Original 427 Street Cobra Suspension Rebuild

David Kirkham · #1 (**permalink**) 09-03-2007, 12:09 PM

Here is a picture of the interesting "locking" mechanism for the rear hub bolt. I am sorry the picture is not 100% in focus, but Sandwich is working faster than I can take pictures and post them on the web!

Anyway, this it the infamous locking tab the English were so enamored with. At first glance it looks like a good answer to the question of keeping the bolt in place...in practice it is incredibly stupid. But, as they say, "Hind sight is 20/20" and who knows what people will be posting about me on the web 20 years from now!

This is how the locking tab is "supposed" to work. First you place the locking tab into the two little drilled holes in the drive flange. Then you tighten up the bolt to the required torque (we use 225 foot pounds BTW) and then bend over the tabs against the flats of the bolts to prevent the bolt from loosening up. Very BAD idea.

In order for the tab to even be able to be bent, they have to be made out of a SOFT steel. Soft steel will pound out as you drive down the road. The rear suspension takes an incredible abuse. If you have ever driven with a professional driver, you know what I mean. If the steel yields (which it will surely do) YOU WILL LOSE ALL PRELOAD ON THE BOLT! ONCE YOU LOSE THE PRELOAD ON THE BOLT YOU LOSE THE PRELOAD ON THE BEARINGS!!! This means your hub bolt is about to play "Free Willy" and exit the premises. This means your hub is now loose and is about to fall off--which will loosen the preload on your sphincter as you face Turn 1 going 150 mph with a Miller Motorsports instructor showing you things you didn't know cars could do.

Talk about a YOU TUBE moment! "Original Cobra into the wall at over 100 mph!!!" I bet there would be 1,000,000 hits the first day alone.

David Kirkham · #2 (**permalink**) 09-03-2007, 12:12 PM

Here you can see Sandwich taking a screwdriver to the tab to bend it out of the way so he can get a socket on the bolt. (Don't worry, it isn't a Snap On screwdriver!) I guess this is the one that is in bad focus! Sorry! Notice the little divots in the bolt where someone else had taken the upright apart earlier in its life.

David Kirkham · #3 (**permalink**) 09-03-2007, 12:15 PM

Here Sandwich is taking a socket to the rear hub bolt to loosen it.

David Kirkham · #4 (**permalink**) 09-03-2007, 12:17 PM

Here you can see the bolt, washer, and "locking" washer have been removed. In the "locking" washer you can see the two ends that are bent AWAY from you as look at the washer in the car. In this picture, they are bent up. Those two tabs stick into the flange and are "supposed" to prevent the tab from turning.

BUT,

Already we are starting to see problems.

David Kirkham · #5 (**permalink**) 09-03-2007, 12:22 PM

Here you can see Sandwich putting the straight edge of some calipers across the washer. You can see it is severely bent! The steel of the washer indicates is is probably mild steel and so it has no spring to resist permanent deformation from the pounding of the rear suspension. As the suspension beat on the washer over time, it has yielded letting all the preload out of the suspension--major bummer waiting to happen in the driver's seat.

David Kirkham · #6 (**permalink**) 09-03-2007, 12:27 PM

Now Sandwich is going to take the caliper off. (I took this photo earlier in the process.) Notice the nice safety wire job someone did on the brake caliper bolts. Nice to see some nice work.

You have to cut the safety wire to get the caliper off so you can get the hub out to inspect it.

David Kirkham · #7 (**permalink**) 09-03-2007, 12:32 PM

Here is another shot of the rear caliper. The rear caliper on a 427 Street Cobra is made out of cast iron. In the photo you can see the original brass Lucas brake line fitting that is screwed into the caliper. The brake flex lines then bolt into that brass fitting. The fitting is screwed down to the caliper by a banjo bolt and crush washers. We have capped the brake line with an AN #3 cap. ALWAYS cap your brake lines! If you leave them open, crap will find its way inside and eventually make it to the caliper pistons...

SCRATCH

LEAK

Call Kirkham and spend big $$$ to get my caliper fixed.

These calipers are one of the big reasons why making an EXACT copy of an original 427 Street Cobra (or a 289 Street Cobra) is almost impossible. These calipers are a strange beast. They are EXTREMELY rare and as such are worth a small fortune. But, no one really wants them as they want the big aluminum Girling calipers like the Comp 289's, Comp 427's and, 427 S/C's had. They are a strange 3 piston caliper and they are IMPOSSIBLE to find now. The "Big Aluminum Girlings" are just that...they are BIG and they will NOT fit under wire wheels.

kris-kincaid · #8 (**permalink**) 09-03-2007, 02:45 PM

The Navy uses lock-tabs on a lot of secondary nuclear steam valves and conventional main steam valves. Shelby continues to use them on the suspension. I've never seen one fail, either in a Cobra or on a ship.

I've never questioned them, so it's interesting to see your opinion. Have you had problems with them failing?

BTW, nice thread. Always nice to see original parts.

Quote:

Originally Posted by David Kirkham

Anyway, this it the infamous locking tab the English were so enamored with. At first glance it looks like a good answer to the question of keeping the bolt in place...in practice it is incredibly stupid. But, as they say, "Hind sight is 20/20" and who knows what people will be posting about me on the web 20 years from now!