Looking to change drums to disc from 71 CBody to 68 - anything to know?

EurekaSevven

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So, while looking on eBay, I actually found a 1971 Chrysler 300 parts car, only around 2 hours away from here. The engine had been gutted, but it had the Disc Brakes, and the booster/master cylinder still inside. I was wanting to go up there and take the parts and fit it onto my 1968 Newport, which only has 4 wheel drums.

As far as I know it should be a bolt-on operation since I believe all the C-Body rotors are interchangeable, but is there anything I should know with swapping it? And in the case I need to rebuild the calipers, how easy are the parts to come by?
 

thrashingcows

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Years ago you could not get the rotors for the 69-72 brake system, but they now make new rotors in all the grades you desire...economy to high performance, so go get the parts and swap away. ;)
 

ayilar

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Years ago you could not get the rotors for the 69-72 brake system, but they now make new rotors in all the grades you desire...economy to high performance, so go get the parts and swap away. ;)
Any pointers to preferred choices? My 1970 300 needs new rotors.
 

69 300 vert

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I checked it out here and found he's correct:

1969 CHRYSLER 300 7.2L 440cid V8 Rotor | RockAuto

rotors at rock auto.JPG
 

69 300 vert

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So, while looking on eBay, I actually found a 1971 Chrysler 300 parts car, only around 2 hours away from here. The engine had been gutted, but it had the Disc Brakes, and the booster/master cylinder still inside. I was wanting to go up there and take the parts and fit it onto my 1968 Newport, which only has 4 wheel drums.

As far as I know it should be a bolt-on operation since I believe all the C-Body rotors are interchangeable, but is there anything I should know with swapping it? And in the case I need to rebuild the calipers, how easy are the parts to come by?

Might as well snag the cruise control, cables and steering column while you're there.
 

EurekaSevven

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Might as well snag the cruise control, cables and steering column while you're there.

Heh, I take it you've seen the listing as well?
Yeah, the cruise control tempted me heavily: I might get some extra cash besides what I put down for the discs for that as well, looks like it's in good condition. I don't know how different the system is from the 68 model year, I remember hearing the 68 cruise control was a one year design and not very good.
 

Davea Lux

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On any drum to disc conversion, be sure to install a proportioning valve to re-balance the brake system. The factory used a metering valve located at the driver side front frame rail just above the cross member for that purpose. If the one on the parts car is intact, that would be another option if you wish to retain a stock appearance. You will also want to have the Bendix dual diaphragm booster rebuilt. If your vehicle had manual brakes, you will also need the booster mounting plate and the brake pedal as the manual brake pedal and mount are different.

Dave
 

69 300 vert

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Heh, I take it you've seen the listing as well?
Yeah, the cruise control tempted me heavily: I might get some extra cash besides what I put down for the discs for that as well, looks like it's in good condition. I don't know how different the system is from the 68 model year, I remember hearing the 68 cruise control was a one year design and not very good.

I checked it out after you mentioned it. I doubt the servo actually works, mebbe it can be repaired? I have no idea.

The '71 cruise will fit and work. The '68 servo is specific to 1968, TS switch and brake switch are specific to 1968 and 1969. The '69 servo is specific to 1969. After that they're pretty much alike.
 

69 300 vert

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On any drum to disc conversion, be sure to install a proportioning valve to re-balance the brake system. The factory used a metering valve located at the driver side front frame rail just above the cross member for that purpose. If the one on the parts car is intact, that would be another option if you wish to retain a stock appearance. You will also want to have the Bendix dual diaphragm booster rebuilt. If your vehicle had manual brakes, you will also need the booster mounting plate and the brake pedal as the manual brake pedal and mount are different.

Dave

Dave, isn't there some problem with the later disk booster and column shift on the older cars? I seem to recall something about that.
 

Davea Lux

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Dave, isn't there some problem with the later disk booster and column shift on the older cars? I seem to recall something about that.

The potential problem lies in which booster is on the '71 parts car. Some of the '71's had the Bendix dual diaphragm booster and some had a larger diameter single diaphragm booster. The larger diameter booster usually won't fit onto a '68 application for the reasons noted. OP will have to determine by inspection which booster the parts car has.

Dave
 

EurekaSevven

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the eBay listing has a picture of it, kind of obscured by the leaves and such but it might be obvious what type it is from the picture:
s-l1600.jpg
 

Davea Lux

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the eBay listing has a picture of it, kind of obscured by the leaves and such but it might be obvious what type it is from the picture:
View attachment 466822

That is the single diaphragm booster, it won't fit your '68, so you will need to try and find a dual diaphragm booster '68-'70 (some '71's had this booster and some '72's with either the police option or heavy tow option).

Dave
 

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Just to be clear, you need the entire steering knuckle/spindle to do the swap.

Rebuilt calipers were readily available and cheap up until just recently. Now no one seems to stock them anymore. Not sure if that's a COVID 19 thing or not. If demand is high enough for multiple companies to be making rotors, you'd think demand for calipers would be strong too. Rock Auto does have rebuild kits in stock. The problem is that if the caliper bores are ugly, the kit won't do you much good. Snapped off bleeders are also a big concern.

The booster is going to be the fly in the ointment with your swap. There's at least two booster options, maybe three. Two are hard to find, and one of those is fairly expensive.

Jeff
 
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