Anyone got leaky brake fitting tips before I tackle tomorrow?

Tech tips and how to's

Moderators: notoptoy, S Allen, Solex68

Post Reply
User avatar
cbez
Roadster Fanatic
Posts: 417
Joined: Sat May 27, 2017 5:51 pm
Location: Fallbrook, CA

Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by cbez »

The splitter/switch on the firewall and the fitting to the clutch master are both giving us headaches. The incoming line and the bottom line on the fitting are both leaking. all the fittings are down tight (probably too tight...)

Gonna take everything out tomorrow, check the flares and the unions.

Never had an issue with DOT 5 before.



Image
SPL311-02085
JT68
Talented Enthusiast
Posts: 2962
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by JT68 »

Its not the brake fluid.
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
User avatar
cbez
Roadster Fanatic
Posts: 417
Joined: Sat May 27, 2017 5:51 pm
Location: Fallbrook, CA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by cbez »

JT68 wrote: Fri Aug 06, 2021 7:56 pm Its not the brake fluid.
that's my thought too...gentleman I'm working with thinks its junk but I've never had a problem getting it to seal up or get a good brake pedal.
SPL311-02085
User avatar
redroadster
Roadsteraholic
Posts: 2624
Joined: Tue Mar 12, 2013 10:58 am
Location: KCMO
Model: 1500/1600
Year: High Windshield-68-70

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by redroadster »

I did a line double flare not long ago ..it took me 6 times to get it right . And I've done ? 8-9 cars
Datsun dealer tech 76 to 87
Mitsubishi tech 9 yrs
Volvo, Kia, Toyota too
6 month - Rolls Royce
ASE MASTER TECH 96. - 11
70 SPL 86 Z31 T , Sportster
User avatar
cbez
Roadster Fanatic
Posts: 417
Joined: Sat May 27, 2017 5:51 pm
Location: Fallbrook, CA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by cbez »

redroadster wrote: Fri Aug 06, 2021 8:26 pm I did a line double flare not long ago ..it took me 6 times to get it right . And I've done ? 8-9 cars
I am told they are original lines that have been cleaned up and zinc'd.
SPL311-02085
JT68
Talented Enthusiast
Posts: 2962
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by JT68 »

cbez wrote: Fri Aug 06, 2021 8:00 pm
JT68 wrote: Fri Aug 06, 2021 7:56 pm Its not the brake fluid.
that's my thought too...gentleman I'm working with thinks its junk but I've never had a problem getting it to seal up or get a good brake pedal.
the only folks I know who have problems with it try to bleed too fast. From what I've seen it forms smaller bubbles than conventional Dot3-4 which are more difficult to eliminate. The key is push the pedal SLOOOOW..if you pump it quickly, you will chase your tail for hours. Then let it sit overnight and re-bleed. Kind of tedious, but better than repainting an engine compartment IMHO.

(I have to redo an engine compartment this fall ruined by some dot3. That's way more annoying than extra bleeding.)

Another possibility...with the original fittings and junction blocks, I've seen situations where the threaded fitting is VERY tight in the block, but not clamping the line so well. If the fittings are difficult to turn, the threads may need to be chased (and then cleaned very well of course). You would need a 3/8-24 bottoming tap and a 3/8-24 die.

yet another possibility, if over tightened, the mating fittings of the junction block may be damaged. You would need a replacement block in that case.

hope this helps!
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
User avatar
cbez
Roadster Fanatic
Posts: 417
Joined: Sat May 27, 2017 5:51 pm
Location: Fallbrook, CA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by cbez »

JT68 wrote: Fri Aug 06, 2021 9:16 pm
cbez wrote: Fri Aug 06, 2021 8:00 pm
JT68 wrote: Fri Aug 06, 2021 7:56 pm Its not the brake fluid.
that's my thought too...gentleman I'm working with thinks its junk but I've never had a problem getting it to seal up or get a good brake pedal.
the only folks I know who have problems with it try to bleed too fast. From what I've seen it forms smaller bubbles than conventional Dot3-4 which are more difficult to eliminate. The key is push the pedal SLOOOOW..if you pump it quickly, you will chase your tail for hours. Then let it sit overnight and re-bleed. Kind of tedious, but better than repainting an engine compartment IMHO.

(I have to redo an engine compartment this fall ruined by some dot3. That's way more annoying than extra bleeding.)

Another possibility...with the original fittings and junction blocks, I've seen situations where the threaded fitting is VERY tight in the block, but not clamping the line so well. If the fittings are difficult to turn, the threads may need to be chased (and then cleaned very well of course). You would need a 3/8-24 bottoming tap and a 3/8-24 die.

yet another possibility, if over tightened, the mating fittings of the junction block may be damaged. You would need a replacement block in that case.

hope this helps!
Thanks! My brain was saying it can only be the flare, threads or block but I was praying for a magic trick haha.

My thoughts exactly on the silicone. We already leaked down the firewall by the master AND the junction. It already paid for itself.
SPL311-02085
User avatar
cbez
Roadster Fanatic
Posts: 417
Joined: Sat May 27, 2017 5:51 pm
Location: Fallbrook, CA

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by cbez »

OK well here was the main culprit:

Image

No idea how the flare ended up like this. But, we reflared it and cleaned up a new junction. At some point in all that the bottom was able to seal up also.

Interestingly we found 2 versions in the parts pile. One with smaller passages and less threads on the female ports, and one with bigger passages and fewer threads. Identical from the outside. Not sure if one style is 1500 and one is 1600 or what.

Clutch master fitting still has a tiny seep despite the flare looking good and being in pretty tight. I'll have to take it apart and try again soon.
SPL311-02085
User avatar
redroadster
Roadsteraholic
Posts: 2624
Joined: Tue Mar 12, 2013 10:58 am
Location: KCMO
Model: 1500/1600
Year: High Windshield-68-70

Re: Anyone got leaky brake fitting tips before I tackle tomorrow?

Post by redroadster »

That's what it looks like with the 1st step creating the double part , then use the flair wedge to flair it , which looks like they forgot to do , easy to forget
Also sometimes it takes much more strength to get the flair than other times
Datsun dealer tech 76 to 87
Mitsubishi tech 9 yrs
Volvo, Kia, Toyota too
6 month - Rolls Royce
ASE MASTER TECH 96. - 11
70 SPL 86 Z31 T , Sportster
Post Reply