which 8.8 rear do I have? Actually I need to know which wheel cylinder

[Fairlaniac]

I bought a 90-something 8.8 rear and swapped into my '91 Ranger. How do I tell which wheel cylinder it uses? I have 10" brakes but there are different wheel cylinder part numbers listed '97 and older and '98 and newer. Appears to have been a change in that time period per my RockAuto search and Advanced Auto Search. Shy of removing it and paying local prices (ordering more than wheel cylinders) by I.D.-ing it, any other way to tell? Thanks!

 

[Denisefwd93]

Check the axle code on your door sticker, and look it up on the how to section here on site check the stamped tag that is on a bolt on the differential on the new old axle you picked up, and check that on the how to section, good luck

 

[Fairlaniac]

Thanks but as mentioned, I picked this up and swapped it into my current Ranger. The rear was bought at a swap meet, vehicle unknown. It has been in the truck for two years. I would like to put new cylinders in. The axle tag is missing.

Thanks!

 

[Uncle Gump]

From what I see on Rock Auto... they list one that has a 13/16 bore on newer models and older models use a 3/4 bore. I believe either will work because they both have 10 inch brakes.

 

[Curious Hound]

From what I see on Rock Auto... they list one that has a 13/16 bore on newer models and older models use a 3/4 bore. I believe either will work because they both have 10 inch brakes.

And if that's the case, I would use the 13/16" bore because it will create more braking force for the same amount of pressure. BUT.... Use the same size on both wheels. You don't want one side stronger than the other.

 

[Uncle Gump]

And if that's the case, I would use the 13/16" bore because it will create more braking force for the same amount of pressure. BUT.... Use the same size on both wheels. You don't want one side stronger than the other.

After you said that it made me think... I would go back to Rock Auto and verify that there wasn't a master cylinder bore change that goes with the wheel cylinder change.

 

[adsm08]

After you said that it made me think... I would go back to Rock Auto and verify that there wasn't a master cylinder bore change that goes with the wheel cylinder change.

Nope, they only list them as with or without crusise, looks like the bore is the same for all variations of the rear brakes.

 

[Uncle Gump]

Nope, they only list them as with or without crusise, looks like the bore is the same for all variations of the rear brakes.

Yes... just went and looked myself. So with what we know... we just don't know. LOL

I think I would favor the smaller of the two... these things are pretty sensitive to locking a rear wheel. Even though it is probably not the fault of the wheel cylinder... I would error smaller bore to not create a problem.

 

[Curious Hound]

Yes... just went and looked myself. So with what we know... we just don't know. LOL

I think I would favor the smaller of the two... these things are pretty sensitive to locking a rear wheel. Even though it is probably not the fault of the wheel cylinder... I would error smaller bore to not create a problem.

That's good reasoning. I'm running 35" tires. So bigger is better for me. Size does matter.

 

[Uncle Gump]

That's good reasoning. I'm running 35" tires. So bigger is better for me. Size does matter.

In your case... makes sense.

 

[Uncle Gump]

This just popped into my head...

I'm thinking the bore change probably corresponds to the four door cab and the additional weight that it created. But that is just a guess.

 

[alwaysFlOoReD]

The smaller bore on the slave would mean more movement of the piston. Pretty sure that would lead to lockup quicker.

 

[Uncle Gump]

Just when I think I have it all figured out... here comes Floored!

I think the real question is not how much it moves... but applied pressure.

 

[Dirtman]

Use the auto parts store for their only remaining purpose... go match the part up, find out which it is, say thanks, leave and go buy it online.

 

[Curious Hound]

The smaller bore on the slave would mean more movement of the piston. Pretty sure that would lead to lockup quicker.

I thought the amount of slave piston movement was limited by the shoes hitting the drums or pads hitting the rotors. At that point it becomes a matter of how much pressure the force from your foot can build in the master cylinder and how much force that translates to when that pressure is multiplied by the area of the slave piston.