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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: Catrik on October 15, 2015, 09:11:52 AM

Title: 71-78 brake line thread size?
Post by: Catrik on October 15, 2015, 09:11:52 AM

Guys from Rough Country said their 71-78 front brake line http://www.roughcountry.com/extended-front-brake-lines-89340s.html will fit an 86, even though it doesnt say so.. Well it does fit but the way it attaches to the brake line bracket is different. I thought I just put a nut on the outside thread, but what is the size?

Title: Re: 71-78 brake line thread size?
Post by: Catrik on October 17, 2015, 08:51:01 AM

I mean the thread pointed in the picture

Title: Re: 71-78 brake line thread size?
Post by: bd on October 17, 2015, 11:55:00 AM

Did you ask Rough Country (1-800-222-7023 or email (http://www.roughcountry.com/contacts/)) or post your question under FAQ - ASK A QUESTION (http://www.roughcountry.com/extended-front-brake-lines-89340s.html) on their website?  If you already have the hoses, take them to a local hardware store and use their thread diameter and pitch gauges to determine the size.

Title: Re: 71-78 brake line thread size?
Post by: enaberif on October 17, 2015, 12:59:09 PM

The issue is that from 73-78? They used a 7/8 banjo bolt then in 79 then changed to the 10mm standard banjo. There are differences in the hoses.

Title: Re: 71-78 brake line thread size?
Post by: VileZambonie on October 17, 2015, 01:25:51 PM

It is retained by a stamped nut

Title: Re: 71-78 brake line thread size?
Post by: VileZambonie on October 17, 2015, 01:37:30 PM

Also referred to as a pal nut.

Title: Re: 71-78 brake line thread size?
Post by: bd on October 17, 2015, 04:19:09 PM

Although PAL nuts were used by the factory and are somewhat self-locking, they easily distort when square engagement with the nut using a fixed size wrench is not possible.  If access to tighten the nut inside the frame is limited I recommend an internal star washer and plated steel nut to retain the bulkhead fitting.  For easier disassembly in the future smear a little anti-seize on the external threads of the bulkhead fitting before inserting it through the frame.

Title: Re: 71-78 brake line thread size?
Post by: enaberif on October 17, 2015, 04:58:25 PM

When I did mine I had to use a large fender washer to keep the hose from going through the frame hole then I just used the pal washer on the backside.

Title: Re: 71-78 brake line thread size?
Post by: Catrik on October 18, 2015, 06:05:36 AM

I did ask Rough Country, they didn't know. They just get them in a box and ship them forward.
The local bolt store probably doesnt have so special nuts (I live in a world of metrics), I'm thinking of making one from brass, I just need to know the thread and wouldn't like to take it off just to measure it.

I tried going through Rockauto but didnt see any of those pal nuts, only the hold down clips.

Title: Re: 71-78 brake line thread size?
Post by: VileZambonie on October 18, 2015, 02:14:08 PM

If I have spare in the garage I'll measure one

Title: Re: 71-78 brake line thread size?
Post by: enaberif on October 18, 2015, 03:24:08 PM

Use napas website or rockauto to get the fitting size. It is what I did.

Title: Re: 71-78 brake line thread size?
Post by: Catrik on October 19, 2015, 10:06:26 AM

Quote from: enaberif on October 18, 2015, 03:24:08 PM

Use napas website or rockauto to get the fitting size. It is what I did.

I feel silly now.. That's what I always do first but I just didnt look hard enough. Looks like it is 5/8"-18 and it sounds about right http://www.rockauto.com/catalog/moreinfo.php?pk=1362386&cc=1294938&jnid=511&jpid=3

I hope we have that sized tap at work!