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More braking power needed
#21
(05-14-2019, 10:56 AM)Don C Wrote: Old pads of unknown quality and whether they were broken in correctly may be the problem. Glazed over pads don't work very well. Old, rusted rotors won't help any, either. If the rotors are within specs (thickness and run-out) they can be turned to give them a nice surface to break in new pads with good friction material.


That was a good point - altough they look tidy - who knows what they really are....
  Reply
#22
(05-14-2019, 09:05 AM)Higgins56 Wrote:
(05-14-2019, 07:29 AM)73pony Wrote: Something is amiss here. 20 in at idle is a lot, what cam are you running? I am only getting around 11 - 12 in at idle with a 351c and I can lock up all fours no problem with 17x9 all around and stock brakes.  I do not think your issue is a lack of vacuum.

HI,

the cam is Mechanical Roller Comp Cams Extreme Energy 242/248 @0.050"
Heads are AFR Bullit
Intake is Edelbrock Performer RPM Airgap

I made  another test and  connected the Hella pump directly to the booster - yah - I found more brakes but did not lock up yet....

Interesting  was also to find out that the pressure switch  from Summit cuts the pressure at 14 inHg !!!!!! At this level the brake  pedal was stone hard....
This same look pressure switch seems to be offered in different  kits as well ?

Where to get a  switch  to adjust it till 24 inHg ?
I also added a Hella vacuum pump as yours in combination with a vacuum reservoir to my system.
Here is a brief description: https://www.7173mustangs.com/thread-musc...#pid340221
I ended up using an adjustable vacuum switch from Superior (K058) (https://superiortransmission.com/product/superior-k058/).
I don't think it will get to 24, but 21-22 should be okay.

BTW, vacuum may not be your issue (or your only issue). I have been trying to get my brakes to lock up in the front and have not been successful. I am now working in my last resort replacing the last OEM component left in the system, which is the combination valve. This is my recent thread about it: https://www.7173mustangs.com/thread-fron...locking-up

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes
  Reply
#23
(05-15-2019, 09:12 AM)tony-muscle Wrote:
(05-14-2019, 09:05 AM)Higgins56 Wrote:
(05-14-2019, 07:29 AM)73pony Wrote: Something is amiss here. 20 in at idle is a lot, what cam are you running? I am only getting around 11 - 12 in at idle with a 351c and I can lock up all fours no problem with 17x9 all around and stock brakes.  I do not think your issue is a lack of vacuum.

HI,

the cam is Mechanical Roller Comp Cams Extreme Energy 242/248 @0.050"
Heads are AFR Bullit
Intake is Edelbrock Performer RPM Airgap

I made  another test and  connected the Hella pump directly to the booster - yah - I found more brakes but did not lock up yet....

Interesting  was also to find out that the pressure switch  from Summit cuts the pressure at 14 inHg !!!!!! At this level the brake  pedal was stone hard....
This same look pressure switch seems to be offered in different  kits as well ?

Where to get a  switch  to adjust it till 24 inHg ?
I also added a Hella vacuum pump as yours in combination with a vacuum reservoir to my system.
Here is a brief description: https://www.7173mustangs.com/thread-musc...#pid340221
I ended up using an adjustable vacuum switch from Superior (K058) (https://superiortransmission.com/product/superior-k058/).
I don't think it will get to 24, but 21-22 should be okay.

BTW, vacuum may not be your issue (or your only issue). I have been trying to get my brakes to lock up in the front and have not been successful. I am now working in my last resort replacing the last OEM component left in the system, which is the combination valve. This is my recent thread about it: https://www.7173mustangs.com/thread-fron...locking-up

Thanks Tony Muscle !

I found out that this  miserable switch is  in a way  adjustable but you have to  take the  switch apart out of the "T" and  adjust it by yourself  ( maybe not thought  by the manufacturer in the first place) but anyway I will  give it a try first.
What kind of reservoir you are using  for vacuum - there is not much place  where the original  "tin can " sits.... Can you send a photo ? ( martti56@gmail.com )

maybe I have to go through the  fron brakes as well - clean and check them - maybe renew this and that.... what front brakes you have - original?
  Reply
#24
(05-17-2019, 06:10 AM)Higgins56 Wrote:
(05-15-2019, 09:12 AM)tony-muscle Wrote:
(05-14-2019, 09:05 AM)Higgins56 Wrote: HI,

the cam is Mechanical Roller Comp Cams Extreme Energy 242/248 @0.050"
Heads are AFR Bullit
Intake is Edelbrock Performer RPM Airgap

I made  another test and  connected the Hella pump directly to the booster - yah - I found more brakes but did not lock up yet....

Interesting  was also to find out that the pressure switch  from Summit cuts the pressure at 14 inHg !!!!!! At this level the brake  pedal was stone hard....
This same look pressure switch seems to be offered in different  kits as well ?

Where to get a  switch  to adjust it till 24 inHg ?
I also added a Hella vacuum pump as yours in combination with a vacuum reservoir to my system.
Here is a brief description: https://www.7173mustangs.com/thread-musc...#pid340221
I ended up using an adjustable vacuum switch from Superior (K058) (https://superiortransmission.com/product/superior-k058/).
I don't think it will get to 24, but 21-22 should be okay.

BTW, vacuum may not be your issue (or your only issue). I have been trying to get my brakes to lock up in the front and have not been successful. I am now working in my last resort replacing the last OEM component left in the system, which is the combination valve. This is my recent thread about it: https://www.7173mustangs.com/thread-fron...locking-up

Thanks Tony Muscle !

I found out that this  miserable switch is  in a way  adjustable but you have to  take the  switch apart out of the "T" and  adjust it by yourself  ( maybe not thought  by the manufacturer in the first place) but anyway I will  give it a try first.
What kind of reservoir you are using  for vacuum - there is not much place  where the original  "tin can " sits.... Can you send a photo ? ( martti56@gmail.com )

maybe I have to go through the  fron brakes as well - clean and check them - maybe renew this and that.... what front brakes you have - original?

Which switch are you using. Mine adjust via a tiny screw on the vacuum port.
I am using a Jegs vacuum reservoir. I was able to fit it in the same spot as the original tin can. I also manage to fit the vacuum pump under the reservoir. It took some work due to the tight space but in this location it is hidden from view. I also have a sump fuel pump from my EFI in that corner so things are tight but partially hidden. I still need to start a thread showing the build but here are some pics.

Vacuum pump below brake line installed with custom brackets:
[Image: 20190113-230137.jpg]

Vacuum canister. You can see the vacuum lines and the gauge. The A/C vacuum line connects to the same fitting where the gauge is. I got a vacuum tee and drilled and tapped a barb for the A/C line.

[Image: 20190210-115250.jpg]

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes
  Reply
#25
Thanks Tony Muscle !

i decided to open the pressure switch from its hose connection unit. This revealed a setting screw under the switch. Mine was set more or less half way and it showed 14 inHg at the gauge. I turned the set screw clockwise as far as it went to obtain the max. vacuum - which I did now. It is ab. 22 inHg ( pump gives 24 mmHg ) so it is OK now.
The switch code at Summit is SSB-28146-SW and a similar switch can be found from Comp Cams, too. This switch seems to be present at many kits as well for vacuum pump.
So the switch as it is can give any figures rather than the specified 18-22 inHg range, so it has to be calibrated after the purchase to be sure what it can deliver.
[Image: Pressure-switch.jpg]
  Reply
#26
and finally when the vacuum was OK and the hose connected to the booster revealed something new.
This lower vacuum ment that the booster has to be in tip top condition - no leaks..... but in my case there is a tiny leak which means that the vacuum pump after reaching the desired level starts to start and stop in ab. 2-3 sec intervals which is not good.
The vacuum pump worked as planned till the booster check valve - all connections were tight but when the booster was connected to this the pump started working in intervals = never stops...
This means that I have to buy a new brake booster.

So at the moment I am driving the car getting the vacuum from the intake manifold. Surpriningly it makes a decent vacuum to brake.
There MIGHT be a question as well to go through the front disc brakes calipers and pads to be sure that they work as they should.
  Reply
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