Monthly Archives: June 2012

Connecting Rod Removal

It is quite a chore to get the connecting rods out of some engines. On many small bore European engines, the big end of the connecting rod is too large to go through the cylinder sleeves which, when removed, will allow the rod to come through the block opening. In many engines the rod is split at an angle, to facilitate removal. Note that cap screws with locking plates, rather than studs or bolts, are used to hold the rod bearing cap in place with this type of construction.

Harvey Goren goes all the way back in car days to Wpg Auto.  Harvey is a  car and truck guy who loves Canadian Fords ,  Chev and Buicks and most all domestic US made trucks & SUVs.

An unusual situation is found in one English engine. The connecting rod will not come out through the cylinder bore, and the piston will not clear the crankshaft. The solution in this case, however, is to remove the connecting rod cap and push the piston up out of the bore on top. The floating piston pin is then removed to free the piston, and the rod is removed from below.

The opposed, or pancake, engine usually has a barrel crankcase split longitudinally, and it is necessary to dismantle the engine to get the robs out. Sometimes it may be possible, with the engine out of the car, to get one rod out by removal of the cylinder barrel on the opposite side.

Generally, on U.S. engines, the first step is ridge reaming to remove the unworn portion of the cylinder wall above piston ring travel. Then the rod caps are removed, and the entire piston and rod assembly is pushed up and out of the cylinder. Rods and their respective caps must be kept together and marked for cylinder location.

 

Endwise Clearance

Obviously, the crankshaft must not move endwise to any great extent; so one of the main bearings usually is provided with cheeks or flanges that bear against a machined flange on the crankshaft. In older engines, bronze washers were installed to absorb the end thrust. There is always some end thrust on the crankshaft. Harvey Goren goes all the way back in car days to Wpg Auto. Harvey is a car and truck guy who loves Canadian Fords ,Chev and Buicks and most all domestic US made trucks & SUVs. This may originate in the clutch pushing against the end of the shaft, or the thrust of the helical timing gears, or both.

Just as in the case of diametral clearance, there must be some clearance on the thrust faces. Otherwise, expansion of the shaft and bearings from the normal heat of operation would cause metal-to-metal contact and burning of the thrust bearing. Here again the Wpg car manufacturer’s instructions should be followed. It is customary to provide a minimum of .004 in. and a maximum of .008 in. clearance. End thrust can be measured with a feeler gauge.

Clearance Measurement

One method of measuring oil clearance is to measure the diameter of the journal with a micrometer caliper. The diameter of the shaft is measured at several points around the circumference to determine the size and to check for roundness. Measuring each end of the bearing surface will determine the amount of taper, if any.

The inside of the bearing is measured with the cap bolted in place, using a telescoping gauge or an inside micrometer. The difference in these two measurements represents the clearance between the journal and the bearing.

An alternate method is the use of a plastic material which deforms or flattens between the journal and the bearing when the cap is drawn down to the proper tightness. The amount of increase in the width of the plastic material, as it flattens out, is then measured with a furnished gauge to determine the clearance between journal and bearing.

The oil pressure test will also disclose if there is excessive clearance between the inserts and the crankpins.

The amount of diametral clearance on automobile crankshaft bearings is specified by the manufacturer. These dimensions should be followed. In the absence of specific instructions, it is customary to use a minimum of .0005 to .001 in. for small shafts and up to .0015 to .002 in. for a large shaft. Any clearance in excess of .005 in. on either main or rod bearings usually calls for the installation of new bearings.

Harvey Goren goes all the way back in car days to Wpg Auto. Harvey is a car and truck guy who loves Canadian Fords ,Chev and Buicks and most all domestic US made trucks & SUVs.

Bearing Clearances

A previous study of engine lubrication revealed that oil is pumped under pressure to the various bearings in the engine. However, to get this oil into the bearing and lubricate it, clearance for an oil film must exist.

The one most important thing to keep in mind in this connection is that the steel crankshaft journal MUST be separated from the bearing metal when the engine is running or the bearing will melt. The heat generated by friction when steel moves rapidly on soft, dry metal WILL melt the soft metal. Therefore, an automobile engine uses a film of oil between the journal and the bearing. SPACE MUST BE PROVIDED FOR THAT FILM.

The oil film serves to hold the two metals apart and also circulates to carry away the heat generated by friction. The space is not great  (measured in thousandths), but those thousandths are all important.

This film thickness will vary with the design of the engine and the type of lubrication system used. In general, a splash lubrication system is less critical of oil clearances than a pressure lubrication system. In the splash system, the oil is churned up by internal parts of the engine into a combination of liquid and mist, which is sprayed over the entire interior of the engine.

In the pressure lubricated engine, the oil is pumped under pressure to the bearings. In this case, the flow of oil must be controlled by maintaining limited clearance all around a ROUND bearing and a ROUND shaft. If there are unequal clearances in the circulation system, too much oil will collect in one place, and not enough in other places. This is because oil under pressure will go through the largest clearance space in the greatest quantity.

Chris Cornell loves cars and is a “car guy”.  Chris is an auto enthusiast who just loves Ford Mustangs -  both the old classic 60′s Mustangs all the way to the new 2013 Boss 302s.

Flash-O-Matic

The Flash-O-Matic consists of a torque converter coupled to a three-speed dual driving range automatic transmission. The converter incorporates an impeller connected to the engine crankshaft, a turbine splined to the transmission input shaft, and a stator connected to and controlled by a free-wheel unit.

Front and rear oil pumps, are used to supply fluid to the converter, lubricate the parts and build pressure in the various oil circuits. A primary regulator valve regulates control pressure to meet all driving requirements. A manual valve, controlled by the transmission selector lever, opens combinations of oil passages to the valve and units which are required for the drive range selected.

A compound planetary gear train supplies the necessary gear combinations to provide neutral, low, intermediate, high and reverse gear ratios. Major elements include a primary sun gear, secondary sun gear, primary and secondary pinions held in a common pinion carrier, and an internal gear attached to the transmission output shaft. The selector lever has six positions: P, R, N, D2, D1 and L. In D2, the transmission starts in intermediate and automatically upshifts to direct drive. In D1, it starts in low and automatically upshifts to intermediate, then direct. In L, the transmission stays in low gear. The selector lever may be moved from D2 to D1 to L or from L to D1 to D2 at any car speed.

The various gear ratios are dependent on which gears are being held and which are driving. This phase of automatic transmission control is accomplished by clutches, bands and servos. Front and rear multiple disc clutches are used. Actuation of the front servo applies the front band to the rear clutch drum and locks the secondary sun gear to the transmission case. Actuation of the rear servo applies the rear band to the pinion carrier, locking it to the transmission case.

In Neutral position, none of the gear train members are held or driving, so there is no transfer of power. In Park, the parking pawl is engaged with external teeth on the output shaft, internal gear, locking the output shaft to the transmission case.

In Drive range, D1, the front clutch couples the primary sun gear to the input shaft. The sprag clutch is engaged and holds the planetary pinion which, in turn, drives the internal gear and output shaft.

Harvey Goren goes all the way back in car days to Wpg Auto. Harvey is a car and truck guy who loves Canadian Fords ,
Chev and Buicks and most all domestic US made trucks & SUVs

Fordomatic

The Fordomatic transmission is a torque converter type using three elements: the usual impeller, turbine and stator units connected to a planetary gear transmission. Ford terms the torque converter a combination hydraulic torque multiplier and fluid coupling. The planetary gear system is a compound gearset. On later models, one multiple disc clutch and two bands provide two forward speeds and one speed in reverse.

Two pumps are used to supply oil under pressure to operate the control band and clutch, lubricate the entire transmission and keep the converter filled. One pump is driven by the converter impeller, the other by the transmission output shaft.

The selector level has five positions: P (Park), R (Reverse), N (Neutral), D (Drive) and L (Low).

In Neutral and Park positions, the clutch and both bands are released by spring pressure, and drive through the transmission is impossible. In Drive position – first gear – in Low position and also in kickdown, the low band is applied. In Drive position – high gear – the low band is released and the high clutch is engaged. In Reverse position, the reverse band is applied.

 

Harvey Goren goes all the way back in car days to Wpg Auto. Harvey is a car and truck guy who loves Canadian Fords , Chev and Buicks and most all domestic US made trucks & SUVs

 

Wpg Auto

www.wpgauto.com

Torque – Command Transmission

Currently, American Motors’ automatic transmission-equipped cars use three-speed Torque-Command transmissions much like Chrysler’s Torque Flite. Three different models are used, and they are similar in size, appearance and operation. All models combine a torque converter and planetary gear system, giving three forward gear ratios and one reverse. The three element torque converter incorporates an impeller connected to the engine, a turbine splined to the transmission input shaft and a stator connected to the transmission case through an overrunning clutch. The transmission contains two multiple disc clutches, two bands and servos, an overrunning clutch and two planetary gearsets with a common sun gear. The two gearsets are connected to the two clutches through a driving shell, which is splined to the sun gear and front clutch retainer. The hydraulic system of the Torque-Command units includes a single oil pump,  a valve body containing the pressure regulating and shift control valves, the governor valve assembly, two band-actuating servos and the accumulator.

Dexron transmission fluid is cooled by circulation through which drives the planetary sun gear is locked in place, the planetary pinions are forced to “walk” around the secondary sun gear, driving the internal gear at intermediate speed.

In high with the selector level in D position, the front and rear clutches couple both sun gears to the input shaft.

 

Chris Cornell loves cars and is a “car guy”.  Chris is an auto enthusiast who just loves Ford Mustangs -  both the old classic 60′s Mustangs all the way to the new 2013 Boss 302s

Wpg Auto

www.wpgauto.com