Aftermath

[Nightmist66]

You should have just backed up real hard, would have fixed itself

LOL!

[cjshaker]

Looks like it was real close to being sheared in two. Good thing you found it when you did. Did you upgrade the slip yoke? I just recently went to a Mark Williams driveshaft and yoke. It wasn't cheap but at least now I know I'll bust the tranny before the driveshaft

[Nightmist66]

Here is the replacement I bought, Doug. http://www.jegs.com/i/JEGS-Performance-Products/555/60677/10002/-1

A little pricey, but I have zero complaints with it. Very nice piece. Made by Sonnax, in USA.

Later, when the new motor goes together and I upgrade the trans, I will build a new driveshaft with 1350 joints. Currently running Ford Racing M-4635-A u joints front and rear.

Here are a couple pics of the safety loop I made for the car. (Pre-billet yoke install)


The color I chose was a Rustoleum industrial "Safety Red", I thought it was only fitting.

[fekbmax]

Are the billet steel Graham rockers still available any where ? Always thought they looked like a nice piece.

Hey, that second photo looks familiar.  Yeah, those are good rockers that would be really tough to break.  Thor has been using the rockers in your second photo:

So are they still available or were only a limited number of sets made ?

[afret]

His website is still there but bought them awhile ago.

http://www.bestofbjsbooks.com/grahamracing_39.html

And what I meant is that second photo is the one I took of my actual rocker on the shaft.  LOL

[fekbmax]

Sweet !!   Thanks..   

[Pentroof]

I don't like how far down your adjusters are extended below the rocker body. I believe your pushrods are too short. Have you gone through the geometry at full lift and close? To me, it looks like ball is loading awkwardly and could have contributed to your failure. Simply my 2 cents and fair market value is likely less.

Carry on...

[cjshaker]

The adjusters don't look like the most ideal spot, but they don't look terrible either. It certainly shouldn't have busted the rocker.

I was going to mention though, your driveshaft doesn't look like it's long enough. I've never seen one that far out, and that most likely didn't help matters with your old yoke twisting. It should be in as far as possible without causing any bottoming at maximum rear deflection. Yours looks like it's only about half way in. Hopefully the billet yoke will stop the twisting, but it still contributes to a 'whipping' action which is really hard on the yoke and U-joints as well as the output shaft. Is that a stock length driveshaft for the car?

[Nightmist66]

Pentroof- I fully understand your point, but I don't think the adjusters are terrible. They are not perfect and are halfway in travel. My Erson's going on my next build will be closer. Yes, geometry was checked. I feel the failure was due to a thin section of the rocker body.

Doug- The driveshaft is original to the car. Never been shortened or lengthened. Only thing done to it was occaisional u joints and having it balanced. The yoke sticks out only about 1 1/2", so maybe the picture is deceiving. The old yoke was over 8" from center of u joint to end of yoke, so it was well over halfway in. Also, the output shaft sticks out past the tailhousing about 1/2". I don't understand how this would have caused it to twist. If anything, it should have very noticeable wear on the output shaft bushing, and it looked good. The old yoke stopped about 3/4" short of the full spline on the output shaft. The new yoke goes just to the edge of the spline ends. Hopefully it will last till next year when it all comes apart for long overdue upgrades.

[thatdarncat]

I was going to mention though, your driveshaft doesn't look like it's long enough. I've never seen one that far out, and that most likely didn't help matters with your old yoke twisting. It should be in as far as possible without causing any bottoming at maximum rear deflection. Yours looks like it's only about half way in. Hopefully the billet yoke will stop the twisting, but it still contributes to a 'whipping' action which is really hard on the yoke and U-joints as well as the output shaft. Is that a stock length driveshaft for the car?

I have to agree with Doug on the position of the slip yoke, I had the same thought when I looked at the picture. I don't know if it contributed to your spline failure or not, or if there a preferred engineering theory, but I would think more spline engagement would be better. I do know the Mark Williams driveshaft I got for my car a few years ago sits further into the transmission extension housing and Mark Williams picked the length, it wasn't supplied by me. I was actually a little concerned that mine sat too far into the extension housing, but I moved the rear suspension through it's travel and it was fine. My car is a Mustang though. I don't doubt you on your driveshaft being original but a question I would ask - is your rear end yoke original too? Ford had multiple rear yoke lengths, as does the aftermarket. If your rear yoke was shorter it would move the driveshaft back. Just some thoughts, it sounds like you did check engagement.

Also check the #2 intake pushrod for straightness, often if the exhaust valve can't open to release the pressure the intake pushrod will bend trying to open against the built up exhaust.

Like this?

#2 exh. left, #2 int. right



Luckily there are a few spare pushrods on the shelf, so a few bucks saved. Pushrods are old TRWs

Yup. Been there, done that when I broke a rocker shaft. And I have to give credit to mine & Jays mechanic buddy Bradford for teaching me that one.

[Nightmist66]

Kevin- On the more spline engagement being better, trust me, I feel the EXACT same way. That's why I just bought the yoke I did that has full spline.

As far as the rear end and yoke, I'm well aware on lengths and cap widths and u joint differences, both OEM and aftermarket. I have a few different OEM yokes laying around. Long, short, wide, and narrow.

Here's the setup. I built it myself. Only thing original at this point is the housing.(w/perch reinforcements of course)



I originally ordered a new yoke from Currie that matched the old yoke in length, but was machined for the Daytona support. Also, it was a nodular iron piece. I tried it, but the driveshaft wanted to almost bottom with it. So, I went to Quick Performance where most of my parts came from and ordered this shorter billet steel one. Would highly recommend Quick Performance to anyone. Driveshaft ended up in same location as before I rebuilt the rear. Also, my dad's 67 Lane that is parked next to my car looks the same way. Also has factory driveshaft, trans, yoke. That car has seen 7k w/slicks. I'm not too worried with my wheezy setup. I WILL try to get the driveshaft closer with the next trans and driveshaft.

[ScotiaFE]

I noticed the rubber at the spring perch.
You should remove the rubber.
The springs will work better and even less chance of wheel hop.
The rubber is acting like another spring.

[Nightmist66]

Have I done anything right? I feel like I'm defending myself for no good reason...



As far as the rubber, yes I put them in because I wanted to keep things smooth for the street. I will be removing them when the rest comes apart next year. I haven't noted any ill effects yet.

[My427stang]

Have I done anything right? I feel like I'm defending myself for no good reason...

Standard forum picture posting risk LOL 

The time to be defensive is when people WON'T help that means they don't care   Personally, I think the slip joint and rubber is good advice too, but as with anyone, you choose what to do, and the car clearly is a beauty so I wouldn't take the advice in any negative way

[Nightmist66]

Thanks Ross. I didn't mean to come across as ungrateful. I do appreciate all the knowledge shared on this site. Maybe I have been in the heat and humidity a bit too long. Sorry guys.