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1969-70 Trans Am disc brake conversion.

Started by 1967 eight barrel, February 17, 2019, 04:32:10 PM

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1109RWHP

Drill what threads out? The calipers have unthreaded holes. And why swap them side to side? I did not have to.

1967 eight barrel

Dear God, what a mess.   I did find the article you mentioned. Who ever the writer is was a moron. There is no real information incorporated.   I have 11X 2.75 brakes in the rear.  That should be somewhat helpful.  I put my original rims away and went with something I can get decent rubber for.

                                                                                                        -Keith

Scode67FB

The T-Bird / Lincoln calipers have threaded mounting holes. They have to be drilled out to install and use the adapter brackets.

shelbydoug

#18
Quote from: 1109RWHP on February 17, 2019, 10:34:50 PM
Drill what threads out? The calipers have unthreaded holes. And why swap them side to side? I did not have to.

:)

The T-bird caliper mounting flanges are tapped for 1/2" threads for the original application. The new adapter bolts to the spindles and provides a threaded mounting location, reversing the original mounting design.

The calipers were originally mounted in the back of the spindle in production and are marked left and right. That designation is because of the location of the bleeder valve needing to be at 12 o"clock.

For race purposes, the caliper is now placed in front of the spindle. You need to keep the bleeder high up. If you keep the left caliper on the left side, and reverse the mounting position, the bleeder would be at 6 o'clock. So you switch them side to side.



The rotors in production were also originally a full 12" in diameter. The replacement rotors are 11-3/4".

The caliper pistons are huge in the T-bird calipers as compared to the original 67 K-H Mustang units and the 68 calipers have just one piston. So the clamping force is increased significantly with the big T-bird calipers.

The comment was "they were originally designed to stop a 6,000 pound car, imagine what they can do to a 3,000 pound car?"



The surface area of the pad is also increased a large per cent. In fact until the "Super Car" pads with cars with 18, 19, 20" wheels and Brembo brakes, you couldn't find larger pads.

The way the pads mount in the calipers makes them very much like a quick change design.



Initially Ford experimented with making aluminum calipers along with Doug Nash. Nash largely cast up a bunch of the small Mustang 67 K-H calipers in aluminum and I would suspect in magnesium also. Randy still has a few of the aluminum DN castings. I've never seen any of the aluminum Ford "XE" versions personally. Those are kind of rare.

About 5 years ago, one of the West Coast "classic brake" companies cast up the T-bird calipers in aluminum. They didn't last long and were taken off of the market. They said that they had "porosity" issues with the castings but I suspect that because these are a copy in aluminum of a very compact "molded" design of the calipers originally by Ford, that the change in casting materials proved dangerous and they were failing in use?

That particular aluminum aftermarket casting was also modified by adding an additional hump for mounting purposes. The hump no doubt is there in an attempt to re-enforce the casting but in the case of using them in the "trans-am" kit, the hump proves a mounting obstruction and makes the aftermarket aluminum caliper casting useless. It looks good hanging on the shop wall though?

I suspect that what happen there though was that "racers" were the main market for them, not original T-bird owners cruising around, they became a large or at least a significant legal liability?



Look. This clearly is a modification intended for period Trans-Am racing. As such, there is no suggestion intended for using it on a street car. Just like going too fast on the track, anything that you do could get you killed. You apply these parts as you deem necessary, modify them to your needs and take your risks with it.

68 GT350 Lives Matter!