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drums to disks front on 45s
Posted: Wed Sep 07, 2005 4:33 pm
by 4sum4
Do i need to replace the master cylinder aswell when doing this,its an 81 model
Posted: Wed Sep 07, 2005 10:30 pm
by MY45
You shouldnt need to but you will need an proportioning valve for the rear brake line.
I got an adjustable one from rocket industries. The adjustable ones are not meant to be run if the can be adjusted with out using tools but my engineer didnt care/notice.
Posted: Thu Sep 08, 2005 1:19 am
by beanz2
If the front was drum, the master may have a higher residual pressure valve to counter the return springs. This needs to be removed if used with discs up front, otherwise the brake pads will drag on the rotor.
In older cruisers it is usually a brass valve screwed into the side of the master. You can replace it with one from any disc brake Toyotas of similar years.
Dave
Posted: Thu Sep 08, 2005 4:36 pm
by 4sum4
this what got
Posted: Fri Sep 09, 2005 12:42 am
by beanz2
4sum4 wrote:this what got
See the larger hexagonal valve that the brake line screws into? That is where the RPV is. See if you can remove it from the front circuit and get rid of the mechanism inside. Often it is just a simple spring or a rubber flap.
Dave
Posted: Fri Sep 09, 2005 11:59 pm
by 4sum4
Now looking at replacing the master cylinder with the 80s,Already have the prop valve and hard lines to bolt up,Will i need a LSPV for the rear?
Posted: Sat Sep 10, 2005 12:05 am
by beanz2
I'm also running an 80 series master in my 75. I have no LSPV for the rear circuit but I don't expect to load her to the limit.
It is interesting in the 80 with ABS and viscous transfers the rear brake circuit comes off the front connector of the master and the front circuit comes off the rear conn. I think it isn't reversed in the non ABS 80. Somebody correct me if I am wrong.
Dave
Posted: Sat Sep 10, 2005 12:14 am
by 4sum4
I don`t no much about brakes but correct me if i`m wrong aswell?but i think the ABS MC from the 80s would be usless on a 45s aswell on my 85 4runner???
I`m planning on doing rear disks on both vehicles
Posted: Sat Sep 10, 2005 9:41 am
by 4sum4
is this what your talking about
Posted: Sat Sep 10, 2005 11:12 am
by beanz2
The RPV is a brass valve screwed into the side of the master in the pic below. Inside you can see a little plastic valve held in place by a rubber flap. In this HJ75 master, I can feel a difference in the tension between the front (disc) and the rear (drum) RPV's.
The valve is prone to rounding off when you try to remove it, be sure to use a flare nut wrench or remove the brake line first and use a six-point socket insted of a twelve-point.
Dave