Hydramatics

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Originally posted by Seasalt June 18th 2006:

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Hydramatic badge as used on EH and EJ Holdens. EH shown. Click to Enlargen. Photo by Eddie 63.

Hydramatics:

Introduction:

The Hydramatic was introduced with the EK Holden.

The RotoHydraMatic:

The RotoHydraMatic (sometimes spelled Roto Hydra-Matic or Roto-Hydramatic) was an automatic transmission built by General Motors and used in Oldsmobiles and Pontiacs. It was based on the earlier, four-speed Hydramatic, but was more compact, providing only three forward speeds with a small torque converter in place of the Hydramatic's fluid coupling. Oldsmobile described the torque converter's stator as the "Accel-A-Rotor." (Oldsmobile Super 88 "with a completely new and smoother-than-ever Hydra-Matic Drive featuring Accel-A-Rotor action for quick, silken getaway! ")
Grey 138 cu in Holden Six Cylinder Engine most likely from FB since it has hydramatic gearbox and Vacuum Pump connections under the Fuel Pump for driving the Wipers. Click to Enlargen. Photo by merc9112006.
 
Grey 138 cu in Holden Six Cylinder Engine most likely from FB since it has hydramatic gearbox and Vacuum Pump connections under the Fuel Pump for driving the Wipers. Click to Enlargen. Photo by merc9112006.

Two Models of Hydramatic:

There were two models of the Roto Hydramatic: the lightweight Model 5 (240), which weighed 145 lb (66 kg) and had ratios of 3.03, 1.58, and 1.00, and the larger Model 10 (375), which weighed 154 lb (70 kg) and had ratios of 2.93, 1.56, and 1.00. The stator provided a maximum torque multiplication of 1.2 to 1. Pontiac and Oldsmobile both used the larger Model 10 (375) transmission, sometimes referred to as a "Slim Jim", in various models. Oldsmobile used the Model 5 (240) transmission in the F85 Cutlass. In 1961 Detroit Transmission Division produced the new Model 5 "small Hydra-Matic" for the Oldsmobile Cutlass (F-85), but on the back of series production the Willow Run transmission plant produced a modified version for the British Vauxhall PA series Cresta and Velox models. This transmission was soon being fitted by GM-Holden’s staff to Australian assembled Vauxhall PA’s. A few months later, the same transmission was used in Germany's Opel Kapitän, and in the EK Holden. The EK used the "H561" (released May 1961). This was replaced in later EK's by the "H562". The EJ and EH Holdens were equipped with the "H562" and later "HA563" units with revised ratios. Each unit had "H5xx" (where xx = year), as a prefix for the full serial number stamped on the plate attached to the casing. Holden's HydraMatic manual also refers to the transmission as the RHM 240 series.

The Roto Hydramatic:

In Australia the transmission was just called the Hydramatic. The Roto Hydramatic was cheaper and smoother than the earlier Hydramatic, but slower, softer shifts sacrificed performance for refinement. American owners discovered that it was less durable than the earlier Hydramatic, and was prone to various mechanical problems. The factory caused confusion in describing the 3 speed Hydra-Matic as a 4-S model or a 4 stage transmission, which implied it was a 4 speed. However, "second" gear is actually first gear minus the torque multiplication, which quickly ceases to multiply seconds after the car starts rolling. This change in ratio on the first speed was achieved by activating a valve and filling and unfilling the torus chamber. Very confusing, but you only hear the transmission shift twice, as a three speed will do.

Hydramatic Servicing:

Just like other GM Automatic Gearboxes, Hydramatics are serviced by removing the Pan to change both the Oil and the Filter. The Reverse Gear Band is retensioned (if needed) when the Pan is removed and the procedure is similar to retensioning the Band in a Trimatic.

Hydramatic Oil Filter:

just rang the guys i know at repco hoppers crossing
Filter P/N JXF6000 RRP $335 will do it for $175 (they have to order it in.) i asked him if it included the gear box with the retail price.
Gasket P/N JPG6000 $13.60 (in stock on the shelf)
ask for Adam 0397495350 Repco
he said he will do it for 175 because he appreciates people keeping a good old eh on the road.
damm i should sprook that more often when i get prices hahaha all the best.
ps if your not around hoppers ring em any way they can probaly get it sent to your store.End of submission by Wilson86.

PowerGlide:

The Roto Hydramatic was phased out in 1964 in favour of the two-speed Chevrolet Powerglide and three-speed Turbo-Hydramatic.
 
EH Holden Premier Hydramatic Gearbox. Photo by 63Prem. Click to Enlargen.
EH Holden Premier Hydramatic Gearbox. Photo by 63Prem. Click to Enlargen.

Coupling Plate from EH Holden Premier Hydramatic Gearbox. Photo by 63Prem. Click to Enlargen.

 
Hydramatic Kickdown Mechanism on an EH Holden. Photo by Hackett.
 
Hydramatic Kickdown Mechanism on an EH Holden. Photo by Hackett.
 
Coupling Plate from EH Holden Premier Hydramatic Gearbox. Photo by Hackett. Click to Enlargen.
   
 

Holden 3 speed Hydramatic Ratios:

D (Drive) - 1:1 S (Second) - 1.5775:1 L (Low) - 3.6394-3.0303:1 R (Reverse) - 3.5707-2.5159:1
Hydramatic Kickdown Assembly EK-EJ. Photo by Stock_EJ. Click to Enlargen.

Links:

Oil Filter Thread

Eddie 63's Shed

Hydramatic Image

Kickdown Assembly Thread

Hackett's Shed

Terms:

Terms

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