Brake Problems

Post by **DirtyShirt** » Mon Oct 05, 2009 1:26 am

Hello everyone, new to the Morris Minors but real familiar with Bugeye Sprite.

On to the problem, 1964 Morris Van, 1275 A+ engine, ribcase gearbox, disc brakes (front) drum (rear)
Brake system had silicone fluid so I did a complete system flush and now using Dot 3 fluid (brakes worked fine afterwards)). Rebuilt the front calipers and master cylinder and now I can not get any pedal and it does not pump up like there is air in the line. The pedal has a little resistance but not enough to stop the vehicle. There are no leaks anywhere. It does have the remote fluid reservoir.

Post by **DirtyShirt** » Mon Oct 05, 2009 1:28 am

PS. I did bench bleed the calipers and master cylinder before reinstallation.

Post by **Jefftav** » Mon Oct 05, 2009 6:16 am

Sometimes the minor can be a pain to bleed and can take 2 or 3 attempts. Go over all your connections again checking for leaks and then bleed it again starting with the back ns wheel. I enlisted the help of a mate as sometimes using these one man bleeders you can't see any leaks or air bubbles.

Another trick is to jack up the front of the car and leave it on stands with the front higher than the back. This is supposed to allow air to move to the highest point and make it easier to bleed. Someone also told me to use this method if the brake pedal is spongey but to also wedge the brake pedal down overnight and then bleed again.

My only other thought (and I appreciate you have rebuilt the Mcyl and calipers) if you have had silicone fluid in the system I think you are supposed to keep using silicone?

Post by **bmcecosse** » Mon Oct 05, 2009 8:55 am

Yes - I fear the mix of silicone and DOT3 is not good! If you had the calipers off - are they back on correct sides with bled nipples uppermost ? Basic fault I know - but amazing how many times that happens in Mini world! If you have a servo - sometimes best to hav the engine running while bleeding. And of course - make sure the rear brakes are tightened up - to the point of dragging.

Post by **DirtyShirt** » Mon Oct 05, 2009 1:35 pm

bmcecosse wrote:Yes - I fear the mix of silicone and DOT3 is not good! If you had the calipers off - are they back on correct sides with bled nipples uppermost ? Basic fault I know - but amazing how many times that happens in Mini world! If you have a servo - sometimes best to hav the engine running while bleeding. And of course - make sure the rear brakes are tightened up - to the point of dragging.

Silicone fluid had been flushed from the system before I rebuilt the master and calipers. The calipers are on correct and were bench bled before installing. No servo installed. Rear brakes are adjusted.
Everything thought of has been done but I still don't have brakes.

I have run 2 quarts of Dot 3 brake fluid through the system using Mighty-Vac, A homebuilt pressure bleeder (attaches to the reservoir and put pressure on the system), and finally the buddy system (the wife hates this job) and I'm still without brakes.

Post by **bmcecosse** » Mon Oct 05, 2009 3:23 pm

The silicone fluid will have contaminated the rubber parts of the system - when filled with DOT3 it is not unknown (ie it's very common!) for the seals to swell and distort. I've heard of this happening more the other way - when changing from DOT3 to Silicone - but I guess the contamination can happen either way. I can't comment on your home made bleeder - I just bleed my brakes by gravity - usually an egg-cup full of fluid at each nipple does the trick. Either the seals have failed - or the bleeding is not being done correctly!

Post by **leyther8008** » Mon Oct 05, 2009 6:27 pm

Just bled mine using a gunson eezibleed, worked a treat on my remote reservoir and dual circuit braked machine. (see seperate thread)
I always find it dificult to get all the air out of a minors system,and I've tried every combination of cylinders adjusted up tight, slack, gravity, etc.
This piece of kit did it for me in about fifteen minutes from start to rock hard brake pedal.

Post by **DirtyShirt** » Mon Oct 05, 2009 10:47 pm

bmcecosse wrote:The silicone fluid will have contaminated the rubber parts of the system - when filled with DOT3 it is not unknown (ie it's very common!) for the seals to swell and distort. I've heard of this happening more the other way - when changeing from DOT3 to Silicone - but I guess the contamination can happen either way. I can't comment on your home made bleeder - I just bleed my brakes by gravity - usually an egg-cup full of fluid at each nipple does the trick. Either the seals have failed - or the bleeding is not being done correctly!

Any Silicone fluid was expelled before by purging with the Dot 3 before I rebuilt everything. So the rubber wasn't contaminated with the mixture of fluids. My homemade bleeder works on the same principle as the gunson eezibleed (pressureizes the system).

Post by **bmcecosse** » Mon Oct 05, 2009 10:58 pm

The seals have been in contact with the silicone for some time - they will have absorbed some of the silicone - they WILL be contaminated with it! I can only say that to swap fluids usually seems to end in tears.

Post by **Pyoor_Kate** » Tue Oct 06, 2009 10:51 am

For once I agree with BMC here. If you change from DOT 3/4 to Silicone fluid it's advised to change all the seals because of the risk of the rubber in there swelling / failing in some way.

Although you cleaned up the calipers, you make no mention of the seals in the rear cylinders and it's quite possible that the failure is there...

OOI, why did you change back?