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Veteran
Posts: 131
| My 1960 Matador currently has manual brakes, and a single pot MC. I want to convert to a dual MC with power brakes and am looking for options. A buddy turned me on to these guys, and I wanted to know if anyone has any experience with them? Am I right in thinking this could be used with my current brake pedal assy, if they have something that will work with my model/year? It seems pretty pricey, once I add in the line kit, & such. How inexpensively could I add reliable power brakes to my car via other options?
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Expert 5K+
Posts: 6500
Location: Newark, Texas (Fort Worth) | I am going to get a power brake booster for a cuda with a hemi. It raises the master cylinder up out of the way. On ebay for $224 with adjustable push rod.
http://www.ebay.com/itm/Mopar-8-Dual-Diaphram-POWER-Brake-Booster-M... |
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Expert
Posts: 3778
Location: NorCal |
Any power assembly can be made to fit in the original MC location, easier if it closely matches the original MC bolt pattern....personally, I'd stick with a vacuum booster.
One problem you may have is the pedal ratio, the manual brake pedal ratio is a lot higher (6-1 to 8-1) than the usual PB ratio (4-1) so you could have "touchy" brakes with the higher ratio. A smaller booster with a large-bore MC like the popular 7" hot rod units might work better.
http://www.ebay.com/itm/7-ZINC-STREET-ROD-RAT-ROD-POWER-BRAKE-BOOST... |
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Veteran
Posts: 131
| I hate to ask what may be a silly question, but can someone explain to me the calculation for the pedal ratio? I really don't understand what that's about... |
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Expert 5K+
Posts: 7402
Location: northern germany | oldhippie - 2015-08-19 6:18 PM
I hate to ask what may be a silly question, but can someone explain to me the calculation for the pedal ratio? I really don't understand what that's about...
simply put, you got more leverage with the manual pedal. less effort but longer pedal (m/c piston) travel. |
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Veteran
Posts: 131
| So, is it a difference in the pivot-point distance? (distance from the pedal anchor point to the m/c piston attachment point?) sorry again, but I've never seen these assemblies before and I'm finding it difficult locating these images online...
Edited by oldhippie 2015-08-19 6:57 PM
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Expert 5K+
Posts: 8947
Location: WHEELING,WV.>>>HOME OF WWVA | i've never really pondered the pedal lengths , never really had to but here's a question maybe someone can answer . if the pedal ratios are different between power and non-power
brakes , why do they have interchangeable bolt on pedal pad receivers -------------------------------------------later |
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Expert
Posts: 1740
Location: Alaska | 57-61 Mopar manual and power pedal assys. are different but some manufacturers just have 2 holes in the brake pedal arm, one for power and one for manual. |
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Veteran
Posts: 131
| That's what I was beginning to wonder - why not just change the mounting location for the piston linkage? I mean, as long as each end pivots, it seems like an effective method. Obviously it would require some calculations because it wouldn't be the same straight-line action, but...
Also, I found this picture, which helped me understand a bit better.
Edited by oldhippie 2015-08-20 10:49 AM
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Veteran
Posts: 131
| Also found this interesting...
=====Pedal ratio/bore size vs. pressure output===== '''Pedal Ratio''' | '''Bore Size''' | '''Pounds Input''' | '''Approx. PSI Out''' | 6:1 | 1-1/8 | 75 | 450 | 6:1 | 1 | 75 | 575 | 6:1 | 7/8 | 75 | 750 | | 5:1 | 1-1/8 | 75 | 375 | 5:1 | 1 | 75 | 475 | 5:1 | 7/8 | 75 | 625 | | 4:1 | 1-1/8 | 75 | 300 | 4:1 | 1 | 75 | 380 | 4:1 | 7/8 | 75 | 500 |
Edited by oldhippie 2015-08-20 10:53 AM
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Veteran
Posts: 131
| Now that I see these numbers, I'm wondering... if I have a 6:1 manual pedal ratio, and change out the M/C to 1 1/8 bore size, wouldn't that reduce pressure enough to prevent the brakes from being "touchy"? On the other hand, were I to have a bore size of 7/8, is it possible that there would be enough pedal pressure that I wouldn't need a power assist unit at all? I would guess the only issue with a small diameter bore would be whether there was enough fluid to build pressure in all four caliper pistons!? |
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Expert 5K+
Posts: 8443
Location: Perth Australia | Yep
Smaller bore will require a longer piston travel to move the appropriate amount of fluid, which = a long pedal
This where the trade off happens, the small bore will give you really good brakes, but a really crappy pedal, so if you increase the m/c bore size, you decrease pedal travel, but increase the amount of force (from your foot) needed to operate the brakes
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Veteran
Posts: 131
| Been searching/reading the site for the last couple days on this topic - nobody mentions specifics, so I'm wondering if anyone could confirm if either of these might work, and if not, what might?
http://www.classicindustries.com/product/1972/mopar/parts/mn5008.ht...
http://www.classicindustries.com/product/1972/mopar/parts/mm3066.ht...
edit to add: now that I think about it, the rear axle I picked up has no brake components at all, so I'm buying everything new. Would it make sense for me to just get the rear disc conversion kit as well? If I wanted to do it in the future, I'd have to change out the master cylinder, right?
Just trying to weight the pros/cons of doing it each way. Thanks for any input!
Edited by oldhippie 2017-04-17 11:10 AM
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Expert
Posts: 3778
Location: NorCal |
The 2nd example is like the one Marc mentioned in the first reply, it uses the bracket that raises the booster and has a pivot that reduces the pedal ratio for use with the manual brake pedal/lever.
Your example uses the popular 4-wheel Corvette disc brake MC while Marc's uses the Mopar front disc MC. |
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Veteran
Posts: 131
| thanks, think I'll probably be going with that 2nd example then.
Also, I found this interesting, but I wasn't sure where to post it - not sure it deserves its own thread, but some may find it useful...
https://www.youtube.com/watch?v=oi4BnNA3Ep4#t=2066.749825 |
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Veteran
Posts: 131
| Think I misunderstood earlier, but now I see the M/C differences. If I go with the MM3066 from Classic Ind, I'd have an equal-capacity M/C that would work if I eventually converted the rear to disc as well (prop. valve only needed), but if I want to use it for disc/drum setup, I'd need both a proportioning valve and a residual valve for the drums, correct? (neither of which come with that kit.)
The ebay one should have a residual valve in the M/C, right? Also, it comes with a prop valve. The only issue would be with the M/C, if I wanted to convert to rear disc later, I think?
(old one sold out, is this the same?) http://www.ebay.com/itm/Mopar-8-Dual-Diaphram-POWER-Brake-Booster-M... |
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Veteran
Posts: 131
| Hrm. Now I'm just confusing myself. 1st link shows a setup for disc/drum (that looks surprisingly identical to the 2nd link below):
http://www.ebay.com/itm/Mopar-8-Dual-Diaphram-POWER-Brake-Booster-M...
2nd link shows a setup for disc/disc, but shows an unequal chamber M/C, which doesn't seem like it would have enough volume for the rear calipers (2 1/8" dia pistons):
http://www.ebay.com/itm/Mopar-8-Dual-Diaphram-POWER-Brake-Booster-M...
Both of these appear to have the 4-bolt M/C. This 3rd link shows a 1 1/8" bore, 2-bolt M/C that seems to be for teh same application, just from a different reseller.
http://www.ebay.com/itm/Mopar-8-Dual-Power-Brake-booster-1-1-8-bore...
When I talked to the reseller @ the 1st two links, they told me the M/C bore for theirs was 1", and that it would be enough volume for rear calipers!? Sorry if I'm being a P.I.A., but can anyone offer some advice? I've decided to go ahead and convert to 4-whl disc, which is why I'm re-visiting this topic.
Edited by oldhippie 2017-05-25 6:06 PM
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