LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently April 4, 2020, 12:05 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 590 posts ]  Go to page Previous  1 ... 33, 34, 35, 36, 37, 38, 39, 40  Next
Author Message
PostPosted: January 26, 2020, 11:08 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
The M/C is dry so, no weeping. I am clueless at this point.

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 26, 2020, 11:35 pm 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5354
Location: West Chicago,IL
Do you get air in both the front and rear brake hydraulic systems?

If nothing is leaking and the brakes still are getting soft in a few minutes after bleeding, I would contact OBP and ask for their ideas. See this thread: http://www.locostbuilders.co.uk/viewthr ... tid=211657. You didn't stroke the cylinders while dry and possibly roll the seals did you? I found it by searching OBD master problem (no quotes) :mrgreen:

I'd put new seals in the Master. I would also pay particular attention to the condition of the cylinder walls and the port for the reservoir. BTW, I always use red rubber grease when rebuilding hydraulics.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 4:56 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
Thanks Chuck. I took it apart and the seals are oriented correctly. Here is the piston assembly:
Attachment:
IMG_3265x.jpg
IMG_3265x.jpg [ 341.65 KiB | Viewed 1836 times ]

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 6:53 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6575
Leave off rpv and high mount either the two reservoirs or use a $12 70's vw bug reservoir. Fit 7/16-20 5/16 barbs and connect with fuel hose. The vw res has flanges for mounting and two barbs. There may be a divider inside but I'm not sure.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 7:37 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
The reservoirs are mounted above the bulkhead which places them higher than the calipers. I wasn't sure if I needed the valves or not because I wasn't sure if it is the M/C or the reservoir that determines the need.

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 7:46 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6575
Last picture I saw had them down low. Had to go back pretty far. Best pic I see is on page 31 and that was before you raised the reservoirs. Can you post a pic of the current system? Was there any free-play in the pedal to allow flow from the res? I saw another pic where you were still using the old donor hoses. Do the lines get near the exhaust? Dot 3 fluid?

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 7:59 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
You're right, there aren't any good pictures of the setup. The res that is mounted to the M/C is the clutch. It has valve on it too. Although the M/C is out of the car, you can see the general setup. The rear res is on the other side of the intake tube, out of view.
Attachment:
IMG_3266x.jpg
IMG_3266x.jpg [ 288.04 KiB | Viewed 1824 times ]

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 8:59 pm 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5354
Location: West Chicago,IL
Gavin, did you answer if the air is getting in both the front and rear systems? Maybe I misunderstood. Do you have a dual master? It sure looks like the piston is from a dual Master. But the phot you showed of the system only has one reservoir. I am no expert by any means. For me, I still suspect the seals. The pic you show looks like the sealing lip is very rounded. Maybe it is only the photo lighting. In everything I have dealt with, in both master cyl rebuilds and wheel cylinders, they all have a very sharp defined lip.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 9:12 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6575
I think you said you took off the rpv but have not tested it yet.
Rpvs drag causing additional heat.
Make sure your slides are lubed and move freely to allow the caliper to slide easily with piston movement.
DOT3 fluid absorbs moisture out of the air, lowering the boiling point. It is important to use fresh sealed cans of fluid, keep the cap on can and the res as much as possible to reduce the rate of moisture absorption.
When it boils, bubbles are created that are compressible and soften the pedal.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: January 27, 2020, 9:15 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
Chuck, yes i have a dual master setup with bias bar from OBP http://www.obpltd.com/Pedal-Boxes/Kit-Car-Motorsports/Kit-Car-Premium-V2/Premium-Hydraulic-Clutch/Premium-Kit-Car-Hydraulic-Clutch-V2-OBPKCP102 So, the rear is separate from the front. I am running a .625" front with 0.70" rear master cylinders.

I ordered a rebuild kit from Pegasus Racing today. I hope to be able to report a success by this weekend.

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 28, 2020, 6:39 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6575
Next time, if the pedal goes soft again, pull over and put your hand on the hub/wheel center to feel how hot they are and if the temp is higher on either side. Moist dot 3 brake fluid boils at around 290f. Brake drag is less noticeable on cars with high pwr to weight.

Can't tell much from the pic. I'd be looking at the hoses to see if you installed new. Old hoses tend to be soft; more so once the hose gets warm. You may have a bubble that pops up only when hot and you have the pedal applied.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
PostPosted: January 28, 2020, 9:45 pm 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
Yes, all hoses are new. The last time I drove it, the front brake rotors were around 140deg and the rears were about 115deg. This is using a $9 laser temp gun from HF :) It had enough braking to lock the tires but got very soft over the course of 6-8 miles of pad bedding.

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 29, 2020, 12:07 am 
Offline

Joined: April 17, 2009, 1:28 am
Posts: 181
Location: San Tan Valley, Arizona
The worn spot on that piston may be an indication of a problem. Are there a corresponding wear marks on the cylinder bore?


Top
 Profile  
Reply with quote  
PostPosted: January 29, 2020, 7:46 am 
Offline

Joined: September 24, 2013, 4:06 pm
Posts: 699
Location: Charlotte, NC
waltj - No, the cylinder bore looks unused.

_________________
Gavin

My build: http://www.locostusa.com/forums/viewtopic.php?f=35&t=16005


Top
 Profile  
Reply with quote  
PostPosted: January 29, 2020, 9:35 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5354
Location: West Chicago,IL
Gavin, make sure you use plenty of lube in the re-assembly process. Like I mentioned earlier, I like Red Rubber Grease. A lot of people just use brake fluid. I very lightly coat both the seals and the entire cyl walls. Since you are having issues, it might be good to bench bleed. I've only HAD to bench bleed once. It certainly helped me get rid of the last bit of air on that car.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 590 posts ]  Go to page Previous  1 ... 33, 34, 35, 36, 37, 38, 39, 40  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: Bobber and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY