FYI B & C Body Bendix disc brake dual diaphragm boosters compared

[PH27L7]

There’s a lot of misinformation out there regarding interchangeability between B, E, & C body disc brake boosters from 60’s-early 70’s. Just removed an original booster from a 1970 B for a detailing so I thought I’d compare it directly with the original from my 1967 Fury which I’m sending out for rebuild.

Good news is they are identical in every respect except for the length of the pushrod which is 3/4” longer in the C-body and possibly the check valve means of attachment. There should be a way to extend the pushrod of a more common B-body to make it work on a C. I’m not sure how the pushrod is removed from the booster. They did change the means of attachment of the check valve from a twist on type with gasket to a push-in type with grommet some time in 67-68 but either works the same. They do make a repro B/E-body boosters although they look a bit different than the originals.

Some measurements I took-
Pushrod diameter- 0.500 in
Pushrod hole- 0.578 in
Pushrod swivel bolt diameter- 0.567 in
Stud center-center mounting to firewall- 3-1/4 x 4-1/8 in

C booster is on left in pics.

 

[Ross Wooldridge]

This is EXCELLENT information - I wondered about pushrod length and if it were the true deciding factor.

If this is true, then it's a game changer for our disc conversions. If someone can simply tool up to make the correct length (or better yet, adjustable) main pushrod, then things just improved dramatically.

 

[PH27L7]

This is EXCELLENT information - I wondered about pushrod length and if it were the true deciding factor.

If this is true, then it's a game changer for our disc conversions. If someone can simply tool up to make the correct length (or better yet, adjustable) main pushrod, then things just improved dramatically.

I have no idea how to remove that pushrod. Since the pushrod is a perfect 1/2" diameter, my thoughts were along the lines of cutting & threading it and adding a threaded sleeve to get the longer length. If you were to weld in a section you would have to go hyper slow & careful to avoid hurting the soft parts.

 

[Ross Wooldridge]

Agreed - the push rod is removable during the booster rebuilding process. That would be when the new part could be retrofitted.

 

[Davea Lux]

The '67 C-Body booster is a 8" booster, same as the the B-Body. '68-'70 and some '71 C-Bodies used a 9" booster, B-Bodies for that period used the 8" Booster. The B-Body unit could be adapted to fit the '67 application during a rebuild process if one had the correct C-Body operating rod. Given that the B-Body boosters are significantly more valuable that the C-Body boosters, I am not so sure it would make sense to do that conversion. The after market 8", usually ChiCom repop boosters are all set up for A, B and E-Body applications. I suspect the internal components are probably all metric, so the likely hood of trying to change an operating rod on one of those units might be a challenge especially since the units are not user serviceable.

Dave

 

[PH27L7]

The '67 C-Body booster is a 8" booster, same as the the B-Body.

That is incorrect as far as my original '67 booster goes, it is approximately 9 inches in diameter, the same as the '70 B-body. The '68 Imperial booster currently on my car is also 9 inch. The only difference in the '68 Imperial unit from the '67 is in the check valve mounting.

 

[Davea Lux]

That is incorrect as far as my original '67 booster goes, it is approximately 9 inches in diameter, the same as the '70 B-body. The '68 Imperial booster currently on my car is also 9 inch. The only difference in the '68 Imperial unit from the '67 is in the check valve mounting.

Is your B-Body perchance a hemi?

Dave

 

[PH27L7]

Is your B-Body perchance a hemi?

Dave

I wish, just a lowly V-code.

 

[Davea Lux]

I wish, just a lowly V-code.

I looked it up, 8.75" booster was used on both B and C bodies. Suspect you got the heavier booster with the V-Code application.

Dave

 

[PH27L7]

I looked it up, 8.75" booster was used on both B and C bodies. Suspect you got the heavier booster with the V-Code application.

Dave

Absolutely not. They did not even offer the hemi in the LA plant and the hemi booster is a different animal entirely. I've had 3 67-68 disc brake C's and the all had the external dimensions of the one pictured.

If anyone has a picture of a smaller 8 in tandem Bendix booster that was Mopar OEM for B's & C's, please post. I've never seen one. I think that may apply to some aftermarket replacement pieces. The hemi booster is similar to shown with a special curved pushrod.

 

[Metalmarty]

Did anyone try to modify the b body dual diaphragm booster to fit a C body? (lengthening the rod by 0.75")

And which b body booster do I need? I see a lot of variation in mounting bolt pattern, size (8"-8.75") etc. Can someone point me in the right direction? I might want to try this

 

[RGORHAM29]

Any updates?

 

[C-440-300]

Anyone get more info/updates? I have a 66-300 and converted 4-drum 2 4-disc and the booster was changed to a dual diaphragm Midland 9" type that does have the shorter rod. It's in need of repair, so I wanted an interim solution to swap out while I get the big balloon fixed. I am willing to change back to a correct C-body solution if reasonable. I won't drill or modify my pedal. The mounting/reinforcement plate on the firewall didn't need to change when I converted. ( I often wondered if Ma Mopar was happy wth the 10" single diaphrams on the early and last big boats? )

 

[66l78rat]

I have a nos in the box C body Bendix dual booster if anyone is interested. Book says #ś correct for 70-71, $1K