Transmission / Overdrive: T86 - T90 OD trans

[Phatfenders]

I was just looking at a thread titled, How to ID truck T90 OD trans by PackardV8 that touched on something I have been wondering about for a while. I have a T86 OD (60 Lark V8) that I would like to convert to all T90 internals, for obvious reasons. I do know that jeeps with top loader T86's w/o OD can be completely converted to T90. My question; is it possible to fully convert a T86 OD side shift to T90. Anybody out there done this?

[RadioRoy]

I'm curious. What are the obvious reasons? Whenever someone uses that term and I don't know what the obvious reasons are it makes me wonder if everyone else knows and I am just too dumb to figure it out.

[Phatfenders]

I'm curious. What are the obvious reasons? Whenever someone uses that term and I don't know what the obvious reasons are it makes me wonder if everyone else knows and I am just too dumb to figure it out.

Valid question. The T90's have square cut gears that are stronger than the helical cut T86 gears and with the square cut gears you can shift into 1st gear without coming to a complete stop. Overall its a much improved transmission over the T86.

I should add that the only 2 parts that I question are the OD main shaft and the shift forks. Everything else I all ready know will easily convert.

[PackardV8]

Valid question. The T90's have square cut gears that are stronger than the helical cut T86 gears and with the square cut gears you can shift into 1st gear without coming to a complete stop. Overall its a much improved transmission over the T86.

I should add that the only 2 parts that I question are the OD main shaft and the shift forks. Everything else I all ready know will easily convert.

Just be aware the T90 has a lower first gear which winds out quickly and those stronger straight cut gears have a distinct whine in first. Having said that, I'm using a Stude truck T89 behind the Packard V8 in my E12.

jack vines

[r1lark]

I should add that the only 2 parts that I question are the OD main shaft and the shift forks. Everything else I all ready know will easily convert.

The answers to your questions would be found via a comparison of the part numbers in the car and the truck parts manuals. A Hollander Interchange might also have the details you need.

I'm the opposite of you - I find the T-86 to be a much better transmission for normal driving, mainly for the reasons Jack laid out......first gear is not so low in a T-86, plus the quietness of the helical first gear.

[Phatfenders]

Just be aware the T90 has a lower first gear which winds out quickly and those stronger straight cut gears have a distinct whine in first. Having said that, I'm using a Stude truck T89 behind the Packard V8 in my E12.

jack vines

Jack, thanks for that info, having a lower !st gear will be a good thing in my case. Now you've got me curious about T89's.

The answers to your questions would be found via a comparison of the part numbers in the car and the truck parts manuals. A Hollander Interchange might also have the details you need.

I'm the opposite of you - I find the T-86 to be a much better transmission for normal driving, mainly for the reasons Jack laid out......first gear is not so low in a T-86, plus the quietness of the helical first gear.

r1lark, very good idea, thanks!

[Ron Dame]

For strength, the T89 is better. It was used behind V8 trucks, while the T90 was behind 6 cylinder trucks.

[PackardV8]

For strength, the T89 is better. It was used behind V8 trucks, while the T90 was behind 6 cylinder trucks.

Yes, some V8 trucks, mainly '59 and later 289" trucks.

No, maybe not all. Didn't '55-58 V8s use the T90 also?

Maybe, if strength is what one wants, the T89 is definitely stronger.

jack vines

[Phatfenders]

Well now I'm completely rethinking this whole transmission situation, the T89 sounds like what I was trying to accomplish. Since I'm not very familiar with the T89, are they side shift? I know they mostly came with OD. I would be very interested in a T89 W/OD if anyone knows of one that's for sale.

My T86 is just not holding up (I think I'm to hard on it), I've gone through it twice in as many years and now 3rd gear syncro is giving me trouble. I really like what I'm hearing about the T89. Another option is a T85 if anyone knows of one for sale.

Thanks for all the input, Chuck

[PackardV8]

Well now I'm completely rethinking this whole transmission situation, the T89 sounds like what I was trying to accomplish. Since I'm not very familiar with the T89, are they side shift? I know they mostly came with OD. I would be very interested in a T89 W/OD if anyone knows of one that's for sale.

My T86 is just not holding up (I think I'm to hard on it), I've gone through it twice in as many years and now 3rd gear syncro is giving me trouble. I really like what I'm hearing about the T89. Another option is a T85 if anyone knows of one for sale.

Thanks for all the input, Chuck

Stude T85s are pretty much unobtanium, but the truck short tailshaft T89s are found occasionally. I may have one under the workbench somewhere and we're not as far apart as some.

jack vines

[rkapteyn]

I have a N.O.S.long tail T85 as used in the 1958 Golden Hawk and Packard Hawk for sale at $1200.00 , still in it original crate.
I am also selling my two Packard Hawks because I will never restore these due to my health problems and age.
I also have most of the parts to convert an automatic in these cars to stick shift.
Robert Kapteyn
Text me at eight one five 212 2389 if interested.

[Don Jeffers]

I have a N.O.S.long tail T85 as used in the 1958 Golden Hawk and Packard Hawk for sale at $1200.00 , still in it original crate.
I am also selling my two Packard Hawks because I will never restore these due to my health problems and age.
I also have most of the parts to convert an automatic in these cars to stick shift.
Robert Kapteyn
Text me at eight one five 212 2389 if interested.

PM sent and phone message left.

Don J

[Phatfenders]

Stude T85s are pretty much unobtanium, but the truck short tailshaft T89s are found occasionally. I may have one under the workbench somewhere and we're not as far apart as some.

jack vines

Thanks Jack, I may want to have a look under that work bench one of these days.

[JoeHall]

Stude T85s are pretty much unobtanium, but the truck short tailshaft T89s are found occasionally. I may have one under the workbench somewhere and we're not as far apart as some.

jack vines

My experience with T86 lasted about 50,000 miles, and was same as the OP described in post #9. For my use, they are total POS.

I have several hundred thousand miles' experience with T85 & T89, and they are comparable to T10 when it comes to ruggedness. I have never "broke" one. I prefer T89, since its lower first gear is more compatible with the 3.54 and 3.31 rear ends, which I run. As for difference in first gear cuts between the two, it is all but unnoticeable to me. Neither are synchronized in first; they shift and sound about the same.
JMHO