RM351 148 Posted February 19, 2022 Ok, I'm not sure about this one but I'm assuming these were used in XB GT's with rear drums? Or rear discs as well? I replaced my XB ute drum rear end with a B/W disc brake out of an XC. So will I need this Proportioning Valve or not? 1 Outback Jack reacted to this Share this post Link to post Share on other sites
Outback Jack 6,352 Posted February 19, 2022 Ok, I'm not sure about this one but I'm assuming these were used in XB GT's with rear drums? Or rear discs as well? I replaced my XB ute drum rear end with a B/W disc brake out of an XC. So will I need this Proportioning Valve or not?You will need to reduce the flow to the back brakes, as it's set up for drum.I have an OBP motorsport one here from England.Yours for $120 Inc postage.Was £52 plus customs and shipping.It's a motorsport one, not some el cheapo.Just put it on the line for the rears and restrict the flow to them.Done.Sent from my motorola edge 20 pro using Tapatalk Share this post Link to post Share on other sites
scottly 475 Posted February 19, 2022 Hey mate, have you driven the car since changing to disc brake rears? Do the rears lock up unusually under Heavy braking? Some times the brake master cylinders are built differently from drums to discs, you should only need to change the brake master cylinder to the a four wheel disc brake type and problem should be solved! If your rear brakes are not locking up/ behaving strangely under heavy braking and providing that they still function correctly, you may be able to leave the factory brake master cylinder. that’s from my experience any way. 1 bear351c reacted to this Share this post Link to post Share on other sites
bear351c 10,270 Posted February 19, 2022 Agreed. Done the conversion on the XB, from drum to disc brake 9", haven't changed a thing. Brakes hard and straight. Heard many stories about rears locking up, etc, but haven't had it on both conversions I've done. Fully rebuilt calipers from an XC/ZH, and new discs. 1 1 Outback Jack and gregaust reacted to this Share this post Link to post Share on other sites
RM351 148 Posted February 19, 2022 3 hours ago, Outback Jack said: Just put it on the line for the rears and restrict the flow to them. Done. Is there a way to know if it's adjusted correctly or do you need to do a trial and error thing? 1 Outback Jack reacted to this Share this post Link to post Share on other sites
Outback Jack 6,352 Posted February 19, 2022 Like the guys said if it doesn't lock the rears when driving it will be fine.But there's only one way to find out.,Sent from my motorola edge 20 pro using Tapatalk Share this post Link to post Share on other sites
RM351 148 Posted February 19, 2022 2 hours ago, scottly said: Hey mate, have you driven the car since changing to disc brake rears? Do the rears lock up unusually under Heavy braking? Car still a few months away from being driven so I thought before I do I need to find out whether I need this valve or not. I've bought a new brake master cylinder, it's from Bosch Part No. P6258A so I don't know it's suitable for 4 wheel discs or disc/drum only. 1 Outback Jack reacted to this Share this post Link to post Share on other sites
Outback Jack 6,352 Posted February 19, 2022 Have you bought a booster yet?I'm doing a booster delete on my lil car.Maybe that sort of Master is like my old one, side and lower outlet for the fronts and one side one for the rears.That and an adjustable length master cylinder rod kit ($120 Wilwood kit). Should pull up your car easy without all the vac hub bub to fail. Sent from my motorola edge 20 pro using Tapatalk 1 RM351 reacted to this Share this post Link to post Share on other sites
RM351 148 Posted February 19, 2022 5 minutes ago, Outback Jack said: Like the guys said if it doesn't lock the rears when driving it will be fine. But there's only one way to find out., No worries, try that first and go from there. Share this post Link to post Share on other sites
RM351 148 Posted February 19, 2022 1 minute ago, Outback Jack said: Have you bought a booster yet? Was going to use the original booster, still works. Share this post Link to post Share on other sites
gregaust 319 Posted February 21, 2022 On 2/19/2022 at 9:01 PM, bear351c said: Agreed. Done the conversion on the XB, from drum to disc brake 9", haven't changed a thing. Brakes hard and straight. Heard many stories about rears locking up, etc, but haven't had it on both conversions I've done. Fully rebuilt calipers from an XC/ZH, and new discs. Spot on yes . Done many the same XY , XA XC XD with the XC calipers and XF and no issues at all . As long as you have the XC or XD front lever also for the handbrake you'll be sweet . 1 RM351 reacted to this Share this post Link to post Share on other sites
RM351 148 Posted February 22, 2022 On 2/21/2022 at 5:04 PM, gregaust said: As long as you have the XC or XD front lever also for the handbrake you'll be sweet I have a cable specifically for XB handbrake to XC rear calipers. Share this post Link to post Share on other sites
bear351c 10,270 Posted February 24, 2022 On 2/22/2022 at 10:48 PM, RM351 said: I have a cable specifically for XB handbrake to XC rear calipers. .........thanks for reminding me..... really should put mine on, bought it 2 years ago. My shed isn't on a hill, so didn't bother. 3 Outback Jack, 2redrovers and RM351 reacted to this Share this post Link to post Share on other sites
