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View Full Version : Resolved issue - Solid axle play and fixed brakes



Blitzboy54
07-16-2023, 07:57 PM
Hey gang,

So a little background. When I purchased my kit I ordered a solid axle complete kit with the Wilwood brake upgrade on both front and rear. At the time of my order we were hitting the great parts shortage so I started getting out in front of things and purchasing parts I was sure I wanted (as an aside this is not a strategy I would use again, patience is a virtue). I knew I wanted a more modern looking rim so I jumped on a set of wheels from LMR. They had a great package with Nitto's. I received them a full 3 months before delivery of my kit. Before I purchased them I looked up the specs on the 17" Halibrands, the LMR wheels were identical. Well, when they arrived it turns out the ID of the rear wheels is actually a touch narrower than the Halibrands. I discovered this when I received my brakes form Wilwood and the calipers didn't fit the wheel. Since I already purchased the wheels it was too late to upgrade to 18" wheels. I mean, it wasn't but I had already spent the money and didn't want to spend more. I reached out to Gordon and he turned me on to this 4 piston setup. They sit much lower and have no clearance issues. So I returned the FFR kit and ordered the new set from Gordon.


https://thefactoryfiveforum.com/attachment.php?attachmentid=147711&d=1620779435


As most of you know the axles on a Ford 8.8 are held in place by using a "C clip" that keeps it from sliding back out. They are kept from moving too far in by a center pin. There is a certain amount of "slop" built into this design. My axles both move in and out by about .030" (this is in spec). This is not something I had thought about since I didn't understand what that meant for my setup. Fords solution to this issue is use a floating caliper. This makes sense, floating axle uses a floating caliper. I however am using a fixed caliper because the floating caliper from FFR doesn't fit my wheels. The issue this creates is when I corner the axle moves and pushes the calipers back open a little. The practical effect is after cornering the brake pedal goes really deep. Effectively I have pump the brakes once after I corner to get them working properly again. The reason this is a problem is obvious. It took me forever to figure out what was going on. I bled them 5 times and checked every square inch of my braking system over and over. Once I figured it out it all makes sense. I found a couple old threads with guys that ran into this.

My problem was simple. I already purchased all these parts and I need to reduce the amount of axle play so the brakes that I already own work correctly. Gordon recommends rebuilding the traction lock but my axle is already recently rebuilt. He also said I could pull the axle and put a weld on the end and grind it back down to the desired thickness. This is a great option but I don't own a welder. Either I purchase new wheels/tires, purchase an entirely different brake system or remove most of the play. I opted for door number 3.

The C clips are a fixed width of .150, I have .030 of axle play so I purchased .025 shims from McMaster that are the same OD and ID of the Clip. I cut them with a cutting wheel. I opened up my rear end and removed the center pin. I pulled the C clips and married up the shims. The important step here is to make sure the shim in on the outside between the C clip and the differential side gear. Once installed the shim is housed nicely and cannot come loose. After re installing the center pin the play was reduced to .005.

https://thefactoryfiveforum.com/attachment.php?attachmentid=187254&d=1689513636

https://thefactoryfiveforum.com/attachment.php?attachmentid=187255&d=1689513636

Post installation.


https://thefactoryfiveforum.com/attachment.php?attachmentid=187256&d=1689513636


I have driven the car 300 miles since this mod and it is working as I had hoped. I realize I should have used a different brake setup or different wheels but the money was spent and I didn't know what I didn't know. The end result is this. There is no more pedal issue. It no longer requires more distance to brake no matter the driving conditions. The problem is resolved.

Cheers

J R Jones
07-17-2023, 09:56 AM
That solution is clever. The fretting on the clip suggests side load is causing the tolerance to open-up over time. You might explore options like clips of greater thickness, or clips with more hardness.
A thicker clip may have to be ground to required dimension.
jim

RoadRacer
07-17-2023, 02:23 PM
Cool, Gordon said something about shimming being required when I spoke to him about big brakes, so this makes perfect sense. You not tempted to take away that 5thou? Or is that what Gordon recommends.. some remaining 'play'?

Blitzboy54
07-17-2023, 02:50 PM
That solution is clever. The fretting on the clip suggests side load is causing the tolerance to open-up over time. You might explore options like clips of greater thickness, or clips with more hardness.
A thicker clip may have to be ground to required dimension.
jim

The mark is just the wearing of the copper coating where the notch in the axle shaft makes contact. The overall thickness is unchanged. I searched high and low and nobody makes a thicker C Clip. I considered a C clip elimination kit but those are exclusively for drum brakes.


Cool, Gordon said something about shimming being required when I spoke to him about big brakes, so this makes perfect sense. You not tempted to take away that 5thou? Or is that what Gordon recommends.. some remaining 'play'?

There was no need. The play is so minute that it's undetectable in the pedal. I have some thinner shim material if I ever needed to revisit it but I think I'm good.

MB750
07-17-2023, 03:24 PM
Well played sir, well played.

tonywy
07-17-2023, 10:20 PM
I've been chasing this issue a long time and never been able to figure it out. I have even though about using residule check valves. I will post the results after the mod.

MB750
07-18-2023, 06:40 AM
I've been chasing this issue a long time and never been able to figure it out. I have even though about using residule check valves. I will post the results after the mod.

If you put check valves in the line, your rear brakes will automatically be applied during turns because the fluid will not move back to the reservoir.

CraigS
07-19-2023, 08:04 AM
I tried check valves in mine which did nothing. I was really surprised that no one makes shims in optional thicknesses. I guess, like Blitz says, floating calipers kind of fix the problem. I think also the OE Mustang had a larger MC so it moved more fluid per inch of pedal movement and made any problem less noticeable. I made similar shims but no longer remember details.

Mastertech5
07-19-2023, 08:51 AM
Have you looked into C- clip eliminated kits. They will definitely solve your problem and are required by some race sanctioning bodies to compete.

Blitzboy54
07-19-2023, 09:22 AM
I've been chasing this issue a long time and never been able to figure it out. I have even though about using residule check valves. I will post the results after the mod.

I did, but they all seem to be only designed for drum brakes. Couldn't find a set that also worked for the disk upgrade.