I am doing the front brakes ( new rotors, calipers, pads, and rubber lines) on my 2008 Dakota and because everything is old and frozen I need to work on the brake lines. They seem to be an odd size, I was hoping to splice a piece on to the right side brake line instead of trying to replace the whole line but I can't find the right size locally. It measures at 5.2 (ish) mm and so 13/64 doesn't work as the line won't fit into the fitting so I can flare the end and attach it. My next move was to try and remove the line and maybe just replace front lines with 13/64 lines but a not sure if that would create a problem in braking. I think theoretically it should be fine but always open to smarter people than myself to chime in. I am certain others must have run into these issues so turning here for help and advice.
Thanks in advance

 

The trick is to use correct fittings for the caliper threads ... with what you describe, I wonder if they are metric?
Hopefully someone else can chime in with correct answer .... I recently installed a Toyota MC on a old truck and I bought 10mm brake line for the thread size and fittings on one end.
Then used the SAE fittings from a 3/16" line on the other end .... if that makes sense
3/16" is the most common size for passenger vehicles today.

If the 3/16" will not fit through your fittings ....do the SAE 3/16" fittings screw into your stock original parts?
If you can screw them in easily by hand and tighten them, then just use them.

Here is my HillBilly sticking out, if you need to reuse the original fittings and the new line is too tight to slide into the fittings .... is it close enough you can just drill out the center of the fitting?
What I mean, if you need to drill it out 1/8" of a inch, that is too much and need correct lines.
If you just need to ream out a couple 32"'s ... I would try that.
The flare on the line does the sealing, while the fitting is actually formed into a cone shape ... the drill ing you do will be covered by the flare and make zero difference to sealing.

I suspect a independent supplier had a contract to make X amount of specific line shapes to supply to the Company and they had odd sized tooling for the lines ....
While the threads on the the rest of the truck have to be uniform and exact, the lines just needed to work and thats what they supplied.


My 49 Dodge truck actually had 5/16" line coming from the MC to a brass T and then the lines dropped down to 1/4" to the wheel cylinders and worked fine that way.
Currently it has 3/16" line going to the T's and then running 1/4" ... will work fine.
Eventually it will just have 3/16" line 100% of the way.

 

Checking rockauto.com for parts info on the brake hose, it says it's a M10 x 1.0 female fitting. Any parts store should carry generic brake lines that you can bend to match with the right ends already on them.

Also grab the factory service manual for the 2005+ dakotas. It will save you some headaches when it comes to figuring things out.

https://www.dropbox.com/s/0xh46mwvxwbk9ze/2005.Dodge.Dakota.5249.Page.Dealer.Service.Manual. ND.SM.pdf

 

Thanks for the replies guys. I probably wasn't explaining the situation properly. I am trying to extend the last several inches of the original line as it twisted when trying to remove the fitting from the rubber hose connector to the caliper. I picked up some 3/16 line and yes, the fitting will thread into the rubber hose no problem. The issue is at the the other end where I am trying to slide the fitting onto the original line before flaring it. It just will not go on there, the original line is bigger. I need it on there in order to join the original line and the short new piece together with a double female threaded union, Thanks again for you replies.

 

Interesting problem ... How much bigger is the old line?


I would think they are pretty much a standard size ... unless some shop has different tooling? .... On the right is 3/16", then the next size up is 1/4" .... there is a big difference in size and can visually see.
If the original line is 1/4", then the 3/16" fitting would not screw in ... so I'm guessing it is some freak made line ... might even be a issue flaring it?
In this case, can you slightly drill the center of the fitting out .... Sometimes it just may be easier to just replace the line and not splice into it.

If by chance it is a 1/4" line, then use the 1/4" fitting and get a adapter to drop it to 3/16" in size.

Just a heads up, the brass couplers and adapters cost about $15 each, then individual line fittings about $9 each ... it adds up ... cheaper to just get a longer line for $15-$20 and replace it.
I do have one line for my RF, they did not sell a long enough line so I used 2 with a coupler .... it works but cost more.

I just fear that dealing with a oddball line is going to bring headaches ... like you are dealing with right now ... when/if you do get a fitting on there, will your tool make a proper flare on it that seals? .... or is it going to leak and have to start all over?

 

Thanks, I did find fittings that fit over the old line (M10-1) and also into the rubber hose to the caliper. The problem seems to be the brake line size which measures at 5.1 mm .I picked up some 3/16 line but it is 4.75mm so just slightly smaller than the original line. I don't see 5.1 or 5 mm brake line listed anywhere and will have to size down to the 3/16 line but also have the same concerns about how the flare will match since it is slightly smaller. I looked online to just bite the bullet and order a full replacement line but they are not available that I can find. I guess I will just have to try the reduction and be prepared to deal with a leak if one shows up. The left side will have th original line so do you think the difference in line size on each side will present any problems with braking? I mean pulling or unbalanced braking.
Thanks for your input, it is all helpful.

 

Shame on Dodge
In my best uneducated guess, I say it might be noticeable if you had fancy machines to actually test the pressure from the lines.
But, not enough difference you will notice it while driving.

Where the real difference comes in is with the bore size and pistons on MC and calipers. ... If you ran a larger bore caliper on one side and normal on the other .... you would notice that and hate it.
But the actual line size supplying the pressure to the caliper .... the difference can be measured ... I just doubt you will feel it in the steering or braking of the stock brakes.

That is simply my best uneducated guess ... that means I think it is worth a shot to try it. .... if there was a issue, I would probably change the other original side to the same so you can work on them next time.

Again the flares may become a issue ... I'm not sure of the correct answer ... seems you know what you need ... Amazon does have a large selection of adapters for almost any situation ... you might search there for a fitting to convert.
Also look at their brake line flaring tools. There is a large selection of tools there, typical average tool $20-$40 ... then there are some better quality hydraulic tools starting around $75 and they claim to be able to make any or almost any flare ... they just have more options and really do a better job .... you may need to invest in something like that.
Just things to consider. ..... I have been looking at them myself, I'm just tired of cheap tools that barely get the job done and would like something different.

 

If you can get the line to thread together, the size of brake line should not matter to much as the amount of fluid flow through the line is very small it just has to get filled initially and hold pressure. Also wouldn't hurt to verify inside diameter, one could be a thicker wall tube but the internal flow would be the same

 

At the pressures the brake system operates, and the way it operates, (moving tiny amounts of fluid) line size is pretty much irrelevant..... I don't think the difference will be noticeable.

 

Thank you