Staggered wheel setup 15x6 & 15x7 for 1964 Chrysler 300K?

Brakes, Suspension, Rims and Tires

  1. Quietlion79

    Quietlion79 New Member

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    Hey all, new to the forum and soon-to-be 300k short ram owner. I was looking at the reproduction Rallye rims and wanted to know if anyone has done or knows someone who has a 15x6 front 15x7 rear setup on their K or J (or similar) car...tire size suggestions would be great as well. I appreciate any help/advice. It will be awhile as there is a front disc brake conversion kit on it (need a dual master & possibly a different hydrobooster), but I wanted to start making plans...and figure out which organs I will need to sell...
     
  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    If you plan to do a disc conversion later on, I would suggest going to 15" on all 4 corners. They will be necessary if you plan to use stock disc brake components. The brake booster needed is a Bendix dual diaphragm unit from 68-71. You want to avoid the dual piston brake calipers from '65-68 as they are hard to get parts for and a PIA to work on. Use the single piston caliper disc brake from '70-'73 C bodies. (Can also use from '69 Fury Polara, Newport). The same spindles will also work. The '73 spindle is easier to find rotors for as these rotors were used on some pickups and vans as well. You will also need to install a brake portioning valve as part of the conversion to re-balance the brake system, one of the adjustable type usually works the best. Scarebird and others make aftermarket disc conversions that can use the existing spindles. Aftermarket disc conversions vary widely in quality, so do your homework. I personally would use a 15" wheel from the mid '70's as these have a stouter construction and less flexing with radial tires. Check to be sure the repop rally wheels are up to the task of radial tires, they should be, but be sure. These cars do not have a whole lot of room in the rear fender well and wheel house, so be sure to find a wheel that has the proper offset to gain maximum tire width if that is what you desire. Good luck.

    Dave
     
    Last edited: Mar 22, 2019
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  3. Quietlion79

    Quietlion79 New Member

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    Thanks for all the info, Davea Lux! I really appreciate it and I'm sure it will come in handy. The booster situation will be a bit more involved as the short ram intakes do not allow for a booster mounted on the firewall. I am even hoping I have enough space for a dual bowl master cylinder. The front calipers seem to be single piston and have 256 4 KH90 735 stamped on them...any ideas as to where they came from?
     
  4. 4spd300J

    4spd300J Member

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    I have a set of the 15 x 7" "police car" wheels on my 300J with 235-75R-15 tires. I've had absolutely zero clearance issues with this combination and the original wheel covers fit perfectly. I would be interested in what you come up with on a disc brake conversion. When I built my J, I wasn't able to find a master cylinder / booster combination that would fit in the 8-1/2" between the left carburetor and the firewall. Years ago, I did a disc conversion on a '63 New Yorker wagon using the spindles, calipers, rotors, and m/c and prop valve from a '74 thru '78 C body. I used the original '63 lower ball joint in the upper position and modified the lower control arms for the '74 lower joints. Also used the '74 outer tie rod ends. Everything on that project worked well with the 15" oem wheels also.
     
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  5. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    That does not sound like a mopar number, so I am guessing you have an aftermarket unit. Does the car have an iron caliper mount (stock) of a mount fabricated out of steel plate? (aftermarket) Chrysler used mostly standard brakes on the '63-'64 cross ram cars, does your single pot master cylinder have a high dome on the cap? If so it is probably a'65-'66 disc brake master. The cross rams are a highly sought after collector piece, but as a practical matter, they were something of a pain in the butt. The engines had solid lifters which necessitated pulling the cross rams every time the valves need adjusting, about every 4-5k miles for street use. They also had a bad habit of burning out the aluminum heat tubes for the automatic chokes. But, cross rams are hard to beat as a conversation piece. I do not think there is an aftermarket power brake booster that will fit this application unless you plan to remove the cross ram setup. The 300 G was offered with power brakes, but those tubes were the "long" variety and had a different profile. See www.chrysler300club.com website has some photos of the power brake system on the 300 G in their archives.

    Dave
     
    Last edited: Mar 22, 2019
  6. BIGBARNEYCARS

    BIGBARNEYCARS Senior Member FCBO Gold Member

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    If you have an original Ram K, I'd think you'll be shooting yourself in the foot if you start messing with the existing booster in it's original location under the left fender, and disks on any Ram K. Your tapered rear axles require a special puller also just to get the drumz off without screwing them up, But their's no reason you can't run 15" wheel on your K if you chose, The title is in your name. Adjusted properly those '64 Drums work fine. If you need inspiration I'd suggest you think seriously about joining the 300 Club Int. Inc. and when you get your copy of the club roster contact Don C. up in Boston. He and his Black Ram K Convertible I believe are still the K Guru of the 300 club and he's good people and you will find him to be more then helpful, Jer.
     
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  7. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    BigBarneyCars is right, only about one third of all 300k cars had the 390 horse cross ram setup. You do not want to mess with any of the stock equipment as these cars have good collector interest and are bringing premium prices if kept stock.

    Dave
     
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  8. fury fan

    fury fan Senior Member

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    Don't both longram cars and shortram cars use the same booster/MC setup? The ram tubes are the same length, it's just the divider length in the castings that's different.

    Either way, IMO a well-done disc conversion makes the cars safer to drive and shouldn't hurt collector value. but on a crossram car that's not a simple as a 'regular car'. It looks like the MC outputs to the output-thingy on the booster, and then splits out to all 4 wheels. How much of that system is repairable, except by specialty experts?

    As for the booster, it looks like you could put any booster under the fenderwell that would fit, as long as it would mate to that output thingy that goes out to the brakes. I can't tell in this truncated picture if it gives you a dual-brake system like used in 67-newer. Regardless, the original probably won't have enough boost for discs for a heavy stop (that's the downfall of drum-brake boosters). The larger single-diaphragm booster that started in 71, if it will fit, is far cheaper than the 68-70 dual-diaphragm unit. Or you could look at any disc-brake booster that would fit to that output-thingy, and then plumb your rear brakes separetly out of a dual-section MC?

    OR...
    Were any Newports available with manual brakes in 63-64? If you're up to manual brakes, then you can have manual disc brakes, and it saves the headache of mounting the booster. You'd need whatever the factory used for manual drums (different pedal bracketry?) and then a MC from a mid-70s Dodge pickup with manual discs. I have this setup on my 68 Fury and I *love* it. Yes, the pedal is stiffer, but the long pedal travel makes things nice and controllable. And it stops VERY well.


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  9. fury fan

    fury fan Senior Member

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    But to your original question -

    I would think that 15x7 Mopar wheels would fit better all around. Most of the 15" rims I've measured have around 4-1/4" of backspace. I would review whether to use 15x7 up front also, to fit out the wheelwell better?

    I've run 235-60-15 fronts and 255-60-15 rears (on 15x7 wheels) with good results, and that would give the staggered result you're looking for.
     
  10. CBODY67

    CBODY67 Senior Member

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    I'll concur that keeping the car mostly stock, no matter what, protects and can enhance your investment . . . period.

    If you want better brake performance, seek out some "metallic" linings for your existing brake shoes. Like the "police" option would have had, back then. The Chrysler police linings were made by a rebuilder in Amarillo, TX, back then. Not sure if they are still around, though.

    There were manual brake Newports, but manual drum brakes, which take less pressure to work than disc brakes do. Hence, you might find you need to do a leg workout in order to stop the car in a panic situation. Be that as it may.

    Perhaps one of the '80s aluminum Chrysler master cylinders (like's on my '80 Newport) might be small enough in diameter to clear the intake set-up?

    On "the stagger" . . . "Why"? I'll concur that 15x7s should work well all the way around. Then find a 70-series radial that's the same OD as the orig tires for the car. It might look better with wider-tread rear tires, but very little real benefit in performance (for more cost), to me.

    Just my thoughts,
    CBODY67
     
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  11. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    I was thinking that the short ram cars had the ram tubes closer to the firewall, but it might just have been a sheet metal difference, so you may be right as far as the tubes themselves go.

    Dave
     
  12. fury fan

    fury fan Senior Member

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    I agree mostly with that, but don't metallic linings require a little warmup period to work the best? The semi-metallic is more for fade resistance? I guess it depends on the driver's needs and driving/traffic situation.

    I was always afraid of needing to do a hard stop in freeway traffic, and 'old' drum systems make me nervous. 'Old' meaning - even if everything is in good working order, are they as good as they could be vs back when people knew how to make drumbrakes perform at their best? From that perspective, IMO the discs are superior.

    As for manual discs - I'm not a big strong guy, I'm wiry at best. But with the manual disc setup on my 68, 1-leg braking is fine for normal use, and if I put leg #2 on it it'll almost make your corneas separate. I've done some hard test-stops from 30-40-zero and by the 2nd one I almost get a little queasy. The only other old car that has done that to me was my Dippy copcar that I put 12" R-body brakes on front - that one was the best!

    Big caveat to all of this - as you increase the braking, your tires must be up to it. Meaning - plain-Jane Hankook whitewalls may leave some performance on the table.

    And depending on the anti-squat a 300K has, if the back end goes up in the air like a cat's ass, maybe that's the first thing to address. No point having great front brakes if you hafta let off to keep the back end under control.
     
  13. fury fan

    fury fan Senior Member

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    Ahhh, good point.
    I've never scrutinized them from that perspective. They are different castings, different than just the internal runner length. I just mentioned the runner to help prevent misconception by future readers that the shortrams are shorter overall than the longrams. MAybe the castings are a little fatter, too? They look fatter due to being flatter on the top in the area where there's no runner.
     
  14. CBODY67

    CBODY67 Senior Member

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    The older metallic linings did need some heat to work best. Which is why many '61 Impala SS drag racers replaced them with normal brake linings, so they could better stage the car at the starting line (especially automatic cars which were torqued against the foot brake).

    Disc brakes were about better fade resistance, PLUS less assembly line complexity (read cheaper to do than the "more pieces" drum brake systems). The disc brakes were known to have much better heat dissipation attributes than drum brakes ever could. Many of the '60s racers used flex ducts to the backing plates for their drum brake road race cars, plus holes drilled in the backing plates, too. So, as vehicles got heavier with increasing road speeds, the heat dissipation features of disc brakes became more advantageous. Plus that "performance" heritage didn't hurt, either.

    Along about 1969, some FMVSS standards of brake pedal pressure vs. stopping deceleration went into place. Ensuring that a weaker person could stop the car well enough, as needed. Hydraulic leverage (master cylinder bore size vs. wheel cylinder bore size) can do some of the "boosting", but general power assist came with factory disc brakes (one exception was the '71 Camaro base equipment). Not to say that non-power discs can't work, but there had to be a reason that all of the OEM systems, by far, had power assist as a part of the upgrade, at least in the USA.

    The last link in the braking equation is "tire/road friction interface". The older systems generally had enough capacity to lock-em-up in a panic stop. That was also when tire treads were about 4.5" wide, too. They stopped better with radials and wider tread widths, which came later. ONCE, at least. As long as it stops straight, which most did. Otherwise, some fancy footwork and steering wheel work. not like the later/current "stomp and steer" anti-lock systems.

    I understand the reason for the dual master cylinders and such, but IF somebody was really concerned, might they adapt an anti-lock system from a mid-'80s Caprice or similar to an older vehicle, too? Or might that be "past the tipping point" of desirability? Just some thoughts.

    Having grown up when "cup holders" were on the inner side of the glove box door and all mothers seemed to have a spring in their right arms (to keep their child sitting beside them in place in a hard stop), AND living to tell about it . . . some of these "gotta have power disc brakes for better stopping" can take on a different light, to me. There were still mountains and freeway traffic, back then, possibly just not as prevalent to some, but they were still there. We depended upon the factory drum brake systems and they did well for us. Everybody knew now to make them work well, even with open containers of brake fluid at the lube rack. Of course, only really HP vehicles had 4-wheel power disc brakes, back then (i.e., Corvettes), which were exotic enough to need somebody who knew how to work on them. Now, it seems these things have reversed, in the repair/maintenance situation.

    Brake linings were more important back then, too. Some were really "not so good", so we opted for the name brands/OEM spec stuff. Stopping quickly was more about skill rather than just "stomp and pray to not hit anything" (letting the tires do the work!).

    But adding disc brakes surely led to less anxiety at the end of the race track, being able to slow down enough to make that last turn to the return road.

    Enjoy!
    CBODY67
     
  15. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    The fender well booster in the in the photo was used on '63-'64 Letter cars that were power brake equipped. It is a "slave" type booster that is activated by fluid pressure from the firewall master cylinder, note the two brake lines attached to the slave master cylinder. One is from the firewall unit, the other goes to the cars brakes. This booster is very similar to the units used on GMC and International trucks. They used the same system with the booster mounted under the driver's seat on the frame rail. This is a different booster than the one used on the earlier letter cars G's and H's that was mounted directly below the firewall MC. In any case, these slave boosters were not really up to the task of disc brakes. Not sure if they made a later slave unit for some other application with discs that could be substituted.

    Dave
     
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  16. fury fan

    fury fan Senior Member

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    I can't speak for any standards or regulations for that, I'm sure they play a role. But I believe another part of the reason that power assist was integrated was because making things easier for the driver, from a marketing perspective, was alive and well back then. I've watched a number of B&W automotive documentaries on youtube over the past year, and the marketing toward the public of 'easier, less effort, more convenient', etc, was happening back in the 1930s-40s. And if one EOM did it, they all followed suit. An example is when manual-trans shift levers moved from the floor to the column in the late 30s, by '41 or so they all were.

    I have wondered about this also, and what would be involved. I believe that an older system, less sophisticated, rear-wheel-only, would have a decent chance, as the algorithms might be based simply on wheel rpms and less on the vehicle characteristics.

    Or... some 80s mini-pickups (Toyota?) had a link from the rear axle to a mechanical pressure-bleed valve in the rear brake system. As the rear of the frame raised further from the axle, brake pressure was reduced. Allowed a loaded truck to use its rear brakes better, and an empty one less likely for wheel lockup. I think that would be the simples thing to install, and having adjustable linkage would allow you to tune it until it was 'right'.

    I get that sentiment. But I'd bet that back then a lot more people died. It would be difficult to really normalize the data, because one would need to factor in population size, miles traveled per year per person, accident cause, typical travelling distance, etc. I think people were maybe more cautious and paid more attention back then, but probably because vehicles, tires, etc, were less capable, and so the risks were more obvious.

    Now - outfit everyone in the US with a brand-new, pre-1970 car overnight - a SHITLOAD of people are gonna get killed in accidents! Pandemonium! Or maybe not - because 90% of us won't know how to start a carbureted car.
     
  17. CBODY67

    CBODY67 Senior Member

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    Actually, the first anti-lock systems from Ford and GM were "rear wheel only", taking the speed reading from a sensor on the rear axle ring gear. Later 4-wheel systems took readings from EACH wheel.
    The rear wheel pressure modulation/pressure adjustment was a neat idea, which some others had, too. But with ABS, it was not needed. It could be that, like other neat ideas, after put into production (with related "ballyhoo"), after a few years, they were quietly discontinued. Nobody noticed, usually. Many examples of that! Especially IF they were something that the customer could not readily see and brag about.
    CBODY67
     
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  18. fury fan

    fury fan Senior Member

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    So true, gotta brag about it, sometimes on every wheel!
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