russell-t

My Roto-5 hydramatic is shifting great through all three gears,but I cannot

sense when it is shifting into 4th gear. Starting off and moving up to high-

way speed I am only feeling 1-2,2-3. Even up to 75mph I still haven't felt

any shift into the 4th speed. 1-2 shifts and 2-3 shifts occur smoothly

and without any jerking or lag. Trans was rebuilt approx.500 miles ago and

I have not ever felt the 3-4 shift.

I feel as if I may have the TV rod that comes up from the transmission

pulled up too far,the adjustment being at the clevis on the top of the

TV rod. Carb TV lever is adjusted to give smooth shifts and that seems

to be at the right setting. Adjusting the clevis back down is creating

longer shift points and rough 1-2, 2-3 shifts.

Is there anyone out there who is familiar with the slim-jim Roto 5

and it's adjustment procedure? I'm afraid if I keep messing with it I will

slowly destroy it.

jensenracing77

i am in the middle of the very same thing on my Jetfire. i still need to play with it more but i am almost sure i am getting 4th gear. i think the problem with mine is a 1-2-3 shift so fast that both shifts feel like one. next time after the third shift, pull the shifter down into the 2 position. if it down shifts, you were in 4th gear. the first gear on the indicator is 1st gear. second gear on the indicator is 2nd and 3rd gear. third gear on the indicator is 4th gear. the extra gear they added in 62 over the 61 3 speed is VERY generic. my transmission guy said that GM was walking the line with false advertising when they made these a so called 4 speed. i will update you on what i find but it may be another week or two.

rocketraider

I'm not that familiar with the 5 but on the 10 (big car) what you feel as the 1-2 shift is actually the 2-3, then what you think is 2-3 is the shift into direct drive or 4th range. The Accel-a-Rotor in the 10 is where the 1-2 shift on those actually happens, within a few feet of car starting forward and so quick as to be imperceptible. I understand the 5 to be a lighter-duty version of the 375/10 so I think it probably works similarly.

Tedd Thompson

I don't think the roto 5 or the roto 10 are truly 4 speed transmissions.I seem to remember that the 4th gear was a myth gear promoted by the advertising gurus of Oldsmobile. One year the roto was advertised as a 4 speed and the next it was a 3 speed. Rocketrader you must have the technical manuals that describe the gear shift engagements does it in fact say there are 4 separate gears? ..Tedd

jensenracing77

there are 4 fluid changes and 4 ratios that creates 4 speeds but there is not 4 gears.

Tedd Thompson

This is how I remember it , I should have said 3 speeds not gears....TeddFrom Wikipedia, the free encyclopediaJump to: navigation, search
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2009)

Roto Hydramatic (sometimes spelled Roto Hydra-Matic or Roto-Hydramatic) was an automatic transmission built by General Motors and used on Buick and on some Oldsmobile and Pontiac models from 1961-1964. It was based on the earlier, four-speed Hydramatic, but was more compact, providing only three forward speeds plus a small 8" fluid coupling with a stator in place of the Hydramatic's fluid coupling. Oldsmobile, one of the users of this transmission, called the torque converter's stator the "Accel-A-Rotor." The lightweight, aluminum-cased transmission was sometimes nicknamed the "Slim Jim."

There were two models of the Roto Hydramatic: the lightweight Model 5, which weighed 145 lb (66 kg) and had ratios of 3.03, 1.58, and 1.00, and the larger Model 10, 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 1.2:1.

In 1961-62, the "Model 5" was used on the Opel Kapitan, Vauxhall Velox/Cresta and EK Holden. The Roto Hydramatic was cheaper and smoother than the previous Hydramatic, but its slower, softer shifts sacrificed performance for refinement. Owners discovered that it was also less durable than Hydramatic, and was prone to various mechanical problems.

The Roto Hydramatic was phased out after the 1964 model year in favor of the two-speed Super Turbine 300 and three-speed Turbo-Hydramatic. As with previous Hydramatic transmissions, auto safety experts criticized GM for the Hydramatic design which had a shift quadrant sequence of Park-Neutral-Drive-Second-Low-Reverse (P-N-D-S-L-R) due to the placement of reverse adjacent to a forward gear as opposed to the more common P-R-N-D-S-L sequence found in most other automatic transmissions at the time that placed "reverse" between "park" and "neutral", which was also incorporated in the new Turbo Hydramatic design introduced on Buicks and Cadillacs in 1964, and then other GM divisions in 1965.

jensenracing77

they are listing the 61 ratios there, they were only 3 speeds. in 62-63 there were 4 ratios.

russell-t

To Rocketrader; Your explanation is making sense to me. When adjusting

the TV rod from the transmission all the way down to it's lowest setting,

I was still not feeling a 3-4 shift. Have not paid close attention when

starting out to feel anything that happens in that short time. Been trying

for weeks off and on to get this thing to shift into it's 4th gear,believing it

was out of adjustment.Feels good to know I can quit beating a dead horse.

To Jensenracing77; Your explanation also doesn't really put this question

to rest for me too. I appreciate your input and would like to hear what

you have found out in your search for the (mysterious) 4th gear.

To Tedd Thompson; Thanks for your input and the tech article you posted.

All this info helps so much. Will post anything I find out about in MY search

for the 4th GEAR.

rocketraider

Hmm. HydraMatic was introduced in 1940, and the N-Dr-Lo-R sequence and its variants continued thru 1964. The way I understand it the L-R design was to make it simpler to rock the car out of mud or snow, which made sense in the original HMT design.

DynaFlow appeared in 1948, again with a P-N-D-L-R shift sequence as did Chevrolet's PowerGlide in 1950. The DynaFlow variants kept the L-R sequence thru 1963, just before they went to T400.

The Borg-Warner automatics used by Studebaker and a few other independents were- you guessed it- P-N-D-L-R.

Ford was the only one at the time to use a P-R-N-D-L shift sequence starting with Ford-O-Matic in 1951.

Chevrolet did change PowerGlide over to P-R-N-D-L for 1958, supposedly as a response to the safety weenies.

Chrysler? Well, between pushbuttons and dash mounted shift levers, nothing was standard with them. It's telling that Chrysler also left the pushbutton TorqueFlite behind and incorporated column and floor shift PRND21 shift sequences for 1965- but only to be able to bid government vehicle supply contracts, since that "standard" PRNDL sequence was spelled out in the bid package.

So, since everyone but Ford was using an L-R shift sequence, and people were used to them, and those transmissions had either a reverse blocker piston or a physical detent that had to be bypassed to engage R, why was it a safety issue other than the government safety folks as usual had their continuous hard-on for GM?

It's also telling that Oldsmobile reported replacing a lot of parking lot fencing in 1964 when the 2-speed Jetaway was introduced for Cutlass and J-88. People would grab a motor pool car and, being used to HydraMatics, would instinctively pull the shifter all the way to the bottom to back out of a parking space. When they toed the gas, they found themselves climbing the chain-link fences. I've seen my parents and kin do the same thing when they changed from a HMT car to a THM car. I've also seen my dad lock the brakes many times when he was driving the car, when he'd been driving his stick-shift truck for a while and was trying to push the clutch pedal.

Can't tell you how many old car articles I've read that made a big deal out of Olds/Pontiac switching to T400 in 1965, saying "Oldsmobile had finally standardized!" Pfft. Looks like everybody else were the ones who changed, since HMT was the standard for 25 years.

joe_padavano

The only way to get your trans to shift into fourth is to replace it with a four speed transmission.

Yeah, the CSM optimistically shows four different ratios, but "second" is simply the different fluid flow through the fluid coupling. I've never actually sensed this shift in my 62 either. I would not waste my time playing with the TV linkage - you're not going to feel another shift point.

d2_willys

Chevrolet and Buick did change over on two of their transmissions. Turboglide (1957-61) and Flight pitch (1958-59). PRNDG. Chevrolet might have thought that it would be wise to change Powerglide over to the PRNDL quadrant, however Buick kept the Dynaslush to the LR quadrant.

Chrysler in 1953 and 1954 had quadrants of RNDL (no park) for Powerflite.

russell-t

Took the Cutlass out today for a nice long ride with lots of stops and starts.

Paid close attention to the car as it started out up to the first shift point

(1-2). Felt slight change in motion that is barely noticeable,and didn't feel

it all the time. Rocketraider..you seem to have the best explanation for

what's going on. After reading other posts from Joe and d2-****** I'm

satisfied that my transmission does not and never will have a 4th speed.

Thanks to you all I now know one more thing about this mystery that is

my Cutlass F-85.

rocketraider

d2 ****** and coldwar are probably the best transmission guys here, so their explanations and diagnoses can be banked on.

PetChemMan

In the full sized '61-64 Olds cars with the Roto "slim jim" transmission, they were referred to as 4S transmissions. Not 4 speed, just 4S . Lots of people mistook that to mean a 4 speed. They were in fact 3 speed transmissions, with a little temporary help off the line from a fluid coupling.
Reportedly, in the 1961 service manual, Olds does refer to the transmission as a 3 speed automatic. GM took some heat from the automotive press in those days for misrepresenting the actual number of forward gears, as compared to other transmissions with torque converters and 3 speeds.

rocketraider

I think a lot of the confusion stems from the fact that HydraMatics thru 1960 (1964 for Cadillacs and LWB Pontiacs) WERE true 4-speed automatics.

jensenracing77

if you look at the specs between the 61 and 62 manual, it is a 4 speed in 62 and 63. even showes the 4 ratios. it is a little generic how they got it but it is. about like the 6 speed Allison trans in the diesel truck. there is not 6 gear sets in them but they have 6 ratios.