Talk to me about making a SWB handle

[Cal MX5]

My car is a 1967 912 with a 2.4L 1973 911E motor in it. I've just had it off the road for 12 months doing a rebuild on the 901 trans and a full engine bay overhaul. Anyhow now it's back on the road I want to make it stop and handle. A cage is out of the question as I use the back seats for my 3 year old. It's currently still at US ride height, so firstly I'm going to order some Elephant Racing QuickChange spring plates, so adjustment time is greatly improved. Is upping the size of the torsion bars a good idea for a road car? What about shocks?

[HarryD]

Nice looking car.

I am assuming you want a nice street ride.

Make sure all of your suspension bushings are good. Replace as needed.

Keep the stock T-bars and set the ride height to "euro". I do not think you need the fancy adjustable spring plates as you will only need to adjust them once.

Replace your shocks with Bilstein HD's all round.

If you have the solid 912 brake rotors, look into getting some type of ventilated rotors and matching calipers. I am thinking you may be able to do a brake and rotor transplant from a suitable 911.

[ajwans]

For brakes you could go vented fronts with PMB's Brembos which bolt right up PMB - LWB Brakes

They also do vented rears now PMB - SWB Brakes

andy

[chris_seven]

We have a 912 fitted with a Carrera 3 motor on carbs and a 915 transmission.

There are a few issues with SWB cars that always seem to be overlooked.

Front Camber Plates have often been changed for those of the later car and they have an impact on the front suspension settings.

The original plate takes an interchangeable rubber bush and are easy to re-furbish.

Many cars have had Koni Strut top bushes fitted into this location and they are not quite correct and don't locate as well as the original bushes which have been NLA for years.

We have just re-manufactured the correct bush in a hard HNBR rubber.



We use Kuhmo Ecsta V70 185 x 70 x 15 on mots of our SWB cars in a Medium Compound .

We typically use Parallel Toe, 1.5 degrees Negative Camber, 6.5 degrees Caster with the front 1.5 degrees nose down.

We use stock 19mm torsion bars and a 15mm sway bar.

We use Bilstein Inserts P36-0113.

These inserts can be a little short when fitted into a Boge Leg and may need packers - up to 3mm to make sure they are axially clamped by the gland nut. We generally use 1 mm thick pcakers so the form to the bottom of the inner casing.

We fit a 15mm diameter front sway bar.

At the rear we normally use a 26mm diameter Turbo Torsion bar and a 16mm diameter sway bar.

The rear trailing arms tend to be a bit 'bendy' and I would be careful of fitting thicker than stock spring plates as this can generate some twist in the trailing arm.

The early spring plate is 3mm thick with the later plates being 4mm.

If you have a small rear inner spring plate bush this does not locate the control arm well and we replace this bush for a part made from a bearing grade Polymer GUR 4150 which improves the location of the spring plate substantially.

We set the rear at about 1.5 degrees toe in and 1.5 Negative camber.

We fit an adjustable rear shock made by a small specialist UK manufacturer of race that we have worked with for many years but they are basically an simple adjustable shock filled with a gas emulsified oil and they do work very well at a very reasonable price.

[Cal MX5]

Chris, is that a road or race car?

Is there a thread anywhere on here about that car?

[chris_seven]

Road Car - occasional track day.

Excerpt from Road Test in Total 911 Magazine.

[Cal MX5]

Thanks. Mine is pretty firm as it is, it would be nice if that didn't change. I'll look into sway bars.

I got offered a set of Turbo torsion bars on the weekend. Sounds right for the rear anyhow.

[safe]

I think the advice from Chris is great.
Stiffer t-bars, stock rubber, stock swaybars (or a set of adjustable, anything but Weltmeister) and good shocks (not "stiff" shocks). Thats the ticket for a street car.

On LWB cars I've fitted 21/29 and 19/29 torsionbars. They just perform like they should have from the begining. Torsionbars have a small impact on comfort compared to shocks.
SWB are a bit different so 26 mm rears have a higher wheel rate than on a LWB.

[Cal MX5]

The torsion bars I've been offered are off a 3.2L Carrera, not a Turbo. Might try them once the adjustable spring plates arrive. Sound to be about the size Chris is recommending. Then I'll move on to bars.

[HarryD]

Originally Posted by Cal MX5

The torsion bars I've been offered are off a 3.2L Carrera, not a Turbo. Might try them once the adjustable spring plates arrive. Sound to be about the size Chris is recommending. Then I'll move on to bars.

If they are off of a G50 Transmission car, they may not fit.

[Cal MX5]

I had not considered that.

[M Bryan]

Chris, i have a 67 SWB that has had all the original SWB front suspension swapped out for the later model with the aluminum cross brace. It uses the under body sway bar as well as the thru body SB would have required welding a bracket to the powdercoated a-arms. This wa easler for now. The top strut mounts are also the later style. I have not had it aligned since the conversion. Will I have alignment issues with the later top mount? I have the Rebel racing bushings for the top and also for the-a arms. Don't mean to high jack the thread but it does follow the same topic. Thanks.

[chris_seven]

The later camber plate will restrict the amount of adjustment that you can obtain with a 1967 shell.

The Rubber Bush has a larger diameter and the 'hole' the body shell and the angle of the inner wing changed in around May 1970.

The later mounts will bolt up but they do compromise the settings.

Typically you will only be able to adjust to around 4 degrees of Caster and about 1 degree of negative camber.

You could enlarge the hole in the body but I don't like to do this as it stops anyone putting the shell back to standard.

We spotted the later bushes on a Period F Appendix K Race Car that a team in the UK ran and we sent him the correct parts to use the early camber plate.

He fitted the new plates tells us that making the adjustment to the caster and camber did significantly improve the car.

[stlrj]

Do you really think you could make it handle better than this?

https://www.youtube.com/watch?v=6nTSqzBbmvU

[Trackrash]

There is a guy in our local PCA region with a 66 912 who spanks me at every autocross.

PM me and I can try to get you in contact if you wish, I imagine he would be willing to share some info.

[Cal MX5]

PM sent

[Cal MX5]

Do you guys think 195/65/15's on deep 6's are going to rub when I lower this thing?

[Cal MX5]

Originally Posted by chris_seven

We fit an adjustable rear shock made by a small specialist UK manufacturer of race that we have worked with for many years but they are basically an simple adjustable shock filled with a gas emulsified oil and they do work very well at a very reasonable price.

Chris, do you have contact details for the UK firm who make your adjustable rear shocks?

[blue72s]

Originally Posted by chris_seven

There are a few issues with SWB cars that always seem to be overlooked.

Front Camber Plates have often been changed for those of the later car and they have an impact on the front suspension settings.

The original plate takes an interchangeable rubber bush and are easy to re-furbish.

Many cars have had Koni Strut top bushes fitted into this location and they are not quite correct and don't locate as well as the original bushes which have been NLA for years.

We have just re-manufactured the correct bush in a hard HNBR rubber.

Very interesting information. I will be keen to get those bushes at a later date.

Hypothetical question - I think nobody has ever tried 930 front anti-dive in a non-turbo 911, let alone a SWB but if you add it to a SWB, do you think it could improve the handling even further?