Engine/Transmission (1998.5 - 2002) jacobs brake question hole in butterfly

[odieub]

i just installed one on my 01 ho 6-speed. i bought the brake used from a member on another site. i have never really been around one of these before so this might be nothing. i checked to make sure it closed all the way before i installed and it did. the question is the hole in the butterfly. there is supose to be one correct. mine hase one and if so would anyone know how big it is supose to be. i just don't think it is getting the breaking power it is supose to get.

 

[WestTN]

I don't recall the exact size of the hole, but it belongs there. It is sized to prevent excessive exhaust backpressure which could cause an exhaust valve to remain open and collide with a piston. Just downshift to keep the RPM's in the 2,000 to 2,500 range and you will have good stopping assist. I drive it like that and my brakes are still original at 139,000+ miles with plenty of pad left.

 

[CKelley1]

the jacobs has 60 psi back pressure at red line and 0 psi at 1,000 rpm if you get a chance to get a bd or pac do it , they have the same psi all the way

 

[MrMike]

I would agree with CKelley1 I have installed several brands on different trucks and the PAC seems to be the simplest and most effective

 

[AH64ID]

the jacobs has 60 psi back pressure at red line and 0 psi at 1,000 rpm if you get a chance to get a bd or pac do it , they have the same psi all the way

The Jacobs has 30 psi at 1000 rpms, 20 psi at idle. The Jacobs hits 60 psi at about 2400-2500 rpms, and is above 50 psi at 1600-1700 psi...



Personally I don't want the max pressure at every rpm, I like the ability to vary my braking power by selecting the gear...