Overdrive transmission for K 49-50

[Jim B PEI]

What model overdrive transmission was used--a T96? What interchanges from other makes such as Studebaker/Chrysler/Etc are possible to use?

[HJ-ETEX]

T96 was used on small cars like the HJ and 2WD Jeeps and Stude Champions. Big KFs used a T86. The top cover on the T86 has 6 bolts while the T96 has only 4 bolts.

[HJ-ETEX]

An additional conversation point: The T86 Trans used on KF cars has an unusually long input shaft. A few months ago I was looking at transmissions for another project and found that the T86 I had loose was actually from a Studebaker truck, so I had to look up a real KF trans my brother had. The input shaft lengths are: 9 3/4(KF) and 7 1/2(Studebaker) while a typical Chevy is 7 1/4 inches. The input shaft as used on Jeep vehicles with T30 trans & 226 equipped is also 9 3/4 inches. I have not seen an explanation why vehicles with the 226 engine needed such a long input shaft. However this feature was used designing adapter plates for 4WD Jeep motor swaps.

[Jim B PEI]

So....If I had a KF input shaft in my parts stash (I just might--I remember seeing one) and a Studebaker V8 T86, then a suitable overdrive transmission could be made up?? Thats if I can't find a KF one at some other place on one of my wanderings?

[Fid]

The overdrive equipped cars also had a different rear axle ratio.  I've heard mechanics claim that it is important to change the rear end too because although the OD transmission may allow the engine to run 33% slower, it has much less torque and as a result the engine still works harder to turn the higher axle ratio.  Anyone else have any thoughts / comments on this?

[HJ-ETEX]

Yes, I think your idea is quite possible Jim B.
All OD units on US cars from about 1939 to around 1969 were Borg/Warner add on units. The complete trans consisted of the straight trans gear box, an adapter plate/casting, and the OD unit. I am told there was a unit for larger transmissions (e.g. T86 or T85) and one for smaller transmissions (T96) although I have doubts. The OD unit gave a reduction of 30% so OD equipped cars typically had 4.55 rearend ratios that were reduced to 3.00 when the OD engaged.
Quite a few Chevy and Ford trans were equipped with the B/W OD unit. In fact, I saw a letter in a 1966 issue of Rod & Customs explaining how if you had a 3spd Chevy Saginaw trans w/OD and a Saginaw 4spd, you could switch out parts and end up with a plain 3spd Saginaw and a Saginaw 4spd w/OD. HOWEVER, it wasn't explained how you would fit a shifter to this - it is difficult enough to fit a floor shift to a 3spd w/OD.

[Jim B PEI]

HJ--it wasn't likely discussed because they hadn't thought THAT point through, I betcha! Just that the internal parts could be swapped. Its why I ask the questions, because I know I will overlook something that someone who has eyed many a part can say for certain it might or won't work.

Fid--Say my 49 K Special with 100hp has a 4.10 rear end with its 3 speed straight shift, but a hypothetical guy down the road with the 48 Frazer with overdrive and 100 HP has a 4.56 rear end. In effect he will have a more MPH and better MPG and maybe a bit better takeoff. Now, my car roars along at about 3100 RPM at 60 mph, but with the 0.7 overdrive transmission with the 4.10 = 2200 RPM at 60, which is the same RPM I have right now at a bit over 40. The difference between the 4.10 and the 4.56 is 0.9 which isn't all that much. (with a 4.56 and no overdrive, that would be about 3450 RPM) That my engine is now rebuilt at 30 over, tight and properly adjusted on the valves, with very good compression, it is likely the equivalent of a 245 engine, which is about 9% larger--and likely if I put the gas to it, nearly the same amount more powerful than the factory standard build. So, it is a wash, more or less. I think that my rebuilt engine could handle an overdrive without changing the rear end out. I have heard mention--it was someone like Curt Bonser or Robert Oleson who talked about it--of a 48 that this was done to, and it made it a fine freeway cruising car without any noticeable drawbacks, just giving it a 4th gear. Mind you, this was in flatland territory in the midwest. There aren't too many hills around this region either, and I'd have to get well into Nova Scotia or central New Brunswick before that's a worry, and then I could just lock out overdrive. If I were driving such a K/F, I think that I'd normally go 1st, 2nd, O/D 2nd and hold it there, and then shift to third at about 45 mph.

[Jim B PEI]

HJ-  The T96 was used in light duty applications. In Studebaker, behind the small 6 170/185 of 80 to 112 HP. The T86 was used behind moderate power engines--the 226 Continental from 100 to 140 hp in KF, as you pointed out. In Studebaker, this was the small V8, 232/224/259 of the 120-roughly 180 hp (and the Commander 6 also?) , and very unfortunately, some 289 as well. It seems that the T86 failed quite often behind the 289 which had higher torque, as well as HP into the 200s. In the 50's, Studebaker had used the T-85 for the Packard V8 and the supercharged Golden Hawks and 57 Packards and 58 Packard Hawk, all nearly 300 hp. The basic transmission for an Avanti was a 3sp floor shift, although maybe a single handful of cars were built that way. I have been in a 62 Hawk which had a 3 speed straight floor shift as well. Most had the automatic, and some had the 4 speed floor shift which was much more robust. This seems to be why the 3 sp with overdrive was never offered for the R1 R2 R3 cars, as all they had to deal with by the 60s was the T86 which just can't handle too much power or torque.

A friend has a nice 63 Avanti R1 with A/C, and he wants to convert the 4 speed to a 3 speed with overdrive sometime to get lower highway revs and heat. I think that a T86 would fit without too much problem, but I'm not so sure that a T85 would without some redesign work. Of course, he would have to use the T85 with an R1.

[HJ-ETEX]

Jim B: The 4 spd used in Hawks & Avantis was the B/W T10 which is an adaptation of the T85 3 spd. So if he really wants an OD, he should be looking for a Stude or Ford T85 OD trans. I can't say how easy this would be to find because for Fords I think it was a HD replacement for the Ford (weak) manufactured 3 spd. Ford started making their own HD 3 spd and 4 spd trans (TC type) in 1962. In the 80's these TC 4spds were used in Ford F150s and they had an OD 4 gear but it was probably only 10% rather than the 30% on the B/W unit.
Now I would say that the easiest solution would be to install a lower (numerical) rear end, but I knew a SDC member in Central Texas who had a 4 spd Avanti with a 2.92 rear end (Parts book says this was available on special order). It was said to have been ordered new by a 'shady' person in Arizona. It could probably hit 130 mph, but it had trouble starting off from a stop even on level ground.  I assume the 4 spd had an appropriate 1st gear ratio (high numerical), but may be it didn't. Well, the point is a 2.92 rear end and probably anything less than 3.31 wouldn't give satisfactory performance from a stop with a Stude V8/straight shift trans.

[HJ-ETEX]

Further on Studebaker trans: You know, once upon a time I assumed that most if not all 56 Golden Hawks had Ultramatics and I was surprised to find so many reports of 3 spd/OD equipped cars. But in a similar vein, there were a surprising number of 54/55 Manhattans with 3 spd/ODs.
In the case of Kaisers, the HD replacement for the T86 would be the T30. This was the trans specified for the Taxi cabs if any were built.
While 4WD Jeeps used T30s, the 2WD variants used either T96 or (still) T86  up to the late 60s.
All the T30s I have seen were bolted to transfer cases!