Improve the handling of the 981 - X73

[daz05]

A video I made documenting trying the X73 anti roll bars you can buy from the 718 and 981 with X73.

Recommend you guys try this!

 

 

[michelin]

Superb vid Daz. I viewed it before.

Another little add on I've now got to do! 

I thought my BS drove really well too but this, I assume, will make it far far better!

😀

[daz05]

42 minutes ago, michelin said:

Superb vid Daz. I viewed it before.

Another little add on I've now got to do! 

I thought my BS drove really well too but this, I assume, will make it far far better!

😀

Cheers mate.  Yes you should.  It addresses a few things, a tad more feel through your seat, better turn in and reduces understeer. 

I've had some comments saying the next step on a PASM car is adding the X73 springs!  Maybe something for the future.

[CliveH]

Interesting. I've been toying with adding the 987 Spyder rear anti-roll bar to my 987.2 now I have the Spyder shocks and springs on it. I'm guessing the result will be similar - I did drive a Spyder recently and it did feel a tad tighter than mine (in a good way).

[daz05]

1 hour ago, CliveH said:

Interesting. I've been toying with adding the 987 Spyder rear anti-roll bar to my 987.2 now I have the Spyder shocks and springs on it. I'm guessing the result will be similar - I did drive a Spyder recently and it did feel a tad tighter than mine (in a good way).

Do it Clive. It was driving the 987 Spyder and 718 which inspired me to investigate this.

[Lennym1984]

I thought the Spyder had the same rear ARB as an S? I was under the impression that only the Cayman R had a different one

[CliveH]

Hmmm...that needs further investigation then.

[daz05]

I would imagine it would depend on how you specified the Spyder.  If it has X73 then you get the stiffer bar. 

[Lennym1984]

50 minutes ago, daz05 said:

I would imagine it would depend on how you specified the Spyder.  If it has X73 then you get the stiffer bar. 

Sorry I was talking specifically about the 987. X73 as an optional package was not available until the 981

Edited July 15, 2020 by Lennym1984

[mneil]

The full X73 kit drastically improved the handling of my 981s, I want happy with the feel of the car on the standard set up. You can't just have the springs, you have to have the correct matching shocks, springs alone will be too short.

[Stuart21UK]

nice video again @daz05 I like your presenting style keep it up mate 👍

[daz05]

1 hour ago, mneil said:

The full X73 kit drastically improved the handling of my 981s, I want happy with the feel of the car on the standard set up. You can't just have the springs, you have to have the correct matching shocks, springs alone will be too short.

Probably my fear also but with pasm this is your only option if you to go lower on an OEM set up.

 

Apparently it works quite a few messages on this topic today. I put shorter springs on my m3 with EDC suspension (BMW pasm) and the handling improved ride comfort a little worse.

Not something that I'm considering right now anyway.

[daz05]

30 minutes ago, Stuart21UK said:

nice video again @daz05 I like your presenting style keep it up mate 👍

Thanks mate, very nice of you to say that and appreciated 👍. Enjoyed making this one and trying to think of the next thing to tinker with.

[Ringer250]

Great video Daz. 👍. Have subscribed to your channel.

Interested in the change - what is the full part number of the X73 bar you fitted? My car has PASM.

 

Edited July 16, 2020 by Ringer250

[daz05]

1 hour ago, Ringer250 said:

Great video Daz. 👍. Have subscribed to your channel.

Interested in the change - what is the full part number of the X73 bar you fitted? My car has PASM.

 

Good stuff left the part numbers and torque specs in the video description.

For a PASM Boxster 981 333 703 14 is what you need. Your bushes can be reused.

👍

[Buzzfox]

Another great video @daz05which has got me thinking (which happens very rarely!).

I've just come back from a trackday. I don't do them very often so every time I do I'm amazed at epic handling of my GTS, I'm sure it gets me out of a lot more trouble than it should! The only (very tiny) fly in the ointment that I can think of is that, as I don't have an LSD, I do find the inside wheel spinning up a bit on tight corner exit. I know absolutely nothing about car set up so this might be a really stupid question but do you think a stiffer anti-roll bar would reduce the weight transfer to the outside wheel and therefore reduce the willingness of the inside to spin up resulting in better traction and acceleration out of a tight corner?

Please feel free to tell me that's a complete numpty question, I won't be offended - if you don't ask you don't know!!

[daz05]

1 hour ago, Buzzfox said:

Another great video @daz05which has got me thinking (which happens very rarely!).

I've just come back from a trackday. I don't do them very often so every time I do I'm amazed at epic handling of my GTS, I'm sure it gets me out of a lot more trouble than it should! The only (very tiny) fly in the ointment that I can think of is that, as I don't have an LSD, I do find the inside wheel spinning up a bit on tight corner exit. I know absolutely nothing about car set up so this might be a really stupid question but do you think a stiffer anti-roll bar would reduce the weight transfer to the outside wheel and therefore reduce the willingness of the inside to spin up resulting in better traction and acceleration out of a tight corner?

Please feel free to tell me that's a complete numpty question, I won't be offended - if you don't ask you don't know!!

Thanks Buzz, the purpose is to document and share experiences so glad you enjoyed. It's a great point you raise.

In answer to your question, increasing the bar stiffness should reduce traction at the rear in relation to the front. This works positively when entering a corner as the car wants to rotate quickly, and when applying power again we have less traction which again helps the car to rotate. 

However, in isolation, fitting a stiffer bar I guess in theory, is likely to make your specific problem worse.

My own experience hasn't confirmed that though, in fact, I found the stiffer bar allowed me to adjust the rear end with the throttle to get a better exit. I can turn in and dab the throttle a little to push me round moreso than before. The track guys on Rennlist suggested the X73 bar was also an improvement on track and at their X cross events they seem to enjoy over there.

To avoid the inside spinning up I would recommend you try to be smoother in applying power.

Interested to hear what the others think but I think overall you would be happy with the benefit you gain with regards to understeer.

Cheers

 

 

 

 

Edited July 22, 2020 by daz05

[GTSMarky]

Nice work Daz. 

on the road my BGTS is pretty much spot on I’d say. Just back from 650 miles down into Devon with my wife for a walking, work catching up with mates trip and the car was great. Motorways and twisty Devon roads have me hitting the Sport button on and off To suit. 
At road speeds handling is very good and I’ve 20” wheels with pretty worn P Zeros on 32/33 psi.  It’s a firm ride and you know it after a while. I don’t ever use the stiffer PASM setting on the road as it’s far too hard. 
 

however on track it’s a different story and the understeer is drastic getting worse with tyre temp increasing. I keep my pressures to 32/33 and adjust as they get hotter. 
 

I think the only real fix is a geo set up and MPS4S tyres all round or Cup 2’s if they were available in the right sizes. The stiffer rear AR.bar may also help and I can see why you say what you do in the excellent summary. 
 

inside rear wheel spin on track I also get but be careful as that can also be your clutch! There isn’t really enough power to light up the rears GT3 PDK style in our boxsters and a PTV would help improve this . essentially if you push the 981 hard on track it’ll understeer badly unless you really sort the geo and even then you still have the drive/grip/PTV or nor issues which is why I have canned track days in my car now as they just ruin the car if you’re pushing on and what’s the point of a track day when you don’t push on so I ride bike track days to get my fix.  
 

[daz05]

1 hour ago, GTSMarky said:

Nice work Daz. 

on the road my BGTS is pretty much spot on I’d say. Just back from 650 miles down into Devon with my wife for a walking, work catching up with mates trip and the car was great. Motorways and twisty Devon roads have me hitting the Sport button on and off To suit. 
At road speeds handling is very good and I’ve 20” wheels with pretty worn P Zeros on 32/33 psi.  It’s a firm ride and you know it after a while. I don’t ever use the stiffer PASM setting on the road as it’s far too hard. 
 

however on track it’s a different story and the understeer is drastic getting worse with tyre temp increasing. I keep my pressures to 32/33 and adjust as they get hotter. 
 

I think the only real fix is a geo set up and MPS4S tyres all round or Cup 2’s if they were available in the right sizes. The stiffer rear AR.bar may also help and I can see why you say what you do in the excellent summary. 
 

inside rear wheel spin on track I also get but be careful as that can also be your clutch! There isn’t really enough power to light up the rears GT3 PDK style in our boxsters and a PTV would help improve this . essentially if you push the 981 hard on track it’ll understeer badly unless you really sort the geo and even then you still have the drive/grip/PTV or nor issues which is why I have canned track days in my car now as they just ruin the car if you’re pushing on and what’s the point of a track day when you don’t push on so I ride bike track days to get my fix.  
 

Nice one Mark, what I like most about this is the increased feel and direct feeling you get from the car even at slower speeds. I'm tempted to get the front one done now too to maybe feel even more and to balance it out as Porsche intended.

After a bit more driving I took it up the mountain with a group of other Porsches and it's definitely riding ever so slightly stiffer on the rough sections which I hadn't realised before  on the roads I drove in the video.  The handling in the tight sections was great, properly adjustable on the throttle and a nice direct feel from the rear.

I find the PS4S ride a bit better than the P zeros they are definitely softer.

 

[Buzzfox]

18 hours ago, daz05 said:

Thanks Buzz, the purpose is to document and share experiences so glad you enjoyed. It's a great point you raise.

In answer to your question, increasing the bar stiffness should reduce traction at the rear in relation to the front. This works positively when entering a corner as the car wants to rotate quickly, and when applying power again we have less traction which again helps the car to rotate. 

However, in isolation, fitting a stiffer bar I guess in theory, is likely to make your specific problem worse.

My own experience hasn't confirmed that though, in fact, I found the stiffer bar allowed me to adjust the rear end with the throttle to get a better exit. I can turn in and dab the throttle a little to push me round moreso than before. The track guys on Rennlist suggested the X73 bar was also an improvement on track and at their X cross events they seem to enjoy over there.

To avoid the inside spinning up I would recommend you try to be smoother in applying power.

Interested to hear what the others think but I think overall you would be happy with the benefit you gain with regards to understeer.

Cheers

 

Thanks Daz, that makes sense now I think about it with less beer inside me! Would it be fair to say, very basically because I know there's a lot more science to it, that the stiffer rear bar kind of moves the balance of the car slightly more forward giving the front wheels a little more say in the handling?

[Buzzfox]

7 hours ago, GTSMarky said:

Nice work Daz. 

on the road my BGTS is pretty much spot on I’d say. Just back from 650 miles down into Devon with my wife for a walking, work catching up with mates trip and the car was great. Motorways and twisty Devon roads have me hitting the Sport button on and off To suit. 
At road speeds handling is very good and I’ve 20” wheels with pretty worn P Zeros on 32/33 psi.  It’s a firm ride and you know it after a while. I don’t ever use the stiffer PASM setting on the road as it’s far too hard. 
 

however on track it’s a different story and the understeer is drastic getting worse with tyre temp increasing. I keep my pressures to 32/33 and adjust as they get hotter. 
 

I think the only real fix is a geo set up and MPS4S tyres all round or Cup 2’s if they were available in the right sizes. The stiffer rear AR.bar may also help and I can see why you say what you do in the excellent summary. 
 

inside rear wheel spin on track I also get but be careful as that can also be your clutch! There isn’t really enough power to light up the rears GT3 PDK style in our boxsters and a PTV would help improve this . essentially if you push the 981 hard on track it’ll understeer badly unless you really sort the geo and even then you still have the drive/grip/PTV or nor issues which is why I have canned track days in my car now as they just ruin the car if you’re pushing on and what’s the point of a track day when you don’t push on so I ride bike track days to get my fix.  
 

I know what you mean about the understeer, mine used to understeer like crazy and it always seemed an age waiting for the front end to 'bite' before getting on the power for corner exit.

As you say the geo makes a world of difference. I took the car to Center Gravity to see if they could dial some of the understeer out but without it becoming snappy and still being great for daily driving - not much to ask eh?!!

I was sceptical that I would notice any difference but it was almost like a different car when they'd finished. Basically after initially driving it they said the rear was having too much influence in the handling leading to a fidgety front end (which I hadn't noticed until they'd fixed it!) and more understeer than necessary. 

The basic settings the car now has are: 

Front camber: -1°15'   (0°10' outside Porsche factory spec maximum tolerance)

Front total toe: 0°02'

Rear camber: -1°35' (right on the minimum Porsche factory spec)

Rear total toe: 0°12'

The car really feels great now on road and track, just need to control my right foot a bit more to stop the inside rear spinning up!

I guess with Daz's ARB change it could be even better?

 

 

Edited July 23, 2020 by Buzzfox
added a bit!

[daz05]

23 minutes ago, Buzzfox said:

Thanks Daz, that makes sense now I think about it with less beer inside me! Would it be fair to say, very basically because I know there's a lot more science to it, that the stiffer rear bar kind of moves the balance of the car slightly more forward giving the front wheels a little more say in the handling?

You are confusing me now mate 😂

When we turn into the corner the car wants to lean outwards, the front digs in as before but by adding the stiffer rear bar we are reducing the suspensions ability to lean which means the load is transferred to the tyres sooner than before, and therefore we reduce our traction at the rear sooner than before.

This is good at turn in because we gain the sensation of the rear being pushed out toward the outside of the corner and therefore helping the front end by pushing us around the corner.

What happens at the front is unchanged but it gains more help than before.

At corner exit the same applies and we can steer a little more with the throttle, an LSD would be great because we could control that but because of the cars natural mid engined balance it's not a big problem. An open diff in 300 bhp front engined rear wheel drive car would be a pain.

We can also adjust the alignment to enhance or dial out the changes from adding a stiffer bar. We could increase rear camber to compensate a little for the lose of traction. All of this is down to preference and driving style.

The GT4 rear bar is actually adjustable at the mounting point so you can tweak this without swapping bars. 

The main benefit for me is that the car feels more like what I associate with the brand, I am feeling more of what is going on and the car feels more darty without being unruly or lairy.

 

 

 

 

[daz05]

We only have to look at the 718, Porsche hasn't fiddled too much with the front end but they have actively stiffened up the rear by adding an extra brace, stiffer AR bar and stiffer springs and dampers. Some of this is because the engine is heavier but for me it could link back to what you've said about the rear having too much influence over the front.

Thanks for sharing your settings, they may be too aggressive with my set up but nice to have for reference.

Edited July 23, 2020 by daz05

[Buzzfox]

7 minutes ago, daz05 said:

You are confusing me now mate 😂

 

Rest assured I'm confusing myself far more than I'm confusing you 🤣

[GTSMarky]

This all just confirms that I need a 4.0 GT4!