C4 Rear Sway Bars
 

I grabbed my PCA $100 discount voucher (Thanks PCNA!) and headed over to my Porsche dealer for the privilege of paying through the wazoo for some new bits. One of the parts that I ordered was a new 21mm rear sway bar. This should help dial out some of the understeer inherent to all C4's.

When I arrived at the parts counter today to pick up my order I found that some meat-head ordered a 22mm sway bar from a 965 Turbo instead!

I ordered (964-333-701-07) and was given (965-333-701-04) instead. The wheels in my head started turning..... Hmmmm.... If a 21mm rear sway bar is good for a C4 is a 22mm sway bar better? As tempting as it was to give it a go, I erred on the side of caution and handed it back and decided to wait for the correct part to arrive.

....But still, I'm curious.... Would a 22mm bar fit? What would it do for my handling? Any thoughts?

Not that you want to hear it now, but when you get your next $100 certificate early next year, there are several Porsche dealers that offer 20-25% discount and you can still use the certificate. So, for example, I ordered around $260 of parts for $110, plus shipping. Not bad. Brumos in FL was taking $40 off, Reeves in FL did their normal around 25% off, and Crescent City in LA offered a free Porsche poster with coupon orders.

Terry,

It won't fit since it's longer than the 964 swaybar. I whent through the same story but with FVD and ended up buying a 2nd hand part from the dismantlers. Not to disappoint you but there is no significant improvement with the 21mm non adjustable bar that many others claim, at least not together with the rest of my set-up.

Ciao,

Johannes E.

Thanks for the tip Bill. I ordered my parts from Champion Motors in Pompano Beach, Florida (They're a 15 mile drive from my home). I was able to get a 15% discount and my $100 voucher. Champion isn't exactly known for their discounts. As a Floridian, I've been to both Reeves in Tampa and Brumos in Jacksonville. I've heard "good-things" about both dealers. Next year I'll remember Reeves & Brumos and get an even better discount!

Johannes - I'm disappointed to hear that you weren't very satisfied with the changes the sway bar made. I have that series of articles from Excellence magazine - circa 1992 -
<a href="http://www.porsche964.co.uk/rev_rep/excellence.htm" target="_blank">Wringing Out The Carrera 4</a> While I don't think it's going to cure my ills, I feel that it's at least a step in the right direction.

21 mm worked for me,
Ciao,
Adrian
911C4

21 mm made a noticeable difference for me. One of the best / easiest upgrades I have made.

Johannes, perhaps you can elaborate on your comment? Many of us feel the sway bar change was worthwhile, but there are some things which it cannot cure. At autocross, my car continues to push when I overaccelerate in very tight turns. But this is the same for all 964's and 993's whether they are C2's or C4's. Jim Michael's recommendation is to disconnect the front sway bar if you really want to bring the tail out under these circumstances but I have yet to try it.

On the track, however, the improvement is quite evident. I have a very neutral car but power oversteer is easily achieved in long sweepers and the push is all but gone. My only off-track excursions have been due to a loose tail--not nose. So in general, my car handles exactly as I would like it to.

Terry, that old "Excellence" article is spot on in terms of driving technique. I've taken hairpin turns like Tommi Makinen by applying the late-braking technique described in that series. Even at autocross, this approach works well. It's sort of a power slide but your car simply rotates around very nicely. This is the only way to go fast since turning while accelerating, as mentioned above, is not very satisfying in a late-model 911.

Joey - apparently yours are bigger than mine! :D

The "toss-and-catch" technique described in Excellence sounds interesting, but I don't have the experience or the "nads" to try it just yet. (Though I'm working on it!) Trailbraking until the rear steps out and then applying the throttle to pull yourself out will really give your `nads a workout!

With luck, the proper 21mm sway bar should be here sometime this week and on the car soon. (as soon as I fix my damn oil lines :mad: ) I believe our local PCA chapter has one more autocross on the calender before years end. I hope the new sway bar and my new tires come together and help me work on my driving skills. I'm really looking forward to it!

No 'nads, No glory! ;)

I will probably be adding the 'Sway bar/Strut brace' mod soon, but a question. Why did Porsche not fit a 21mm bar in the first place?!

BR
Piers
1990 C4 Coupe
55K Miles

[quote]Originally posted by C4 Guy:
<strong>No 'nads, No glory!</strong><hr></blockquote>

Er, that's one way of looking at it. ;)

But seriously, this isn't some daredevil stunt. Find yourself a nice, secluded surface and just give it a go. You don't need high speeds to feel the effect and it's all very much under control--you're rotating the car, not breaking it loose. Then get off the brakes and experience how the locked differential propels you back on course.

Piers, Common conjecture is that these cars were produced at a time when litigation against car manufacturers was on the rise. To limit its liability, Porsche designed their cars so that off-road excursions would occur in a forward direction, hence the use of a stiff front suspension and smallish rear sway bars. It was simply understeer by design. I believe this topic was also covered in the same Excellence article.

Perhaps someone can add to this?

Dear Joey,
Have you tried 225s up the front. These tyres made a huge difference to the pushing effect on my C4. It still pushes a little but massively reduced as compared to 205s on the front.
Piers, to reduce oversteer or to induce understeer you reduce the size of the rear sway bar diameter. Based on changing nothing else. The 18 mm rear sway bar on the C4 made it understeer too much especially when the traction control engages. It was worked out long ago that the best compromise was the 21 mm rear sway bar fitted to the 1990 model C2 only. We also know that this 21 mm sway bar fits without problems.
Ciao,
Adrian
911C4

PS: Always purchase and use new mounts when replacing a sway bar. Correct part number for the specific sway bar helps as well.

Thanks Adrian and Joey

Adrian, coincidentally my tyres are getting close to needing replacing. If I'm doing the 'sway/strut upgrade' should I and Can I fit 225's to my standards 16" Design 90's fronts which, incidentally, are the most beautiful wheels ever made! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Thanks in advance.

BR
Piers
1990 C4 Coupe
55K Miles

Yes, Adrian, I'm running the 225/255 combination on street and track tires. Previously, I had the 205's up front, but feel the 225 provides a more-balanced, neutral setup.

[quote]Originally posted by Roygarth:
<strong>Thanks Adrian and Joey

Adrian, coincidentally my tyres are getting close to needing replacing. If I'm doing the 'sway/strut upgrade' should I and Can I fit 225's to my standards 16" Design 90's fronts which, incidentally, are the most beautiful wheels ever made! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Thanks in advance.

BR
Piers
1990 C4 Coupe
55K Miles</strong><hr></blockquote>

Piers, a minority of owners confirm that the 225 tyre physically fits on to the 6 inch wide rim on the front. Whether you get ANY benefit because of 'ballooning' of the tyre is a totally diferent question - I would definitely not recommend it.

Dear Piers,
No! 225s do not fit safely to 6 inch wide wheels. The minimum safe width is 7 inches. A reputable tyre retailer/installer would not allow such a thing to happen on a road car.
Ciao,
Adrian
911C4