Opinions please: Full or partial suspension refresh

[jerzybondov]

Thanks for all the updates - as drmark says keep us posted on the conclusions of CG’s subframe inspection.

 

[chowgar]

I did the full refresh at CG, including shocks. But don't expect it to last 10-15 years. In the 5 years - and 20k miles - since mine was done I have had to have 2 further coffin arms and toe links all round (also done by CG). These cars are very hard on bushes and toe links. At least they are on the roads around me...

My recently sold 2005 Carrera S did not need a single suspension component replaced in the 10 years I owned it and believe me, I drove it hard. I used the same Indy during this time and they were astounded that nothing perished. The suspension remained tight throughout my time with the old gal. I think my bushings were made of kryptonite!

 

[Mac68]

Good luck with the sub frame, disspointing to find such a thing but as you say much better to be found at this stage than on the road.

 

[Neven]

Hopefully I’ll get to collect my car from CG later this week. I’ll get the full story then…

 

[Mac68]

Hopefully I’ll get to collect my car from CG later this week. I’ll get the full story then…

Like everyone else on this thread, and many others, I've only ever experienced and heard good things about CG. I've taken my two 997s there and on both occasions they've gone above and beyond.

 

[Neven]

Collected my car from CG this morning

The following work was completed as part of my suspension refresh:

• Front struts removed and rebuilt with Eibach Pro springs, new Porsche OE top mounts and bump stops (trimmed to accomodate lowering springs). All existing strut components such as the bearings were serviced, then the struts refitted.
• Front track control arms (coffin arms) and bolts initially replaced with Meyle parts, but then changed to Design 911 OE Match parts (more on that later...)
• Front diagonal control arms and bolts replaced with Meyle parts.
• Inner and outer track rod ends relaced with Meyle parts.
• New OEM front anti-roll bar bushes fitted.
• Rear struts removed and rebuilt with Eibach Pro springs, existing top mounts and bump stops (which were again trimmed to accomodate lowering springs). The rear OEM shocks were modified by machining an additional groove 7mm lower for the circlip that holds the spring mounting ring to sit on).
• All 5 rear suspension arms (on each side) were replaced along with excentric bolts, etc. I undertook the replacement of the 4 upper arms myself before taking the car to CG.
• Full geo setup for road bias.

I'm absolutely delighted with the way the car looks and feels following the work. Pete and I went out for a drive as part of the handover process. He asked me to think back to how the car felt before the work, and to try and dismiss any placebo effect, then provide feedback on how it feels now. Straight away I noticed that the low speed ride was smoother with the steering lighter and more nimble feeling. As we came to a faster dual carriageway it was very apparant that the car was tracking absolutely straight, albeit gently moving left as it followed the road camber. Again, the most profound characteristic was how much smoother the ride was with the PASM dampers in standard mode. Pete said that this was down to 2 things, the fact that all the bushings were new, and the Eibachs which are significantly softer in their initial rate of compression being they are progressive. Next we drove on some B roads that had some nice sweeping bends, but were badly surfaced in several spots. I noticed that I didn't have so much of an urge to really 'hold on' to the steering wheel, rather I was more comfortable holding the wheel in a more relaxed manner as the wheel wasn't tugging one way or the other as much. There was also much more controlled lateral body movement, which again contributed to the more relaxed steering feel. When we got back to the workshop I commented that my shoulders didn't feel fatigued, whereas previously they had after a spirited drive. Pete advised that I should monitor the speedo whilst I reclaibrate to the new setup as he said most people will naturally carry more speed without actually realising it.

As for ride height, the following shows the differences achieved. I think Pete has gauged it just right in that the stance has been vastly improved, but without slamming the ride so as to make it impractical. I guess time will tell on this front, but I purposely drove on some roads with what I consder to have aggresive speed humps and I didn't experience any scraping

Chassis Heights	Front	Rear
Porsche OE specification	133mm	153mm
My car on its stock springs (before)	124mm (-9mm from OE spec)	145mm (-8mm from OE spec)
My car on Eibach Pro springs and modified rear stocks (after)	106mm (-18mm from stock springs)	128mm (-17mm from stock springs)

Before - stock springs



After - Eibach Pro springs and modified rear shocks
Excuse the filthy car

 

[Neven]

Further to the above, I did promise to share the outcome of the 'complication' associated with the suspension refresh.

I sought permission from Pete to do this write up, and he was more than happy for me to do so.

The crack in the front aluminium subframe was actually caused when Pete attempted to torque up the bolt that holds the front drivers side coffin arm. There was nothing untoward, but nonetheless, this is what happened. Initially, Pete sought advice from CG's engineering partner who sent over a welder to assess whether the subframe could be repaired. The chap was confident he could repair it with a TIG weld; however, it turned out his portable welding equipment couldn't work off of AC power, and CG didn't have a DC power supply in their workshop. This being Friday afternoon at this point, it was therefore arranged for the welder to come back on the Monday morning with AC compatible equipment. As it was clear I wasn't going to be driving my car home, I caught a train home instead.

After dropping me to Atherstone station, Pete returned to the workshop and discussed the situation with Chris. They decided to whip the subframe off of the car so that the welder could do his work on Monday morning without having to work in the confines of the wheel arch. They also decided to order a subframe replacement as a fall back.

On the following Monday, the subframe was repaired as per the photo below. I've drawn a red line to show where the crack was before the welding repair:



Whilst all this was going on, Pete turned his attention to why this would've occured in the first place. Straight way he suspected the Meyle coffin arm way have been undersized. Essentially, when he started to torque up the bolt, with there not being much resistence coming from the arm on the other side of the casting, this may have cracked it.

It was important to Pete that he found out exactly the root cause because he didn't want to risk further damaging my car on the passenger side, or indeed the repaired side. However, this is bread and butter work for CG and he didn't want this to happen to any other customers' cars. So with that in mind, CG actually took a selection of front coffin arms out of their stock (inc. Meyle and Porsche OEM), and they additionally bought a series of equivalent parts from multiple suppliers, including more Meyle, Porsche, CTE, Optimal, and OE Match from Design 911. Pete has since accurately measured around 20 arms both as they come straight out of the packaging, and also when they are compressed in a vice. He has photos of detailed caliper readings for each arm, and has logged all the readings in a spreadsheet. There have been some interesting findings...

Firstly, the bushings in all the arms manufactured in 2024, other than those from Porsche or Design 911 OE Match were undersized by around a millimeter. Some in their compressed state or a few in their uncompressed state. Arms from Meyle, etc. that were manufactered in 2023 were fine. So the initial findings indicate that there may have been a change in the specs for the bushings, or a bad batch. CG have escalated and are in dialog with Meyle - this is onging so I can't really comment much more this for now.

Given the above, CG feel they have to now measure the dimensions of any arm they fit. For my car, they have replaced the Meyle arms in question and have sent them back to Meyle via Design 911 who are also actively helping with this matter. They have used the Design 911 arms as the replacement. Until there is a satisfactory conclusion, Pete said they will only fit either Porsche OE or Design 911 OE Match components to a 997, and even then they will measure each components as part of their installation process.

Regarding the subframe, CG decided to replace the subframe on my car with the unit they bought in as a fallback. Pete said he has inspected my repaired subframe and it looks like a good strong weld; however, he said using it introduces a further unknown factor and he doesn't want to take that risk.

All in all, a somewhat dramatic turn of events that I thought would be valuable to share with this community. Especially if you are considering refreshing your own suspension as there are some important additional things to check.

I should also point out that CG checked the rear coffins arms too and have concluded the problem only affects the front arms.

 

[jerzybondov]

Super helpful info, thank you so much for taking the time to write it up.

So glad you’ve got your car sorted now too!

 

[drmark]

Thank you for the update. I shall add candour to CG's long list of attributes
Glad it all worked out for. Enjoy!

 

[pk2904-997]

Yes brilliant info here thanks.Happy you got it sorted pal.

Now go have some fun and enjoy your car!

it's been a few weeks now since my CG work was completed and I'm still shocked at how I can push the car, mine was night and day difference. I think this was mainly due to the fact I changed every suspension component and fitted the dsc at the same time.

 

[Neven]

DSC is still on my wish list. Pete recommended I live with my refreshed suspension as is for now, then get the DSC a little further down the line so that I would appreciate the next step on when I eventually do upgrade the controller.

I know it's been said a thousand times on this forum, but CG really do work wonders with these cars. A combination of refreshed parts and an optimal geo has made my car feel tight, controlled and has even improved the ride quality. Very happy indeed. As you and others have said, I need to go and enjoy it now...

In fact, first adventure is the Tribal Gruppe drive out to Rindt this coming Sunday. May see some of you there...

 

[pk2904-997]

I need to join these tribal gruppe drives they sound awesome .

As for the dsc definitely get one in the future but its not essential right now. I think letting your wallet chill abit is the best option right now

 

[Neven]

I think letting your wallet chill abit is the best option right now

Amen to that

 

[pk2904-997]

Amen to that

 

[Gizmob73]

Further to the above, I did promise to share the outcome of the 'complication' associated with the suspension refresh.

I sought permission from Pete to do this write up, and he was more than happy for me to do so.

The crack in the front aluminium subframe was actually caused when Pete attempted to torque up the bolt that holds the front drivers side coffin arm. There was nothing untoward, but nonetheless, this is what happened. Initially, Pete sought advice from CG's engineering partner who sent over a welder to assess whether the subframe could be repaired. The chap was confident he could repair it with a TIG weld; however, it turned out his portable welding equipment couldn't work off of AC power, and CG didn't have a DC power supply in their workshop. This being Friday afternoon at this point, it was therefore arranged for the welder to come back on the Monday morning with AC compatible equipment. As it was clear I wasn't going to be driving my car home, I caught a train home instead.

After dropping me to Atherstone station, Pete returned to the workshop and discussed the situation with Chris. They decided to whip the subframe off of the car so that the welder could do his work on Monday morning without having to work in the confines of the wheel arch. They also decided to order a subframe replacement as a fall back.

On the following Monday, the subframe was repaired as per the photo below. I've drawn a red line to show where the crack was before the welding repair:

View attachment 109383

Whilst all this was going on, Pete turned his attention to why this would've occured in the first place. Straight way he suspected the Meyle coffin arm way have been undersized. Essentially, when he started to torque up the bolt, with there not being much resistence coming from the arm on the other side of the casting, this may have cracked it.

It was important to Pete that he found out exactly the root cause because he didn't want to risk further damaging my car on the passenger side, or indeed the repaired side. However, this is bread and butter work for CG and he didn't want this to happen to any other customers' cars. So with that in mind, CG actually took a selection of front coffin arms out of their stock (inc. Meyle and Porsche OEM), and they additionally bought a series of equivalent parts from multiple suppliers, including more Meyle, Porsche, CTE, Optimal, and OE Match from Design 911. Pete has since accurately measured around 20 arms both as they come straight out of the packaging, and also when they are compressed in a vice. He has photos of detailed caliper readings for each arm, and has logged all the readings in a spreadsheet. There have been some interesting findings...

Firstly, the bushings in all the arms manufactured in 2024, other than those from Porsche or Design 911 OE Match were undersized by around a millimeter. Some in their compressed state or a few in their uncompressed state. Arms from Meyle, etc. that were manufactered in 2023 were fine. So the initial findings indicate that there may have been a change in the specs for the bushings, or a bad batch. CG have escalated and are in dialog with Meyle - this is onging so I can't really comment much more this for now.

Given the above, CG feel they have to now measure the dimensions of any arm they fit. For my car, they have replaced the Meyle arms in question and have sent them back to Meyle via Design 911 who are also actively helping with this matter. They have used the Design 911 arms as the replacement. Until there is a satisfactory conclusion, Pete said they will only fit either Porsche OE or Design 911 OE Match components to a 997, and even then they will measure each components as part of their installation process.

Regarding the subframe, CG decided to replace the subframe on my car with the unit they bought in as a fallback. Pete said he has inspected my repaired subframe and it looks like a good strong weld; however, he said using it introduces a further unknown factor and he doesn't want to take that risk.

All in all, a somewhat dramatic turn of events that I thought would be valuable to share with this community. Especially if you are considering refreshing your own suspension as there are some important additional things to check.

I should also point out that CG checked the rear coffins arms too and have concluded the problem only affects the front arms.

Thanks Neven, that is a very timely update. I have just tracked down the creaking on my front suspension and it is the bush in coffin arm that connects to the sub-frame. I was just about to push the button on Meyle parts when I read this. I have now ordered the OE Match parts kit with bolts from Design911 instead now.
I'm fitting this myself so could really do without cracking the sub-frame. Super helpful post, thanks.