C30 dually rear brake line and bolt sizes

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

atup1996

Junior Member
Joined
Dec 21, 2024
Posts
4
Reaction score
4
Location
York, PA
First Name
Aaron
Truck Year
1989
Truck Model
r3500
Engine Size
350 SBC
Hello I'm working on swapping a D70HD into my truck but the project is not at my house. I'm looking for the correct mounting bolt sizes for the rear wheel cylinders. I also have to make new hard lines on the axle. Seems the line size is 3/16 (correct me if I'm wrong) but what size are the flare nuts on the hard lines? The wheel cylinder sides and the sides that go to the soft center line? Thanks in advance.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
31,199
Reaction score
30,641
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
The line that goes to the rear hose is 1/4" line. Just the standard stuff you get at the parts store, the tube nut will be the correct size. The lines from the rear hose to the wheel cylinders are 3/16" line. Same deal, the tube nuts will be correct for the wheel cylinders. I don't recall the sizes of the wheel cylinder mounting bolts.
 

Forum statistics

Threads
44,901
Posts
971,005
Members
37,747
Latest member
alittle
Top