I'll take a model T on the rocks, please

[Jeff I]

A few weeks ago, I got to enjoy an interesting experience driving my model T. Leaving the house on an early Saturday morning, everything looked fine until I got to into town and tried stopping at an intersection only to find there was a thin layer of ice on the roads. So of course, I slid up to my first stop light. My T has no outside or auxiliary brakes and only uses the transmission brake. I had to "pump" the brakes 2 or 3 times before I came to a stop, but not how I would in a typical fashion. I had to release the brakes to get the car straight again! When I was braking, the wheel(s) locked up and the rear of the car slid to the right. That had happened twice that morning. It was pretty early, so there wasn't really any other vehicles on the road and I drive the T pretty cautiously as it is so I was never in panic mode nor was I stabbing the brakes. Just an along for the ride event. It did bring a thought to mind though, I never bothered to think about it but do model T brakes only apply braking power to one wheel? What happens to the driver's side wheel when braking power is applied?

[Hal]

If the drive shaft is locked up, the differential carrier is locked. In this condition, one of two things can happen. Either both wheels are also locked or else one is turning forward and the other backward. Which side does which is dependent on many variables, but none are because it's the drivers side or passenger side.

[mtntee20]

Jeff,

I'll take the first shot at this one. Two wheel drive vehicles are actually ONE wheel drive. Four wheel drives are actually TWO wheel drives. Due to the differentials in the axles, when one wheel slips the other drives. In the case of a T, when one wheel stops, the other slips. That's why "posi-trac" and locking rear ends were developed. The differential will supply power or braking to only one wheel while letting the other wheel slip.

On newer cars, the braking is on EACH wheel. Thus, the skidding due to one wheel grabbing and the other not, is eliminated due to the source of the braking being the wheels and not the drive shaft through the differential. That was confusing, wasn't it? With accessory brakes such as AC, Rocky Mountain, or Sure Stop, the braking is on the wheels the same as with newer cars. The transmission brake is now more of an auxiliary or additional brake rather than the primary brake through the differential.

I hope this makes it a little clearer.

Good Luck,
Terry

Dang, Hal beat me by one minute.

[ironhorse]

Braking is applied to the transmission and under normal driving it is controllable. on a slick surface such as ice (or black ice) both rear wheels may not get equal braking when first applied causing the car to "Skew" to one side or another. If you have lined brakes for the rear wheels (emergency brakes) and they are adjusted properly with equal force being applied to each wheel then braking using the hand brake might be safer on slick roads, just remember to be ready to release them if they lock up then re-apply. JMHO YMMV.

[Rich Eagle]

Thanks for the insights. It is nice to know what is going on back there. So far I have just enjoyed the excitement of sliding.
Rich