5-speed vs. 4-speed with overdrive

[Rupert]

My truck officially has a four speed with a overdrive manual transmission, as opposed to a normal five speed. I know old manual transmission Volvos had the same thing, and that the overdrive gear is engaged by pushing a button on top of the shifter with the clutch in, just like changing any other gear. So, what's the difference between a four speed with overdrive and a five speed manual transmission?

[Soup DeVille]

My truck officially has a four speed with a overdrive manual transmission, as opposed to a normal five speed. I know old manual transmission Volvos had the same thing, and that the overdrive gear is engaged by pushing a button on top of the shifter with the clutch in, just like changing any other gear. So, what's the difference between a four speed with overdrive and a five speed manual transmission?

Possibly nothing.

Overdrive just means that the driveshaft is turning faster than the engine. Many five and six speed trannies today are overdrive units, but nobody ever calls them that anymore.

[S204STi]

Marketing jargon.  Soup's point pretty much explains it.

[Secret Chimp]

It's kind of like how almost all late 80s/early 90s GM cars had little "ABS" tags on their bumpers if so equipped. Just a new doodad we take for granted now.

[Danish]

It's kind of like how almost all late 80s/early 90s GM cars had little "ABS" tags on their bumpers if so equipped. Just a new doodad we take for granted now.

or "EFI" tags on 80s Toyotas

[MX793]

My truck officially has a four speed with a overdrive manual transmission, as opposed to a normal five speed. I know old manual transmission Volvos had the same thing, and that the overdrive gear is engaged by pushing a button on top of the shifter with the clutch in, just like changing any other gear. So, what's the difference between a four speed with overdrive and a five speed manual transmission?

So there are only 4 gear positions and you have to push a button to engage overdrive?  If so, I suspect there is some sort of reduction gear located either between the gearbox and the differential(s) or in the differential itself that is activated by the button.  In which case, your gearbox itself only has 4 ratios, with the overdrive being something outside of the gearbox.  This is in contrast to a 5 speed gearbox which has 5 ratios actually inside the box and 5 gear positions in the shift pattern.

[Eye of the Tiger]

Perhaps the name "4-speed with overdrive" was started with a vehicle that had a regular 4-speed trans with a 1:1 4-th gear, and a separate overdrive unit was bolted on behind that. Of course, then it would actually be an 8-speed. I don't know.

[Eye of the Tiger]

So there are only 4 gear positions and you have to push a button to engage overdrive?  If so, I suspect there is some sort of reduction gear located either between the gearbox and the differential(s) or in the differential itself that is activated by the button.  In which case, your gearbox itself only has 4 ratios, with the overdrive being something outside of the gearbox.  This is in contrast to a 5 speed gearbox which has 5 ratios actually inside the box and 5 gear positions in the shift pattern.

Where did you come from?   

[Rupert]

So there are only 4 gear positions and you have to push a button to engage overdrive?  If so, I suspect there is some sort of reduction gear located either between the gearbox and the differential(s) or in the differential itself that is activated by the button.  In which case, your gearbox itself only has 4 ratios, with the overdrive being something outside of the gearbox.  This is in contrast to a 5 speed gearbox which has 5 ratios actually inside the box and 5 gear positions in the shift pattern.

My truck has five shifter positions, but old Volvos have four. My fifth gear position is labled with a circled D instead of a 5, though.

[Soup DeVille]

Perhaps the name "4-speed with overdrive" was started with a vehicle that had a regular 4-speed trans with a 1:1 4-th gear, and a separate overdrive unit was bolted on behind that. Of course, then it would actually be an 8-speed. I don't know.

No, on his truck the overdrive transmission was optional. Both trucks used the same display quadrant and shift linkage, but the overdrive transmission got the  button.

It's a five speed transmission.

[giant_mtb]

Sometimes I wish I had a second overdrive on my 4-speed+O/D.  2100 RPM at 60 MPH seems a bit high.  I'd like it a lot more if it were 1500-1750.  Better mileage and less noise. 

[Byteme]

So there are only 4 gear positions and you have to push a button to engage overdrive?  If so, I suspect there is some sort of reduction gear located either between the gearbox and the differential(s) or in the differential itself that is activated by the button.  In which case, your gearbox itself only has 4 ratios, with the overdrive being something outside of the gearbox.  This is in contrast to a 5 speed gearbox which has 5 ratios actually inside the box and 5 gear positions in the shift pattern.

Yup, typically in the past overdrive has refered to a seperate device external to the tranmission itself.  My sister once owned a 64 Rambler American 440 that had a three speed manual.  Next to the gear change lever on the console was s seperate lever that engaged the overdrive.  Once engaged one could disengage it for passing by simply pushing a button on the gear change knob.

Today overdrive pretty much refers to any high gear with a ratio under 1:1.

[Laconian]

Citroens labeled their overdrive gear as "S" instead of "4" because they were afraid customers would be intimidated by having 4 gears to shift. "S" stood for "surmultiple" (sp?) or something. basically French for OD. So yeah, it was just marketing in this instance.

[Danish]

Sometimes I wish I had a second overdrive on my 4-speed+O/D.  2100 RPM at 60 MPH seems a bit high.  I'd like it a lot more if it were 1500-1750.  Better mileage and less noise. 

That actually seems quite low.

And also, your car would need to be a torquey beast to be able to maintain 60 mph at 1500-1750 RPM

[MX793]

Sometimes I wish I had a second overdrive on my 4-speed+O/D.  2100 RPM at 60 MPH seems a bit high.  I'd like it a lot more if it were 1500-1750.  Better mileage and less noise. 

2100 at 60 seems high?  My car turns 3000 at 65.

[Rupert]

Sometimes I wish I had a second overdrive on my 4-speed+O/D.  2100 RPM at 60 MPH seems a bit high.  I'd like it a lot more if it were 1500-1750.  Better mileage and less noise. 

That's definitely not high...

[Rupert]

No, on his truck the overdrive transmission was optional. Both trucks used the same display quadrant and shift linkage, but the overdrive transmission got the  button.

It's a five speed transmission.

There's no button... That's with old Volvos.

[Eye of the Tiger]

No, on his truck the overdrive transmission was optional. Both trucks used the same display quadrant and shift linkage, but the overdrive transmission got the  button.

It's a five speed transmission.

I know what a Ranger has, I was just considering the origin of the term came from. It's dumb to say "4-speed with overdrive", unless it's a 4-speed transmission, and an external overdrive unit was added on. Or maybe it was just some stupid marketing thing. They used to say all kinds of stupid things to make cars seem more spectacular than they really were.

[VTEC_Inside]

Sometimes I wish I had a second overdrive on my 4-speed+O/D.  2100 RPM at 60 MPH seems a bit high.  I'd like it a lot more if it were 1500-1750.  Better mileage and less noise. 

Accord = 2500rpm@60mph in 5th
RSX = 2800rpm@60mph in 6th

Last time I drove a 3.8L Buick I couldn't help but stare at the tach turnig half those revs at speed.

Edit: One of the reasons I'm happy I got an '04 RSX-S is because they shortened the final drive on the '05s so it revs 3200rpm!!!@60mph in 6th....

Someone must have come to their senses because the new Civic Si has that same shorter FD, but a taller 6th.

[Danish]

At the other (lower performing) end of the spectrum, my Corolla does 80 at around 2800 RPM.....

[Soup DeVille]

At the other (lower performing) end of the spectrum, my Corolla does 80 at around 2800 RPM.....

The Si cruises around 4000 RPM at 80.

The S2000 was at like 4500 at that speed.

[VTEC_Inside]

Also in 6th,

[The Pirate]

At the other (lower performing) end of the spectrum, my Corolla does 80 at around 2800 RPM.....

My car runs about 3300 rpm at 70 mph.  Gearing is way too short, IMO.

[Secret Chimp]

My Accord doesn't see anything less than 2500RPM on the freeway. Usually 2700 at 70-ish.

[TheIntrepid]

At the other (lower performing) end of the spectrum, my Corolla does 80 at around 2800 RPM.....

2400 at 80.

[giant_mtb]

That actually seems quite low.

And also, your car would need to be a torquey beast to be able to maintain 60 mph at 1500-1750 RPM

My mothers' '02 V6 Explorer turns about 1750 at 60 MPH and doesn't hit 2K until about 70.  That thing isn't a torquey beast at all, especially considering how much weight it's pushing.  I guess, compared to your guys' cars, 2000 RPM at 60 MPH isn't so bad.  I guess I'm just used to looking down and seeing considerably lower RPM.

[heelntoe]

mine does 2100 at 80 km/h in 5th. i don't go much above that though.
normal cruising to me is 1700 in 5th at 60km/h.and crap, i don't think i've ever been above 3000rpm in this car.

[Rupert]

!!!

[r0tor]

my tach in 6th gear = mph/2*100

[cozmik]

My car revs at around 1900 RPM at 60mph, about 23-2400 at 80