On another thread it is implied that $995.00 is the price point for front wheel brakes. Having worked on this subject I am curious about this?
Bang for the buck, they're worth three to nine times wheel brakes on the rear, depending on the car's weight distribution.
Competition determines the price:
What it would cost somebody to design and make their own.
Finding an old set of Orville Enyart Metro front brakes.
Rear wheel brakes: see above.
Front brakes convert a T from a high anxiety ride to a Go Anywhere fun time.
You and I know this
It's not written in stone but certainly a number that seems to make sense.
I personally would think that small front drum brakes in combination with the rear Rocky Mountains would be most well received by the T crowd. Let's face it: disc brakes do not work better on a T based on the small surfaces of the tires that touch the road. They are easier to service at the cost that they are obviously something that has been added decades later.
And Ralph, I don't think the weight transfer from rear to front under braking is not much pronounced on a T. Yep, if you step on the brake pedal in your modern car on the freeway, you'll mostly use the front brake. But if you putter along at 25mph in a T and apply the brake, I think what matters most is that you have 4, not just two, surfaces that help slowing the car down.
Those calculations do not take into account the fact that the car has suspension... The angle of the SVSA ("Side View Swing Arm" which is the imaginary line from where the tires contact the road to the "Instant Center" at the ball socket of the driveshaft tube) on a T makes the braking even less effective, and is why the rear suspension will hop if you lock up the brakes.
An accessory transmission (Warford, Muncie, etc) that requires shortening the driveshaft shortens the SVSA, making the hop more pronounced, and brakes even less effective than a stock T.
Weight shift is less of a concern than brake-hop in my opinion when calculating the effectiveness of front brakes on a T.
Simply adding front wheel brakes of any type without a total rethink of the front end design is dangerous. If you apply heavy braking on the stock front end the axle will almost for sure go to negative caster and your steering can flop over center. Think about the lack of steering stability that happens when the axle goes beyond vertical. Heavier radius rods split and attached to frame rails is a must and even then I would make darn sure that the maker knew what he was doing. I think it is better to drive slower. Negative caster on the front end is a killer.
Reinforced wishbone with front brakes is a given, John. I use a late wishbone welded to the early one.
Splitting the wishbone is ugly and unnecessary, and "ruins the whole Model T experience." .
The contact area of the tire does not figure into the brake force calculation. This a proven fact
Driving slower does not prevent some one from stopping to quickly in front of you (or other driving miss adventure). Also I do not presume to tell you that they right for you. I have them on the totally stock '27 roadster I have had for 40 years. They are cable operated mechanical and only 7" in diameter. They hide behind the T wire wheel centre and operate with the stock transmission brake
Les — you made this comment in the current Becky thread in relation to adding front brakes to a T: "Option 3. Rework the front axle geometry so the king pin lines up with the centre of the tire where it contacts the ground (like all production cars with front brakes have)", but I think it is better addressed in this thread.
As you know I am contemplating adding cable-operated front drums to my '24 Speedster. Could you please elaborate with particulars to the Option 3 above? Thanks.
Ralph — I would be interested in photos of how you reinforced the wishbone on your T and anything you might do differently the next time around. Thanks.
On the T the king pins are vertical as far as camber is concerned. T spindles have about 2 degrees of camber (T wheels lean out at top about 2 degrees) built into them (probably so they are not leaning in when things wear a bit).
I bent the axle so the king pins lean in at 9 degrees (like a model A). I made new spindles with 101 degrees between the king pin and the spindle and so retain the 2 degrees of camber. Now the centre line of the spindle hits the ground in the middle of the tire contact patch. With this you get no torque put into the steering linkage on braking etc.. Another feature is you now don't need any caster to have stable steering. The car steers as well in reverse as forwards. Still it is a lot of work to accomplish (even for me).
Some style of non-reversing mechanism in the steering is easier (but maybe not as good overall)
I had the car at the Pincher Creek tour. If you make it down to Calgary some time we can go for a drive.
I don't have any pix of the wishbone, Chris, but the ball and stub are cut off the late wishbone at the apex, then that part is welded to the early wishbone. Antique T Motorsports sells a bolt-on bracket that does the same thing, but possibly less secure.
Next time I would not mess with the stock rear brakes, but put in a slave cylinder to actuate the stock tranny brake using this pedal setup:
The slave cyl will keept the brakes front/rear balanced at all times. It's just a matter of choosing the slave cyl diameter ratio relative to the wheel cyl diameter.
Les, have you done any serious stopping tests? I almost threw a young guy over the windshield demonstrating the brakes at 10 mph. I won't do that again unless the pax is belted in.
No tests I can quantify. My testing has consisted of "hands free" panic stops with one side on dry pavement and one side in the grass with no swerving of any sort
Thanks Les and Ralph for the additional info.
Les, looking forward to another visit sometime later this year.
And to paraphrase your comments to make sure I understand: The concern with the stock geometry is that the extended centrelines of the kingpins hit the ground slightly outboard of the centre of their respective tire-contact patch. So for example, if the brakes are applied hard when the RF tire is on gravel/snow/ice, the LF tire could grab the dry pavement and want to rotate around the kingpin axis — with a tendency to swerve steering to the left. Is that correct?
Correct. Except "tendency" would be a understatement!!!
The KP centerline is at the inboard edge of the tire patch or even more inboard.
I drove three Greatraces and a lot of other driving with T 5:1 steering, and had a death grip on the steering wheel at all speeds above 50. I installed the modren '37 Ford box in 2001, and it helps a lot, but is not a cure-all.
I suspect the hubs could be re-made to move the wheels inboard more than an inch. I would look seriously at it, but that would mean different front brakes.
Les, does this mean you are getting closer to a small production run?
Ricks, should be wheel cylinder diameter relative to master cylinder diameter, not slave cylinder to wheel cylinder.
Or I am missing your point completely?
A wheel cylinder is a slave cylinder.
If you are referring to one of Les's plans of having a slave cylinder on the frame at the sides near frame center to pull on cable/rod to each wheel. In that case it would be Master cylinder in relation to slave cylinder.
Having tried different brake combinations I must say that I believe Les' front brake set-up alone would more than double the stopping power of a T even without rear brakes.
I drove a '41 Ford coupe, '46 fordor and an MG 1100 sedan with the rear brake line disconnected and blocked off.
On the two Fords there was slight noticeable loss of stopping power, on the MG we could not tell the difference.
In doing work on a Ford Aerostar I discovered the rear brakes were not doing a thing. The shoes had never touched the drums since the brakes were installed in the rear.
I told the owner but she drove it several years that way.
I would say it stopped as well as my Aerostar with all brakes working, but we know that can not be.
rear brakes do not do much and are hardly needed when you have large drum or disc front brakes.
There was a post a while back on some accessory front brakes that were of the contracting band type. No K/P inclination changes were needed for those but i suspect they were less effective than disk brakes.
For leverage on front drum brakes like I have, Aaron, the MC diameter is same as each wheel cyl. The foot effort required is then determined by the relative length of the actuator tab on the pedal.
To get the right mix of front brake pressure and tranny brake pressure, it is easiest to vary the tranny brake's slave cyl diameter with relation to the wheel cyl diameter. Slave cyls should be available from off-road outfits.
We drove our '86 Sable 30K miles with rear brakes not bled, thanks to idiot dealer mech. It kept warping front rotors, and otherwise was
noticeable only on wet road.
For economy, simplicity, reliability and safety, hydraulic front brakes are better than mechanical. Hydraulic drum brakes can be argued to be just as authentic as mechanicals, because every Duesenberg from their beginning in 1921 had 4-wheel hydraulic drum brakes. By 1926, Chrysler, Franklin, Studebaker and lots of others had hydraulic 4-wheel drum brakes.
John Steele; no not significantly closer. Still patterns and castings to make
Kep; truly there are two distinct issues to consider
1; a good easy to install brake design that satisfys the "aesthetics" for the arbitrators of good T "taste".
2; ensuring that the handling is safe in all conditions of the road
I perhaps got it backwards upthread, when I was paraphrasing Les' comments for personal clarity...
Photo below is my '24 Speedster RF wheel and kingpin. An imaginary line extended from the kingpin to the ground hits INBOARD of the tire-contact patch, not OUTBOARD. My method is hardly exact, but the offset looks like 2"-3". (And it also looks like my headlamp lens has become discombobulated.)
Therefore, a LF tire grabbing dry pavement when the RF tire is on ice will want to rotate the LF tire around the kingpin to the RIGHT not the LEFT.
Hmmm — I see Ralph caught my error yesterday.
Can small drums on an early T, be converted to rear braking ( without going to rocky mountain or similar knock offs ) and without being noticeable from when viewed from behind the car ??
Lined brake shoes in small drums have better braking. There also AC outside band brakes made for the small drum. Together they work reasonably well especially if the trans brake is retained as well. This what I currently have on my '13
Les, I'd like to see some pics if you have them, either here or directly to me email@example.com -remove all of the slashes.
Les, I too would like to see some pics of your AC brake setup on your 13. Thanks, Neil
I am not home at the moment, so no pictures
This thread has truly drifted!!!