• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

brake booster question 5 lug conversion

  • Thread starter Thread starter insanestang
  • Start date Start date Oct 15, 2007

insanestang

Founding Member
Dec 17, 2000
311
0
17
NJ
Oct 15, 2007
#1
  • Oct 15, 2007
  • #1
Just finished up my 5 lug conversion tonight and when i start up the car there is a hissing sound coming from under the dash where the booster is. Does anyone know the cause of this? Is it a bad booster? I hope not cause I don't feel like taking it out.

Also, my left rear disc brake is not grabbing, but the right rear is working great. any suggestions?
 
S

speedytang

Founding Member
Jul 28, 1999
765
1
17
Marengo,Ohio,US
Oct 15, 2007
#2
  • Oct 15, 2007
  • #2
Sounds like a Bad Booster. Torn diaphragm
 

Blandnuts

I don't swallow; I only swoosh
Founding Member
Aug 21, 2000
1,172
124
124
FloorDuh
Oct 16, 2007
#3
  • Oct 16, 2007
  • #3
How did you convert your ports over from the master cylinder?
 

Shakerhood

20+ Year Stangneter
Oct 28, 2004
3,356
208
114
Ohio
Oct 17, 2007
#4
  • Oct 17, 2007
  • #4
a 3-2 Kit
 

Blandnuts

I don't swallow; I only swoosh
Founding Member
Aug 21, 2000
1,172
124
124
FloorDuh
Oct 17, 2007
#5
  • Oct 17, 2007
  • #5
When you bled the brakes, you got brake fluid out of the left rear?
 

bullitstang1313

Member
Jan 21, 2003
713
0
16
Indianapolis / Columbus, Indiana
Oct 17, 2007
#6
  • Oct 17, 2007
  • #6
Which rear caliper did you bleed first? Are you sure the line to the driver's side rear isn't kinked or plugged? Like Blandnuts asked, did you get fluid out of that caliper? Is the vacuum line to the brake booster tight? Could be a bad booster.
 

Georgie

New Member
Jul 13, 2005
455
0
0
Montreal, Canada
Oct 17, 2007
#7
  • Oct 17, 2007
  • #7
sorry to but in..i have 4 piston brembos in front and cobra rears..just waiting to install everything...but i purchased a cobra master cylinder..the 1" bore... should i have gotten one from a 95 + mustang( the bigger bore)?
 

insanestang

Founding Member
Dec 17, 2000
311
0
17
NJ
Oct 17, 2007
#8
  • Oct 17, 2007
  • #8
thanks for all the replies. I used a 3-2 conversion at the M/C.

I bled the rear passenger caliper first anf then the rear driver. both had fluid come out of them. but only the passenger rear is working. (I can tell by the rust on the rotors haha). could the piston be stuck on the rear driver? is that common? Any way to fix that if it is?

As for the booster, I am just going to order a new one.
 

Blandnuts

I don't swallow; I only swoosh
Founding Member
Aug 21, 2000
1,172
124
124
FloorDuh
Oct 17, 2007
#9
  • Oct 17, 2007
  • #9
Was the caliper new or used? And how did you "push" the piston back in place?
 

insanestang

Founding Member
Dec 17, 2000
311
0
17
NJ
Oct 17, 2007
#10
  • Oct 17, 2007
  • #10
used. I rented the tool from autozone that has the two points on the end that lets you turn it. it seemed to turn pretty good. any way to lube up the piston?
 

Blandnuts

I don't swallow; I only swoosh
Founding Member
Aug 21, 2000
1,172
124
124
FloorDuh
Oct 17, 2007
#11
  • Oct 17, 2007
  • #11
I would try and see what the side of the piston looks like....I'm just not sure how you can do that with it being stuck. It should push out with the pressure of the brake fluid, because normally it would get stuck on the rotor and burn up the rotor.

I asked about the tool because I've seen people use pliers to turn it while using a c-clamp. Yeah, it'll work but you have a high chance of scratching the sides of the piston....

Anyways, maybe someone will chime in.




Fred
 
You must log in or register to reply here.

Similar threads

Brakes FOX BRAKES ISSUES
  • PonyGTrider
  • Jan 11, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
53
Views
2K
Fox 5.0 Mustang Tech Jan 31, 2026
Mustang5L5
8
87 lx 4cyl to v8 project 4 lug disc conversion questions
  • 87lx428
  • Mar 24, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
2
Views
492
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Mar 25, 2026
87lx428
8
J
Wheels-Tires Need Some Help - Brakes Upgrade/Wheel fitment
  • jaygee15
  • Dec 8, 2025
  • Fox 5.0 Mustang Tech
  • 3 4 5
Replies
81
Views
2K
Fox 5.0 Mustang Tech May 6, 2026
AeroCoupe
F
5 lug disc brake pad help
  • Foxrider714
  • Nov 14, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
3
Views
232
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 17, 2025
KRUISR
Rear Disc and Rims Offsets
  • TripleYellow
  • Nov 11, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
19
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 9, 2026
TripleYellow
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?