Front disc hose size?

[fireguywtc]

Today I was putting my brake lines together when of course I ran into a snag. I have two new brake hoses for the front that go between the frame and the calipers. The passenger side when in just like its supposed to, but when I tried to install the drivers side, the threads are to big to fit in the caliper. I checked and both brake hoses I got are exactly the same and that is what I was told from the parts store is supposed to go on 71 front disc. So is there supposed to be two differnt sizes of holes going into the calipers or are mine messed up? Please BTW I checked the schematics page and it did not specify any differences in brake hoses for the front end.

Auto zone agrees with them being the same: http://www.autozone.com/autozone/catalo ... id=2065842

Perhaps I can get an adapter to make it fit, but I am concerned about the smaller size effecting braking. Anyone ever had this issue? TIA, Bill

[knightfire83]

I searched calipers for a f250 on rockauto.com. Seems the hose inlet sizes are different between bumps and dent era trucks.

Your Drivers side caliper would be of the 73-79 variety and your passenger side one would be the up to 72 version. You may want to try "Brakeware / Brake Hose - Front #77061" this is for a '77 f250 2wd 2 piston caliper and should be the smaller 3/8" thread for your drivers side.

thru- 72 inlet Thread=7/16X20

73-79 Inlet Thread=3/8X24

Edit:
I did another search on Auto Zone and they also come up with two different hoses for 68-72 depending on VIN numbers you may want to check what the difference is between them.

[fireguywtc]

Thanks knightfire, I must of gotten kinda screwed, but I don't know how. I bought all used parts to upgrade to disc but had to buy rebuilt calipers since the old ones were worn out. I bought everything for the same place (carquest) all for a 71 to include the brake hoses, calipers, rotors, and bearings. My only theory is perhaps the calipers where mixed with the different vin codes from factory or warehouse. Other then the different size inlet hole they look exactly the same.

[robroy]

Hey Bill! Yikes, I'm sorry to hear that you're in this situation. You did such an outstanding job putting those brakes together, it would be a shame to have to rip it all apart again just because of this.

I was curious to see if an adapter existed that could adapt your 7/16" brake hose to your 3/8" caliper, but I couldn't find anything like that on McMaster.

I'd understand wanting to avoid this, but have you considered running a tap in the 3/8" hole to enlarge it to 7/16"?

On the topic of brake fluid pressure and how that's impacted by using a smaller hose, I'm under the impression that the smaller hose will actually translate in to more pressure at the caliper than a larger hose would. That's my impression from reading articles about which brake line size to use when implementing brakes from scratch on custom cars. I'm not sure if it applies here or not.

Yet they were talking about entire brake lines--not just the hose at the end. Or more accurately, the fitting on the end of the hose.

Bill, do you happen to have the boxes that your rebuilt calipers came in, or your receipt? What are their part numbers?

The calipers that were right for my 1972 were the 3/8" ones: Raybestos RC7004.


http://www.robroygregg.com/Number50/IMG_8089s3.JPG


http://www.robroygregg.com/Number50/IMG_8090s23.JPG

Robroy

[fireguywtc]

Thanks Robroy, you have some good points and here are my thoughts. I had considered drilling out the hole and retaping it but I have two concerns about that. 1: I would have to go by a tap and dye set, 2: I worry about any metal shavings or maybe casuing damage.
As far as the hydraulics are concerned I have a fair understanding of hydraulics and necking it down with an adaptor just does not seem right to me if that is not how it is supposed to acutally be. I may have mis-spoke when I say it would effect pressure, it would acutally affect the flow volume. It seems minute, but why did they make it 7/16? On the other side of that the drivers side has a lot less distance then the passenger side to build pressure. And yes you are right I would only be trying to change the size at the very end.
I don't have the boxes anymore, and the recipt will be a search, but I am almost certain the recipt info. is limited. The calipers have numbers on them and when I was looking at them they are the same. Also your calipes look similar to mine, but keep in mind they are made for your truck which is a higher GVRW and has a beefier front end.

[fordman]

as far as the search for the reciept. does the auto parts place keep your warranty on thier computer. if so then maybe they can go in and look it up for you so you wouldnt need to find the reciept.

[fireguywtc]

I can't take them back now because they are painted, and the parts store had adaptors, but none that would fit. It looks like I will need to find an adaptor or drill and re-thread.

[fordman]

oh man. ok what type of adapter would it have to be and what size on inlet and outlet?

[fireguywtc]

according to the info. above from Knightfire it would be 7/16 in 3/8 out. I have yet to actually search for some on the internet. Will keep you all posted.

[fordman]

but could you just get the other size line to make it fit? that to me might be the better or easiest option.