Ford 9" pinion support bearing

[DJs74]

Has anyone experienced a crack / split in the 9" case at the rear pinon support bearing?
If yes, what was your fix... new case or weld up the split or something else?

I'm there. The case has crack right between the tail of the pinion and the ring gear. Looks like there has been some grinding done at some point on this case for ring gear clearance reasons maybe so it might've weakened it.

I have gone ahead and put a spot of weld on it and the bearing goes in fine - I was a little hesitant because I wasn't sure if the roundness would be distorted by the heat and maybe the bearing wouldn't go in, but it did and seems OK

I've not reinstalled the center section yet - just wondering if others have experienced this and if it is an eventual catastrophic failure waiting to happen or if the other two bearings plus welding up the case will be good enough.

This is not a street vehicle - its the racer... so if any vibration or heat causes problems based on highway use or long runs, that won't apply. However, I am launching on a transbrake so the driveline is getting a lot of abuse initially and for about 4.5 seconds at a time.

I'm trying to understand how the two tapered bearings toward the yoke allow any linear movement of the pinion. If the proper torque is reached and the bearings are properly seated, how does the end of the pinion have any movement that could cause the case to split - or does something else I'm not understanding cause this?

I can't really say what version this case is (I'm not too familiar with them). It is a Ford case, it has Ø3.062" carrier bearings, it has no drain plug in the side, the pinion support has an eyebrow above the yoke - if any of that is useful information.

See attached photo

Thanks in advance.


DJs74

 

[jim3326]

In my opinion, you will have catastrophic failure at some point. To weld it up enough to (hopefully) avoid that would almost definitely distort the seat. Risk/reward, how much do you want to spend for a maybe fix vs replace with a good part.

 

[metal1]

I`ve been building 9"rear drop outs for a long time and that is the worst clearance job I have seen ,and with that crack you now have a boat anchor do not reuse it racing shock loads are so high you are asking for a big mess .the pocket bearing is to help keep the pinion from climbing the ring gear ,and welding cast has a lot of other problems going for it also ,so if it was mine I would find another case save the expense of exploding the rear at speed ,although it might be a way cool action photo or video

 

[broncodriver99]

I have had a cracked case at that location. It is not super common but it does happen. Everything I found in research when I had one that was cracked is that it happens when cases are ground for lower gear ratios like 4.11+. That area has to be clearanced for the ring gear in 4.11 and deeper gears. I tossed the one I had, luckily it was a cheap one that I had picked up in a parts swap.

It is a failure waiting to happen as that bearing is what controls pinion deflection. The taper bearings are not enough to control deflection the way a 9" is designed. Time to toss it and pick up another case. No way I would trust that, even welded up. In a racer you should probably be running a nodular case anyway, the stress of the launches you describe is likely what caused the break.

 

[nvrstuk]

Buy a Nodular rear case and don't look back! These cases and metal that we are using and expecting to work perfect are decades old...50 year old parts are common... sometimes metal just plain fatigues and wears out... like us! : (

Buy a new Nodular case, Summit has a no-name case that I've used before with great success AFTER grenading stock 9" Factory cases...

 

[DJs74]

Thanks Guys, I'll get a new case on the way - exactly what I was looking for.

My gut was telling me the same so that's why I posted it up and thought I'd see if anyone else had experiences with these things.

I actually didn't see this at first. I fabricated some brackets so I could mount the third member to my engine stand and after I got it up on the stand and started rotating it, I noticed the crack - knew it wasn't Ford's intention right away.

Yeah, the clearance job was pretty poopie, I agree. The PO installed 4.86s and I am replacing them with 4.11s, is it reasonable to assume that I'll have to do some clearance work on the new case or are they already clearanced for the thicker gears?

thanks again

DJs74

 

[broncodriver99]

is it reasonable to assume that I'll have to do some clearance work on the new case or are they already clearanced for the thicker gears?

Depends on the case. Most of the aftermarket ones likely have a little more clearance built in. If you are running 4.11 you won't need to clearance it much if it does require it. The last one I did(a stock case) only required a few minutes with a file when switching from 3.50 to 4.11.

 

[DJs74]

Depends on the case. Most of the aftermarket ones likely have a little more clearance built in. If you are running 4.11 you won't need to clearance it much if it does require it. The last one I did(a stock case) only required a few minutes with a file when switching from 3.50 to 4.11.

Thanks bronvodriver99 and to all for the insight.

I ordered a new nodular iron case, was going to go the Summit brand route but it wasn't available to ship until 8/8 and I have an event 8/11 so I went with the Strange case.

I appreciate everyone's input.

DJs74