I'm not starting a Manual Vs Auto or UK Vs Import discussion here! ;)

 

What are the "true" performance times of Auto TT Zeds?

I have searched this site and seen loads of conflicting information.

Some posts say 7.5 secs to 60???

WTF! That's slower than a quick hot hatch!

Other info says they are 5.5-5.7 to 60 and Nissan say they are faster to 100 than a manual.

 

Also I have seen loads of different power figures showing the UK Auto is around 260BHP compaired to the US/Jap 280HP...

Is this true or just a UK Vs Import thing?

 

I don't mind an auto cause I like them and do lots of traffic driving, but I don't want an auto if it's going to be 2 seconds slower to 60 and have problems keeping up with a manual above that:(

Not that I'm likely to find out on the road, but it's the thought of being slower that hurts! :p

 

I'm hoping I'm not going to have to try and find a Jap/US manual :(

Originally posted by Nelson MainFella

The Overdrive setting allows the use of a parallel set of gears ... so an auto 300 has 8 forward gear ratios.

 

This is true for traditional overdrive boxes (like the old triumph ones) the Z gearbox adds a 4th gear. You can switch overdrive on and off as much as you like in 1st & 2nd and it'll make no difference.

 

If it's switched OFF then it will allow the box to lock in 3rd. If it's switched ON then lock will only function in 4th. It's that which makes a lot of people think that it introduces an extra range because it feels like it changes the ratio in 3rd. But it doesn't. Honest !

 

Dave

Originally posted by Hairsy

This is true for traditional overdrive boxes (like the old triumph ones) the Z gearbox adds a 4th gear. You can switch overdrive on and off as much as you like in 1st & 2nd and it'll make no difference.

 

If it's switched OFF then it will allow the box to lock in 3rd. If it's switched ON then lock will only function in 4th. It's that which makes a lot of people think that it introduces an extra range because it feels like it changes the ratio in 3rd. But it doesn't. Honest !

 

Dave

 

You obviously haven't read The Enthusiast's Companion (it's at home so cannot quote it) but it does say that there is a second set of gears if my memory serves me correctly.

 

Dave.

You're right, I haven't read it.

 

But, you never know, I could be right even if it says something different in the enthusiasts companion. Just coz it's written somewhere doesn't mean it's necessarily true.

 

Perhaps someone with an auto could try getting the box to behave differently in 1st & 2nd when overdrive is on and off - that would give some evidence of my being wrong.

 

I promise I'm not speaking from guesswork or hearsay !

Originally posted by smw1

Will sort this tonight LOL

 

 

But saying that I have actually seen a Z towing a caravan. The guy had the cheek to wave at me so I dropped the window and shouted FFS mate are you serious ??

Q TT TIM :D:D:D

Originally posted by Hairsy

 

Perhaps someone with an auto could try getting the box to behave differently in 1st & 2nd when overdrive is on and off - that would give some evidence of my being wrong.

 

 

I know what you mean - it seems the same until the revs go up - I'll have a look at the book again tonight if I get time.

I've had a few autos & always used my left foot for breaking. Gives you a different driving experience.

Usually the experience of headbutting the steering wheel when it's me doing it ;)

I'm with Hairsy on this too. I had an old 60's sportscar with an overdrive and in those days it was actually an additional Borg Warner gearbox strapped on the back of the manual gearbox that stepped up the input shaft speed by about 25%. It was selected electrically with its own clutch and could on TR6's be switched in on 2nd, 3rd and 4th. The zed overdrive is nothing like this. It is a discrete gear and only called an overdrive because like in the old overdrives the input shaft speed is geared up on the output shaft when in 4th or overdrive. The output shaft is therefore overdriven.

 

3rd on an auto is exactly the same as 4th on a manual. i.e. the engine speed in is the gearbox output speed out 1:1. By this definition you can call the 5th gear in a manual an overdrive too because it gears up the output. Minimum transmission loss on a dyno is always in 4th in a manuals and 3rd (overdrive off) in an auto.

 

The lock up clutch on the torque converter then makes it feel like yet another gear can be selected because the slip is suddenly cancelled when the clutch locks up the converter and the revs fall again. Made me think the auto had five gears when I first got it as you feel 5 distinct changes in engine rpm. Although I never yet felt the 3rd gear lock up when I switched the overdrive off which locks off 4th. I knew wot I meant when I wrote this but am not sure it reads right!

I know what you mean but then I mean it too !

 

I was thinking of the TR6 as well when I posted. But I didn't like to actually admit it in case people thought I had decided to grow a beard.

I had a Sunbeam Alpine series V with a whopping 85bhp and overdrive 3rd and 4th! the TR6s were too expensive for me at the time and I didnt have a beard either! Got to know its workings in great detail tho.

Originally posted by WillieO

I'm with Hairsy on this too. I had an old 60's sportscar with an overdrive and in those days it was actually an additional Borg Warner gearbox strapped on the back of the manual gearbox that stepped up the input shaft speed by about 25%. It was selected electrically with its own clutch and could on TR6's be switched in on 2nd, 3rd and 4th. The zed overdrive is nothing like this. It is a discrete gear and only called an overdrive because like in the old overdrives the input shaft speed is geared up on the output shaft when in 4th or overdrive. The output shaft is therefore overdriven.

 

Sorry to be pedantic but the O/D on a TR6 was a Laycock de Normanville unit. Pre '73 it was an A-Type post '73 the j-Type was used. Overdrive was only available in 3rd and top, due to the inhibitor, the removal of which meant that OD was available in all gears, effectively giving 8 forward gears, but this really was not advisable!

 

I'll just get my annorack!

 

Tim

you're dead right TT Tim. It was Laycock. Now where's my anorak! Borg Warner was the maker of the autobox in my old Scimitar. Get confused these days - it was the fumes off me zed before I fixed all those petrol hoses on the engine.

 

And not using it in 2nd was because the huge torque of those days could rip up the overdrive in 2nd gear!

Willie

Auto's = non stop spooling whie changing gear = Go-Go-Go and the dump valve dont cut it , you can forget 0-60 its on the move where it counts.....god i wish i had a Auto now!!!

Wheel police alert ! ;)

 

 

Originally posted by Geoff

It definitely feels different with overdrive on and off. The ratios are identical in the first 3 gears wherever you have the switch but it seems to 'let the clutch out' sooner with overdrive off, giving a more direct feeling pullaway. I'm not imagining this, I often thought the car felt a bit sluggish on pullaway and would look down and see that the overdrive was on (in the same way that the Hold mode slows down the gearchanges).

One day I'll remember where I stole this :-

 

The 4 speed automatic transmission is a lockup type. When in drive mode, gears change 1-2-3 then 3 lockup, giving the effect of 4 gears. When overdrive (4th) is switched in, the change goes 1-2-3-4 then 4 lockup, giving the effect of 5 forward gears. There is a communications link between the automatic transmission control computer and the engine management computer, and this amongst other things, allows the engine computer to retard ignition, thus momentarily reducing engine power, during auto gear changes. Auto gear changes therefore are very smooth. The automatic transmission fitted to the turbo model is stronger than the one installed in the non turbo. Although the gear ratios are almost identical, there are many minor differences between the two transmissions.

 

The Japanese automatic transmission has many more features than the export models. A "power", "normal" and "hold" switch is fitted to modify transmission shift points. The effect of the "power" setting is to delay upshifting, but does not alter the maximum RPM that change occurs. In order to change at the red line or rev limiter speed, one must operate the shifter manually. The hold setting allows holding prevents downshift into second when the shifter is set to "D", and prevents downshift into first when the shifter is in "2". Another curious feature with the Japanese version is that lock up is also available in second gear.