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Unrealistic expectations for chassis sophistication? (esp compared to modern GT cars)

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Unrealistic expectations for chassis sophistication? (esp compared to modern GT cars)

 
Old 02-27-2019, 10:31 PM
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johnsopa
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Default Unrealistic expectations for chassis sophistication? (esp compared to modern GT cars)

My '90 C2 has 50k miles. I bought it a bit about a year and a half ago and put on about 4k miles since getting it. It's in very good condition, no rust anywhere, all of the fasteners release easily (not of the exhaust stuff was rusted at all).

I felt the suspension was a bit crashy so I replaced the original shocks and H&R green springs with a KW v3 coilover setup with Rennline monoball top hats. Also replaced the engine mounts with Wevos. Some of the suspension harshness was gone and the engine mounts seemed to help improve the feel of the driveline. However, I felt that the the chassis still doesn't feel as tight and controlled as I'd like so I figured I go for an RS-style suspension when the time was right.

This fall, the clutch was getting a bit sticky, having trouble disengaging under deceleration once the engine warmed up, so I replaced the master and slave cylinder. Unfortunately, that didn't fix it so I'm planning to clean and grease the main shaft splines. While I'm in there, I'm installing a LWF. Parts are on the way...

Over the weekend, I dropped the engine and trans successfully and decided that now is the time to upgrade the suspension.

I have the following stuff on the way:
  • Walrod bushings for up front
  • Elephant Racing (ER) rear trailing arm bushings
  • ER spring plate sealed monoball kit
So, last night I remove the front control arms and tonight I removed the spring plates and got the trailing arm completely ready to take of except for the axle nuts (dang it, don't have a 32mm sockeet on hand).

I'm surprised that for a 30 year old car, the bushings (all original) seem to be in perfect condition. The only thing I've seen with wear so far is one side of the seals on each spring plate bushing is slightly torn so you can see/touch the grease inside, but the joint is still tight.

SOOOO.... Given that I already have a good shock/spring setup and solid top hat mounts, and that the original bushings, etc. are in great shape, I'm getting a bit worried that my expectations for a significant upgrade in chassis sophistication (mainly tightness) from the remaining components are quite unrealistic.

I've got a GT4 and GT3 currently, I know they are completely different animals and are almost 30 years newer. I don't expect my C2 to be on the same level, but I was expecting that that my original suspension components would be old and tired when I took them off.

Did I set myself up for disappointment?

I remember my old '92 Cup Car and I think (although it's been almost 20 years since I had it) that it would have compared pretty well to the modern GT cars.

Curious to see what others think...
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Old 02-27-2019, 10:41 PM
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cobalt
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Not quite sure what you're expecting. As you say it is a 30 year old car. I have no issue with the 964 platform it has a lot to offer although I would not recommend the KW as I am not a fan along with most coil over kits . IMO MCS would be my choice and there are a number of modifications you can still make but in these earlier cars you sacrifice street ability as you go further down the slope. You might need to go a bit further and consider seam welding and eliminating all rubber bushings to achieve what you expect.
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Old 02-27-2019, 11:06 PM
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Hmm. I had forgotten about seam welding. The Cup Car had it, of course. And, now that I think about it, it also had a Matter roll cage installed (yeah, bad idea for a street car, but it came that way when I bought it).

So those two things probably increased the chassis stiffness significantly, allowing the suspension to work more directly compared to my '90 C2.

I'm preparing myself to be disappointed.
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Old 02-27-2019, 11:48 PM
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Marine Blue
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Considering there’s a 30 year gap in technology between the current cars and the 964 which in itself is a platform that was sorta 30 years old when it was introduced I think you’ll be disappointed.

The beauty of the 964 is that it presents a different challenge, a very analog feel that rewards more for driver skill. They’re still very capable cars and incredibly fun but certainly they won’t match a current GT car and if they did Porsche is doing something very wrong.
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Old 02-28-2019, 02:12 AM
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Probably a pretty good weight difference between your car and cup car right? If so that’s where I’d start. Weight vs spring rates.
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Old 02-28-2019, 08:02 AM
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My track build is down to 2650 pounds has a full welded in cage seam welded and full metal on metal suspension. Just think were you want it to go and it does. Not very comfortable on the street though.
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Old 04-29-2019, 03:10 PM
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Short version: I am back to say that my expectations were met.

Longer version: Here's what I did since I bought the car two years ago.

Initial starting point:
  • '90 C2, 50k miles at time of this project. Purchased two years ago with about 45k miles.
  • Original everything except for the original dual mass flywheel which was replaced at some point in the past with the updated DMF
  • All bushings, shocks were original. H&R green springs were installed by the previous owner.

Last year -- installed KW V3s:
  • Replaced OE shocks and H&R springs with KW V3s and Rennline monoball strut mounts
    • This was definitely an improvement but I still felt that the setup was a bit harsh and a bit vague, especially compared to modern cars.
  • Clutch started sticking when downshifting, classic sign of splines getting dry.
This winter:

  • Engine drop, adjusted valves, replaced spark plugs, wires and distributor caps/rotors, replaced various weeping gaskets. Powder coated the engine tins.
  • Even though all of the OE bushings looked new, I replaced them with the parts listed in my first post.
  • Installed LWF.
Thanks to Mr. Steve Weiner (Steve Weiner-Rennsport Systems) for putting together the kit of parts to do the tune-up and LWF install. He's great and was a big help along with way.

Also thanks to Andreas (AOW162435) for cleaning up the lower A-arms and trailing arms for me -- and for taking on installing the bearings, various bushings, etc. Perfect work!


Well, I've got maybe 400 miles on here since getting everything back together.

Bottom line, Walrod bushings up front, ER trailing arm bushings and spring plate monoballs, combined with KW V3s are great. I have ZERO regrets, and combined with the LWF and fresh tune-up, I am very happy and this car feels very similar to what I remember from my Cup car -- except that I have A/C and power steering. Ha ha -- and a sunroof, too!

My current point of reference in a GT4 and 991.2 GT3. While my 964 is not quite as razor sharp and refined as the newer cars, the suspension is no longer harsh while still being firm and controlled. It's definitely not as razor sharp as the new GT cars, but it's a blast to drive on twisty country roads because I can really wring out the car compared to the newer cars due to the their super-high limits.

Anyone thinking that your OE bushings are fine due to looking good, think again. Mine looked perfect except for some small tears in the rear monoball boots. The new hardware made a ton of difference.

BTW, just turned 50,964 miles yesterday. That special mileage that only happens every 1k!

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Old 04-29-2019, 03:37 PM
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I'm amazed these old cars can even get close.

Do you have a steering rack brace and upgraded bushing installed?
What tie rods are you using?
In addition to the WEVO motor mounts, the Function First trans mount insert (60A Orange) does a really nice job of further improve the feel of the driveline, without being harsh.
Heim jointed forward rod shifter (replacing the stock ball and cup system)
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Old 04-29-2019, 03:42 PM
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Originally Posted by 911Jetta View Post
I'm amazed these old cars can even get close.

Do you have a steering rack brace and upgraded bushing installed?
What tie rods are you using?
In addition to the WEVO motor mounts, the Function First trans mount insert (60A Orange) does a really nice job of further improve the feel of the driveline, without being harsh.
Heim jointed forward rod shifter (replacing the stock ball and cup system)
I did NOT change the steering rack brace/bushing.

I also have NOT changed tie rods yet.

I forgot to mention that I did install WEVO motor mounts. IIRC they are blacks.

I'm thinking about the trans mount you mention. I also have a SSK and Golden Rod -- but didn't get around to drilling out the flipped bushing holes yet. Don't feel like putting the car back on the lift, LOL.

Agreed, amazing how good these cars are when freshened up!
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Old 05-03-2019, 08:46 AM
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I have Cup suspension with monoballs, and I’m very impressed with the way mine handles, even compared to newer cars. It’s like it’s connected directly to my brain. It does exactly what I want and I can feel everything.

I’ve been debating changing to more modern coilovers, but I wonder if it’s really worth the cost. Sure, it will give me adjustability, but I’m not racing it and don’t feel like I am missing that.

i also have oem motor and trans mounts. I’ve been debating changing those.
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Old 05-03-2019, 08:49 PM
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Thanks for sharing your experience. I've been driving my 964 a lot now that the weather has turned for the bright side and this has had me thinking about it's handling. Hum...Time to call Steve up.
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Old 05-03-2019, 11:00 PM
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my car is solid everything and it has a feel not so different from my 997RS which is also solid everything. But, the chassis on the 997 is way more developed, you can feel it. But the 964 is excellent too. Stock, i don't like them at all. Too soft and wallowy.
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