How do I get a 930 to handle like a 911?
 

Gents,

In a turn or when cornering, my 930 has a "heaviness" to it that my 911 doesn't and I want my 930 to perform like the 911. In all, it comes down to the 911 being more nimble in a turn than the 930.

How do I get my 930 to do the same? What equipment or changes can be made to improve it?

My 911 has newer OEM struts and shocks. Would that be the difference?

What are your alignment settings? specifically front caster. Too much caster angle will make the car really stable in a straight line yet will take away from the light steering and nimble feeling.

Jamie,

My front caster is 0.13 degrees on the 930 and I don't know what the 911 is. Is 0.13 degrees a setting that would cause it to be less nimble?

Most racy 911s use about 6-7 degrees caster because it makes the wheels lean into a turn for more grip. 0.13 degrees is hardly anything.

My 911 has no track history and from what I know of the previous owners they didn't make any changes. I haven't had the 911 aligned for the 5 years I have owned it. It drives great so I didn't see the need. With that said, would a 911 be different than the 0.13 degrees set on the 930?

some threads on caster where people talk about their values:

http://forums.pelicanparts.com/porsche-911-technical-forum/569002-3-2-carrera-sc-handling.html

http://forums.pelicanparts.com/porsche-911-technical-forum/561337-bump-steer-question.html

Weight, track (wheels are further outward than a 911), wider tires, are all contributing factors. The factory also set up the 930 to push in the turns to counter oversteer induced by sudden turbo onset.

Thanks for the thread links! I was looking at the difference all wrong. I was thinking it must be because of their body types. The real difference must be in their alignments.

It could be a lot of things combined. You might never get it to feel 'just right' if 'just right' is how your 911 feels. They are different vehicles when you look at the specs.

You can try adjusting the alignment and such on your 930 as long as you understand that you are attempting to make a 930 feel not like a 930, but like another car with a narrower track and different weight proportions and different stance, different tires, different power delivery, different suspension, ect.

You probably should look at it from the point of view of optimizing the 930's handling to be a more nimble 930. Trying to imitate a 911 might not be possible or ideal.

You probably want a more aggressive stance for the 930 so it turns sharper yet not so much that the rear comes around under power.

And its great question! Love to see how this turns out.

Are you sure you're talking about Caster, not toe?

One thing is also tire combo and tire pressures. It might feel better for you if the tires are NOT very staggered. Try 245 front 255 rear but that feels a bit oversteering for most people. I liked that setup though.

Here is what I have planned for the 930 in the coming months.

Will this get me further away or closer to the 930 turning like the 911?

My tires/rims are going from 205/16 front and 245/16 back to 235/17 front and 315/17 back.

The 911 has 205/16 front and 235/16 on the back

I'm planning to use the Elephant racing Street Perf 2 package:

Front:
Torsion Bar 21mm
Polybronze control arm bearing
Low-friction Control arm mounts
Strut inserts- Bilstein Sport
Strut brace

Back:
Torsion Bar 27 mm
Polybronze Spring plate
Rear shocks Bilstein Sport

I also misread the 930 alignment; the caster is 5.8 to 6.3 degrees. The toe is -.44 degrees.

The 930 carries a significant weight penalty over a normal 911, especially over the rear wheels, and moving backwards because the engine is heavier as well.

I don't know where you live, but even in So Cal here, I made due without the AC system(which on any 911/930 is a substantial amount of dead-weight from one of the car to the other.) Also, if you go this route, mount the battery in the smugglers box, since you want as much mass to be inside the wheel base, not outside(one reason why mid-engined cars handle so favorable).

Rear seats? Do you really need them? Spare wheel inside of nose? Unless you are going cross country, or a road-trip, and have AAA, do you need this?

Every pound you shave off the car is a pound that the engine will never have to accelerate again. Dead weight shaved off also is mass not having inertia to carry into corners, banking, etc.

And remember...every tweak you make in a suspension, engine, chassis comes at some cost in driveability, noise/vibration/harshness, so be careful what you wish for.

I'm trying. I have removed the entire AC and heat system, spare tire, rear and passenger seat, rear wiper motor, and have a smaller Optima battery. I'm thinking on mounting the battery in the smugglers box. The car is brutally fun to drive, but still doesn't have the nimbleness of the 911.

Even with all that I have done to the 930, it is no match for my 911 if running downtown or with areas with 90 degree turns. I know they are different cars with different abilities, but can a 930 be made to compete with a 911 without compromising its strengths?

You may want to take a second look at your t bar choice. I think 21/27 may add more understeer to the car, as I think you are adding higher rate to the front relative to the back than the stock rates. I think the stock rates were already adding some oversteer...

Somewhere on here is a chart with the various sizes of t bars and their relative ratios to stock. I searched but could not locate it for you. It is here, somewhere.

You may want to go 21/28 or 21/29. Or maybe not...

Good luck.

I think my 930 handles as well as my old targa did, so I think it is achievable.
It just feels a little different because the track is wider and there is more rubber on the road.

+1 on the torsion bar rethink.

930's have a better suspension geometry than 911's and a fair amount can be done with tires and alignment. (Tires can often be the softest link in your suspension chain.) To much toe in will slow turn in and should be zero pressed or 15min non pressed per factory spec I belive. AutoX racers run toe out for quicker turn in. Also, more front camber can help front bite.

Stiffer torsion bars are a great upgrade.

However, for a 930 22mm front's are about right for a street / sport car. 21's are more for a light early car like a pre 74. 23's start to get on the serous side for the street.

For the rear, the 930 seems to need to go up one size over what a 911 might run with its heaver rear balance and limited slip. Thus a 30mm rear bar would probably be a good balance. This probably makes your car's wheel rate about 40% stiffer I would guess. (I can double check if you wish.)

New or upgraded bushings, a good sport alignment and corner ballance and you should have a very nimble car.

If you want to go one step up you might consider having the front spindle's raised on the front struts about 30mm and add a bump steer kit. This will greatly improve your front camber curve, make it better match to the 930's rear camber curve. More importangly it will help the front tires bite better in a corner.

First of all I would check alignment on both the 911 and the 930.

Secondly for a lower cost handling fix/adjustability add a adjustable rear swaybar, that way you can tune the over-understeer a fair bit.

The Elephant mods will make a big difference for sure but as others have said with 21 front bar you will need a bigger rear bar than the 27 to make the car more nimble than stock and I would go with 30mm rear maybe 29.

(Run 22/31 in my 930 and its perfectly neutral, a perfect road/track compromise. For autocross / slower tracks 22/32 would be perfect but I need my car to be stable enough for highspeed tracks.)



http://forums.pelicanparts.com/uploa...1289959167.jpg

I don't think much bigger tires, stiffer suspension and shocks will make the car more nimble. I don't even recommend Bilstein sports unless you get them custom dampened, they are way too stiff over potholes IMO. The dampening just isn't good. Several shops will sell them with better dampened inserts however.

If you want the car to turn sharper it will need a more aggressive stance/rake but to make it feel like a different car is going to be tough. It would be simpler to optimize how your 930 feels than try to make it a 911.

What's your budget?

I'm willing to spend what it takes to do it right, but I like to be educated before I spend a dime.

Agreed and from what you guys have been telling me it is possible to optimize my 930 to be more exciting. In the end, I may not match the 911. If I can get closer or make me want to drive the 930 on sharper roads then I have won!

Now, I'm really pumped about upgrading the suspension and alignment.

I know bigger tires will not make it more nimble, but I'm really exciting about the Toyo R888s that will be on my new rims. These tires look great and from what I read they handle very well.

Guys, I writing down all your ideas so when I update the suspension I don't lose your wisdom. Thanks.:)