Update: Quick Performance Explorer rear disc conversion

[skrit]

Check the outer register on the axle. If there isn’t a chamfer on it you’ll need to add one. The drum inside doesn’t have a square corner and it will prevent the rotor from fully seating against the axle flange.

There is a chamfer. The rotor is completely flush against the axle flange.

 

[Bgood115]

Quick question for those who have done this conversion. How hard should it be to turn the wheel after install? I used the quick kit, new axles, new gears 456 and curries retainer. Torque to 30lb and I can barely turn the tire. Talked to Currie and they said that is normal. Just doesn’t seem right to me so wanted to some input from others. Thanks

 

[lars]

Quick question for those who have done this conversion. How hard should it be to turn the wheel after install? I used the quick kit, new axles, new gears 456 and curries retainer. Torque to 30lb and I can barely turn the tire. Talked to Currie and they said that is normal. Just doesn’t seem right to me so wanted to some input from others. Thanks

That sounds tight. There will always be some drag though, especially with new parts. You can try opening the bleeder screws very briefly (as in a second or so) to see if there is residual pressure in the brake lines. And be sure you don't have a residual pressure valve in the master cylinder on the rear brake circuit. Needed for drums, not for discs.

 

[Bgood115]

That sounds tight. There will always be some drag though, especially with new parts. You can try opening the bleeder screws very briefly (as in a second or so) to see if there is residual pressure in the brake lines. And be sure you don't have a residual pressure valve in the master cylinder on the rear brake circuit. Needed for drums, not for discs.

Copy. Thanks for reply. I don’t even have lines hooked up yet. I think what’s making it hard to rotate is the Currie retainer pressing on the bearings.

 

[DirtDonk]

Are these tapered roller bearings? You're saying the retainer is putting preload on them? How much?
And of course an important aspect of being hard to turn, is what differential is installed. The difference just between an open diff and a factory limited slip is quite a bit. With an open diff, you can easily spin a wheel. With a limited-slip it's very hard and the tire will NOT keep spinning.
Are both wheels still off the ground? Have a limited-slip or locking differential?
Does it spin freely without the brake calipers installed?

Paul

 

[toddz69]

I'll second what Lars said - that sounds too tight to me too. I'd do what Paul suggests and maybe loosen the retainers a bit and see if that helps? Or if the calipers are installed, take them off and try again. Just to see what might be the cause of the excessive force to turn the wheels.

Todd Z.

 

[DirtDonk]

Binding on a 9 inch rear end is usually from three areas.
Brakes too tight, wheel bearings too tight, or a limited slip.
Perhaps a bent housing as well, but that’s not very common. Luckily!
For the wheel bearings to be that tight, though, there would have to be a huge amount of force on a tapered bearing. No other scenario, I can think of that would make them extremely hard to turn. Even if overly tensions, they still turn.

But it’s not impossible to have an to have a bent housing either.
If you had one tire on the ground when you were trying this, and you have a limited slip differential, then yes, it would be extremely hard to turn the tire.

 

[Bgood115]

Are these tapered roller bearings? You're saying the retainer is putting preload on them? How much?
And of course an important aspect of being hard to turn, is what differential is installed. The difference just between an open diff and a factory limited slip is quite a bit. With an open diff, you can easily spin a wheel. With a limited-slip it's very hard and the tire will NOT keep spinning.
Are both wheels still off the ground? Have a limited-slip or locking differential
Does it spin freely without the brake calipers installed?

Paul

Copy. Yes, new housing, new 456 limited slip, new tapered bearings. I haven’t even put oil in it yet… It spins with some force with wheels off the ground without preload on the bearings. Once I put preload on the retainer plate it gets real hard to spin. The brake pads are not installed. I’m doing a frame off restoration and about a year away from even driving it. Just one of those things that keep ya up at night. I’m thinking I’ll just put lock washers on the retainer plate and not torque it down so much and drive it a little when it’s time and recheck it.

 

[ntsqd]

Lock washers are always a bad idea.

You've got a problem that needs to be sorted out. Pick one of the possibilities and work to eliminate it. Then pick another one, etc.

 

[DirtDonk]

So I guess the last thing that I can think of at the moment, would be is the driveshaft connected?
If so, then eliminate another layer of potential resistance and disconnect the driveshaft.
We already know that something is wrong because it should not get tighter as you tighten the bearings. But at least you can narrow it down to just the axle assembly and no engine/transmission/transfer case resistance.
If it’s already disconnected, then you were right and something is amiss.
Although a limited-slip does tighten things up, and a 4.56 gear ratio is gonna be harder to turn at the tire than a taller ratio like a 3.50.
So there’s that…

In their factory Ford 9 inch applications, on the big Ford cars and mainly the full-size trucks, there is zero preload on the bearings. That’s correct. Zero preload.
So there should never be enough preload to make the axles harder to spin.

 

[Bgood115]

Man… you guys are a wealth of information. Thank you

 

[ntsqd]

Loosening the bearing retaining plates allows it to turn much easier? Does loosening only one retaining plate only make it ~1/2 as easy to rotate? If so, I suspect that the axle shafts may be too long and are slightly bottomed out in the diff.

 

[lars]

Loosening the bearing retaining plates allows it to turn much easier? Does loosening only one retaining plate only make it ~1/2 as easy to rotate? If so, I suspect that the axle shafts may be too long and are slightly bottomed out in the diff.

Good point. This happened to me 20 years ago. New Currie housing with Torino ends, new Currie axle shafts set up for Explorer discs etc. Axle shafts were around 1/16" too long and bottomed in the diff. I had forgotten about that. Careful trimming with a die grinder, lots of filing with a small triangular file, cleaning etc solved the problem.

 

[DirtDonk]

What’s your go-to method for determining depth in this scenario?
Do you measure to the shoulder in the bearing housing end, then measure how far the bearing goes in?
Or do you take something like a long wooden dowel and insert it until it bottoms out in the differential and transfer that measurement to the axle?

 

[ntsqd]

I used the latter technique when figuring out what length axles to order for Snowball's D60.
The real trick is to work out where the inner edge of the side gear splines are. Length further into the diff is pointless. If the splines are big enough then an actual tape measure with a hook in the end could be used, but it might be easier to screw a tab onto the end of the dowel that you can use to 'feel' that inner edge.