Rear brakes no fluid after VT brake upgrade in VH

[vc commodore]

Would the shoes need to be adjusted if they haven’t been touched? I only replaced the Fronts and didn’t do anything in the rear.

What’s the best way to check for a clogged line?

Possibly.....Something to check to help eliminate the issue.....

 

[Hole Denn]

The line out of the master closest to the booster is to the rears.

Those 2 rear ports on the VT master cylinder are for the 2 front line/brakes

The rear brakes use the single port closer to the strut tower

 

[Hole Denn]

I put a reply down below but just further to this, yea did the modification to the bolt head. But I didn’t get it completely flush. Sticks out about 2-3mm, you think this could be a problem. I currently have fluid coming through, but the spongy brake pedal is the problem here currently.

Yes incorrect threaded rod length will be an issue.

Just an update. Drum brakes on rear. Further, I had since got fluid coming to the rears. It seems the rear passenger side isn’t bleeding as well as the others. It’s gets fluid, but doesn’t shoot it out through the tube as the other 3 do. I’ve bled it twice now, and the 2nd time feels better, but still no where where it should be in terms of brake feel. I am googling troubleshooting possibilities online, but can’t seem to find the answer. I know when I cut down the screw head in the booster I didn’t make it exactly flush, prob 2-3mm longer than flush, could this be the cause? Further, can anyone please clarify which lines on the master are for front and rear? Better double check they’re going to the right place.

Edit: there also seems to be a noticeable sound of air being pushed when the brake is pressed. I don’t recall the same sound prior to doing this work

Your booster pushrod in master issue is causing booster having excess/expelling air at half way when brake pedal movement completely down.
This will not cause any issues to braking just feeling of brake pedal and effort to press it down hard.

The rear brakes are the front port in the m/c and your incorrect threaded rod is causing air/fluid bypass issues with m/c piston/inside seals.

You will have to measure the depth inside master cylinder at the rear where the booster threaded rod hits and pushes piston/fluid inside m/c and then screw down threaded rod into booster to your earlier m/c measurement.

 

[vpower13]

Yes incorrect threaded rod length will be an issue.


Your booster pushrod in master issue is causing booster having excess/expelling air at half way when brake pedal movement completely down.
This will not cause any issues to braking just feeling of brake pedal and effort to press it down hard.

The rear brakes are the front port in the m/c and your incorrect threaded rod is causing air/fluid bypass issues with m/c piston/inside seals.

You will have to measure the depth inside master cylinder at the rear where the booster threaded rod hits and pushes piston/fluid inside m/c and then screw down threaded rod into booster to your earlier m/c measurement.

So I guess pull it all apart, fix the length of the rod and then put it all together, re-bleed and hope it all works again

 

[Hole Denn]

So I guess pull it all apart, fix the length of the rod and then put it all together, re-bleed and hope it all works again

well thats the point of cutting thread rod nut head off because it does not fit in the back of m/c.
All the 1's I have done mod, I measure the length into m/c to set the thread rod correctly as its import for the m/c piston operation, also smear some blue loctite on the thread rod to keep it in its correct length.

 

[Hole Denn]

So I guess pull it all apart, fix the length of the rod and then put it all together, re-bleed and hope it all works again

I found my old notes in pc on previous conversions and the measurement for the inside master cylinder is 15.40mm but it doesn"t matter as the threaded rod is screwed in flush on the splined booster rod and then hopefully it all bleeds ok for you.

PS, you will notice your VT m/c plastic reservoir leans back to firewall a lot and cuts fluid down for front brake compartment, you can swap it with a VS or AU plastic reservoir/redrill bottom holding M5/M6 nut/bolt and it will sit more level

 

[Balfizar]

Brake fail switch has activated blocking off the rear M/C port. You need to take off the Big nut on the front of the M/C and push the slide in until the switch pin seats in the slide groove. (neutral position). you can also put a meter (any brake fails switch pin to earth) the push the slide in until the meter goes open circuit)