Type 964 - Detailed suspension questions

[roadsleeper]

Hi all,

I am trying to ascertain the finer details of the 964's suspension bits as I am trying to upgrade said bits on my trackday car. I have added in parentheses the planned upgrades. Hopefully someone (wiser) knows the answers to some of my questions.

Also, apologies in advance for misuse of some of the terms, I am in learning mode and doing so whilst waiting for my Bentley manual to arrive.

Front suspension components which are replaceable:

- Struts and springs (KW Clubsport for Carrera RS)
- Upper and lower tie-rods (993 Carrera RS parts)
- Uprights (wheel/brake carriers) (993 GT2 Evo)
- Lower A arm (no change)
- Suspension mounts (monoballs)

Rear suspension components which are replaceable:

- Struts and springs (KW Clubsport for Carrera RS)
- Semi-trailing arms
- Suspension mounts (monoballs)

Am I missing anything?

[kurquhart]

How about adjustable sway bars? Rear spring plates (e.g. ERP)?

I assume you know that the front suspension changes you are considering will also cascade into significant front and rear brake upgrades (rotors, calipers, pads, M/C).

[roadsleeper]

Thanks kurquhart, both noted!

Suspension

I had been looking at Elephant Racing's adjustable spring plates, which look like serious kit, but they are only applicable to Impact Bumper 911s. I'll check out ERP's as their spring plates are 964 specific.

Would you change anything else? I am in a position to upgrade all the relevant parts to RS parts (964 or 993, if they fit) as I'm taking the entire car apart.

I'll be seam-welding the chassis, as well as installing a Heigo front strut tower bar and bolt-in roll cage, which should help torsional rigidity somewhat (the latter not so much perhaps as it'll be bolted in).

Brakes

Originally Posted by kurquhart

I assume you know that the front suspension changes you are considering will also cascade into significant front and rear brake upgrades (rotors, calipers, pads, M/C).

Yes, I've got the 965 "Big Reds" and Pagid Yellows on my car currently and am planning on replacing the rotors and calipers with the 993 RS "Big Reds" kit, along with a new set of Pagid Yellows.

I am also planning to upgrade the ABS system to 993 RS spec, but am still reading into this to make sure I can do such a thing. I'm stripping the entire car out, so if I would need to upgrade the wiring harness to a 993 one, it could be done to make everything work.

Standard upgrades such as stainless steel braided brake lines and Castrol SRF brake fluid will go in as well.

[kurquhart]

Originally Posted by roadsleeper

Would you change anything else? I am in a position to upgrade all the relevant parts to RS parts (964 or 993, if they fit) as I'm taking the entire car apart.

I'll be seam-welding the chassis, as well as installing a Heigo front strut tower bar and bolt-in roll cage, which should help torsional rigidity somewhat (the latter not so much perhaps as it'll be bolted in).

Camber plates and expert alignment pretty much round out the suspension side, although some folks would consider engine/tranny mounts and LSD as part of the suspension, too.

On the RS front, the shifter assembly is a nice upgrade. Some prefer a manual steering rack, some don't.

Of course, add as much lightness as you can!

[roadsleeper]

Great, thanks so much for your advice, much appreciated!!

It looks like ERP has camber adjustment plates, so I'll have a look at those. I'm definitely planning to get it laser-aligned once done with everything!

Ha ha, for the sake of my sanity, I'm trying to categorize as much as I can, so I have lumped engine / tranny mounts and LSD as part of "transmission and transmission-related". That said, the plan is for the RS mounts like those sold by Patrick Motorsports, along with a Quaife ATB LSD for the G50/21 'box I'm hoping to find (custom gear ratios).

I saw in one of your other posts that you have a Fabspeed SSK installed, have you had a chance to compare yours to an Euro-spec RS one?

Going to keep power steering and A/C as I do plan on using it for our local Porsche Club's annual drives.

A stripped interior, Euro-spec RS thin glass (rear plexi if possible), an aluminum hood and certain carbon fibre parts should round out the lightness bit Aiming for around 2,600 - 2,700 lbs! *fingers crossed*

[Bill Verburg]

It sounds like you are going to do the whole shebang and do it right
front suspension
you probably are going to be better off using 993 struts, JIC, Bilstein, Moton etc are all great choices, some are more track oriented and expensive than others is all. I like the JIC w/ monoball and camber plates
993RS uprights and either 993RS or EVO tie rods, the latter is all monoball, the RS still has a tiny amount of rubber
964 3.6t front calipers are the same except for color as Big Reds used on 993RS & 993tt. The rotors on the other hand are quite different, as long as the 993RS uprights are used the 322x32 2 piece 993tt rotors can be used, these are the same size as the 964RS /964t 322x32 1 piece rotors but much cheaper. Note that w/ this setup no caliper adapters are used.

rear
of course the shocks need to be matched to the front
use 993 rear calipers on stock 964 rear rotors or 993 rear calipers on 968M030 rear rotors

use 993 m/c and booster

[Bill Verburg]

As far as the trans, a /21 would be nice. They are on the rare side, do use a 40/65 or 50/80 lsd, the former for dual use the latter for a dedicated track car.

TomW just put a factory rebuilt /32 which comes w/ all the good stuff into his. This would be a super choice.

There also have been a # of early 996Cup g50s on the market, they have great gearing and internals except for the use of 8:32 cwp, these are probably excellent for a dedicated track car(but still too low for 964/994 revs, JMO) and even less appropriate for a dual use car. Just from my experiance w/a Cup /30 in my car, I wouldn't ant anything shorter for dual use.

[Bill Verburg]

Here's an example of a modified 996 cup trans, I think 4 & 5 were changed from stock 996Cup gearing, have to look it up to be sure.

[kurquhart]

Originally Posted by roadsleeper

I saw in one of your other posts that you have a Fabspeed SSK installed, have you had a chance to compare yours to an Euro-spec RS one?

Tom W has the Fabcar set up. I have a B&M short shift kit, which is OK but not great. I have held the RS shifter bits in my hand, but we were unable to mount them in my 90 C2; it is supposedly easier in later years (i.e. 92+).

Originally Posted by roadsleeper

A stripped interior, Euro-spec RS thin glass (rear plexi if possible), an aluminum hood and certain carbon fibre parts should round out the lightness bit Aiming for around 2,600 - 2,700 lbs! *fingers crossed*

I have spent a lot of resources removing weight; I finally got down to 2550# empty, but it was not easy. Again, Tom W is farther down this path, but I'm not sure what his current numbers are.

[roadsleeper]

Bill Verburg - Thanks a bunch for your very informative posts! It's going to take me some time to digest some of this stuff, especially the gearing info, but it's all very helpful!

Suspension

Would you happen to know if the mounting points for 993 struts match up with those on the 964s? I am aware of the MY '89 - '91 change in the height of the rear strut mounting point for the 964s, as well as the changes in the positioning and bolt holes. I'd be keen to know if this happened during the 964 to 993 generation change.

Brakes

Will most likely go with the 993 RS brakes with the larger discs and 993 rear calipers on 968 M030 rear rotors as you mentioned.

Apologies in advance for the newbie question, but are there any other 993 braking system parts that I need (aside from the booster, ABS controller, master cylinder and brake fluid lines) to make this upgrade work?

Transmission

I would love to have a G50/32 'box in my car, but the PET system says that we cannot simply order a /32 from Porsche, rather that we would have to send in a core /32 box for refurbishment or in exchange for a replacement.

With that in mind, buying a /21 'box and fitting custom parts to it sounds more probable.

I'm going to re-read your posts a couple more times to understand it better!

BTW, I'm a Siena College alum, it looks like you're from that part of the world?

kurquhart - Thanks again for your inputs!

I'm going to plan on fitting a 993 RS shifter into the G50/21 'box in that case. I've been reading posts of people who are happiest with the OEM SSK when it comes to the post-IB, air-cooled 911s so this seems to be the most sensible option.

The weight loss part is going to be tough, I've tried to set my goals to be as conservative as I can

[Bill Verburg]

Originally Posted by roadsleeper

Bill Verburg - Thanks a bunch for your very informative posts! It's going to take me some time to digest some of this stuff, especially the gearing info, but it's all very helpful!

Suspension

Would you happen to know if the mounting points for 993 struts match up with those on the 964s? I am aware of the MY '89 - '91 change in the height of the rear strut mounting point for the 964s, as well as the changes in the positioning and bolt holes. I'd be keen to know if this happened during the 964 to 993 generation change.

Brakes

Will most likely go with the 993 RS brakes with the larger discs and 993 rear calipers on 968 M030 rear rotors as you mentioned.

Apologies in advance for the newbie question, but are there any other 993 braking system parts that I need (aside from the booster, ABS controller, master cylinder and brake fluid lines) to make this upgrade work?

Transmission

I would love to have a G50/32 'box in my car, but the PET system says that we cannot simply order a /32 from Porsche, rather that we would have to send in a core /32 box for refurbishment or in exchange for a replacement.

With that in mind, buying a /21 'box and fitting custom parts to it sounds more probable.

I'm going to re-read your posts a couple more times to understand it better!

BTW, I'm a Siena College alum, it looks like you're from that part of the world?

kurquhart - Thanks again for your inputs!

I'm going to plan on fitting a 993 RS shifter into the G50/21 'box in that case. I've been reading posts of people who are happiest with the OEM SSK when it comes to the post-IB, air-cooled 911s so this seems to be the most sensible option.

The weight loss part is going to be tough, I've tried to set my goals to be as conservative as I can

The brake part has been thoroughly documented 964RS brakes

you use appropriate 964 suspension pieces in the back. Only the front is converted to 993spec

you don't need a like kind exchange box( at least some dealers can accomodate you for a fee) I know several people that have purchased them outright or w/ a /20 exchange

Small world, I've been playing tennis at Sienna for over 40 yrs.

[roadsleeper]

Thanks very much for the link!

I'm going to keep trying to get my hands on a /31 if I can, but it's a bit difficult dealing with the local dealer (I'm no longer located in the Capital Region).