HELP...PLEASE Old fittings to new 1/4" line--can it be done
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MKMike
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HELP...PLEASE Old fittings to new 1/4" line--can it be done
Bought copper nickel 1/4" brake line to replace the lines from the master to the EBCM.
Can't get the darned fittings onto the new line.
Must I buy new fittings or can the existing fittings be drilled out or am I overlooking something in my presently aggravated state?
TIA
Can't get the darned fittings onto the new line.
Must I buy new fittings or can the existing fittings be drilled out or am I overlooking something in my presently aggravated state?
TIA
- harofreak00
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
You need 3/16" line, not 1/4"
Andrew - owner/operator of Bonnevilles Unlimited

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- MattStrike
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
While I can't speak for what the '00+ stuff came with from the factory, I know that all the '92-'99 came with 6mm lines between the master and ABS module, and 4.75mm lines to each wheel.
All the brake lines in the stores are SAE, so 3/16" (4.76mm) & 1/4" (6.35mm). If you had the 6mm lines, you had to drill out the fitting to get the 1/4" line in. The other fun part is getting a bubble flare tool to fit a 1/4" line. The only other option is to use an adapter that converts the bubble flare fitting to a standard double flare fitting.
I would not drill out a 3/16" fitting to fit a 1/4" line, you lose the radius/shoulder on the end that seals it off and the sharp edge would cut into the line.. So don't do that if your fittings were not originally sized for 6mm line.
All the brake lines in the stores are SAE, so 3/16" (4.76mm) & 1/4" (6.35mm). If you had the 6mm lines, you had to drill out the fitting to get the 1/4" line in. The other fun part is getting a bubble flare tool to fit a 1/4" line. The only other option is to use an adapter that converts the bubble flare fitting to a standard double flare fitting.
I would not drill out a 3/16" fitting to fit a 1/4" line, you lose the radius/shoulder on the end that seals it off and the sharp edge would cut into the line.. So don't do that if your fittings were not originally sized for 6mm line.
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The Fleet:
'93 SSEi - Twincharged + manual Build thread
'97 Camaro - Top swap
'05 STS - V8, AWD, her DD
'92 Trofeo - Fair weather DD
'99 Montana - top swap 3800
'04 Sierra 2500HD - LLY Duramax
Current project:
Something cool, trust me.
Upcoming projects:
'92 Bonneville SSE
'87 LeSabre T-type
'67 LeSabre
Gone to greener pastures:
'84 Sierra Classic - Twin turbo 3800
'97 LeSabre - Top swap
RIP:
'86 LeSabre - pictures
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- harofreak00
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
Or just buy the correct lines and be done with it:
https://amazon.com/ACDelco-25698848-Equ ... 00H91NP6O/
https://amazon.com/ACDelco-25698855-Equ ... 00H91NQA4/
https://amazon.com/ACDelco-25698848-Equ ... 00H91NP6O/
https://amazon.com/ACDelco-25698855-Equ ... 00H91NQA4/
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 57k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 115k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 280k | Official Bonneville Hauler

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 57k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 115k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 280k | Official Bonneville Hauler
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MKMike
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
I have 3/16" line but it seems much too small for those MC line fittings--really flop around on it, so I didn't want to risk it.harofreak00 wrote:You need 3/16" line, not 1/4"
Measuring the OD of the OE lines from the master cylinder, it is truly 6mm.
However, it does look like all the rest of the brake lines may be 3/16....unless there's some other bizarre metric line size.
Haro, have you installed copper nickel line in any of the veritable fleet of Bonnevilles you've repaired or do you use factory lines?
I've never used anything besides steel and thought I was giving myself a break
Yes, indeed.harofreak00 wrote:Or just buy the correct lines and be done with it:
https://amazon.com/ACDelco-25698848-Equ ... 00H91NP6O/
https://amazon.com/ACDelco-25698855-Equ ... 00H91NQA4/
I went that route yesterday... a few hours after posting. Bought them from Rockauto.
25 feet of 6mm NiCopp with some fittings was actually slightly more expensive than the 2 ACDelco pre-formed lines.
MattStrike, I was truly pretty frustrated at the time I posted ---having expected a relatively brief chore---and wanted to know what others have done when using NiCopp line .
I'm never one to jury-rig at the expense of safety.
You're spot on about flaring, too.
My Mastercool kit only has metric bubble flare dies.
Sage advice, indeed from you gents.
Thank you both!
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2000_bonne
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
MKMike, keep us posted on how the final repairs go and what it took to do so.
As I mentioned, I am soon going to have the enjoyment of replacing brake lines myself.
As I mentioned, I am soon going to have the enjoyment of replacing brake lines myself.
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dougtoth
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
My 2000SLE brake lines are starting to look pretty rusty.(surprise here in Wisconsin)
The company I am looking at is Inline Tube located in Michigan.
They have a 9 pc. stainless steel brake set for Bonneville (2000-2005) for $180.00.
Website inlinetube.com.
Phone number (800) 385-9452.
This looks like a good possibility.
Also where have you been lately MKMike?
Thanks.
Doug.
The company I am looking at is Inline Tube located in Michigan.
They have a 9 pc. stainless steel brake set for Bonneville (2000-2005) for $180.00.
Website inlinetube.com.
Phone number (800) 385-9452.
This looks like a good possibility.
Also where have you been lately MKMike?
Thanks.
Doug.
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MKMike
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
Sorry for the late reply.
Changing the MC lines was easy enough. In road salt states, soaking the line ends with Kroil is helpful.
Actually needed to cut one line and tap a socket on it to get it removed.
The problem with all the aftermarket lines that I've seen for the master cylinder is that they have no strain relief---they're just solid lines, without any coiled or flexible section--unlike the ACDelco OE parts which have 2 flexible segments per line.
Glad I was missed, Doug.
Had 2 family members hospitalized, more than once, these past few months.
Both are nearly fully recovered now.
Changing the MC lines was easy enough. In road salt states, soaking the line ends with Kroil is helpful.
Actually needed to cut one line and tap a socket on it to get it removed.
The problem with all the aftermarket lines that I've seen for the master cylinder is that they have no strain relief---they're just solid lines, without any coiled or flexible section--unlike the ACDelco OE parts which have 2 flexible segments per line.
Glad I was missed, Doug.
Had 2 family members hospitalized, more than once, these past few months.
Both are nearly fully recovered now.
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dougtoth
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Re: HELP...PLEASE Old fittings to new 1/4" line--can it be
MK Mike.
Sorry to hear about your 2 family members.
Hope things are now better.
I know how those things take priority.
I lost my father in law in July and my mother in October.
Hopefully 2019 will be a better year.
Does the strain relief make that much of a difference?
If so I guess ACDelco OE parts are the way to go.
Sorry to hear about your 2 family members.
Hope things are now better.
I know how those things take priority.
I lost my father in law in July and my mother in October.
Hopefully 2019 will be a better year.
Does the strain relief make that much of a difference?
If so I guess ACDelco OE parts are the way to go.

