Transmission / Overdrive: T-90

[Bo Markham]

I've never seen one, never heard of one in a 6 cylinder passenger car, much less a 1960 1/2 ton 6 cylinder (170)T-cab pickup. Is the T-90, 59-63 a 3 spd WITHOUT Over Drive? Does anyone have one? I have a customer that seems to think the truck he has came factory equipped with one, at least that's what PO told him. The transmission he described to me is in a case stamped T-86E-1A and has over drive? The book and all the truck transmissions I have, the cluster gear has straight teeth 1st/Rev. with all other gears being helical. He indicates the cluster gear in the transmission in question has all helical teeth. This would seem to me to confirm that it is a car version T-86 w/od? I was under the impression that cars were equipped with T-96 transmission?

[StudeRich]

Six Cylinder Trucks, Heavy Duty Sedans, Taxis and Police Cars all had the Heavier Duty T-90 instead of the Standard 6 Cyl. T-96.

It would have the Larger Input shaft for a H.D. Clutch and a 6 Bolt top Cover T-86 Case, either Std. OR Overdrive.

Not News to most.

[RadioRoy]

The six cylinder cars had T-96. The V-8 cars had the heavier T-86. The high power cars had the even heavier T-85.

The trucks generally got a heavier transmission than the cars, so the Champion six trucks got the T-90, which looks like a T-86, but has the straight-cut low gears.

[Bo Markham]

The six cylinder cars had T-96. The V-8 cars had the heavier T-86. The high power cars had the even heavier T-85.

The trucks generally got a heavier transmission than the cars, so the Champion six trucks got the T-90, which looks like a T-86, but has the straight-cut low gears.

Roy,

The last part of your reply is just the problem. All the truck transmissions I have have the straight-cut low gears, and coincides with what the parts catalog lists as replacement parts. The transmission in question doesn't have straight-cut low gears (Cluster, 1st/Rev. Gear, and Rev. Idler), but rather all are helical. As I stated in my post, this would seem to confirm that it is the car version. Which would indicate that at some point the transmission has been changed out. That would explain why the owner has ordered the correct parts indicated for the truck, and received the wrong parts for the actual transmission installed.

What I was really asking for was confirmation that my conclusion about the transmission (based on description) might be correct? Namely, that it is the car version and not the truck version, In the mean time, the shop is sending me the bad pieces and I will have them to compare. I just didn't want to send them the wrong parts, based merely on what the parts book says is correct, as (Not News to Most) others apparently have.

Thanks Roy.

[PackardV8]

Does anyone else share a vague recollection of SASCO/SI et al once having a big stack of the straight 3-speed trannies? Seems if I even remember them having both the T89 and T90 versions. Back then, I'm not even sure if I knew the car and trucks were different.

FWIW, I once saw a '56J drag car with a straight 3-speed, no overdrive. That was right before it dropped a valve/broke a piston. The stock Packard V8 did not like high revvs.

jack vines

[RadioRoy]

Roy,

What I was really asking for was confirmation that my conclusion about the transmission (based on description) might be correct? Namely, that it is the car version and not the truck version, In the mean time, the shop is sending me the bad pieces and I will have them to compare. I just didn't want to send them the wrong parts, based merely on what the parts book says is correct, as (Not News to Most) others apparently have.

Thanks Roy.

Bo, I am at the edge of my knowledge here (never having owned a truck) but it seems to me that there are two/three differences between the truck T-90 and the car T-86:
-the T-90 has straight cut gears as you notice
-different 1st and 2nd gear ratios?
-the T-90 also has a unique input shaft. It has the big splines for the Commander car clutch, but has the small pilot nose for the Champion engine.

If your customer has a truck with a Champion engine, and it has helical cut gears in a case that says T-86, then it's possible/likely that it is a car Commander T-86 transmission, but the input shaft has either been changed to a T-90 shaft, or the pilot shaft has been turned down to a smaller diameter by a machine shop.

As far as I know, all of the transmissions came in overdrive, or no-overdrive variations: T-96, T-86, T-90, and T-85.

Does/did the customer's truck actually have the transmission installed, or is it one that he plans/hopes to install? If the latter, you might have him check the input shaft for the proper clutch splines and pilot shaft diameters.

[r1lark]

Bo, I am at the edge of my knowledge here (never having owned a truck) but it seems to me that there are two/three differences between the truck T-90 and the car T-86:
-the T-90 has straight cut gears as you notice
-different 1st and 2nd gear ratios?
-the T-90 also has a unique input shaft. It has the big splines for the Commander car clutch, but has the small pilot nose for the Champion engine.

If your customer has a truck with a Champion engine, and it has helical cut gears in a case that says T-86, then it's possible/likely that it is a car Commander T-86 transmission, but the input shaft has either been changed to a T-90 shaft, or the pilot shaft has been turned down to a smaller diameter by a machine shop.

As far as I know, all of the transmissions came in overdrive, or no-overdrive variations: T-96, T-86, T-90, and T-85.

Does/did the customer's truck actually have the transmission installed, or is it one that he plans/hopes to install? If the latter, you might have him check the input shaft for the proper clutch splines and pilot shaft diameters.

Let me add a little to RadioRoy's response. There will be some truck T90s with V8 input shafts. A '55 (and maybe '56) V8 half ton used the T90 with a V8 input shaft. Also, 8E half ton trucks with 6 cylinders used the V8 input shaft along with a V8 bellhousing and clutch (there was a special adapter plate to mate the V8 belabouring to the OHV 6).

This additional info still doesn't solve Bo's issue however........

[jts359]

The back of a 6 cylinder truck is all V-8 The pilot shaft is larger , Don't ask me How I know

[Studebakercenteroforegon]

When you say "6 cylinder trucks" you need to differentiate between Champion sixes and Commander sixes. The Commander Six transmission has a pilot shaft - or "main drive gear" if you prefer - that is completely interchangeable with the V-8 version.

[Bo Markham]

Bo, I am at the edge of my knowledge here (never having owned a truck) but it seems to me that there are two/three differences between the truck T-90 and the car T-86:
-the T-90 has straight cut gears as you notice
-different 1st and 2nd gear ratios?
-the T-90 also has a unique input shaft. It has the big splines for the Commander car clutch, but has the small pilot nose for the Champion engine.

If your customer has a truck with a Champion engine, and it has helical cut gears in a case that says T-86, then it's possible/likely that it is a car Commander T-86 transmission, but the input shaft has either been changed to a T-90 shaft, or the pilot shaft has been turned down to a smaller diameter by a machine shop.

As far as I know, all of the transmissions came in overdrive, or no-overdrive variations: T-96, T-86, T-90, and T-85.

Does/did the customer's truck actually have the transmission installed, or is it one that he plans/hopes to install? If the latter, you might have him check the input shaft for the proper clutch splines and pilot shaft diameters.

Roy,

The truck in question is a 60 5E6-122. Should be a Commander 6 with truck T90 according to the books. The owner claims the truck has never been touched and is all original. Correct parts were sent to the transmission shop for the original transmission, as per the parts catalog. These proved different then what is in the T86E-1A case. No straight cut gears, all helical. So I'm thinking it is either a passenger car version of the T90, or possibly T86? The problem here is that parts for the two are different and not interchangeable.I will know for sure shortly, as they are sending the bad parts to me so I can look them over and match to either T90, or T86 parts. I just want to make sure I send the shop the right parts.

Thanks Again, Bo