Lowering VS Ride Quality, Opinions, Experience?

[hoss4659]

Setting up an '88 911 for comfortable touring and satisfying personal taste on appearance. Some conflicts here. I would like to minimize the gap between the edge of the fender and the tops of the tires. To my eye this gives the car an unwanted "up on tippy-toes" look and means some lowering. How far to go before ride quality is compromised?

Running 7 & 8 X 16 wheels with Continental Extreme Contact DWS 06 tires 205/55 and 225/50 (recommended by TireRack). In retrospect I should have gone for 15" wheels and 60 and 65 series tires for higher sidewalls.

Current work underway:
--Renew all rubber bushings front and rear
--Adjustable Koni Sport strut inserts and shocks. As a first try will set these up and one notch above full soft.
--Turbo tie rods
--Stock torsion bars front and rear
--Install Elephant Racing's adjustable spring plate kit.
--Probably some lowering. How much TBD
--Probably some sort of rack spacers to counter act bump steer.
--May have to trim the fender lip flanges, depends of the amount of lowering.
--Alignment (Raises the question of the utility of corner balancing for a touring car sometimes with and sometimes without a passenger.)

A note of thanks here to Bill Verberg for all his informative posts to various ride height threads. Useful stuff

Now the Key question: How far can the car be lowered before ride quality is adversely effected? How to measure? My preference is to use the wheel center to torsion bar center dimension usually shown as dimension C in various diagrams. Will start with stock, front 108mm +/- 5mm, rear 16mm +/- 5mm. Admittedly the fender lip to floor measurements are easier, but no one ever notes the rolling radius of the tire.

"Ride Quality" is a very subjective thing. I would appreciate hearing from people who have some experience or have some analysis on the effect of lowering on the ride quality. Thanks

[Driven97]

Stock TBs? You definitely don't want to lower enough to get into the bump stops under any conditions. That'll be a rough ride plus some scary handling dynamics. The factory torsion bars are like Cadillac soft, too, so don't go too low.

Next up is the front steering geometry. When you lower and get outside of the intended range, you start to get some kickback over bumps (bumpsteer) that gets really annoying / tiring.

Ultimately, your best bet is going to be factory designed (Euro) height. Make sure it's true Euro height too, a lot of people seem to think Euro is lower than it is.

Not sure of the Koni yellows are the best best, don't they have a Koni Red that is a little less aggressive? Hopefully someone can chime in.

[chrisbruck]

I had mine "lowered" to the Euro height (maybe actually a tad less). Bilstein green shocks all around. Rides perfect. Never bottoms out, sporty comfortable ride, not harsh. A little bump steer here and there but it's part of the charm. To me it's the perfect look and feel while driving.

Any lower than this and I'd think it would get uncomfortable for regular street use, plus the hazard of bottoming out.

[patz]

Rougher since less shock travel. Agree with going with larger sway bars. Be advised there may be issues with tires rubbing on full lock, spacers or fender rolling may be required.

[javadog]

Originally Posted by chrisbruck

I had mine "lowered" to the Euro height (maybe actually a tad less).

Yours started out at "euro" height, so you might want to supply some measurements or photos for reference.

JR

[Tidybuoy]

I think you are on the right track with replacing all the rubber bushings. I went with Elephant Racing rubber bushings and that was the most noticeable improvement for my car.

Regarding the Koni Sports..I would recommend only HD Heavy Duty in the front. Sports can make the ride too harsh. They are fine for the rear.

Euro height is what the car was designed for. Any lower and you could start having ride quality issues but Euro height, in my opinion, looks the best anyway.

16" wheels are fine but tire choices can make a difference. I have had Michilens, Bridgstones, ad Goodyear on my car and my favorite was the Bridgestone Potenzas. When I switched to Michilens, the ride changes so dramatically that I had them removed after a week - they worked fine on my 944 but not the 911.

Alignment makes a big difference too. If you can find a good shop, you should be able to discuss your ride preferences and the guy should be able to get the car the way you want.

Although I have not yet had my car corner balanced, that is next for me as I have read a lot of good comments regarding this.

Lastly, take your time and do things in stages. If you change everything all at once and don't like the result, you might not know what item caused the issue.

[RSTarga]

Elephant rubber bushings are excellent.
I wouldn't drop it below Euro ride height.
Make sure you don't have US spacers at the top of the shocks.
You don't need bump steer spacers unless you are dropping below Euro.
Bump Steer is NOT the same as Kick Back. The spacers keep the camber curve back into relationship with the suspension after lowering your car.
Why do you need the spring plate kit? Are you planning on changing TB's and or ride height constantly?
Definitely corner balance when you align and change ride height, even on a street car.
I prefer Bridgestones too, but the Contis are probably a comfortable ride.
If you want a softer ride don't use sport shocks, their softest setting is normally harder than normal shocks.
I wouldn't use 15's as the tire choices are really limited.
If you want a nice ride don't use larger Torsion bars.

[Nachtfalter]

I have two cars from that era, both on 17' Euromeisters. The coupe has Michelin Pilot Sports which are incredible, and the cabriolet has Continental Extreme Contacts which were a mistake and ride like crap (way too soft and mushy feeling compared to the Pilot Sports). Both are slightly below Euro height and have Koni's. I think the height measurements only work if the car being measured has your exact wheel/tire combo.
I can't answer the ride quality question, I lowered them both immediately after purchase. They never bottom out but will rub in the front on a hard turn up a steep driveway..... but honestly, so will anything cool enough to be worth driving.

[RSTarga]

Lower profile tires do affect ride quality. Some don't mind, some do.
16 inch original Fuchs are sufficient rubber for these cars, although the 17's look nice, I'd worry about tire rub in hard cornering.

[Bill Verburg]

Originally Posted by hoss4659

Setting up an '88 911 for comfortable touring and satisfying personal taste on appearance. Some conflicts here. I would like to minimize the gap between the edge of the fender and the tops of the tires. To my eye this gives the car an unwanted "up on tippy-toes" look and means some lowering. How far to go before ride quality is compromised?

Running 7 & 8 X 16 wheels with Continental Extreme Contact DWS 06 tires 205/55 and 225/50 (recommended by TireRack). In retrospect I should have gone for 15" wheels and 60 and 65 series tires for higher sidewalls.

Current work underway:
--Renew all rubber bushings front and rear
--Adjustable Koni Sport strut inserts and shocks. As a first try will set these up and one notch above full soft.
--Turbo tie rods
--Stock torsion bars front and rear
--Install Elephant Racing's adjustable spring plate kit.
--Probably some lowering. How much TBD
--Probably some sort of rack spacers to counter act bump steer.
--May have to trim the fender lip flanges, depends of the amount of lowering.
--Alignment (Raises the question of the utility of corner balancing for a touring car sometimes with and sometimes without a passenger.)

A note of thanks here to Bill Verberg for all his informative posts to various ride height threads. Useful stuff

Now the Key question: How far can the car be lowered before ride quality is adversely effected? How to measure? My preference is to use the wheel center to torsion bar center dimension usually shown as dimension C in various diagrams. Will start with stock, front 108mm +/- 5mm, rear 16mm +/- 5mm. Admittedly the fender lip to floor measurements are easier, but no one ever notes the rolling radius of the tire.

"Ride Quality" is a very subjective thing. I would appreciate hearing from people who have some experience or have some analysis on the effect of lowering on the ride quality. Thanks

Besides some of the stuff i've written before, i've been doing some further research playing w/ an articulated model of the 911 suspension.
some further comments
stock the Roll center is well above ground and jacking and packing forces are minimal(like bump steer these can't be eliminated but can be minimized). As the front is lowered the roll center drops and will eventually go beneath the ground at this point the handling gets really ugly regardless of bump. I'd caution to go no lower than having horizontal A-arms static, a slight droop is preferred,

It is very worthwhile lowering the cg limited by the above

[Arne2]

Some thoughts from the peanut gallery:

As pointed out by JR (javadog), all US 84-89 3.2 Carreras came from the factory at the same height as the RoW cars. So true "euro height" is how your car was originally delivered.

But by today's standards, that factory height looks quite tall. Set your car to true "euro height" (108 mm front, 16 mm rear) and you can expect to look like you are preparing for the Paris-Dakar rally.

It's a fine line. My car came to me looking reasonably low, looked good but was bouncy feeling up front. After a few months I measured it, front was about 155 mm, rear at -30. We are talking about 2" lower than factory. I raised the front about 15 mm, made a big improvement in ride, since I suspect I got the car up off the bump stops.

For function, when I replace all the bushings over the winter, I'd like to think about bringing it up another 15 mm or so both ends. But for appearance, I don't know if I can bring myself to do it. I suppose I really ought to have the spindles raised, but would like to avoid the expense of that if possible.

[algs911]

I have an '86 couple with a similar set up as you. I have it at euro-ride height and love it. Had the fender lips cut as well (by someone who had done a thousand of them, so it turned out perfect).

I very much love the way it rides and handles. I will say this though, it's tough going up/down some driveways and over speedbumps in parking lots. If that's something you plan on doing a lot of with your touring car you may want to re-consider.

Al

[winders]

Originally Posted by Bill Verburg

stock the Roll center is well above ground and jacking and packing forces are minimal...

Are you correlating the two or are these independent of each other? In other words, are you saying the jacking forces are minimal BECAUSE the roll center is well above ground?

I ask because jacking forces increase as the roll center is raised on a 911. As you lower a 911, the jacking forces decrease because the roll center lowers faster than the cg.

[Driven97]

You guys have convinced me to raise my car up and see how the handling changes.

[stlrj]

"euro height"







Personally, I like the look.

[Bill Verburg]

Originally Posted by winders

Are you correlating the two or are these independent of each other? In other words, are you saying the jacking forces are minimal BECAUSE the roll center is well above ground?

I ask because jacking forces increase as the roll center is raised on a 911. As you lower a 911, the jacking forces decrease because the roll center lowers faster than the cg.

I understand that
Modifying a 911 a juggling act w/ multiple balls in the air that all need to be accommodated
bump steer
jacking/packing
scrub radius
shock curves
spring rates
wheel width
intended use
the factory did a pretty good job of getting these cars into a nice ballpark, owners can bias them to a particular purpose but should be cautious about going too far.

If a little is good, then a lot must be better. Is not true here.

[tirwin]

I was thinking about the original subject line of this post and it occurred to me that maybe we need to be a bit more precise in terminology. Maybe there are two issues here instead of one. Ride quality ('feel' or 'harshness') and handling.

They are, of course, related but I think this is a case where words can get in the way of meaning.

There are some aspects that will contribute more to feel than handling and vice-versa.

When I think of ride quality I tend to think about things that have to do with dampening the energy transfer from the road surface to the driver's seat. Those things would be things like motor/transmission mounts, trailing arm bushings, shocks, etc. If you took your existing setup and only changed to solid motor/transmission mounts and monoballs then I think you would say that the ride quality suffered. Maybe you got something out of it like the car shifts better, but the tradeoff was ride quality.

When I think of handling I tend to think about rigidity and stiffness so things like sway bars, torsion bars, strut braces, etc. These factors influence under/neutral/over-steering.

I'm saying this because my experience in working on my rear suspension was different than what I expected. I changed to polybronze bushings, 28mm torsion bars and had the Bilsteins re-valved. I expected the ride quality to suffer but I felt like the ride quality actually improved. So why did it improve? I think it was because the rear shocks were shot and I didn't realize just how bad they were. If I had ONLY replaced the rear shocks I might have been just as happy with the ride quality. But that's my point... it is very hard to get an apples-to-apples comparison and you almost have to change things one at time to isolate the impact of the change. And that is not always realistic.

My advice, if you're concerned about ride quality, would be to limit the number of changes you make at any one time. Of course, that can be hard to do if you just want to get done with a project and don't have infinite time to devote to it so just try to do things in a reasonable manner. Maybe do the rear bushings and shocks first and then change the torsion bars later. Not only will you spread out the cost but you'll develop a better sense of how the things contribute to how YOU feel the car drives, which is all that is important at the end of the day.

Back to lowering. I think the main point is that lowering is about trade-offs. When you lower the car below 'Euro' height you start to quickly hit a point of diminishing returns. You increase 'kickback' (or whatever you want to call it) in the steering and you also limit the amount of suspension travel (assuming you don't do anything to compensate for lowering by itself). Those two factors contribute to 'feel' in very direct ways. The question is really 'how much lower than Euro' can you go before you cross the cost/benefit threshold? I'm not sure I've seen a good general answer to that question. But I do know there is a huge difference in that one little inch.

I don't know if this is useful or not -- it's just how I tend to think about it.

[enzoducoing]

Personally I have all my cars in stock height since they get driven on the street 99% of the time. I revamped their suspension completely (all the goodies from Elephant and Tarrett and Rebel) This gives them more controlled dynamics at a reasonable and comfortable ride. They never feel too harsh as daily drivers, but handle much better than with stock components. I have Street Fixed Level 2 Von Shocks with 22/29 bars and Tarrett sways set at the softest (just a tad harder on front). After fiddling a lot with different street set-ups, I dropped front and rear mono-balls in favor of hard rubber bushings, and I also dropped the semi-solid engine and tranny mounts in favor of stock rubber. Basically all the components that have axial movement I left with semi-solid and solid materials (spring plate bushings, front arm bushings) and all the components that work more as vibration absorbers I left with rubber ( front and rear shock mounts, engine and tranny mounts). This gave me the street combination and balance I was looking for.
Hope this helps.
Cheers
MD

[tirwin]

Originally Posted by enzoducoing

After fiddling a lot with different street set-ups, I dropped front and rear mono-balls in favor of hard rubber bushings, and I also dropped the semi-solid engine and tranny mounts in favor of stock rubber. Basically all the components that have axial movement I left with semi-solid and solid materials (spring plate bushings, front arm bushings) and all the components that work more as vibration absorbers I left with rubber ( front and rear shock mounts, engine and tranny mounts). This gave me the street combination and balance I was looking for.

Good advice.

[ClickClickBoom]

All the above is good stuff. Do not underestimate the necessity of corner balancing after doing changes, if you will be driving it in the process.