Turbo Brake Conversion

[jonvo]

I have an 87 NA and I may want to convert to turbo or turbo s brakes in the future. It looks like I would need to change out the spindles in order for the calipers to mount up. Do these spindles have the same strut mounts as my car? Will I need new struts to do this conversion?

And for the rears, do these calipers just bolt on?

[Techno Duck]

You need '87+ 951, S2 or 968 spindles. If you want to use the Turbo S brakes you need the adapters also for axial to radial mount.

Your current struts will work fine.

Rear calipers are bolt on, but you need a spacer in the rear.. a 1/2 inch washer has worked for me in the past.

[ideola]

Originally Posted by Techno Duck

If you want to use the Turbo S brakes you need the adapters also for axial to radial mount.

Can you elaborate on this? To what adapter are you referring? Pix or drawings?

[smokin_944]

LR and other performance shops sell adapters to use the Turbo S brakes on turbos or S2s. They are available. Different adapters for different years. Remember the offset.
BIG KIT COMPONENTS at LINDSEY RACING - Your Porsche Performance Parts Center

[jonvo]

So just for future reference (regarding struts bolting up to spindles), which year spindles/struts are NOT interchangeable?

[ideola]

I've done a bit of research into this issue, and this is what I've found. I'm not claiming this is 100% accurate, so you should verify if you have specific questions. However, my research indicates that there were four versions of spindles on the 944 series:
1. 1983-1986 944 NA (includes 1987-1988 924S)
2. 1986 951
3. 1985.5-1991 944 NA (non M030)
4. 1987-1991 951 and all M030 optioned cars

#1 has mechanical speedo cable, 31.7mm spindle diameter, 76.5mm caliper bolt spacing, 58mm strut housing bolt spacing, and 20mm strut housing flange thickness

#2 has no speedo cable hole, 31.7mm spindle diameter, 94mm caliper bolts spacing, 63mm strut housing bolt spacing, and 18mm strut housing flange thickness

#3 has no speedo cable hole, 35mm spindle diameter, 76.5mm caliper bolt spacing, 63mm strut housing bolt spacing, and 18mm strut housing flange thickness

#4 has no speedo cable hole, 35mm spindle diameter, 94mm caliper bolt spacing, 63mm strut housing bolt spacing, and 18mm strut housing flange thickness

So from this info, we can conclude:

• big brakes (requiring 94mm caliper bolt spacing) are not a direct bolt-on affair for cars with #1 or #3 spindles
• strut housings from 1986-prior cars are not a direct bolt-on for 1987-onward spindles, and vice versa. The strut housing mounting flange can be shaved or shimmed as necessary, but the bolt spacing also has to be addressed, and I'm not sure that slotting the strut housing bolt holes is a good idea.
• 1987-onward hubs will not work with 1986-prior spindles due to the difference in spindle diameter. Which is a bummer because 1986-prior hubs have the rotors mounted behind them, while the later hubs have the rotors mounted over them (i.e. rotors have a deeper hat on the later setup, and don't require the hub to be removed in order to service them).
• I don't recall when the 944 switched over to electronic speedo, I think it was in 1985.5. From what I have seen the 1985.5-1986 NA cars retained the spindle with speedo cable hole, even though it was unused, while the 1986 951 spindle (which is a completely unique part) did not have the speedo cable hole. I have also seen some of the "transitional" spindles that have the boss present where the speedo cable hole would have been drilled, and then this boss was eliminated in later castings. I don't recall off hand when this change occurred, but I do remember making mental note of it when I was compiling the figures.

HTH. More info here.

[Techno Duck]

These are the adapters i am referring too...this is just one such maker, there are a few.

Racer's Edge -- Racer's Edge Big Brake adapter blocks

[ideola]

So as I understand it, those are designed to allow the OEM 4-pot Brembo calipers with 94mm bolt spacing to be fitted onto non-Turbo/non-M030 spindles, correct? In other words, only required if you don't have the correct spindles...

[Techno Duck]

These allow the use of the Turbo S (S4 caliper) or the even larger Big Reds to be used with standard turbo spindles. The calipers use a different mounting point; axial vs radial. In other words, these adapters are only for cars with Turbo, S2 or 968 spindles that want to run larger brakes (such as the S4 or Big Reds/Big Blacks).

Im not aware of any adapters to fit the Brembo's on non-turbo spindles. Dont think it would be possible either due to clearance issues with getting an adapter to fit.

Mind you, when i say 'turbo spindle' i am basically referring to the 951 (not including '89 or the '88 Turbo S), non M030 S2 and non M030 968 spindles.

Here are some pictures to illustrate what im talking about. The 1st picture is a standard turbo caliper (AKA Baby Brembo). Note the way it mounts to the spindle (Axial).



Here is a Big Black caliper (same as the 993TT Big Reds, but inverted). Slightly different dimensions than the Turbo S calipers to allow for larger diameter rotors, but these use the same bolt spacing and mounting. Note it uses a radial mount to the spindle.

[ideola]

Got it! Very helpful, thanks! So are the Turbo S spindles different still from the variations I posted above? Or is the caliper accommodated by a stock bracket of some sort?

[Techno Duck]

The spindle is unique to the Turbo S and M030 S2/968. Most say however the standard turbo spindles are stronger however. I forget exactly why but there is a good explanation of it on RL.

[Warwood]

Originally Posted by ideola

while the 1986 951 spindle (which is a completely unique part) did not have the speedo cable hole. I have also seen some of the "transitional" spindles that have the boss present where the speedo cable hole would have been drilled, and then this boss was eliminated in later castings. I don't recall off hand when this change occurred, but I do remember making mental note of it when I was compiling the figures.[/list]
HTH. More info here.

I can confirm having seen '86 951 spindles with the bosses. Very useful for an early 944 owner wanting big brakes. With a little machine work you can know how fast you're going. Before you have to slam on the binders for that trooper behind ya!

[Endat]

About these brackets... WHAT ON EARTH makes them worth $150? I'm just wondering.. its a chunk of metal with holes drilled in it.

[Techno Duck]

If you can get the machine work done, plus cost of two blocks of billet, good grade hardware and have the proper dimensions, go for it!

[Endat]

I'm just saying, I have seen the spindles sold for only a little bit more.. but it's a waiting game

[Schumi]

I do not like how Lindsey's axial to radial mount adapters had threaded aluminum holes. Very easy for someone to overtorque if not installed properly. Non-sleeved tapped aluminum holes are just a no-no on a part with such high install bolt torque and size.