SC front suspension/brakes & steering upgrade- worth the trouble?

[craighardy]

I'm building a 1967 912 hotrod/911R style car and am wondering if the SC stuff is that much of an upgrade. This will be a streetcar but I do plan to do some track days with it.

Here's the deal. I picked up a 1965 912 project a few months ago and it was completely torn down to the bare tub. The previous owner glued on some fiberglass SC quarters (very badly) and also welded in the center section of an SC torsion bar tube to convert the car to a LWB RS clone. He also shaved the door handles and gutters (WTF?). The car came with all of the SC suspension, brakes and steering rack etc. I decided I didn't want to mess with this frankenstein tub and I also prefer the look of the narrow body SWB cars. I sold off the tub and picked up a 1967 912 roller.

I realize the rear suspension will not work but I'm wondering if I should even bother with the front. Is the later stuff really that much better? Can I still lower the car with the torsion bars and not totally mess up the handling? I have a lot of body and drivetrain work ahead of me so I guess I'm trying to lighten the load.

Also one of the struts has a bent steering knuckle and needs to be replaced. I found this out after dropping my struts off at Elephant racing to have the spindles raised and braced. Including the bump steer kit the bill comes out to about $750 add another $250 for a used strut. So if I stick with the stock stuff this will leave me with a grand that I can put back into the budget. I have never driven an early 911/912 and have only driven an SC on a short trip. The plan is to have a sub 2000lb car with around 210hp. Will the car be that much better with the SC equipment?

[super9064]

I have not done this so, I'm no expert. Part of the reason for the "up grade" is that the stock suspension bushings are very expensive and wear out quickly. The other reason is the ease of adding the larger brakes from the SC. Also the reduced weight of the Aluminum crossmember. I'm not sure if the handling is better. Again there are many on this board that know more about it than me, maybe someone else will chime in. I've seen quite a few posts on Pelican about this, so you may try searching there too.

[304065]

The answer is an absolute YES.

First of all, the SWB ball joints are about $200 a SIDE. Compare that with about $80 per side for LWB, or $350 a pair if you want the Elephant Racing decambered ball joints that allow you half an inch more track and three-quarters of a degree of negative camber with no other modifications. Ball joints are one of those must-replace items for any suspension refresh, so you're ahead of the game economically right there.

Next: the way that the SWB ball joint attaches to the A-arm is with a pair of M12 bolts that run through the lower antiroll bar bracket, through the a-arm, through the ball joint carrier, through the a-arm again and then terminate with a pair of castle nuts. This is a VERY complex arrangement that doesn't necessarily result in ideal kinematics for the ARB and has the whole thing relying on a couple of big bolts (which is why Porsche used TWO of them). There's not much adjustability built in to this arrangement, and big changes in camber require modification to the a-arms-- you'd be a test pilot on this.

Next: most SWB a-arms are full of RUST

Next: the design of the SWB front suspension allows for very limited stock alignment settings-- the LWB had more flexibility and range even with stock parts.

Next: There are WAY more trick goodies available for LWB front suspensions-- I will list a few:

Wevo Camberking-- integrated monoball and strut tower bar, VERY slick, adds negative camber and tightens up the front end.

Elephant Racing Self-aligning control arm mounts-- these work with the LWB arms-- allow you to use spherical washers to capture the control arm mount so that the front and rear mount are collinear-- avoids the binding of the a-arm that results from small tweaks in the chassis binding the arm when you tighten the mounts down.

Suspension bushings-- while both needle bearings and polybronze bushings are available for SWB, there is more experience in the community with installing them on LWB.

Next: the all-important issue of bump steer- if your car is lowered you MUST take action to raise the steering rack and correct the handling issues-- LWB struts come in adjustable verisons OR you can get them pre-welded for lowered cars. Elephant even has a double-shear mount for the steering arm, also very trick that eliminates the bump steer issues. Trust me, when you are holding the wheel for dear life trying to keep the car tight to the apex so you don't run off at the track-out, NOT having the steering fight you can literally mean the difference between a fast lap and a high-speed spin.

I personally prefer the SmartRacing ARB, it's a very high quality part.

Here is a link to Chuck's page:

http://www.elephantracing.com/suspen...iondiagram.htm

Good luck!

[speedo]

I concur with John. Nothing to add as it relates to the front of the car...however treat the rear of the car to some SWB adjustable spring plates. Chuck sells them, or you can easily modify a set of LWB adjustable spring plates to work. I presume you will rebush the rear of the car and/or replace the torsion bars. While you are in there...swap the spring plates. Whoever does your final alignment/lowering/corner balance will thank you.

Speedo

[craighardy]

Wow, thanks for the very detailed answer. This is exactly what I wanted to hear. Thanks a lot for educating me guys!

[Neunelfer]

I would do it. So... what John said. I'll add a bit on brakes as well.

You'll get a larger pad surface (same piston size) so, your stopping power will increase up front. You may have a bit of a problem with bias as the SWB rear arms are set up for L-Calipers with the 2.25" mounting ears. Those also have a smaller pad than the basic 911SC rear. All 911's from 1970 through 1983 used the same size rear pad on a 38mm piston. So... only concern might be bias. You'll be front heavy.

Speaking of heavy, your A-Calipers are heavy ones. That front strut would accept S-Calipers which are my favorites (I don't buy into that flexing myth too much). You might want to look into a nice set of vintage S-Calipers (basically the same as a 908 caliper) for your hot rod 12.

Sounds like a fun project.

[MarkS]

Eric/All what are your thoughts on using different compound pads F/R to adjust bias W/O installing a manual set up? On my 67S I want to go with front alloy S calipers with the stock 67S rear. Since the piston size F&R match I would think a more aggressive pad on the rear may do it.

[Sean F]

To echo what others are saying, keep in mind that suspension is a system. You can really mess yourself up if you just start swapping/adding components but not thinking about the entire system. It's important to address the rear as well as the front. Start with an objective for how you want the car to perform and feel and go from there. That means thinking about valving + t bars, anti-roll bars (including bar diameter) ride height, alignment, etc. Issues don't always show up on the street because you don't ever get close to the limit but they'll really show up on the track if the car is properly set up.


MarkS - this is a pretty common approach for track cars. I have used different compounds front and rear on my SC race car to try and get more bite in the rear.

[Flieger]

What compounds would you reccommend to shift a little braking force rearward on a 1971 911S? I have S front, rear M calipers and the car is setup like an autocrosser. I need good intial bite while cold but also the ability to take a bit of heat (not serious track duty, though). I was considering Porterfield R4S at the next brake service.

Sorry for the hijack.

[Neunelfer]

I'm not a fan of pad mixing on street cars. I know of people who do it on the track but it takes a lot of seat time to get it just right.

Having too little brake in the wag-happy rears of these cars is not the end of the world. Nothing like a panic stab with the rear starting to wag to finish things off for good. That said, I'd try to find a way to balance it out with the proper calipers if you feel the need. It might be the SWB adapter solution recently brought to the top or, it might be some creative ear welding with a skilled fabricator. This will be a hot-rod right?

Max, I think you're well balanced as your running the car the way it came from the factory.

I can't stress it enough; a lot of times that big brake upgrade is less than $150.00 bucks away (meaning; Porterfield R4S pads).