How Much is too much...

[Reiver]

For a street 911?
Went for a ride in a friends 911 SC that was highly modified as many do.... a laundry list of high speed low drag parts everywhere. Bigger wider wheels w/ sticky tires. Upgraded everything...poly bushings, heavier torsions, etc.etc....

On a very nice piece of new asphalt it rode nicely..very...but on anything else I had to keep my mouth shut to retain my fillings. It rode like crap.

On the twisty's it was flat but vibrating like hell with every road imperfection....I swear I could hear the chassis screaming over the engine whine.....'Help! Give me a break!'

On a 40 year old chassis adding modern parts not even designed when the car was made does what to chassis stress? I get it when you strip it down, inspect , add gussets and supports where required for the track but when that is not done and all of this 'stuff' is hooked up what is the stress result on this 40 year old tub? I know they are well made/strong etc.

I think about that even when I watch guys putting huge sticky tires on a 200 hp car? Why (other than the look)?

Not a rant but wonder. from our builders here, what kind of stress issues they may have encountered on heavily modified chassis....

[dw1]

Probably the ultimate subjective question.

For a track car, your friend's SC is probably just fine, but for a street car....

Personally, I like to keep my '87 911 reasonably streetable, even on the lousy roads in my area. Because of that, when I installed 17s not that long ago, I actually raised the suspension. I'm now running at or slightly over European ride height specs.

Our older 911's are great cars, but one should (IMHO) recognize their limitations relative to more modern cars, especially if one wants to regularly drive them. Again, IMHO, for a street car one should enjoy these at or near their original configuration; anything more and one might be better off looking for a newer higher-performance car. (Full disclosure: I'm not a big fan of restomods.)

If it's not solely a street car (e.g. if it's a track day special, off-roader, or other) - well then, anything goes.

So, to answer your question "How much is too much?": It depends on one's objectives and budget.

Oh, and to answer your other question: The reason why I keep my '87 close to original for the street is that I went way too far (not all that much different from your description of the SC) with a previous build and the car ended up at the body shop getting rewelded to fix cracks and panel separation. In my case, the much stiffer and lower-travel front and rear suspensions appeared to have been the major culprits.

[GH85Carrera]

Very subjective for the answer. One of my physician friends spent big money on his 78 SC. Long hood conversion and about every bell and whistle for go fast and lightened a lot. At an autocross I was still faster, and on the trip home I was in ice cold air conditioning. I did not ride n his car, but with the roll cages and all the suspension mods I bet it sucked on the regular roads.

In the end, it was built to his specifications. A Boxster S would wax him on a track and cost way less. He still loves his car, and that is all that is important.

[rattlsnak]

I always build my cars to be track oriented.. A rough ride on the street doesn't matter to me. A great ride in the twisties or on the track is way more important/fun for me..

[fintstone]

I am pretty happy with a car that is just a bit more in HP and suspension than stock in my middie...since I drive only on the street. An extra 50 to 80 HP goes a long way...probably need an oil cooler/SSIs. Just the usual suspension...with larger sways and torsions...and turbo tie rods...new shocks/brakes. Good tires on 7"x15" fuchs vice the 6" ones it came with. As long as everything else is in good state of repair/like new...it can be stock. It handled well when new and the improvement have really make it a much more capable car. Sports seats to keep me in the seat and the car is much better than my driving ability (or what I can use on the street)...and no less comfortable than stock.

[G450X]

I have old high mile ‘82 911SC with a worn out suspension that I will get into next month.

I hope to achieve a decent ride with improved handling. I plan to keep my stock torsion bars and replace the old rubber bushings with Elephant Racing rubber, add the KW V3 dropped spindle set up, and swap in Eibach adjustable anti roll bars.

Based on the feedback from many KW V3 set ups on our old G bodies, they seem to consistently handle and ride better than a good stock set up. I think I could leave the anti roll bars soft for the street and set them firm for the track. I hope to drop at least 20 pounds from the back (remove AC, backdate heat, pull rubber bumpers) which should help the old stock torsion bars.

From what I’ve read, really stiff torsion bars make for a harsh ride…

[ahh911]

81 sc stock with new bilstein green regular shocks. 16's stock. Non-turbo tie rods.
First I thought the tie rods needed changing to turbos, after 1000km with the car I realized that no, they are perfect, turn the wheel 1/2 inch and direction change hold steady and steady, but a nice road feel. What I could / maybe will do next time the top end is out, find a way for an extra 50 hp, that may be a challenge while keeping the cis (which I like, it's like an old/friend foe that keeps me ever trying to improve, but rides like gold), the small intake ports.. I can live with it as is, I enjoy it for what it is, but an extra 50 hp, that would be the ticket.

Phil

[Reiver]

It is subjective but I did say street not track....I tightened mine up by removing weight. Rebuilt the front end using stock shor rubber, stock T bars, Carrera sway and HD shocks...rears did get poly bush in the stock t bars with adjustable ride height plates and a slightly heavier roll bar with new rubber. Sport shocks there.
Basically tightened it up with a close to stock set up by lightening it 400 lbs.
It rides nicely on the street but is sweet when driven hard.

I think a lot of new owners go overboard buying Gizmo's when Porsche made a nice handling 911 out the door....so for me, freshen old stuff and... a little goes a long way.

[1979-930]

I've found excessive spring rates and shock valving to be the culprit in poor ride quality.
Solid bushings are a minimal add to NVH. I switched from sport rubber to Rebel solid bushings a year later and there was zero change in the ride.

[Trackrash]

It's all about the details and getting all the upgraded components to function together as you would want.

If you can give us all the specific details of your friends upgrades then it may be evident what is causing the harshness. Any number of things can cause a 911 to ride harshly. I will say that shocks and ride height are the two main culprits.

[stownsen914]

Sounds like he put solid engine mounts in it

[Reiver]

Originally Posted by Trackrash

It's all about the details and getting all the upgraded components to function together as you would want.

If you can give us all the specific details of your friends upgrades then it may be evident what is causing the harshness. Any number of things can cause a 911 to ride harshly. I will say that shocks and ride height are the two main culprits.

Thanks but this wasn't a query to fix his 911.... he thinks it is a bit rough but fine.
Just made me bring up the subject ....
Specifically if any of the builders here have seen chassis damage due to over aggressive street builds...stress damage.

[Bill Douglas]

To be honest. I just love my SC the way it is, which is fairly much factory.

[Gordo2]

Specifically to your point - from what I'm aware of, very few chassis / body points / mounts have been known to fail, with or without suspension modifications or due to track use.

Tracked vehicles often reinforce chassis and mount points - typically as a means to stiffen the chassis and reduce body flex as opposed to reducing likelihood of failure.

The few chassis failures that I'm aware of include:
---------------------------------
Rear Sway Bar Mounts
Rear sway bar mounts are a weak point (relatively speaking) that can break due to normal stress and wear - therefore some folks (including me) choose to replace the mounts with Wevo reinforced mounts.

Front Sway Bar Upgrade to Full Adjustable, Pass Though Design
Upgrading to a pass-through style front sway bar has resulted in some folks recommending reinforcing the mount points in the front wheel wells. Most upgrade kits come with a mount that attaches to / sandwiches on the sheet metal in the wheel well. Early 911's with this style torsion bar seem to have experienced some amount of failure (probably from track use) and the metal mounting points were sometimes reinforced - a modification often recommended for track cars.

Rusted chassis / mounts is another topic...
---------------------------------

That aside - my car is as you describe with a highly modified suspension that uses semi-solid / poly mounts in place of rubber (in addition to many other upgraded / track ready mods).

The chassis / suspension does transmit considerably more road noise and clunks when driving over rough surfaces, as compared to stock. I think it would be easy to correlate the noise to a rougher ride, but I don't think that's necessarily the case with my car.

In terms of comfort / ride feel, I'm reasonably certain my car rides as smooth as vehicles with unmodified suspensions. I've gone from my car to my brother's unmodified Cabriolet (Pelican Cabmando) and noted the differences on similar roads. Mine rattles and clunks considerably more, but ultimately feels similarly smooth to the driver / seat of the pants. Seats also make a huge difference...

Bottom line - my suspension is overkill for street, but I love how planted it feels. Meanwhile, I don't think the upgrades have introduced risk of chassis damage.

Opinions may vary...

Gordo

[Jonny H]

The worst thing you can do for ride quality is fit bigger wheels and low profile tyres. 911 suspension comes from an age where the compliance relied on the sidewall to some extent.

Even 16’s kill the ride quality a little bit. Anyone who doubts this should take a ride in a car with 15 inch wheels and normal profile tyres.

[winders]

Originally Posted by Jonny H

The worst thing you can do for ride quality is fit bigger wheels and low profile tyres. 911 suspension comes from an age where the compliance relied on the sidewall to some extent.

Even 16’s kill the ride quality a little bit. Anyone who doubts this should take a ride in a car with 15 inch wheels and normal profile tyres.

Sure. But, with the 16" tires with the shorter sidewalls you get less sidewall movement (wiggle) so the car reacts faster to steering input and feels a bit more planted.

It's all about trade offs and what you are willing to accept....

[Steve W]

The hard ride comes from the shocks and stiction in the suspension. Rubber bushings, sport rubber bushings, polyurethane bushings, polybronze - they all have a noticeable of amount of stiction, that I'm estimating is at least 100 lbs/corner that jerks the chassis not only when the wheel is pushed up, but jerks the chassis back on the way down. The stiction is proportional to the force of the impact to the component, also known as the coefficient of friction or μ. You don't realize this until you drive a 911 that has zero suspension stiction in every component. You didn't think that those rubber doughnut bushings in the rear swingarms twist inside those steel housings on each suspension movement did you? Standard Bilsteins or Boges combined with the suspension stiction and bigger torsions and sway bars makes for a really harsh ride. Stiff torsion bars and big sways don't really make for a poor ride. Modern sports cars have springs stiffer than big 911 torsion bars and they don't ride harsh. Once you get rid of the stiction, combined with shocks that are adjustable to the spring setup you have, you can have 24 front/31mm rear torsions, and big JWE 31/27 sway bars, and the ride is better and more comfortable than a stock suspension, but amazingly better handling. That said, the Rebel Racing RSR solid front and rear bushings are amazing with zero stiction, and KW V3 shocks with what is like 15 position independently adjustable rebound and compression settings, and it's digressive valving makes for a ride that can be as smooth comfortable as you want with big torsions and sways. Installation is key and taking the time to detail and coalign each component makes every part work together flawlessly with exacting precision, with no noise or vibration.


There is something that is the next level up by Craig Watkins and that is the Tractive active shock system for the G body 911s, like PASM, that's so effective, they guys who have been testing them removed their SRP 31/27 sway bars (so no sway bars), and were at two seconds faster around Laguna Seca than their previous best. It rides completely smooth on a straight, but knows when you're cornering or braking and tightens up the corresponding corners accordingly.

[dw1]

On a related note, I have to wonder how many people in search of better handling should first look at replacing old &worn components.

These cars handled pretty well when new, but they are now quite old, and I've seen my share of dried-out bushings, worm-out shocks. etc.

[winders]

Originally Posted by dw1

These cars handled pretty well when new...

No, not really. Not at least compared to what people expect today.

[AG81]

I found middle ground for my build. It may be a tad bit on the "rattle side" when the asphalt road sucks but better on improved roads. Superior on the twisty's. If I change tires it should improve greatly....which I plan to do. I bought too aggressive a tire on my first go....... Just waiting to get a bit more mileage out of them.