I am in the process of converting my '86 951 to '89 turbo S front suspension and brakes (already had the struts/t-bars, now I'm converting to late offset and upgrading the brakes..)

I thought some of you might be interested in SEEING the difference in some of the parts...

A-Arms:


obviously you can see the difference in length between the two. What you can't see is all the extra reinforcement on the turbo S arm (sorry, should have gotten a shot of that...) Porsche did something similar to the reinforcement that racers weld along the edge of the steel arms, plus made the ball joint area stout.

Now the brakes -
951:


951 S (928 S4 calipers):


besides the obvious difference in caliper size (whew!), check out the difference in rotor thickness... Those cooling vanes are so big on the new rotors that I lost my keys in there...

...and so it goes. I am concerned about pedal travel with the new brakes, since there is so much more fluid to displace (44mm and 38mm pistons - larger than big reds, even) with the '86 master cylinder. Oh well, we'll see, I guess!

Hope someone gets some curiosity settled with the photos.

 

Correct me if I am wrong, but it is my understanding that the '88 M030 a-arms are the same length as the '88 non-M030 a-arms. The difference lies not in the length, but in the ball joint.

The reason there is a difference in length is because you have an '86 with the old offsets.

 

Yes, that is correct.

 

any updates?

 

[quote]Originally posted by keith:
<strong>I am concerned about pedal travel with the new brakes, since there is so much more fluid to displace (44mm and 38mm pistons - larger than big reds, even) with the '86 master cylinder. </strong><hr></blockquote>Actually, the 'S4' type calipers from the '89 turbo have 36 and 44 mm pistons. Your old '86 had 36 and 38 mm pistons, so the difference is about 18% more piston area with the new calipers.

 

Keith,
Thanks for the great photos. I also have an '86 951, and I have decided to upgrade to the S4 brakes. However, I am planning to keep my stock control arm, spindle, and hub. I am running the stock 16" Fuchs wheels

Will I be able to use the larger (thicker) "S4 rotors" with my existing setup? I'm concerned that the additional thickness of the rotor may be a problem...unless the thickness is just around the outer edge (braking surface) instead of the center where it mounts to the hub.

Also, where did you get your caliper mounting adapters to get the radially mounted S4 calipers to fit on the axially mounted 944 spindle.

Thanks for the clarification...

 

I don't remember if the GTS and S4 were the same brakes. Love the site Tom, just chock full of valuable information.

If you need to know about 944 running gear, I haven't found a better site than Tom's.

<a href="http://www.944s2.com" target="_blank">www.944s2.com</a>

 

No, the GTS and S4 were definately different set-ups- the GTS is the same as the Big Reds, but the piston size of all three are the same- most people would assume that the GTS/BR's would have larger pistons than the S4, since they have larger pads, and use larger rotors, but they don't....