Spongy brake when going forward then in reverse

[Petemac]

This is a really weird one
When driving forward the pedal initially goes soft then pumps up and is fine
Then when you reverse the pedal initially hits the floor then pumps up and is fine until you change direction again and the process starts again
Some background to what I have done
New discs, pads, shoes, adjuster’s, wheel cylinders, master cylinder, drums and flexible pipes.
I have adjusted the wheel bearings and bled the brakes with a pressure bleeder and the good old fashioned pedal to the metal.
I clamped off the rear flexies and the problem persisted
I clamped off the front flexies and the pedal was hard and the problem was gone.
Inspected the callipers and pads all looks good
All suspension bolts are tight
Anyone have any kind of a clue for this one

[silverbullet]

Drum adjusters fitted the wrong way round or shoe springs fouling, something simple as you have been in there and its pretty much impossible to assemble the front pads wrong, so I'd look in the drums.

[mioba]

You are gonna need a helper for this. someone pressing the brake pedal while you inspect the brakes (front and rear) when stripped of wheels and drums (rear).

Have you checked for leaks under pressure. The way you describe is that it lets in air but then maintains pressure.

I am thinking brake servo assuming you just changed the cylinder?

[Petemac]

Yes I did have the adjusters on the wrong way around but replace them with new and fitted them correctly (easy mistake) problem still there
And the problem goes when the front flexes are clamped off which would indicate the fault lies with the front callipers or discs but everything looks spot on even changed all the suspension and steering bushes to polly

[clift_d]

Maybe check that any adjustments to the front wheel bearings haven’t left them with too much play …

[Petemac]

Yep checked and adjusted bearings all good

[silverbullet]

Reading this again, I suspect that the change of direction may be a red herring. You still have an air lock to the rear brakes, from experience sometimes you have to bleed a lot of fluid through at a high flow rate.
Try elevating the rear of the van using ramps on a hill when bleeding to help the air bubble move.

[ZsZ]

A local T3 friend had the exact same problem.

In his case it was caused by wrong bearings used in the front hub (early vs late).