Author Topic: !968 DeVille front disc brake conversion  (Read 248 times)

Offline CarsandDrums68

  • Posts: 27
  • Name: Alex White
!968 DeVille front disc brake conversion
« on: January 12, 2018, 01:25:57 AM »
I got all 4 drums on my '68 deville, was thinking about converting the fronts to disc. I wanna know if there is a noticeable difference in braking with discs as opposed to the drums in the front, is the conversion worth it?? Also i know i would have to change the master cylinder but i read that there would also need to be a proportion valve put in as well, is this true?

Thanks,
Al

Offline TJ Hopland

  • Posts: 6872
Re: !968 DeVille front disc brake conversion
« Reply #1 on: January 12, 2018, 10:00:05 AM »
I think a lot of the question is when and where do you drive?     If you are in a smaller city or more rural area you may not notice a big difference.  If you are in a bigger city and drive on the modern roads with modern traffic you will likely notice the difference. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline Dave Shepherd

  • Posts: 1952
Re: !968 DeVille front disc brake conversion
« Reply #2 on: January 12, 2018, 03:38:21 PM »
Yes you will need a proper proportioning valve.  Discs were an option in 68, std in 69.  Big advantage is no brake fade, no bothersome pulling, adjustments and still brake well when wet.

Offline bcroe

  • Posts: 2092
    • CLC Member
      CLC Member #14630
!968 DeVille front disc brake conversion
« Reply #3 on: January 12, 2018, 08:02:10 PM »
I never drove a full size car with adequate drum brakes, and they could
be REALLY dangerous in the wet.  Front discs fixed all that.  I would
move on to a 70s system conversion, those optional setups in the 60s
have early development problems.  Bruce Roe

Offline DeVille68

  • Posts: 458
    • CLC Member
      CLC Member #30616
  • Name: Nicolas Hubacher
Re: !968 DeVille front disc brake conversion
« Reply #4 on: January 13, 2018, 02:19:24 AM »
Properly maintained drum brakes work perfectly. I live in the alps and drive quite a lot over mountains with my 68 DeVille. Braking is no problem. You may get just a little bit of fading, but use your engine brake anyways. Drum brake do not pull (at best just a bit) if adjusted correctly.

If you want to use the car as a "race" car, you might want to switch to disc brake.

Advantage of disc brake: linear braking from all velocities and less fading. Because of linear braking it is easier for most people to prevent lock up.

Disadvantage of disc brake: lot of effort and money involved. Since brake surface is smaller you need a larger force acting on the pads. Hence you need a different brake booster. Since you keep the rear drum brakes, you need to maintain to proper brake force, hence the proportioning valve.

You don't get the self increasing braking from the drum brakes. So a similar disc brake has less braking power than drum, but is better controllable because of linear brake force increase.


I would not switch to disc brake. Rebuild your drum brakes using the shop manual. Buy new shoes and adjust the brakes according to the manual. Be careful, because some of the springs are not available. You want to reuse your original one or get some from a junk yard (maybe usa parts supply?)
I did this and it took some hours. It also takes time to get the adjustment right. If done correctly you will have awesome braking power.


You can check out my restoration blog on how to rebuild the drum brakes: http://forums.cadillaclasalleclub.org/index.php?topic=130360.msg275698#msg275698

Best regards,
Nicolas
1968 Cadillac DeVille Convertible (silver pine green)

Offline TJ Hopland

  • Posts: 6872
Re: !968 DeVille front disc brake conversion
« Reply #5 on: January 13, 2018, 10:49:18 AM »
Cost tends to be pretty minor these days unless you are trying to go with original parts that can be very hard to find which I suspect may be an issue in this case.  Just about anything that used the 4 piston calipers that everyone was using in the mid 60's seems to be getting tricky to support today.  Oddly its not the calipers that are the problem, its everything else. 

The big thing that can be a huge pain when it comes to a conversion is wheels and hubcaps.   May or may not be an issue here since its so close to standard disc time.   For a lot of people its not a problem because the trend is to larger aftermarket wheels anyway but people like 'us' seem to like to keep the original look.   Drum wheels tended to have an extra step in them which usually gets in the way of calipers and was often the area the hubcaps gripped on so finding a later wheel only solves one problem.   I'm surprised there isn't more people making wheels like I have seen for a Corvette where its like a 17" wheel that used common modern tires but is still machined for the original hubcap and then the 'extra' is painted white to look like the whitewall.   Except for loosing some sidewall height (comfort) it seems like a  a good way to go.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline cadillacmike68

  • Posts: 1310
  • Still finishing up this 1968
    • CLC Member
      CLC Member #15823
  • Name: M Santos
Re: !968 DeVille front disc brake conversion
« Reply #6 on: January 14, 2018, 01:33:31 AM »
Differing with Nicolas, I would recommend the conversion, but only if done with the right parts.

As stated you need a proportioning valve. Adjustable ones are available.

You Might need a different booster and master cylinder. These are available from rockauto, etc.

Now to the real parts. You need:
A: If you have your original steering knuckle and arm with the camber eccentric you would need the disk brake backing plate from a 1969 (or a 68 with disc brakes). You Should have the original knuckles, but that disc backing plate is going to be hard to fine. (I have 2 here).

B: Two rotors, bearings, rear seals for a 1968-71 Cadillac. These are HARD TO FIND. I have one NOS rotor available.

C: Calipers. The GM Single Piston Sliding Caliper was very durable and reliable and you can get them for Cadillac to around 74, 75 or 76. The catalogs will state different parts, but the difference is the piston size with the later ones having a larger (75mm vs 70mm) piston. After a certain year the inlet line and bleeder were moved and changed to metric. Check rockauto and get a 1972 pair if you can't find 1968-71.

D: Pads. Here's the best news. These fill size RWD Cadillacs (and B bodies) took the SAME pad from 1968 up to the last 1996 Fleetwood. And you can get them in ceramic. Yes, my 1968 and 1996 take the same disc pads.

Alternatives are 1970-71 steering knuckle with arm and bracket integrated in one piece. For this you will need 1970 camber eccentrics and 1970 lower ball joints and 1970 outer tie rod ends, because Cadillac changed the angle of the dangle of the cone shaped places where these things fit.

Another is 1972-76 disc rotors and rear seals You have to mill away a small amount of the steering knuckle shield around where the rotor's rear seal fits, but this works just fine.



Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

Offline DeVille68

  • Posts: 458
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      CLC Member #30616
  • Name: Nicolas Hubacher
Re: !968 DeVille front disc brake conversion
« Reply #7 on: January 14, 2018, 02:25:24 AM »
Mike, you were describing the parts for a original type conversion, as if the car came with the optional disc brakes. If originality is not important, one could buy a new disc brake setup.

I know that CPP makes disc brake conversion kits:
Disc brake retaining the stock spindles and probably wheels to: http://www.classicperform.com/Store/Brakes/5055WBK-S.htm

Larger disc brake retaining stock spindles but requires 17'' wheel: http://www.classicperform.com/Store2/Brakes/6162CBK-13.htm

They don't state it clearly but you need a different brake booster too. In one of the kits, its included. I don't see the proportioning valve, maybe this is built into the disc brake ready booster?


Has someone done the CPP-conversion? Experience?
1968 Cadillac DeVille Convertible (silver pine green)

Offline signart

  • Posts: 195
Re: !968 DeVille front disc brake conversion
« Reply #8 on: January 14, 2018, 09:54:06 AM »
If you look closely at your link of the ccp booster m/c, lines are plumbed to the proportion valve below the m/c. Most applications for aftermarket kits the proportion valve is provided to the side of the m/c.
Art D. Woody

Offline CarsandDrums68

  • Posts: 27
  • Name: Alex White
Re: !968 DeVille front disc brake conversion
« Reply #9 on: January 14, 2018, 01:34:32 PM »
I think im gonna think about it for a couple of weeks and do some more research, im only considering because ive had failures with the drums and its getting to where i dont really feel comfortably safe driving it, i dont mind splurging on brakes to keep me and anyone in or around the car safe.

Offline cadillacmike68

  • Posts: 1310
  • Still finishing up this 1968
    • CLC Member
      CLC Member #15823
  • Name: M Santos
Re: !968 DeVille front disc brake conversion
« Reply #10 on: January 14, 2018, 03:54:43 PM »
Mike, you were describing the parts for a original type conversion, as if the car came with the optional disc brakes. If originality is not important, one could buy a new disc brake setup.

I know that CPP makes disc brake conversion kits:
Disc brake retaining the stock spindles and probably wheels to: http://www.classicperform.com/Store/Brakes/5055WBK-S.htm

Larger disc brake retaining stock spindles but requires 17'' wheel: http://www.classicperform.com/Store2/Brakes/6162CBK-13.htm

They don't state it clearly but you need a different brake booster too. In one of the kits, its included. I don't see the proportioning valve, maybe this is built into the disc brake ready booster?


Has someone done the CPP-conversion? Experience?


The problem with some or most, possibly all of those conversion kits are undersize rotors & calipers and not knowing what to look for when either the pads, rotors or calipers wear out.

I have the 1970 hybrid setup in my car: the one piece 1970 steering knuckle (with the right size camber eccentrics for the upper -1968-69- ball joint), 1970 lower ball joint and outer tie rod end, 1972 rotors. The rest is 1968. I can put on 1968-71 rotors any time, bur they are 2-3 times as expensive ad the 1972-76 ones.

Front drums are a real PITA to service, and fade way too fast.
Regards,
"Cadillac" Mike
Current:
1968 DeVille Convertible
1996 Fleetwood Brougham
2009 STS NorthStar Platinum ed RWD
2011 CTS PRemiun ed Sedan RWD
Past:
2008 CTS Premium ed Sedan AWD
2005 CTS Hi-Feature Sedan RWD
2000 ElDorado ESC Hard Boot Convertible
1995 Fleetwood Brougham
1973 Sedan DeVille
1970 Fleetwood Brougham
1969 DeVille Convertible

 

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