is what gets the mounts so hot. Each over-travel lessens the mounts' ability to both recover from blows and to protect from future blows, by literally tearing at the 4 hidden interior bonded interfaces between the 3 integral metal rings and the rubber core material itself. No matter how well or poorly the mount is held still laterally the stock auto-destruct process takes place vertically. A strut bar cannot abate this: &

c) As top-mounts shrink in height as the above damage takes place, they also lose their ability to fix the core laterally as that internal core is progressively & increasingly torn. Worn mounts heat up internally even faster as there is less intact material remaining to resist inputs. Braking, cornering & acceleration loads can increasingly displace the central core more easily each time. Again, a strut bar cannot abate this either.

Steve, when the fender turret moves, it may be because the strut is pushing against it; and the mount being in between the two could here be -less- flexed (but not meaningfully so) than if it were better braced. More significantly though, if an un-braced fender turret is flexed side-ways slightly some distance from its' twin on the other side, the top-mount won't behave any differently as it is too busy trying to re-center its' own core relative to its' shell both laterally & vertically if it still can, but is quite oblivious (in behaviour) as to whether its' receiver in the fender has moved slightly sideways. It may be in your case, that simply tired mounts (and/or bushings?), perhaps not totally vertically collapsed yet, but not really able to really resist displacement and then self re-center themselves with alacrity well anymore, are masking your bar. Their strictly internal condition might be subtracting more than a strut-bar can add.

To conclude, just like a lower sub-frame brace, which can provide a discernible driving benefit, but won't help save lower control arm bushings because there is no preventative aspect it can supply to said bushings, similarly, the upper bar has that relationship to top-mounts, it attaches nearby and can have a complimentary effect on driving, to what mounts in "as new" condition provide, but gives no direct benefit to their life-span. To truly enhance mount life-span, the only way I know of is to install an aid such as a "Strut-Stop" inside each to limit their central core's available travel & to best prevent the above failure; before they see use.

Unless you can convince me otherwise, this is what I believe.

Lago

[Rusty]

Glad the springs sorted things. Is this a quattro or 2wd with the trailing beam?

As ever, upgraded bushes and sportier geometry are other options but the further you go, the more noise and stiffness you introduce. My S2 is now all alloy, poly, spherical bearing and has a pretty extreme setup yet the wife and I did 600 miles over Christmas with little more discomfort than her Clio 172. When you turn the wheel, there's little to no delay in the reaction, unlike the stock setup!

[steve briance]

"Unless you can convince me otherwise, this is what I believe"

o.k