Converting 68 Valiant Rear to use 15" wheels

Hello! I've been looking at buying a 68 valiant (slant 6, 225 cu in version, if that matters). The car comes with a kit to convert the front to disc brakes and after I'll have it all installed, I'll have to use 15" wheels. This is all fine and good but I'm not quite sure what I'm going to do for the rear. I've done some searching but am still a bit confused so I just wanna make sure I'm thinking straight. From this one thread in particular, it seems like I have to either, A) buy a whole new rear axle assembly, B) run "lower profile tires for the front and/or taller 13's in the rear". While it may be overkill for just a (hopefully eventual) daily driver, if I got a rear disc break conversion kit, like this one I ended up coming across, I think I should be able to run 15in wheels with a 4.500/4.750 in bolt pattern, at least according to the sales page for this kit and I wouldn't have to source another rear axle assembly or shorten my drive shaft.
Aside from this being a bit overkill, is there a reason I should steer clear of this route?
Sorry if this isn't in the right place to post this, I'm new to this forum.

A) All day long, put an A body 8 3/4" and put LBP axles from Mancini in it.
Then install 15" wheels that are matched.
Is the disc brake conversion telling you that you have to run 15" wheels for caliper clearance, or are you being told that by someone else?
I installed wilwood front discs on my 69 Dart and just put 14" magnum 500's on it and they cleared the calipers. I had 15" steelies on it and was concerned the magnums wouldn't fit, but they are fine. If there is a slight rub, you can grind the caliper down for clearance, but that is not always preferred. 4.75 is GM bolt pattern.

The best route would be-find a A Body 8 1/4 rearend or a 73 up 7 1/4 if you are staying with the Slant 6. It sucks having 2 different wheel bolt patterns on your car. The 73 and up A Bodies with drum brakes continued to use the small 4 inch bolt pattern-so don't get one of those.

Wow you have a lot going on.

SincerePuppet said:

Hello! I've been looking at buying a 68 valiant (slant 6, 225 cu in version, if that matters

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Congrats on the soon to be purchase.

Assuming your valiant is stock...Your slant 6 valient has 5x4" wheel bolt pattern. Your wheels will either be 13" diameter or 14" diameter. The stock wheels will either be 4.5 wide or 5.5 wide.

SincerePuppet said:

The car comes with a kit to convert the front to disc brakes and after I'll have it all installed, I'll have to use 15" wheels

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I assume you have read the manufacturers instructions on that.

The kit will probably change your front wheel pattern to 5x4.5".

SincerePuppet said:

This is all fine and good but I'm not quite sure what I'm going to do for the rear. I've done some searching but am still a bit confused so I just wanna make sure I'm thinking straight. From this one thread in particular, it seems like I have to either, A) buy a whole new rear axle assembly, B) run "lower profile tires for the front and/or taller 13's in the rear". While it may be overkill for just a (hopefully eventual) daily driver, if I got a rear disc break conversion kit, like this one I ended up coming across, I think I should be able to run 15in wheel pattern ls with a 4.500/4.750 in bolt

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For the rear.
You can leave it at 5x4" and get 15" wheels to maintain the look of the front

You can replace the rear, many options that will get you 5x4.5"

Do a disk conversion that changes the bolt pattern to 5x4.5"

SincerePuppet said:

Aside from this being a bit overkill, is there a reason I should steer clear of this route?

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Yes. The car is new to you. Make it drivable and enjoy it for a while. EVERYTHING you have talked about is EXPENSIVE.

Then do the research on front disk conversions, there are other options than aftermarket, that will bolt on (like OEM parts). If it has 13"wheels you will have to swap out to 14" minimum.

you can buy 15 inch 5x4 brand new still

Only just coming back to these replies now. Thanks for all the help thus far!

Veryfastdart said:

Is the disc brake conversion telling you that you have to run 15" wheels for caliper clearance, or are you being told that by someone else?

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For the fronts, the seller told me I'd have to run 15in wheels while for the rear, I'm going of the stats listed on the page that says "Minimum Recommended Wheel Diameter (in.): 15 in".

lemondana said:

The best route would be-find a A Body 8 1/4 rearend or a 73 up 7 1/4 if you are staying with the Slant 6. It sucks having 2 different wheel bolt patterns on your car.

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I guess my question sort of is why exactly finding another rear end would be the "best route". Are you figuring that between the 2 kits, the wheel bolt patterns wouldn't match up? I'm new to A bodies so this is a genuine question. Hope I'm not coming off as argumentative or something haha. Thank you for all the information though!

Dana67Dart said:

For the rear.
You can leave it at 5x4" and get 15" wheels to maintain the look of the front

You can replace the rear, many options that will get you 5x4.5"

Do a disk conversion that changes the bolt pattern to 5x4.5"

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Thank you for breaking this all down I really appreciate it.

Dana67Dart said:

Yes. The car is new to you. Make it drivable and enjoy it for a while. EVERYTHING you have talked about is EXPENSIVE.

Then do the research on front disk conversions, there are other options than aftermarket, that will bolt on (like OEM parts). If it has 13"wheels you will have to swap out to 14" minimum.

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This is a great point also. There really is no rush to get this done asap so perhaps leaving this for further down the road isn't the worst idea.

diymirage said:

you can buy 15 inch 5x4 brand new still

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Thanks for letting me know, I'll have to look around at where I might be able to find tires for this.

Ford explorer 8.8.
Narrow LH long end tube about 2&7/8"
Install a second short side RH axle in LH after shortening. This makes it only 3/8" narrower than a stock A body rear after you shorten it

Has 5 bolt 4.5" bolt circle with 1/2" studs. Same as front discs
Most have good gear ratios 3 23, 3 55, 3 73, 3.90, and 4.10 on sport trak
Most have a clutch type limited slip (rebuildable)
31 spline truck axles
Rear disc brakes.
Everything is SAE except caliper pins
About $100-$150 from the boneyard

What is your eventual intent for the car? Do you plan on keeping it stock 225 slanty, or do you have plans for a V8. If you intend to keep it a slanty but want the option of disc brakes, take a look at the "scarebird" front disc brake conversion kit. It uses the stock existing drum brake spindles and hubs on the valiant, and retains the small 5 bolt 4" bolt circle. It uses toyota previa rotors that are re drilled to the factory small bolt pattern, and uses chevy celebrity rotors. It will require an upsize to at minimum 14" rim, but will work with your existing bolt pattern. More modern stuff for the small bolt pattern, makes spare parts a little easier to find than the old Kelsey hayes small bolt pattern discs that these cars had from the factory from I think 1965-1972. Go this route, and ya sure you will have to upsize the rims to clear in the front, but you may want to upsize all 4 and the spare. This way when you inevitably get a flat tire, your spare will fit the front or the back.

The big bolt pattern kit, your mentioning now sets you up with a larger 5 bolt 4&1/2" bolt circle. Requiring at minimum a 15" wheel. If you do not do the same thing with the rear end, your looking at carrying 2 different spare tires just in case, or just take your chances your not gonna get a flat.

Honestly if your gonna leave it stock, I'd hunt for five 14" steel rims that will fit your 5 bolt four inch bolt pattern, get the scarebird kit, and just enjoy the car. You can always collect up what it needs for a V8 conversion while enjoying it, including storing away the big bolt pattern kit the seller wants to let go with it as the first piece to the puzzle. Theres always buyers out there who would want the scarebird kit and 14s when you dont need em anymore.

moparmat2000 said:

Ford explorer 8.8.
Narrow LH long end tube about 2&7/8"
Install a second short side RH axle in LH after shortening. This makes it only 3/8" narrower than a stock A body rear after you shorten it

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Thanks for all this info. I'll have to keep this in mind.

moparmat2000 said:

What is your eventual intent for the car?

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I'm not big into racing, or drifting, or anything like that. I'm just into regular old sedans and cars and stuff like that. That being said at the moment I'm planning on keeping the car as stock as possible (although I make exceptions for stuff like the brakes as it's a safety thing) and I also plan on keeping the slant 6 for as long as I can then maybe if some years down the line it throws a rod or something, either I'll do an engine swap and/or do a manual swap. I've looked into people doing v8 swaps before with these types of cars but I've only looked at the surface level stuff. Ideally the car will eventually be a daily driver/weekend car type of thing.

moparmat2000 said:

take a look at the "scarebird" front disc brake conversion kit.

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This all being said, I will certainly keep this in mind.

I shortened an 8.8 housing long end and will put this rear under my kids car. I plan on putting it all back together this winter. I will have about $500 in it total with new bearings, clutches, brakes, extra short side axle, and includes its purchase price. I hunted until I found the gear ratio I wanted along with a limited slip, this way it would be minimal shim setup for pinion depth after replacing the bearings. The data tag on it was stamped 3L73 this means it's a 3.73 with a limited slip. Bearing and clutch kits are super inexpensive since I think the bearings, clutches, and seals are all the same as used in mustangs and 1/2 ton trucks, and Rangers, from 1979 till now. Also ford Fairmonts, Aerostars, Bronco ll s , and well anything ford sold that was RWD from the mid 70s on. I went this route on my sons car, because I could not find a complete 8&3/4 ready to go, and if I did, I'd want to convert to big bolt pattern, requiring an axle and brake change, then have to rebuild the center chunk anyways. The 8&3/4 I did put together for my 67 I did a piece from here, a piece from there etc to put what I wanted together. When the smoke cleared I am into an 8&3/4 A body with rear for $1700. Had I known about the exploder rear back then, I woulda done one of those explorer rears for my 67 too.

Your scribe marks are off little , but serious that’s how u do it. I’m not so much handy with the internals of the motor yet but love the fabrication part. Nice work

Mopar Momzee said:

Your scribe marks are off little , but serious that’s how u do it. I’m not so much handy with the internals of the motor yet but love the fabrication part. Nice work

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Close enough on the clocking that it wont matter. Glad you dug the way I shortened it. I know it's definitely straight. Also if you do the big bolt pattern upgrade, hunt for a 2002 Lincoln town car donut spare. Its 25" diameter, and only 5" width. It's the big bolt pattern, with a light weight aluminum rim, and fits nice and flat in the spare tire well. Heres a check fit of a town car donut spare before I replaced the trunk floor with a new one.

If you like steelies with big bolt pattern, look into 85-89 M body chrysler fifth ave, dodge diplomat, and plymouth fury. Last of the old skool V8s. They used a 15x7 steelie that is the big bolt pattern. Some of the earlier M body cars used a 15x6 steelie as well. I suppose you could go 15x6 on the front and 15x7 on the rear. I have only found 2 of the 15x6 rims. I have found a lot of the 15x7 rims though. This is why I decided to just collect up the 15x7 rims. Easier to find.

They will fit the small dog dish caps center used on the 13 and 14" rims as well. The dog dish cap snapped on a 15" fifth ave wheel. I got a set of 4 rims from the boneyard for $8 each. I went back and bought 2 more sets. One set for each car, and one set for spares since the source of em out here is now drying up. They clear the 8.8 discs well too.

I’m going to keep on my sons car what he has for now, stock. May up grade to the 4.00 bolt pattern 15” steely in future. But I’m really detailing his drive train for now then i have just bought a 68 dart i want to also get running soon. But all the ideas and great info for future Reference. Thanks jesse