Technical 60 Rambler front disc brakes

I’d like opinions, will have a solid square spacer made to make this work. Pic above is a 15x6” wheel, 3-3/4” backspace, that I plan on using. I do have a pair of 15x4” old Cragar S/S wheels too. That may help reduce the scrub radius issue too.

 

Please feel free to bash away, or add positive comments!

 

I wonder why Scarebird didn't do that?

 

They list it for ‘64 and up. The weird curved steering arm and forward steering on this particular car are my guess. 58-60 Rambler Americans are like this, not sure what 61-3 are like.

 

You've thought it thru and make a good point with the wheel spacers. To that, most all disc brake kit's add to the track width so why can't you? Your right on about not spacing steering arms or bending them. Solid spacer, good idea. I'd only suggest that you make the holes as exacting as possible so bolts become supported to reduce shear stress's placed upon them.

 

I can check the track width difference between the original drums and the disc setup. That is easy with this removable spindle. My idea on the spacer is just that… exactly match the spindle and brackets with the 7/16” bolt hole size, so the bolts don’t get any shear load. Just like how it is/was originally.

 

Not too shabby, see how it rides and how happy you are with it. Myself, I'd be making up solid plates instead of spacers. Aluminum plate would be good enough.

 

Dont know what this would do to the ackerman,but since the arms appear to bolt on could you swap them side to side so they point inward? Make up a new tie rod set up thats shorter? Might screw up everything,but we are brain storming so expect to hear all kinds of stuff. Another thought....they used that bolt on spindle well in to the disc brake era as I recall early 70"s magazine articles on mating them to cut early Ford spindles to get discs. Is there any chance you could get the later spindles,or the entire spindle assembly from a late disc car,and swap it all on to your car?

 

Changing the arms over would throw the Ackermann princible right out of the window Steve. If you had not got all the Scarebird stuff I would have suggested getting discs with a lower top hat section that went on the original hubs and cleared the steering arm. What I mean by top hat section is "E" in the drawing.

 

I would see if a local machine shop can make you a solid version of the spacer you have. Then the bolts act together as a unit instead a bunch of independent shear /point / bending moments as you have now. I would personally swap the wheels out for something that look a little more Ramblerish while I was at it too.

 

So just to clarify, the car already has a scrub radius issue with the wheel adapters, which you'll remove and end up with less of a positive scrub radius than it already has, right? So that's not perfect, but it's an improvement on what the existing setup. And just to be honest here, we see a ton of cars built using Buick drums that end up increasing the radius much more than this.

I have to add, that is a cool looking car. Not sure how Torque Thrusts or Cragar's are going to look on it, but they tend to look pretty good on most cars so I expect they'll work good on this one too.

 

"will have a solid square spacer made" quote in reply #31.

 

Front steer arms are always a pain it seems when making a revision to at least keep the Ackerman close. Following this tread… good luck.

 

It is what gets the inside front wheel turning on a tighter circle than the outside wheel, when you corner. That way both wheels maintain traction, as opposed to dragging or pushing one.

Front steer (tie rod ahead of axle):


Rear steer (tie rod behind axle):


In both cases, done properly, the result is the same. The front tires on both sides move on a radius that ends on the same center point:

 

I ordered some 1.125” thick aluminum to make a large solid spacer today. I removed the spindle, set it on the floor, and put the original drum and bearings on it. Put a small bar across face of the drum and took a measurement. Then did the same with the rotor. Good news, the discs are 5/16” narrower, again helping with the scrub radius issue! So the end result will be 13/16” outward on the positive side. That is less than the 1.25” wheel adapter! I can live with this, and be happy to upgrade to disc brakes!

 

Sorry I didn't reply sooner, don't check things here on the HAMB that often! I get PMs in e-mail though... and alerts on threads I'm following (made a reply to).

You're going about it the rights way. All 58-63 Americans have steering arms like that due to the short wheelbase (same chassis -- also 50-55 Nash Rambler). With factory AMC discs you still need to space the spindle out some, but only about 1/2". AMC factory discs are getting harder to find rotors for though. I haven't put the latest Scarebird style on a 58-63 American, just the first type that used Ranger rotors. You might have to use deeper offset wheels to keep them under the fenders, but most FWD and 4WD offset wheels will work. Heck, even modern RWD cars (like the Mustang) use the same deep offset wheels! Not like it was in the 70s and 80s...

 

I hope the Torque Thrusts work out. Best wheel of the 60’s. 5” are available too if needed. I use 75 series tires on 6” and they are great.

 

I see farna replied, & I just saw this tonite, but I'm wondering why you didn't just use as whole amc "kit" to do the change-over. Not being funny, or judgmental. Do not the bolt-on spindles mate up from late 70's to the early stuff? I was told, amc/nash/rambler/et-al, used 2 different spindles for 2 different drum brake diameters/widths, & I'm pretty sure they used 2 different spindle "kits" for disc brakes. Rotors, calipers, caliper brackets & bolts were different. One was a solid rotor, other was vented rotor. The factory "kit" came on each car,: bolt-on spindle, steering arm, caliper bracket, caliper & rotor. You'll probably have to bend the steering arm abit to get correct ackerman, but nbd. I have, somewhere, a set of the solid & vented rotor "kits", & from the last time I saw them(a long time ago, since in storage somewhere), they did not appear to be interchangeable, other than bolting onto the suspension upright as a complete "kit". I was always going to use them similar to what's depicted in post #15 & 38.
If farna knows, I'd appreciate any correction(s). TIA.
Marcus...

 

The problem with a lower hat section rotor is that it would take a new caliper mounting bracket and it would probably create a caliper/wheel interference problem.

 

AMC used at least four different spindles. They all use the same bolt pattern from 1952-83, so they will all interchange. All used the same bearing set (disc and drum) EXCEPT for the big bearing 75-78 models. The big cars used a big 3.1" piston caliper those four years, and all 75-76 models did, so they are usually referred to as "big Bendix" spindles. 77-78 Hornet/Concord/Gremlin/Spirit used the same big bearings but a unique rotor and the now ubiquitous 2.6" piston calipers. Those rotors are very hard to find and expensive when you do, ALL the big bearing rotors are, so best to avoid using those.

The 66-70 four piston Bendix discs used a solid rotor and a drum brake spindle. All other disc spindles have thicker bases than drum brake spindles due to the offset needed for the rotor. There are at least two different base thicknesses for drum brakes. The small 2" wide (and under) brakes used a thinner base than the 2.5" wide brakes typically used on the bigger V-8 powered cars. That makes three spindles, but I'm not sure if all 71-83 disc brake cars used the same thickness spindle. 71-74 were Kelsey-Hayes calipers and may use a unique thickness spindle base. 79-81 are Bendix 2.6" piston sliding calipers, and 82-83 are Delco 2.6" piston pin type calipers. 79-83 use the same rotor, and it's the only rotor that is somewhat easy to find new today. They are $40-75 on Rock Auto right now, depending on manufacturer. All the others are $100+ each, and only available through AMC specialty parts places.

If I were using an AMC factory brake setup, the only real choice is the 79-83, with the 82-83 being preferred. Those rotors are unique to AMC, so they aren't going to get easier to find. As demand dwindles so will supplies. That's why I always recommend the Scarebird setup for good driver quality disc brakes. Their small brake setup is on par with the late model factory AMC setup.

Oh, all the spindles (except the big bearing, of course) use the same bolt pattern and bearings, and the dimensions where the bearings ride are all the same. A drum hub will fit a disc spindle and vice-versa, but the offset will be wrong. This can be corrected with longer bolts and spacers or by cutting down the base as needed.

 

Thanks, farna.
Now I gotta figure out what I have, that was saved over the past handful of decades, for projects that never happened.
Sounds like if any of it is any good, it'd be better off in AMC restorers' hands? At least one set solid rotors, one set vented rotors(pacer), & one set I don't remember. Time slithers on... Nuts...
Marcus...

 

If you can describe how the calipers mount or post a photo of the calipers I can probably tell you what you have. The Pacer brakes are probably Bendix. The calipers attach to the mount with a slide that drives in with a leaf type spring. Just measure the piston of the caliper if that's how they mount. Most likely they are 2.6" pistons, but could be the 3.1" depending on the year.

Kelsey Hayes (71-74) use a pin that holds the pads on. IIRC there is a small cotter pin holding that pin on, but I haven't messed with K-H brakes in quite some time -- need to look at one of the factory manuals. The 82-83 (maybe 81...) Delco brakes are like all GM brakes -- the pin the calipers slide on has threads near one end and screw into the caliper body.

 

Hey, Farns;
Seriously, Thanks for the info. Stuff is put away in storage & difficult to access, but I'll have to get at it sooner or later.
I always liked the "factory kit" approach AMC did, thought it'd work well to make "dropped" spindles w/o welding/etc, or at least easy disc conversion(s) for any other make. A bit heavy - but nonetheless very Heavy-Duty, but at the time, easy to get, & inexpensive. Now, I suppose Wilwood or Baer is the cats'ass, esp for lightening both the suspension & wallet. I've discovered "adding lightness" works simultaneously in multiple venues. Just have to decide what will actually get used on what, & what can be used by others. Hopefully the upcoming retirement will net me some time to wade thru these things. Haven't figured out how to post pics, but I suppose it might be worth it for someone else &/or posterity/research, if I can. May have to revive this thread from the dead, but... .
Marcus...

 

And we make drop plates for the spindles! Lower car 1-5/8". You can make them to drop it about 2-1/2" by putting the bottom holes of the spindle over the top holes of the upright, but IIRC that can cause some clearance issues. Don't recall the exact problem someone had with that, might have just been that it wouldn't work with 14" wheels, but I really don't know. I do recommend using 1/2" thick material instead of 3/8" thick if dropping that much though. Structural integrity might be the only reason the 2.1/2" drop is hardly ever used, not clearance...

Bolts needed with a typical AMC disc brake bracket. Some have welded caliper brackets directly to the lowering plates. If you do that some of the bolts need to be shorter by the thickness of the factory bracket. That would be the four that bolt the spindle on -- the upper two and the third row down (the two tapped holes). Sorry, I don't know which length go where. All should be Grade 8, 7/16" x 20 threads per inch 2-3" (1ea side).
For one 3/8" thick plate:
4 - 2"
1 - 2.25"
1 - 1.5"
1 - 3"
1 - 1.75"

A couple photos of the plates on a 68 AMX steering knuckle with Kelsey-Hayes caliper brackets. Note in the second photo that a bit of the corner of the plate was ground off (top right) to clear the caliper bracket.



Much more info found here: https://theamcforum.com/forum/lowering-plate-installation_topic43682.html