Rear brake grab 2007 Ranger
We have a customer with a 2007 Ranger that has developed a severe rear brake grab when braking that results in ABS release. We did a rear brake job (brake shoes, hardware, wheel cylinder) about a year ago. Inspection found all hardware to be installed correctly. Hooking up brake pressures gauges, when brakes applied, rear brake pressure is @1200psi front brake pressure is @1000psi ( engine running). My question is; What controls brake pressure proportioning in this system? Can't find any information in MOD or internet. No external proportioning valve on this truck. My thought is either the master cylinder or ABS hydraulic unit. Customer is not receptive to “trying ”replacement of either master cylinder of ABS hydraulic unit to find out if it means spending $$$ without diagnostic proof. Any help would be appreciated. Thanks in advance
Electronic Brake Distribution (EBD) On initial application of the brake pedal, full pressure is applied to the rear brakes. The ABS module then uses wheel speed input to calculate an estimated rate of deceleration. Once vehicle deceleration exceeds a predetermined threshold, the ABS module closes the appropriate isolation valves in the HCU to hold the rear brake pressure constant while allowing…
Thank you Chris for this information, Customer is coming back in for review. Sorry, I didn't mention that I scanned ABS module..no codes.
I had a similar issue several years ago on an 04 Ranger and the cure was machining the brand new out of the box drums.The original cut on them had s slight taper to them and caused the rear brakes to lock up.Hope this helps.
Is this more prevalent cold, first thing in am, and get better the longer the truck is driven. When I was with Ford, 18 years, we had a lot of these issues with the ranger. Rear brake shoes and sealing the backing plates with a light coat of undercoat resolved the issue. Moisture contamination of the brake shows was Fords answer and eventually revised the shoe compound and released a TSB. also…
I Have Had Many Of These When I lived In Michigan , Always Seemed To Happen When The Brake Drums Were Close To Machine Limits. I bet Two New Drums And Re Adjust The Shoes And Your Problem Goes Away
Mark, Our shop is in So-cal. No environmental issues here. today; dry as abone, temp@85 degrees.
has nothing to do with weather, what are the drum measurements? The Shoes Will Over Extend And Lock Up The Drums. I've Seen It Many Times Before. The Funny Thing Is, Not All Rangers Seem To Have This Issue But About Half Of Them Do
Glen, try a different brake shoe and make sure drums are machined to a smooth finish. Trim edges
Hey Craig, My thoughts when he returns in the next few days, Thanks
I had experience with this truck before,also Chevy Cavalier, same issue, only OEM Drums and shoes fixed the problem.
Joao, I've done hundreds of brake jobs on Rangers, first one with this problem. Always used quality aftermarket parts. I will re-inspect parts issue when customer returns. Thanks
Glenn , Are the backing plate contact points smooth, & no contamination from the axle?
Tommy, The only thing unusual is the drums appear to be heavily heated, like excessive braking. I think Chris is on to something with the HCU. Unfortunately, Ford has discontinued that part. thanks
Swap the drums from one side to the other and see if the problem stays or moves….
Mark, problem affect both sides. Both sides lock up. Thanks
I seem to recall an issue with these where there was a problem with moisture which was already mentioned, but also the length of the brake shoes, or shoe material. Sometimes the “short shoe” was still too long or the long shoe was too long causing premature grabbing.
Matthew, Like I told Rick, In so Cal we don't have weather issues. The sun is always shining. Thanks
Let me also state that when pedal is released, brake pressure goes to zero and wheels (front and back) release. There is no residual brake fluid pressure stored in rear brake lines.
Inspect the wear on the shoes to determine the contact areas. It may be that the shoes are not centered vertically. Do they grab excessively in reverse? Does the application feel about the same in both directions when spinning the wheels by hands?
Stupid question but must be asked, Did someone get the primary shoe and secondary shoe reversed? I've seen aftermarket(usually the cheap stuff) have the primary shoe lining made to long.
Hi All, Sorry for the delay. I took Rick Chandler's advise and replaced rear brake shoes and drums (old drums still in spec with room to spare). Unfortunately, the grabbing persisted. The customer is now debating if he wants to install a used HU because new ones aren't available. I believe that Chris Snyder was right. He best explained what my pressure tests confirmed. I believe that 1200psi to…
EBD (Electronic Brake Distribution) The EBD controls rear brake pressure and acts as an electronic proportioning valve. It is integral to the ABS module and not repairable. It is obviously using other sensors to calculate this. My suggestion is to do a brake flush and use scan tool to activate ABS solenoids.
I just had a 2004 with the same issue on only the right side What we found was the emergency brake cables were not releasing all the way and if you look closely at the top of the brake shoes where they ride on the center pin there will be some clearance between the brake shoe web and the center pin. The brakes will release fine in reverse but lock up going forward. Replaced both rear emergency…
Drum setup work at 500-600psi range. Anything above that means a proportioning valve is defective. Being said the proportion valve is either mount after the master (on some gm it was mounted right on the master cylinder port or further down the line by the rear axle. Being abs. I would expect the valve part of it being build into the hbcu