JB3 to JB5 rear brake upgrade

[Ronno6]

Is there a way to tell the difference between a JB3 single diaphragm booster and a JB5 double diaphragm unit??

[Henry]

Hi Ronno6:
I am pretty sure they will have different diameters of the diaphragm shell...sorry I am not familiar enough with them to tell you what the diameters are...I think the dual diaphragm is going to be smaller. You can probably do an internet search where they are documented. For my 76 truck all the vacuum power booster units were supplied by Delco Moraine or Bendix. Both companies made single and dual diaphragm.
Regards,
Henry

[bd]

The single diaphragm booster is like one wafer of an Oreo cookie while the tandem booster is like a double stuffed Oreo.   

[Ronno6]

The single diaphragm booster is like one wafer of an Oreo cookie while the tandem booster is like a double stuffed Oreo.   

If the pictures I see on the web are indicative, I already have the JB5 double diaphragm booster.
One less thing to buy and change out................

[Ronno6]

I have purchased a pair of "loaded" backing plates for JB5 setup.
I'll completely rebuild them and get a set of drums.
When I install the posi and regear, the new setup will be installed as well.

[bd]

I think you will be pleased with the outcome.

[Ronno6]

I just received my JB5 rear brake assemblies purchased on ebay.
They are splendid and complete, right down to the E-brake cables!
The shows appear to be new..no grooves or wear pattern discernible!

At a C-note for the pair delivered, I am pleased (Shipping was about $45.00...)
He has another set id anyone is interested.