Master Cylinder Upgrade

[diveman76]

I let this bronco sit for 9 years under a carport. (I know fail...) Just recently pulled it out and started restoring. Whoever had it before me did a chevy disc brake conversion. I've already replaced hubs, rubber lines, rotors and calipers. Now on to the master cylinder. It has just a regular master cylinder no booster. From what I remember I didn't have a problem braking. Has anyone used this master cylinder off of ebay? Will it really help that much or should I just replace the master cylinder? What is this part circled in blue? It looks like it might be a proportioning valve but I can't find another that looks like it. I am running 33's on it.

https://imgur.com/O808lLu

https://imgur.com/5cafJXT

https://imgur.com/fuwCAhj

 

[Oldtimer]

Blue circle: H block

Drum Brake Junction Block, 66-75 Ford Bronco - TOMS OFFROAD

This direct replacement of the factory drum brake junction block for 66-75 Ford Broncos is made exclusively for TOMS OFFROAD. It mounts to the top of the f

tomsoffroad.com

 

[diveman76]

Blue circle: H block

View attachment 898117

http://[URL]https://tomsoffroad.com/parts/66-75-ford-bronco-drum-brake-junction-h-block

[/URL]

thank you

 

[bronkenn]

I would be careful of the shiny looking ones on EBAY. I would spend a little more and get a Wilwood. I Have seen those cheap ones leak and that sucks for the paint underneath it.

 

[DirtDonk]

Yeah, those original rubber hoses from the master to the H block look pretty sad.
But not as sad as the steering shaft rag joint appears to be!

I would not drive it until that is replaced also.
Might as well do it at the same time because it looks like it would create easier access while the master cylinder is off.

I don’t know anything about the master and booster you linked to either, but I do know that the factory manual master cylinder is not a bad set up.
It’s what I used with the Ford disc brakes on my’71 for many years. Worked great.
The vacuum boosted GM disc brakes (not ours) on my 68 are actually slightly less powerful. The reason is still unknown at this point but I’m looking into it.
Not enough boost? Not too likely.
Too big of a master cylinder bore? Possible.
Maybe the friction material on the pads is not as good? Very possible.
More engine torque coupled to an automatic transmission and low gearing? Hmmm…
All of the above? Well, it is a Bronco after all… so extremely possible!

 

[diveman76]

Yeah, those original rubber hoses from the master to the H block look pretty sad.
But not as sad as the steering shaft rag joint appears to be!

I would not drive it until that is replaced also.
Might as well do it at the same time because it looks like it would create easier access while the master cylinder is off.

I don’t know anything about the master and booster you linked to either, but I do know that the factory manual master cylinder is not a bad set up.
It’s what I used with the Ford disc brakes on my’71 for many years. Worked great.
The vacuum boosted GM disc brakes (not ours) on my 68 are actually slightly less powerful. The reason is still unknown at this point but I’m looking into it.
Not enough boost? Not too likely.
Too big of a master cylinder bore? Possible.
Maybe the friction material on the pads is not as good? Very possible.
More engine torque coupled to an automatic transmission and low gearing? Hmmm…
All of the above? Well, it is a Bronco after all… so extremely possible!

Thanks again for your input! I think I'm just going to go with regular master cylinder like it was set up. That rag joint wasn't on the list but is now. It's still a pretty long list before she's on the road especially being a weekend garage warrior. I did have it running today though. Sounded good. Needs a timing chain cover and I'll go ahead and replace the water pump while I have it out. Harmonic balancer has slipped position so its on the list too. Had to find TDC with a screwdriver in number 1. I'm sure I'll have more questions.

 

[DirtDonk]

Even with a new damper make sure the marks line up correctly. With several combinations for different applications, the wrong one is often in the right box.
Haven’t heard of it being a big problem lately, but for several years it was a real problem.

 

[diveman76]

Even with a new damper make sure the marks line up correctly. With several combinations for different applications, the wrong one is often in the right box.
Haven’t heard of it being a big problem lately, but for several years it was a real problem.

That's interesting...there's no vibration or anything. It's a 351w. I just assumed it slipped. Maybe just wrong balancer?

 

[DirtDonk]

You can verify slippage, because at some point, usually facing the front, there are a pair of notches in each part that line up.
That’s how you tell if it slipped.

And a slipped damper does not necessarily mean vibration.
Not every time, at least.

 

[DirtDonk]

The different locations for the timing marks are often messed up with Broncos, because over the years many engines have been swapped in from other applications.
If the 351 is using its original damper, but the timing cover and pointer and water pump are all from the original bronco 302, that would certainly cause a misalignment.
Same for if the bronco damper was used with the rest of the 351 stuff.
Broncos put their water pump inlet on the passenger side, whereas most other Ford products that there’s on the driver side.
Not all, but most.
This necessitated a change in locations for the timing, pointer and timing marks.

 

[diveman76]

You can verify slippage, because at some point, usually facing the front, there are a pair of notches in each part that line up.
That’s how you tell if it slipped.

And a slipped damper does not necessarily mean vibration.
Not every time, at least.

Cool. I'll go out and check that tonight. I have no idea what the 351w came out of and I'm probably going to have to pull the starter to get block numbers.

 

[diveman76]

You can verify slippage, because at some point, usually facing the front, there are a pair of notches in each part that line up.
That’s how you tell if it slipped.

And a slipped damper does not necessarily mean vibration.
Not every time, at least.

that is the only groove on the damper i could find. i did figure out my block is from a 68-76 torino or fairlane. the code on block starts with C9OE.


sorry bout the crummy picture i took it with my borescope

 

[DirtDonk]

If the alignment notches are there on your particular damper, they’d be in the form of a V notch, or triangle if you will, facing each other on opposite sides of the rubber elastomer. Sometimes just best described as “tick marks” instead of notches.
So they’d be at the dividing line where the rubber is. Not that notch along the edge.
It’s possible that yours doesn’t have them. And I have seen dampers that did not have them.
Maybe it’s just not a universally accepted manufacturing thing.

Regarding the engines original application, Ford did not usually make separate Windsor engines for different vehicles.
So your Torino and Fairlane block could still have come from a pickup truck, or any other vehicle that Ford put 351W engines in during that period. Including Mustangs and 2wd F100/150’s and probably vans as well.

That may not be a universal truth as far as Ford and engines are concerned, but it’s been mostly the case.
The original 302s that came in our Broncos were not “bronco“ engines. They were also designed for the Fairlane family I believe. Or was at falcon? Yes, I think it was the falcon line.
Don’t quote me on any of that though. I didn’t learn it in school, just heard it on the internet.

 

[diveman76]

If the alignment notches are there on your particular damper, they’d be in the form of a V notch, or triangle if you will, facing each other on opposite sides of the rubber elastomer. Sometimes just best described as “tick marks” instead of notches.
So they’d be at the dividing line where the rubber is. Not that notch along the edge.
It’s possible that yours doesn’t have them. And I have seen dampers that did not have them.
Maybe it’s just not a universally accepted manufacturing thing.

Regarding the engines original application, Ford did not usually make separate Windsor engines for different vehicles.
So your Torino and Fairlane block could still have come from a pickup truck, or any other vehicle that Ford put 351W engines in during that period. Including Mustangs and 2wd F100/150’s and probably vans as well.

That may not be a universal truth as far as Ford and engines are concerned, but it’s been mostly the case.
The original 302s that came in our Broncos were not “bronco“ engines. They were also designed for the Fairlane family I believe. Or was at falcon? Yes, I think it was the falcon line.
Don’t quote me on any of that though. I didn’t learn it in school, just heard it on the internet.

I'll look again but im pretty sure mine is without tick marks. Story of my life. You're probably right on the engine. I got the decode info from here...
http://www.mustangtek.com/FordDecode.html

 

[DirtDonk]

As crusty as your damper looks, it doesn't really look to have slipped to me. The elastomer ring is actually pretty intact looking.
I know that looking at a segment in a pic on the computer is no guarantee, but that's what it looks like from here.

You would do yourself a big favor with any damper, new or old, to clean it up, find actual TDC in the engine (sometimes as simple as looking for the keyway under the bolt if the damper is being serviced anyway), making sure that the pointer you're using lines up with some marks. And if it doesn't, then make your own marks very clearly so that you can easily see them with a timing light at any point in the engine's future.

To this end, Timing Tape is your best friend!
Clean the outer ring, maybe even paint it (but it's not necessary) and then apply the correct timing tape to the perimeter of the outer ring. You'll never want for timing marks in the proper place again!

Paul

 

[diveman76]

As crusty as your damper looks, it doesn't really look to have slipped to me. The elastomer ring is actually pretty intact looking.
I know that looking at a segment in a pic on the computer is no guarantee, but that's what it looks like from here.

You would do yourself a big favor with any damper, new or old, to clean it up, find actual TDC in the engine (sometimes as simple as looking for the keyway under the bolt if the damper is being serviced anyway), making sure that the pointer you're using lines up with some marks. And if it doesn't, then make your own marks very clearly so that you can easily see them with a timing light at any point in the engine's future.

To this end, Timing Tape is your best friend!
Clean the outer ring, maybe even paint it (but it's not necessary) and then apply the correct timing tape to the perimeter of the outer ring. You'll never want for timing marks in the proper place again!

Paul

I have to pull it anyway to change the timing cover or at the very least gasket. So I'll get a good look at when I do that. Timing tape for sure if I don't change the damper.

 

[DirtDonk]

Sounds like a plan. Heck, timing tape is good even with brand new markings on factory replacements. The markings are never all that good like they are on aftermarket performance dampers. But if the new ones are good enough, you won't need the tape.
If they are even borderline, or perhaps even mis-aligned like we were talking about earlier, the timing tape will save the day.
Just make sure you get one for the diameter of your damper. You can fudge it a little bit, but don't put a 6" tape on a 7" damper in other words.

Life becomes a beautiful thing when you pull out the timing light and for once can see all the marks clear as day next to the pointer!

Paul

 

[rocknhorse76]

View attachment 898325
that is the only groove on the damper i could find. i did figure out my block is from a 68-76 torino or fairlane. the code on block starts with C9OE.

View attachment 898326
sorry bout the crummy picture i took it with my borescope

That’s a ‘69 block.

 

[diveman76]

Even with a new damper make sure the marks line up correctly. With several combinations for different applications, the wrong one is often in the right box.
Haven’t heard of it being a big problem lately, but for several years it was a real problem.

What was the problem in the past? I think I have it. I don't think this damper has slipped. But TDC should be at 2 o'clock and on this if that Notch is TDC its at like 5. Someone punched it at TDC.

 

[DirtDonk]

I’ve never seen one of those big notches act as a timing mark. The keyway inside the crank that’s visible in your first picture would indicate TDC of the crank.
At that point your timing marks stamped into the outer ring should be where your timing pointer is.
That’s the variation on different Ford engines. Where the timing pointer was, and how the marks are oriented on the damper ring.