If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
I have been messing about with these brakes for months on and off. I
postede in May time about the difficulty of getting fluid through to the back calipers. See he http://groups.google.co.uk/group/alt...8 023a0e83272 I have spent over 1000 dollars on parts so far and I still have a problem. Four new calipers, the complete set of bits to do the handbrake, new pipes, new pads, lots of odds and ends and so much time that my head spins just thinking about it. I thought it must be the pressure differential sensing valve, but I took it out and pushed the spool back and forth against the springs and the contact made at the appropriate time AND air could get through both ways, i.e. front and rear when it was at rest. I tried bleeding the front brakes with a vacuum pipe on the caliper bleeding nipples. I made up a special bleed nipple that did not seal but let fluid through all the time. With a big reservoir above the master cylinder and a glass jug between the nipple and my vacuum pump, everything looked fine and I got lots of clear fluid going through. This should have not actuated the pressure valve at all. However when I tried the same on the rear calipers, it was as if the valve had sealed again, as no fluid could be sucked through. It was too late to do any more, today, but what do you think about that? As far as I know there is nothing else that could stop the flow. Or could it even be the set up of the master cylinder clearances. It WAS working and when I took it all apart it looked in perfect condition so I put it all back as it was. Cleaned out with new DOT 4 fluid, of course. I am glad to say the lights and wipers and associated vacuum circuits are working perfectly now too. I have not really got that much more to do. This car has got to go out of my workshop very soon as I want to build a bio-diesel processor exactly where it is now. I has been jacked up for months. Anyone got any ideas? Please. Regards George. |
Ads |
#2
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
"George" > wrote in message ... >I have been messing about with these brakes for months on and off. I > postede in May time about the difficulty of getting fluid through to > the back calipers. See he > http://groups.google.co.uk/group/alt...8 023a0e83272 > > I have spent over 1000 dollars on parts so far and I still have a > problem. > > Four new calipers, the complete set of bits to do the handbrake, new > pipes, new pads, lots of odds and ends and so much time that my head > spins just thinking about it. > > I thought it must be the pressure differential sensing valve, but I > took it out and pushed the spool back and forth against the springs > and the contact made at the appropriate time AND air could get > through > both ways, i.e. front and rear when it was at rest. I tried > bleeding > the front brakes with a vacuum pipe on the caliper bleeding nipples. > I > made up a special bleed nipple that did not seal but let fluid > through > all the time. With a big reservoir above the master cylinder and a > glass jug between the nipple and my vacuum pump, everything looked > fine and I got lots of clear fluid going through. This should have > not actuated the pressure valve at all. > > However when I tried the same on the rear calipers, it was as if the > valve had sealed again, as no fluid could be sucked through. It was > too late to do any more, today, but what do you think about that? As > far as I know there is nothing else that could stop the flow. Or > could it even be the set up of the master cylinder clearances. It > WAS > working and when I took it all apart it looked in perfect condition > so > I put it all back as it was. Cleaned out with new DOT 4 fluid, of > course. > > I am glad to say the lights and wipers and associated vacuum > circuits > are working perfectly now too. I have not really got that much more > to do. > > This car has got to go out of my workshop very soon as I want to > build > a bio-diesel processor exactly where it is now. I has been jacked up > for months. > > Anyone got any ideas? Please. Regards George. > Is it possible you have the pistons in the back brake calipers bottomed out? Did you put on new hoses? |
#3
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
On 12 Jul, 23:19, "Dad" > wrote:
> "George" > wrote in message > > ... > > > > > > >I have been messing about with these brakes for months on and off. I > > postede in May time about the difficulty of getting fluid through to > > the back calipers. * See he > >http://groups.google.co.uk/group/alt...wse_thread/thr... > > > I have spent over 1000 dollars on parts so far and I still have a > > problem. > > > Four new calipers, the complete set of bits to do the handbrake, new > > pipes, new pads, lots of odds and ends and so much time that my head > > spins just thinking about it. > > > I thought it must be the pressure differential sensing valve, but I > > took it out and pushed the spool back and forth against the springs > > and the contact made at the appropriate time AND air could get > > through > > both ways, i.e. front and rear when it was at rest. *I tried > > bleeding > > the front brakes with a vacuum pipe on the caliper bleeding nipples. > > I > > made up a special bleed nipple that did not seal but let fluid > > through > > all the time. *With a big reservoir above the master cylinder and a > > glass jug between the nipple and my vacuum pump, everything looked > > fine and I got lots of clear fluid going through. *This should have > > not actuated the pressure valve at all. > > > However when I tried the same on the rear calipers, it was as if the > > valve had sealed again, as no fluid could be sucked through. *It was > > too late to do any more, today, but what do you think about that? As > > far as I know there is nothing else that could stop the flow. *Or > > could it even be the set up of the master cylinder clearances. *It > > WAS > > working and when I took it all apart it looked in perfect condition > > so > > I put it all back as it was. *Cleaned out with new DOT 4 fluid, of > > course. > > > I am glad to say the lights and wipers and associated vacuum > > circuits > > are working perfectly now too. *I have not really got that much more > > to do. > > > This car has got to go out of my workshop very soon as I want to > > build > > a bio-diesel processor exactly where it is now. I has been jacked up > > for months. > > > Anyone got any ideas? *Please. * Regards George. > > Is it possible you have the pistons in the back brake calipers > bottomed out? Did you put on new hoses?- Hide quoted text - > > - Show quoted text - Hi Dad, I'm not sure what bottomed out means. The calipers were brand new and the same style etc. as the ones that came out. I did not change any of the pipes as yet as they are not bad and I want to see it work before I change anything else. All the oil that came out of various places was old, but clean, so I don't expect any blockages. Even if the pistons are at the bottom of the bores, the fluid would still get in. No, the more I think about it there is something very basic stopping the fluid going through and my reasoning is at fault. I shall take the pipes off the master cylinder and the pressure differential again and see where the actual blocking is taking place. I may take them both to the agent and buy whatever he says is faulty. The annoying thing is that they all seem OK but the front works perfectly and I can't get a drop through to the back end. I may be too close to the problem and can't see the wood for all the trees! Regards George. |
#4
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
On 13 Jul, 21:56, George > wrote:
> On 12 Jul, 23:19, "Dad" > wrote: > > > > > > > "George" > wrote in message > > .... > > > >I have been messing about with these brakes for months on and off. I > > > postede in May time about the difficulty of getting fluid through to > > > the back calipers. * See he > > >http://groups.google.co.uk/group/alt...wse_thread/thr.... > > > > I have spent over 1000 dollars on parts so far and I still have a > > > problem. > > > > Four new calipers, the complete set of bits to do the handbrake, new > > > pipes, new pads, lots of odds and ends and so much time that my head > > > spins just thinking about it. > > > > I thought it must be the pressure differential sensing valve, but I > > > took it out and pushed the spool back and forth against the springs > > > and the contact made at the appropriate time AND air could get > > > through > > > both ways, i.e. front and rear when it was at rest. *I tried > > > bleeding > > > the front brakes with a vacuum pipe on the caliper bleeding nipples. > > > I > > > made up a special bleed nipple that did not seal but let fluid > > > through > > > all the time. *With a big reservoir above the master cylinder and a > > > glass jug between the nipple and my vacuum pump, everything looked > > > fine and I got lots of clear fluid going through. *This should have > > > not actuated the pressure valve at all. > > > > However when I tried the same on the rear calipers, it was as if the > > > valve had sealed again, as no fluid could be sucked through. *It was > > > too late to do any more, today, but what do you think about that? As > > > far as I know there is nothing else that could stop the flow. *Or > > > could it even be the set up of the master cylinder clearances. *It > > > WAS > > > working and when I took it all apart it looked in perfect condition > > > so > > > I put it all back as it was. *Cleaned out with new DOT 4 fluid, of > > > course. > > > > I am glad to say the lights and wipers and associated vacuum > > > circuits > > > are working perfectly now too. *I have not really got that much more > > > to do. > > > > This car has got to go out of my workshop very soon as I want to > > > build > > > a bio-diesel processor exactly where it is now. I has been jacked up > > > for months. > > > > Anyone got any ideas? *Please. * Regards George. > > > Is it possible you have the pistons in the back brake calipers > > bottomed out? Did you put on new hoses?- Hide quoted text - > > > - Show quoted text - > > Hi Dad, * I'm not sure what bottomed out means. The calipers were > brand new and the same style etc. as the ones that came out. *I did > not change any of the pipes as yet as they are not bad and I want to > see it work before I change anything else. All the oil that came out > of various places was old, but clean, so I don't expect any > blockages. *Even if the pistons are at the bottom of the bores, the > fluid would still get in. *No, the more I think about it there is > something very basic stopping the fluid going through and my reasoning > is at fault. *I shall take the pipes off the master cylinder and the > pressure differential again and see where the actual blocking is > taking place. *I may take them both to the agent and buy whatever he > says is faulty. * The annoying thing is that they all seem OK *but the > front works perfectly and I can't get a drop through to the back end. > > I may be too close to the problem and can't see the wood for all the > trees! > > Regards George.- Hide quoted text - > > - Show quoted text - See? Do not assume anything and start from the simple facts. I assumed that because I read about the pressure differential valve could block off a failing front or back system. So that must be it - isn't it? NO Twit! Another reason that no fluid is getting to either rear caliper just could be two pipes blocked! And so it was. The flexible pipes at the rear were both solid and I could not even hammer a thin brazing rod through. When I replaced these everything suddenly went right. With my suction pump, I did not even have to prime the master cylinder. The fluid went through so fast I shall have to put a tap on it to regulate the vacuum. I am really looking forward to doing it tomorrow now. Thanks for listening. Nothing like talking to yourself to get an application of logic. Regards George. |
#5
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
"George" > wrote in message ... Snip Rememeber me asking if you had changed the hoses? Now you know why I ask. > > > Is it possible you have the pistons in the back brake calipers > > bottomed out? Did you put on new hoses?- Hide quoted text - > > > - Show quoted text - > > Hi Dad, I'm not sure what bottomed out means. The calipers were > brand new and the same style etc. as the ones that came out. I did > not change any of the pipes as yet as they are not bad and I want to > see it work before I change anything else. All the oil that came out > of various places was old, but clean, so I don't expect any > blockages. Even if the pistons are at the bottom of the bores, the > fluid would still get in. No, the more I think about it there is > something very basic stopping the fluid going through and my > reasoning > is at fault. I shall take the pipes off the master cylinder and the > pressure differential again and see where the actual blocking is > taking place. I may take them both to the agent and buy whatever he > says is faulty. The annoying thing is that they all seem OK but the > front works perfectly and I can't get a drop through to the back > end. > > I may be too close to the problem and can't see the wood for all the > trees! > > Regards George.- Hide quoted text - > > - Show quoted text - See? Do not assume anything and start from the simple facts. I assumed that because I read about the pressure differential valve could block off a failing front or back system. So that must be it - isn't it? NO Twit! Another reason that no fluid is getting to either rear caliper just could be two pipes blocked! And so it was. The flexible pipes at the rear were both solid and I could not even hammer a thin brazing rod through. When I replaced these everything suddenly went right. With my suction pump, I did not even have to prime the master cylinder. The fluid went through so fast I shall have to put a tap on it to regulate the vacuum. I am really looking forward to doing it tomorrow now. Thanks for listening. Nothing like talking to yourself to get an application of logic. Regards George. |
#6
|
|||
|
|||
1970 Corvette 350 cu. in. brakes
Amazing that both hoses were blocked. You would expect only one to be
blocked and if you have the same problem on both rears, then the master cylinder or 'proportioning' valve are the only common elements. Glad you got it fixed. "Dad" > wrote in message .. . > > "George" > wrote in message > ... > Snip > > Rememeber me asking if you had changed the hoses? Now you know why I ask. > >> >> > Is it possible you have the pistons in the back brake calipers >> > bottomed out? Did you put on new hoses?- Hide quoted text - >> >> > - Show quoted text - >> >> Hi Dad, I'm not sure what bottomed out means. The calipers were >> brand new and the same style etc. as the ones that came out. I did >> not change any of the pipes as yet as they are not bad and I want to >> see it work before I change anything else. All the oil that came out >> of various places was old, but clean, so I don't expect any >> blockages. Even if the pistons are at the bottom of the bores, the >> fluid would still get in. No, the more I think about it there is >> something very basic stopping the fluid going through and my reasoning >> is at fault. I shall take the pipes off the master cylinder and the >> pressure differential again and see where the actual blocking is >> taking place. I may take them both to the agent and buy whatever he >> says is faulty. The annoying thing is that they all seem OK but the >> front works perfectly and I can't get a drop through to the back end. >> >> I may be too close to the problem and can't see the wood for all the >> trees! >> >> Regards George.- Hide quoted text - >> >> - Show quoted text - > > See? Do not assume anything and start from the simple facts. I assumed > that because I read about the pressure differential valve could block > off a failing front or back system. So that must be it - isn't it? > NO Twit! Another reason that no fluid is getting to either rear > caliper just could be two pipes blocked! And so it was. > > The flexible pipes at the rear were both solid and I could not even > hammer a thin brazing rod through. When I replaced these everything > suddenly went right. With my suction pump, I did not even have to > prime the master cylinder. The fluid went through so fast I shall > have to put a tap on it to regulate the vacuum. I am really looking > forward to doing it tomorrow now. > > Thanks for listening. Nothing like talking to yourself to get an > application of logic. > > Regards George. > |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
1970 350 cu. in. convertible brakes, on-going problems | George[_17_] | Corvette | 4 | May 3rd 08 11:58 AM |
1970 brakes | George[_17_] | Corvette | 4 | March 29th 08 04:09 AM |
1970 Chevy El Camino Brakes | [email protected] | Technology | 8 | April 23rd 06 09:56 AM |
Corvette 1974 Rear Brakes | goof | Corvette | 5 | July 26th 05 03:33 AM |