Front-end drifting at speed
 

I'm planning to do some work to the front-end to eliminate the lateral drifting my car experiences at higher speeds and in cross-winds. The car is 20 years old and has 54K miles on it. I have not yet jacked it up to inspect the bushings and tie-rods, which are original and probably suspect due to age. What's the best bang for the buck for tightening up the suspension and making it track better? It's not a real extreme drift, but becomes much more apparent above 100 and especially in cross-winds I find myself fighting it to stay centered in the lane.

Thanks, Joe

Sounds like it's due for tie rods anyway. Then, a front end alignment.
Make sure you switch tires around a time or two to see if that affects it. If so, maybe new tires before the alignment.

Joe, do you have a front lip spoiler? This will probably cut down on front end drift if your suspension is in order.

Also you should never run a rear wing without a front lip spoiler.

You might be due for shocks as well. Check your rear sway bar mounts for cracks or a broken mount.

Tires are almost brand-new Toyo Proxes, maybe 1500 miles on them. I will certainly get a balance and alignment after any repairs are made, which brings up a related question: Should I go ahead and get the four-wheel and thrust alignment or just the front-end done? Should I trust generic tire and alignment shops to do this correctly or do I need to take it to the (gasp) Porsche dealer to have it done right? Some of these Car-X/Midas/Goodyear grease monkeys don't really look like they would know or care about the technical requirements and specifications for aligning this car correctly. Any recommendations? What type of equipment should they be using to do it right?

No spoiler, no wing. Plain stock 85 Carrera. No bounce in shocks all around, checked that out when I bought it.

I would recommend taking it to a shop that does alignments for race cars. They would probably be more apt to do it correctly.

If you post where you are located and the intended use of the car (street, track, both), I'm sure someone can recommend a shop and alignment specs.

Also, When I replaced my front struts there was no bounce but the shocks were toast. Definetly gave the front more bite.

These cars do react a bit differently then most when testing the shocks. Due to the torsion bars, when you push down on the car you are flexing them and the shocks making it very hard to know if the shocks are worn. If they are original they could be due. If you want to continue to drive at very high speed, I would put in the Bilstein sports. (in fact, I did on my car right off the bat!)

That's easy...an alignment.

Joe G

Chin spoiler will significantly reduce front end "wander". Also, there is no point in doing a front end only alignment. These cars need all four corners aligned and balanced.

True. Find a reputable independent Porsche repair facility that does alignments and have them do it right. These cars need a proper four wheel alignment and need to be corner balanced. If alignment and/or corner balance is out of tolerances then the car will exhibit strange handling characteristics. FWIW, my '84 can be driven with two fingers on the wheel at 110 mph, so you should not be drifting all over the road at that speed.

Yes, Definitely 4 wheel alignment. A "front end" alignment was back in the day of non-adjustable rear-ends (think frame-based cars). It still applies to some vehicles, but not a Porsche. Basically, they measured the "thrust line" of the rear axle and aligned the front wheels to that vector. That's why you'd sometimes see cars/trucks going down the road on an angle - it's called Dog Tracking.

Some of the national/regional chains hire and train some decent mechanics, and they'll do a great job on your Honda or Toyota - because they've seen/done a million of them. But, if you ask them how many 20 year old 911's they've done, I'm guessing it'll be none or just a few.

Look for a good independent shop in your area that has relatively new (laser) alignment equipment - preferably Hunter. Ask them if they have a dedicated (and hopefully level) alignment rack and how often they calibrate their equipment. Jigs are provided for doing this. Depending on where you live, you may even have an independent shop specializing in Porsche - that's who I'd use. They should also (as a part of every alignment) check for play in bearings, tie rods, ball joints, etc.

I used to work at Hunter. They hold a massive market share in wheel aligners and build the equipment used in almost all the auto factories, including BMW and Ferrari. I don't recall if they supplied aligners to Porsche. I do see that Porsche is using their GSP9700 Wheel balancer that applies simulated road forces to the wheel while balancing. Don't underestimate wheel balance as a source of suspension issues, either.

They have a pretty decent tech section on their website: http://www.hunter.com/pub/undercar/index.htm

Craig

Did you replace all four tires at once?

Several months back, I replaced just my rears with a different design - and the car became a nightmare! After an alignment, and two new fronts (identical brand/pattern as the rear), she's rock-stable again.

And this is when you know you are nearing Nirvana. When you blast down a straight, mash down on the binders and lightly flick your wheel, then back on the mean pedal for a sweet, smooth drift through the twisty!!! ...I gotta go guys, I have the day off. Good luck!

What are your ride heights like?

Quite normal for the early cars without adequate spoilers. Driving a car without spoilers on the German autobahn at speed in a crosswind situation, will push your body's adrenaline production to the limit. That's why Porsche introduced more and bigger spoilers, the faster the cars became. Of course a proper alignment and new shocks will help. Lowering the front and keeping some weight in the trunk will also improve the stability.

The car has stock ride heights as far as I know. It came with the new tires when I bought it. I've been looking for a local independent Porsche specialist with little luck here in Eastern Iowa. There are probably dozens in the Chicago area, a road trip may be in order.

Yes, as stated, you can't test the shocks with a bounce. The suspension's too stiff and the front end too light. My car passed the bounce test, but when I changed my shocks they were really bad. When I unbolted them they compressed under their own weight and they were gas shocks.

Too, at speed with no aero aids you'll get some float. You should replace the shocks and bushings (elephant parts would be good), get a good alignment (the whole thing), and add a front lip spoiler and tail. You will probably notice a huge difference after the new parts and alignment. The lip and tail are not necessary, but for max stability... With a front lip and rear spoiler you reduce the lift on the car at 150mph by 90%. From what I've read this makes a difference as low as 60mph, but probably most noticeable from 80-90 up.

One more thing, make sure that when you get the alignment done you don't get a stock alignment and you get an alignment from a Porsche specialist.

First rule of 911 ownership (at least in my book) is to assume that the previous owner knew nothing about the car (at best), or messed it up and didn't tell you (at worst).

Once you accept that, it's a small leap to ignore what the previous owner told you and check it yourself. In the case of the ride height, it's real easy to check. Get a tape measure and measure from the ground to the top of the fender cut-out at each corner. Post the results and then you'll know if the ride height is even close to right.

The alignment is critical. My 911 has used, well worn, soft Boge struts up front which I just love and have no problems at 80+mph in a crosswind with two fingers on the wheel.

Cheers,

Joe

I'm just curious what you guys are doing with your remaining fingers at high speed. :D

My car is also very stable, but I still like to keep all ten on the wheel except when shifting.

It's the two finger test. Better yet, if you could let go entirely to see if the car tracks straight and steady wthout drifting into the other lane, I'd say your ride had dynamic stability which would make your car very easy and comfortable to drive.

I'll take that over white knucles and cold perspiration anytime.

Just for clarification, coming from Germany the standard definition of "high speed" is +125 mph. Everything below is just considered "cruising".

According to the Iowa Patrol, anything under 90 is cruising and over 125 is waiting for initial appearance.

Agreed, but you must not have as many darting deer in your area, because I'd find it difficult to make an evasive maneuver with two (albeit dry) fingers.

Not only deer but I need to be on the lookout for wild turkey in my neighborhood. But on the freeway, there better not be any 'cause no amount of fingers will do you any good at those speeds bro.

I like the chin spoiler idea, but probably not the tail. Has anyone ever installed the later-model retractable grille spoiler on an earlier model car?

A few guys have. Tyson Schmidt did it with at least one of his cars.

The new Toyos are the problem. Until you break them in, they are going to squirm. And according to my buddy who runs Proxes 4 on his 87 Carrera, until they break in (approx 1-2K depending on driving style) the squirm occurs at straight high speeds and it feels like the front end is loose. They should be damn close to breaking in by now.

My advice is to go for a long drive and get those puppies heated up!

Tyres and alignment is crucial. Fresh shocks as well.

I have a stock '85. Switched the old hydraulic Boge for Bilstein standard. Totally transformed the ride, both low and high speed. BTW, my Boge "passed" the bounce test too..

Joe, what was the eventual fix for your problem? Were your new Toyos to blame, or was it the front shocks? Sorry to resurrect an old thread. Thanks.

Yes, the shocks, tie-rods and alignment fixed the drifting for me. It now tracks very solid at any speed.

Wow, that is an old one! One of the first threads for me, at least.

What's up with the new look to the BBS? Guess it's been about two months or more since I logged in! Porsche is running great, but I've been bitten by the sailboat bug. Cheaper, wetter, just as much fun.

Ahoy.

Thanks for the swift reply. Is there such a thing as a sailboat forum? :)

As all have said check suspension, but dropping the height would fix the crosswind issues at speed, as would the chin spoiler. Mine was the same on the highway (a little scary) until I dropped it. Then I went the suspension route, now it's a go cart.

Before


http://forums.pelicanparts.com/uploa...1186756180.jpg



After


http://forums.pelicanparts.com/uploa...1186756392.jpg

I replaced my shocks/struts, ball joints and had the car aligned and the results are amazing! The car feels more "planted" on the road and hugs the road in the turns better then before. The shocks and struts were completely shot as were the ball joints.

I wouldn't spend money on alignment and corner balance until I established what hardware I was going to replace first.
Check bearings, shocks & struts, tie rods, ball joints to establish what you needs, or will soon need refreshing. Then get the alignment and corner balancing after all the hardware is installed.