Overdrive use

[James]

Nahhhh if you're driving properly OD is useless

Matching revs during braking on downshifts is what it's all about for top speed manic driving

[1967 MkIII]

All who like OD - I agree. Glad I can use it more freely without the nagging worry that I'll break something.

James - I disagree. Once you reach the rev limit in 3rd you'd change up to 4th. At the next tight curve you'll downshift to 3rd then back up to 4th in due course. We'd do the same but using 3rd OD instead of 4th and with a quicker change. But then there's still 4th and 4th OD.

It's like having 6 gears, but fun because you actually think to use them (unlike the computer -controlled drive my Freelander 2 gives me).

Each to his own I suppose

[James]

I just much prefer heel-toe, it feels a much purer experience and is far more fluid than really caning the hell out of an OD.

[neilnaz]

James with Overdrive you can have both. I enjoy dropping a gear and booting it through a corner and then selecting o/d on exit as you accelerate away. The thing is that you can have the best of both worlds. Once reliable (and I understand that people have problems with overdrive gearboxes) they are so much more enjoyable than a modern 5 speed gearbox. I have one of those in my modern(ish) Celica and it works very well it is just not as entertaining in the twisty stuff.

There is something kind of wonderful about driving a nicely sorted Spitfire/Herald/Vitesse/GT6 on A and B-roads snicking in and out of gears and overdrive as your speed, traffic and the road dictates. Oh how I miss all that.......

Time to save up some dosh and get a new Spitfire and start preparation of Frankenstein.... (the amalgamation of the mechanicals of my poorly-bodied Spitfire and a rust-free NZ Spitfire)

[Anthony]

I guess my opinion isnt too valid at this time as I've never used an OD box....but so far my head tells me that James is correct

Guess we'll know for sure once my car is on the road

[Howard81]

Overdrive is brilliant.. But you dont realise how useful it is until you go back to a regular 4-speed. My Sprint has it, but my Spitfire doesn't.. I'm on the lookout for a suitable 'box!

A couple of years ago, I took a couple I know for a blast in my Sprint. Was on the motorway in overdrive 4th and went to overtake the car in front. You know.. flick the overdrive switch off, then when the revs kick in a nice swift blast to overtake. My friends wife exclaimed "wow, it even has an overtaking button!"  ;D

[thebrookster]

A further update here, for what it is worth. I have discovered today that for some reason the OD is active in all four gears on my spitfire. I suspect that someone has bypassed the inhibiter switch at some point, however I have yet to look to confirm. I only noticed because I left the car in overdrive whilst changing down to second, before realising I had not disengaged. I then did so whilst in second, as was rather surprised to find the revs increase :) A further play confirmed OD in all four gears, no idea about reverse, as I seem to recall this damages things!

But anyway, on the issue of getting the OD working in the lower gears. My experience, not worth the hastle TBH. It allows first to be slightly taller, therefore a wee bit more useable, and second again is a bit taller, but the gains compared to the possible reduction in life really do not seem worth it. For me, I intend on taking it back to original when I get the time, and in the meantime try and remember to dis-engage in future. For the small engines, third and fourth is fine IMO.

Just thought I would share that with you, as I thought of this thread when I discovered it ;D

Cheers,

Phil

P.S Forgot to mention, Spitfire is a MkIV with an untampered (as of yet) 1300 engine with 1500 gearbox and OverDrive.

[piman]

Hello Ant,

I think if you drive one you won't agree with James.
The best part for me is driving hard in third up to near maximum revs, engage O\D third and keep accelerating. My overdrive engages instantaneously (A Type) even on full throttle. If there is a lag then the effect is lost, it must be instantaneous. In built up areas, 30\40 limits I use third and flick up for the 40, out again for 30. Who needs an automatic, apart from Lord Sorbington? 5 speeds, no thanks.

Alec

[Anthony]

I still can't figure out why OD is used on 3rd?

If 3rd OD is so close to 4th, then why bother?

Obviously OD on 4th makes sense, but what's so great about it on any other gear?

How hard is it really to change from 3rd to 4th?

[thebrookster]

Personally, same as Alec says, use around town and on twisty country roads. I fully see your point in regards to the gearing being so close, but for conveniance it is damn sight easier to flick an overdrive switch than it is to change gear constantly.

Also, if you are wanting to accelerate fast away from something, the 3OD makes it easier to remain in the power band.

Until you try it, it is hard to explain. I just find it easier, less clutch work, etc etc.

Cheers,

Phil

[Anthony]

The funny thing is I'll probably be completely convinced once I've tried it!

One of my modern cars has cruise control
At first I thought it was a daft idea, but once I found out how else it could be used I soon changed my mind

[neilnaz]

Quoting Ant:

I still can't figure out why OD is used on 3rd?

If 3rd OD is so close to 4th, then why bother? - Because you flick between 3rd and 3rd O/D without touching any pedals and being able to keep your foot on the gas. On my car 3rd O/D and 4th are almost indistinguishable so changing from 3rd to 4th and 3rd to 3rd O/D gives the same effect - it is the difference in how you achieve that change and what the enables you to do as a result.

Obviously OD on 4th makes sense, but what's so great about it on any other gear?

How hard is it really to change from 3rd to 4th? It is very easy to change between 3rd and 4th clutch in, move gearstick, clutch out then back on the gas (etc). As above it is driving through twisty lanes and the ability to keep the engine in the sweet spot flicking in and out as required. Honestly it will bring a smile to your face.

Overtaking is the same thing, switch out of overdrive - get the extra grunt foot down - sail past - and without lifting off the gas flick into overdrive - joyous......  8)

[Howard81]

If you live in London, overdrive third is very useful!  It's very similar to fourth gear, so when in crappy traffic you can just flick the switch to get it, rather than change gear - which undoubtedly you'd have to change down again soon after.  Lazy I know, but after an hour in traffic operating a Dolly Sprint clutch your leg aches!

Next time the 'box cover is off I'm adding overdrive second.. that would be even more useful.. :)

[thescrapman]

1903 wrote:

I still can't figure out why OD is used on 3rd?

If 3rd OD is so close to 4th, then why bother?

Obviously OD on 4th makes sense, but what's so great about it on any other gear?

How hard is it really to change from 3rd to 4th?

BEcause you can keep your foot flat to teh floor in 3rd gear and flick teh switch into OD half way through the overtaking manoevure.

Cheers

[Royboy66]

Ant, whereabouts in UK are you ?

you may get a go in a GT6 with o/drive  ;)

[Pete Lewis]

on Most Rootes gearboxes you can split shift 3rd 3rdOD 4th   but Triumph had a closer ratio 3rd and the 3rdOD and up shift to 4th  ratio's are unfortunaley the same     so if you want a split shift 6 speed box try a Alpine,Rapier,Hunter,Minx,PBvan etc.

Pete

[Anthony]

Roy, I'm in Kenilworth

My dads mate has a vitesse with overdrive and swears by it

[tiggrr1]

royboy66 wrote:

I think Tiggr was running a 3.27 with o/drive.  he should be along at some point to comment.

Im running a 3.63 with D type o/drive attatched to my 2.5 lump, its nice, picks up well,and cruises at 70 ish quite well(whistle)

If your going to use the car a lot once its finished( which you should! :P) , then I'd suggest trying to blag a ride in a few cars with different diffs  ;)

with the 3.63, mine runs at around 21mph/1000rpm in o/drive top gear.

Hope that helps some 8)

Meant to comment on this earlier,

As Roy says I have a 2 litre with a J type overdrive. Very long legged and great for high speed cruising but it Kills acceleration.
I think I would be better off with a 3.63 but that can wait untill I kill the 3.27 ;)

[Anthony]

If I recall correctly, didn't most cars come from the factory without overdrive?

Therefore (at the time) a 3.29 would have been the norm with regards to acceleration?

[GT6 M]

3.27 with 28% OD gives moer MPH in 3RD OD than  direct 4 th!!

16.3 mph x 1.28 =20.84  =127.5
20.20  4th          =              121.2

so is really good for a fair bit o speed,!!

Tigger ole Boy, You need more GG,s :) :) :) :)

[Clive]

killing 3.27's is pretty easy with a 2.5. I have a t shirt or two (more actually) for that :o

[tiggrr1]

796 wrote:

Tigger ole Boy, You need more GG,s :) :) :) :)

Too true Marcus ;D

I think my J type overdrive is of the 25% variety as there appears to be no difference between third overdrive and fourth gear non overdrive.

I get around 25 mph per thousand revs in overdrive top gear.

Goes very well down long hills with a tailwind  ;)

However acceleration is about the same as a 1500 spitfire up to 60mph then I can pull away due to the longer gearing if conditions are right.

(Also get left behind on the Royvoy untill they all run out of Revs  :) )

[Anthony]

Just checking on Mintys gear calculator

A gt6 with OD and a 3.27 diff is geared for over 155mph.....haahaa!!

All I need now is the power to cut through the air!
Reckon I'd run out just over 100mph :(

[tiggrr1]

I've seen 105 on my speedo on a long downhill run, my speedo reads about 5 - 10% slow

The sat nav was showing 115mph  at around 4500rpm acording to Gaz who was riding shotgun at the time. (This was of course on the 10CR on the AutoBahn, wasn't it Gaz  ;) )

[Anthony]

Yeah, the gear calculator has you at around 116 assuming standard circumference Tyres

What are our cars like when driven at higher speeds?