the 83 diplomat i can get has disc brakes can i out them on my valiant with little problem

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trying to keep it low key here in my Valiant200

You can take the spindles, rotors, calipers, and caliper hangers off that M-body Diplomat and put them on your Valiant. The other things you'll need are:

1. Upper and lower ball joints from a 73-76 A-body, which you can get at the parts store. Only trick here is that you may need to grind off the bump stops on the lower ball joints, or grind the bottom corner of your LCAs, where the bump stops hit.

Side note: when I did this to my '64 Dart, I think I also had to grind the LCAs a bit where the back side of the calipers hit them.

2. 73-76 A-body upper control arms. This is the only tricky/expensive part. If you can't find a donor car in a junkyard (I couldn't), then you can:
-Look for them on car-part.com, an online junkyard database (cheap but unknown quality)
-Buy tubular ones from FirmFeel or other online vendors (expensive but best quality)
-Buy large upper ball joint sleeves, which must be welded in after you torch or cut out the smaller ball joint sleeves from your existing UCAs. This is the cheapest option, and it gives you a solid end product. The downside is that it requires access to a plasma torch and (preferably) a TIG welder, along with someone whose welding abilities you don't mind betting your safety on.

Another note: Because you're using M-body spindles, you may need MOOG "Problem Solver" offset bushings in your UCAs to get proper wheel alignment. The MOOG number is K7103.

3. New brake hoses from a 73-76 A-body (parts store again). The M-body brake hoses won't fit properly.

4. New wheel bearings would be a good idea, in my opinion. Buy these for the Diplomat.


Final note: If you want to make sure all your components are in good condition, you can get brand new rotors and calipers at the parts store as well. All you really need from the junkyard car are the spindles and caliper hangers. I say this because when I got everything hooked up, I discovered that the calipers I pulled off a junkyard '84 Fifth Avenue needed a rebuild. Also, the rotors were under the minimum thickness for turning.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Other things to consider- you need a disc brake Master Cylinder that'll fit your Valiant (4-stud mount- manual/power, etc). You need some form of proprtioning valve- there are some adjustable aftermarket units; the Dippy one can work BUT only for a stock brake combo: The '83 (& 73-76 A body) use Large Bolt Pattern (4.5") wheels- with 10" (some had 11") rear drums. Your all-drum Valiant has 9" rear drums that use Small BP (4") wheels. So you'd end up with different wheels front & rear. I don't know if the '83 rear axle will work (width-wise) on the Valiant- but it likely has a crappy ratio. Most folks doing a disc upgrade usually do some form of rear brake upgrade as well.

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63 Valiant Wagon
225 - 4 bbl

Take the one off the dippy if in good shape, I think Raybestos still makes one model new over the counter. If you are looking to upgrade a little, you can also buy an adaptor from AR Engineering that will adapt the later 2 bolt aluminum master cylinder to the classic cars.
He will need the one off the dippy anyway as the stock valiant brake drum model isn't right for he upgrade (and it may be the type that works with the master cylinder meant to use with the expander cup cylinders).
Also most stocker master cylinders and prop blocks are biased that can cause the rear brakes to look up sooner than the fronts, with his 9" drums that might equal that problem out.
The F-body axle is too wide to plug and play under the Valiant (and these cars have restrictive rear wheel wells. He would need to cut and move the perches on the axle housing to be close to the A-body, then run a wheel with the proper offset to make the fit right. Also some M-bodies came with 9 1/4" rear instead of the 8 1/4" rear as the heavy duty option.
Most of these will be in the 2.26-2.45 range, some are 2.76, but the cop cars and some of the late 'Gran Fury' cop cars in this line came with 3.21 sure-grip rears. Another thing to note is the M body has been seen with 10" rear drums on the rear, and some could be 11" drums as well...with the advent of the factory mandatory disc brakes at the beginning of 1976, the typical mopar package was 10" LBP rear drums on a majority of vehicles and 11" rear drums on the bigger or HD cars.

As stated if going discs on the front, you will be on the search for a 1973-1976 LBP rear axle (should have 10" drums on it if a 7 1/4" rear or either if an 8 1/4" rear). Another thing to note on ratios the automatic cars from the late 60's to very early 70's had been equipped with the nicer 2.94:1 rear ratio, these late axles in the A-body behind the automatic will be 2.76:1 which will not be as 'peppy' in daily driving, but will be long in the tooth and low rpm on the highway...

Hopefully the junkyard didn't pitch the cars wheels, you might luck out and get a set of 15"x6" LBP rims.

FYI.

-D.Idiot