Another disc brake conversion question, real 340 swinger

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4mulas

4mulas

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hello all,
I have a real P code 340/4spd 69 swinger and want to convert to 73 and up a body disc brakes. It is an Original drum brake car now.

Question: for the purist's out there, does this harm the value of the car? Or does safety over ride this and most future buyers would appreciate this or want this anyway? I could keep all the old parts to include in a sale if that would help.

Also, because It would now be big bolt pattern on the fron now, I would want to change the rear to large bolt pattern too.

Question: what is the best way to do this? Can I have the axle flange re-drilled to 5 on 4.5" or do I have to/should I buy new axles. It is the stock 8 3/4" diff in there now. If changing axles is required where is the best deal on parts for the job?

Thanks A lot in advance for your replies!!
 
I would just keep all the Original stuff in totes. Having gone both ways, I'd get a set of Kelsey-Hays small BP disc set up. Done right they are really sweet. Add some Hawk racing pads and you'll be good to go. That way you do not have to touch the rear end. No new wheels to buy.

I went this route with the 66 and 68 Formula S.

If you want to go BBP I'd get aftermarket axles. Or get a long, 28" minimum of splinable axle, set of OEM axles from a station wagon or pick up truck and have them shortened. Then you need the corresponding brake backing plates and drums with hardware. I tried the redrilling everything for 4.50 BC and did not like the way it looked. Plus, I like the register circle for the rim to be correct so they were never put on the car.

For either you will need to get the right master cylinder and proportioning valve. At this point, I'd get stainless steel brake lines and fill it with DOT 5 brake fluid.
 
I went the way of Kelsey 4p disc brakes on my 66 formula S too (you can see that car if you search my previous posts, in the for sale section, it was awesome) but was never really all that happy with them. I did a 69 disc brake master and put a. Wilwood proportioning valve on it and retained the original distribution block/proportioning valve too. They seemed to drag a bit and always had a pull to the right. (Not tire pull either as I rotated the, around to eliminate that.

Where I am from the Kelsey stuff will be a lot harder to find in complete useable condition too. I figure that all the box stores will have 73 and up parts available too in case I travel and need emergency parts in a hurry.

Part of the reason I want to do large pattern is because of wheels and wheel selection. I actually want to run painted 15x7 steelies with dog dish, but I also have a set of champ 500's kicking around too which I'd like to try.

It has 14" sbp aluminum slots on it right now which I'm not all that fond of.

I like your idea of all new brake lines and dot 5 too.

Any idea as to what and how much aftermarket axles cost?




66fs said:
I would just keep all the Original stuff in totes. Having gone both ways, I'd get a set of Kelsey-Hays small BP disc set up. Done right they are really sweet. Add some Hawk racing pads and you'll be good to go. That way you do not have to touch the rear end. No new wheels to buy.

I went this route with the 66 and 68 Formula S.

If you want to go BBP I'd get aftermarket axles. Or get a long, 28" minimum of splinable axle, set of OEM axles from a station wagon or pick up truck and have them shortened. Then you need the corresponding brake backing plates and drums with hardware. I tried the redrilling everything for 4.50 BC and did not like the way it looked. Plus, I like the register circle for the rim to be correct so they were never put on the car.

For either you will need to get the right master cylinder and proportioning valve. At this point, I'd get stainless steel brake lines and fill it with DOT 5 brake fluid.
Click to expand...

image.jpeg
 
New axles is the way to go. If you re-drill the stock axles you have to use the original brakes too, with re-drilled drums, because the axle flange offset is different between SBP and BBP axles. So you can't use BBP brakes on re-drilled SBP axles.

New axles are $300 from Dr. Diff. Mopar Axle Package 5 X 4 1/2" (5 X 4.5) Bolt Pattern 30/35 Spline

Of course, you also need a set of 10x2.5" rear brakes if you upgrade to BBP axles, for the aforementioned reason. They're still pretty easy to find in the local yards though if you don't want to spring for all new brakes (which Dr. Diff also sells). Or you could buy a set up like this 10 2.5 PLATES LOADED MOPAR DODGE PLYMOUTH 8 3/4 DRUM BRAKES 8.75 dart duster

I've done business with mothermoparspokaneparts on eBay before, they're a great seller and their prices are pretty much the best you're going to find outside of pulling them yourself at the yard.
 
Good info and excellent point about re-drilling....
New axles it will be. I'm going to head to the junkyard right now and poke around for a while. I fear everything will be a little too new in our main yard.
 
Diplomat's and 5th Ave's carried the 10x2.5" brakes all the way up to 1989.
 
easiest would be early kelsey 4 piston set-up as mentioned
they are awesome brakes,parts are readily available and keeps originality
no messin' with odd front / rear wheels or rear axle expense and work
 
ir3333 said:
easiest would be early kelsey 4 piston set-up as mentioned
they are awesome brakes,parts are readily available and keeps originality
no messin' with odd front / rear wheels or rear axle expense and work
Click to expand...

Another vote for staying with SBP and the Kelsey Hayes setup. I had a factory 1969 P 340 Swinger in R4, and it had the factory SBP discs --- worked GREAT, as long as you drive the car regularly so that the caliper piston bores don't get rusted from sitting. RockAuto has a full supply of everything you need for the SBP Kelsey setup for good prices ---- also, keep in mind, there are sources that exchange the Kelsey Hayes calipers for identical units with stainless steel piston bore insert setups.
Hemix71 has posted the Stainless steel Kelsey Hayes caliper source several times, and the cost is not that much more than the standard non-stainless setup.

Looking at your car --- it looks fantastic --- keep it SBP and you can get 15" steelies made up with more backspacing / offset to mount larger tires.

When you add up all the $$$ to convert to BBP --- it ends up costing significant $$$- Stay SBP.
 
Well now you've got me thinking again. I'm in Alberta Canada and parts are a lot harder to get than in USA. I'm going to do some digging and searching around to see just what I can get as far as parts go and then make a decision. Is there a good source for pre 73 A body rear drums in the states? As memory serves those are also hard to find here.

Last time I converted my 66 formula S, brake hoses were also hard to find.

And because of winters here the car does sit idle for about 4-5 months a year... Regardless of bbp or stp it needs disc brakes. Had to apply them hard last night and the drums scared the hell out of me. LOL

As for the car, mine was originally R4 red, body and roof, with factory stripe delete. Only three options - A01, G33, R11. And D21 four speed but I think that was standard? I think who ever ordeed it was looking to go fast in a straight line! Lol.
 
4mulas said:
I went the way of Kelsey 4p disc brakes on my 66 formula S too (you can see that car if you search my previous posts, in the for sale section, it was awesome) but was never really all that happy with them. I did a 69 disc brake master and put a. Wilwood proportioning valve on it and retained the original distribution block/proportioning valve too. They seemed to drag a bit and always had a pull to the right. (Not tire pull either as I rotated the, around to eliminate that...
Click to expand...

They do not do that if they are done right. I run a manual master cylinder, MC. My 2 Formula S cars sit for years sometime. I had them rebuilt with stainless steel pistons and they are about 30 years old on the brake rebuild. Still work great. I buy new MC, wheel cylinders and Stainless steel brake lines. Then I fill and bleed with DOT 5 brake fluid. I do not build for failure, so I do not understand the use cheap or more available parts. Brake shoes are the same as early Mustangs and Corvettes.
 
UPDATE...

So I think I've made up my mind and am going to convert to the later '73 and up disc brakes and get new axles too.

I've already rounded up the larger backing plates off a Diplomat thanks to 72bluNblu and his advice. Found a set in good shape with new hold down hardware, spreader and e-brake mechanism for $30 bucks.

The other good news is that I have sourced the spindles and upper control arms for next to nothing from a 73 donor 4 door valiant.

QUESTION - will there be a problem with interference fit and using the later front mount caliper discs from the 73 and my factory sway bar on my '69??

I notice Doctor diff differentiates between pre 72 with or without factory sway bar when ordering his basic disc upgrade kit?

Any help is really appreciated!!!
 
The Sway bar goes with the K-member. For a 72 down-K you use the 72downd bar. For the 73up-K you use the 73 up bar. They both anchor near to the same place on the LCAs.
With or without is talking about the welded swaybar tabs.

OOps that was not your question.Sorry.

AS to a front mounted caliper, I don't think it's an issue with the older set up. I think the 73 up bars have a kink in them to help them stay off the tire, but I'm having a hard time seeing the bar and caliper arguing about real-estate. I can't say for sure tho.....
 
Last edited:
Thank you and, Well, we are getting closer. I was looking at the 73 today and yes the mount or the bar or both do look slightly different, although I was going only by memory of what the the 69 looked like though..

Does anyone know for sure if there is clearance issues when using 73 and up disc brakes on a 72 and older sway bar car? (I.e.: my 69 swinger with factory sway bar)

?????
 
4mulas said:
Thank you and, Well, we are getting closer. I was looking at the 73 today and yes the mount or the bar or both do look slightly different, although I was going only by memory of what the the 69 looked like though..

Does anyone know for sure if there is clearance issues when using 73 and up disc brakes on a 72 and older sway bar car? (I.e.: my 69 swinger with factory sway bar)

?????
Click to expand...

You are going to have to mount the calipers facing the Rear when sway bar equipped.
Easy to do, just by swapping the spindles, side to side, and with the caliper having the bleeder screw (caliper) facing upward.
 
hemi71x said:
You are going to have to mount the calipers facing the Rear when sway bar equipped.
Easy to do, just by swapping the spindles, side to side, and with the caliper having the bleeder screw (caliper) facing upward.
Click to expand...

This is exactly the kind of information I was looking for!! I was wondering the same thing myself. Wonder why if you order Doctor diff's kit he charges $25 bucks extra on a drop down menu when mounting the calipers on the rear???

I'm happy with your info for sure! I imagine the splash shields have to stay with the associated spindle too? Or are they not handed?
 
4mulas said:
This is exactly the kind of information I was looking for!! I was wondering the same thing myself. Wonder why if you order Doctor diff's kit he charges $25 bucks extra on a drop down menu when mounting the calipers on the rear???

I'm happy with your info for sure! I imagine the splash shields have to stay with the associated spindle too? Or are they not handed?
Click to expand...
4mulas said:
This is exactly the kind of information I was looking for!! I was wondering the same thing myself. Wonder why if you order Doctor diff's kit he charges $25 bucks extra on a drop down menu when mounting the calipers on the rear???

I'm happy with your info for sure! I imagine the splash shields have to stay with the associated spindle too? Or are they not handed?
Click to expand...


Yes, on 73-76 A body disc brakes, the gravel shields are Right and Left, so they stay with the appropriate spindle.

When mounting towards the rear, different rubber brake hoses are required.
People that have done that swap, use hoses off the Aspen, and Volare, line of cars.
Probably why Diff charges a few extra bucks, for his product.
 
hemi71x said:
Yes, on 73-76 A body disc brakes, the gravel shields are Right and Left, so they stay with the appropriate spindle.

When mounting towards the rear, different rubber brake hoses are required.
People that have done that swap, use hoses off the Aspen, and Volare, line of cars.
Probably why Diff charges a few extra bucks, for his product.
Click to expand...
Again, thanks!!! I'm set now. Will go to the local parts supplier and compare the length of aspen vs valiant hoses. This site is awesome!
 
4mulas said:
UPDATE...

So I think I've made up my mind and am going to convert to the later '73 and up disc brakes and get new axles too.

I've already rounded up the larger backing plates off a Diplomat thanks to 72bluNblu and his advice. Found a set in good shape with new hold down hardware, spreader and e-brake mechanism for $30 bucks.

The other good news is that I have sourced the spindles and upper control arms for next to nothing from a 73 donor 4 door valiant.

QUESTION - will there be a problem with interference fit and using the later front mount caliper discs from the 73 and my factory sway bar on my '69??

I notice Doctor diff differentiates between pre 72 with or without factory sway bar when ordering his basic disc upgrade kit?

Any help is really appreciated!!!
Click to expand...

That's the way to do it! You should be set, after you swap axles. Enjoy!
 
You are fortunate axles are now readily available.
I had to wait a long time to have mine shortened 25 years ago!
Maybe 18 months, but Strange engineering
was in the midst of a huge retooling job,
and I didn't trust anyone else to do it right.
 
Another question for those 'in the know'

Seeing as I need to change the lower ball joint to a 73 and up disc brake ball joint will my '69 tie rod end be the right one for the ball joint or does a guy have to change that too?
I notice there are different part numbers for the tie ride ends. Prior to '70 they are Es319 and '70 onward are es401?
What are the difference between these two? Perhaps I have to change inner and outer? If so will the es401 fit in my centerlink?

THANKS in advance for your reply. Hemi71X (JimV) do you know?
 
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