Overdrive virgin

[glang]

Ive always fancied trying OD operated by one of those floor switches that traditionally cars had for dipping the headlights. Seems the most sensible to me as then theres no need to take hands off steering wheel but the only problem might be the space available in the footwell of my Vitesse or, for that matter, other small chassis Triumphs. Suppose it might also need a dash light to show whether its engaged or not....

[Jason C]

On 29/11/2021 at 02:05, Rutty said:

I can't see a point of a light on the dash but its your car and if that's what you want to do then go for it.

Thanks @Rutty appreciate the advise, no doubt you’re right! And a random hole in the dash for a bulb, no thanks. 🙂 

The more I learn about the OD the more excited I get! 

[Jason C]

On 29/11/2021 at 04:35, RobPearce said:

I've quite often forgotten to switch the overdrive out when slowing for a junction. It's not a problem - the inhibitor does it for you, and you only notice when you've pulled away and accelerated up to change into 3rd, when you get 3OD instead. At that point you either flick it back out to get acceleration or smile at the Vitesse's lovely wide torque curve that means your mistake doesn't matter.

Like Rutty, I also think OD is even better than 5th gear because you can keep your foot down while it engages.

Sounds great @RobPearce Overdrive sounds versatile and forgiving. 👍🏻

[Jason C]

On 30/11/2021 at 10:52, Bish said:

I love the overdrive on my Sprint. As others have said cruising in third round the bends flicking in and out of overdrive is a joy. I also enjoy accelerating hard in forth and flicking the overdrive in which means you don’t lose revs like you would changing into fifth with a clutch. But I guess it’s not doing the overdrive any favours?

I converted my MK1 Vitesse to overdrive too. Best modification you can make in my book. Worth every penny. 

I too thought I was going to break it somehow, and was a bit forgetful with it at first, always leaving it in at roundabouts etc. My advice is to drive it don’t be scared of it. You will get used to it! It soon becomes second nature to flick it out of overdrive when necessary. 

The extra MPG is most welcome of course, especially with petrol prices as they are. Just under £1.60 per litre of super unleaded round these parts now! 

Appreciate your thoughts @Bish - by the sounds Overdrive is a wonderful addition to driving a Vitesse and solid enough to learn on the fly! Reducing fuel consumption is another bonus too. 

[Jason C]

On 29/11/2021 at 15:29, tr250 said:

The later J-Types build pressure when engaging with the switch so it takes a sec or two.

Very interesting @tr250 so a J-Type overdrive is a little slower to engage? Is it noticeable? Does it feel kind of like an automatic delay (sorry newbie here)?
 

From what I gather the Vitesse 2 Litre would have originally had the D-Type, but I’ve sourced a J-Type as several people mentioned they are a stronger unit after refinements and easier to source.

[Jason C]

On 30/11/2021 at 23:58, glang said:

Ive always fancied trying OD operated by one of those floor switches that traditionally cars had for dipping the headlights. Seems the most sensible to me as then theres no need to take hands off steering wheel but the only problem might be the space available in the footwell of my Vitesse or, for that matter, other small chassis Triumphs. Suppose it might also need a dash light to show whether its engaged or not....

Interesting idea @glang do you know if any other car manufactures had this set-up? 
 

I found it interesting that some modern cars have the gear change ‘paddles’ by the steering wheel, to mimic formula one I think. Similar to the Triumph OD steering wheel switch. Everything old is new again. 
 

Here’s a tricky question, preference for a Vitesse overdrive control, the steering wheel switch or the gear stick?  

[yorkshire_spam]

7 minutes ago, Jason C said:

Very interesting @tr250 so a J-Type overdrive is a little slower to engage? Is it noticeable? Does it feel kind of like an automatic delay (sorry newbie here)?
 

I run a J-Type in my 1500 Spitfire and occasionally there's a slight delay to engage, but to be honest you'll just be so happy at having an overdrive the minor differences of A/D/J/P type probably won't bother you!

1 minute ago, Jason C said:

I found it interesting that some modern cars have the gear change ‘paddles’ by the steering wheel, to mimic formula one I think. Similar to the Triumph OD steering wheel switch. Everything old is new again. 

Some of these vehicles actually have "old fashioned" automatic gearboxes, but the paddles allow the user to select rather than the ECU automatically selecting via the solenoids etc. It's a manually selected, epicyclic gear train, hydraulically operated system 🙂 

[glang]

5 minutes ago, Jason C said:

Interesting idea @glang do you know if any other car manufactures had this set-up? 

Never heard of that and thinking about it they probably didnt do it because you cant tell as easily if the OD is engaged or not....

[Jason C]

Thanks all, really enjoyed reading everyone’s thoughts on the Overdrive.

Sounds overwhelmingly positive, are there many if any draws backs?

- Must do’s when rebuilding a second hand unit?

- Ongoing maintenance? 

The OD sounds more flexible than a 5th gear - why did car makers phase them out? Assume once more motorways were built, the 5 speed gearbox become expected by consumers, and more cost effective to manufacture? 

 

 

[Jason C]

2 minutes ago, glang said:

Never heard of that and thinking about it they probably didnt do it because you cant tell as easily if the OD is engaged or not....

I’ve read Volvo used the Laycock OD too for many years, not sure how they handled the change. 

[yorkshire_spam]

3 minutes ago, Jason C said:

The OD sounds more flexible than a 5th gear - why did car makers phase them out? Assume once more motorways were built, the 5 speed gearbox become expected by consumers, and more cost effective to manufacture? 

Cost, building a whole epicyclic 2 speed gearbox just to add effectively a 5th gear... wow, that's a lot more money than just a few extra bits in a manual box (never mind all the added wiring etc.)

For any motor using an OD... GOOD QUALITY EP90 GL4 compatible gear oil. Regular changes. 

Maybe think about modified wiring so that fuse/relay can be added for safety and confidence. (If using stick selector switch they can fray/chaff through!)

 

[Jason C]

10 minutes ago, yorkshire_spam said:

I run a J-Type in my 1500 Spitfire and occasionally there's a slight delay to engage, but to be honest you'll just be so happy at having an overdrive the minor differences of A/D/J/P type probably won't bother you!

Some of these vehicles actually have "old fashioned" automatic gearboxes, but the paddles allow the user to select rather than the ECU automatically selecting via the solenoids etc. It's a manually selected, epicyclic gear train, hydraulically operated system 🙂 

Wow, sounds fantastic - enjoyed reading that! Im usually enjoying the sound and scenery, a little delay is not a worry. I wasn’t aware there were so many flavours of OD, quite a fascinating invention. 

Very interesting about the modern paddles, I was fooled into thinking they were “high tech”, some brands do a good job on marketing them, in sports models. 🙂
 

 

[Jason C]

9 minutes ago, yorkshire_spam said:

For any motor using an OD... GOOD QUALITY EP90 GL4 compatible gear oil. Regular changes. 

Maybe think about modified wiring so that fuse/relay can be added for safety and confidence. (If using stick selector switch they can fray/chaff through!)

Excellent, quality oil and a regular maintenance schedule. I was on this train of thought with oil. A local chap with an admirable collection of Heralds and Vitesse's told me to be very particular with gearbox oil - using something too modern, can give trouble with gear selection?

Great tip! Will remember to include  a fuse in the system as a safety precaution if the wiring fails. I have heard the drawback with the switch on the stick - the wiring being the weak point. For some reason I’m sold on the steering wheel switch, I think I’d like it’s location and I prefer the look of it. The gear stick switch feels more modern in appearance. 
 

 

[RobPearce]

51 minutes ago, Jason C said:

so a J-Type overdrive is a little slower to engage? Is it noticeable?

I would say, from my experience of Vitesses and a GT6 with both D- and J-type, that a well sorted D-type should engage in about a quarter of a second, where a J-type may take half a second. So no, not really noticeable. Slower engagement times usually indicate low oil, wrong oil, worn bits, etc.

13 minutes ago, Jason C said:

For some reason I’m sold on the steering wheel switch, I think I’d like it’s location and I prefer the look of it.

I definitely prefer it. I have two cars with that (Vitesse and Spitfire Mk3) and one with the gear knob type (GT6 Mk3). The column stalk is just at your fingertips, always ready, where the gear knob one needs you to move your hand off the wheel.

[glang]

There are some disadvantages to OD apart from cost although these dont normally put people off:

Cant use any additive in the gearbox oil as this could affect the OD clutches,

They can be unreliable although this is often due to electrical faults,

They consume quite a bit of energy so the fuel saving is arguable,

Small chassis Triumph OD boxes seem to wear out quicker than non OD,

They add quite a bit of weight and size to the gearbox so making installation and removal from inside the car harder,

Their overhaul is usually a specialist job.

[Jason C]

56 minutes ago, RobPearce said:

I would say, from my experience of Vitesses and a GT6 with both D- and J-type, that a well sorted D-type should engage in about a quarter of a second, where a J-type may take half a second.

Great detailed info @RobPearce - for a newbie like me a negligible performance difference.

1 hour ago, RobPearce said:

The column stalk is just at your fingertips, always ready, where the gear knob one needs you to move your hand off the wheel.

Brilliant! You’ve sold me. 

[Jason C]

25 minutes ago, glang said:

There are some disadvantages to OD apart from cost although these dont normally put people off:

Cant use any additive in the gearbox oil as this could affect the OD clutches,

They can be unreliable although this is often due to electrical faults,

They consume quite a bit of energy so the fuel saving is arguable,

Small chassis Triumph OD boxes seem to wear out quicker than non OD,

They add quite a bit of weight and size to the gearbox so making installation and removal from inside the car harder,

Their overhaul is usually a specialist job.

Interesting points @glang thanks so much for sharing. Very helpful understanding the pitfalls, whether large or small before converting to an OD.

 

With reliability, is there a common fault with the wiring that typically occurs, any methods when installing to prevent? Or is this due to wear and tear overtime.

By energy consumption, being a more complex system, ultimately requires a little more fuel to run?

 

Have you found gearbox overhauls more frequent through everyday driving with an OD fitted? Side note: my existing gearbox needs an overhaul - noisy in gears except 4th - hence wanting to convert to OD at the same time. Sadly, have a potential head gasket to deal with first. 
 

Hadn’t thought of the overall unit being more cumbersome for removal. The OD itself is quite a beefy unit. Plus removing some of the tunnel to accomodate.  

Thank you 

[glang]

Not sure on the wiring but its quite an aggressive enviroment for wiring and electrical switches with oil, heat, road dirt and vibration plus the risk of cables chaffing due to gearbox movement. However although the OD unit itself is robust many must now be getting rather long in the tooth...

The OD reduces engine revs which should be good for fuel consumption but uses quite a few gears and bearings to do it plus has a high pressure hydraulic oil pump all of which consume additional energy.

Nobody, as far as I know, has proved that OD makes for a weaker gearbox but theories include less support from the shorter mainshaft leading to more stress on the gearbox internals to spending more time driving in 3rd gear (4th gear is best as its direct so doesnt use the laygear which introduces a lot of radial thrust on the needle roller bearings). This last point probably explains the noise of your current box...

Due to these points and the cost/difficulty of finding good units some people are now fitting a higher ratio differential instead which of course will reduce engine revs but with the loss of some acceleration.

[RobPearce]

1 hour ago, glang said:

Nobody, as far as I know, has proved that OD makes for a weaker gearbox but theories include less support from the shorter mainshaft leading to more stress on the gearbox internals

The theory is one I tend to agree with. When I fitted an overdrive gearbox to my first Vitesse, it was straight out of a scrap car. While it looked good, the mainshaft rear bearing was past its best. The result was a fairly rapid (and fairly terminal) failure of the mainshaft tip bearing. That failure is not exclusive to OD boxes but does seem more common on them. The reason being that the non-OD mainshaft has two proper bearings to keep it aligned, where the OD one has only one - the front end sits in the weak tip bearing, the back end in the overdrive cone assembly.

[Rutty]

2 hours ago, RobPearce said:

The result was a fairly rapid (and fairly terminal) failure of the mainshaft tip bearing That failure is not exclusive to OD boxes but does seem more common on them. The reason being that the non-OD mainshaft has two proper bearings to keep it aligned, where the OD one has only one - the front end sits in the weak tip bearing,

One of the issues I was told by a gearbox repairer is the D type overdrive uses a spring to return the pump plunger and this puts a constant pressure on one side of the mainshaft causing uneven wear on the small tip bearing. This was resolved on the J type by using a ring to return the pump plunger therefor putting pressure although alternating on both sides of the mainshaft. But unless you use your classic as a daily driver the mileages most of us do in our classics I wouldn't worry about it.

[RobPearce]

4 hours ago, Rutty said:

One of the issues I was told by a gearbox repairer is the D type overdrive uses a spring to return the pump plunger and this puts a constant pressure on one side of the mainshaft

Not convinced. Firstly, the pump is located really close to the one proper bearing, so the leverage reduction by the time you get to the tip bearing makes it irrelevant. Especially in comparison to the gear mesh pressure from third gear. Second, the argument about "balance" on the J-type just means the J-type is thrashing the shaft both sides instead of only one. It doesn't help anything.

[Jason C]

18 hours ago, glang said:

Due to these points and the cost/difficulty of finding good units some people are now fitting a higher ratio differential instead which of course will reduce engine revs but with the loss of some acceleration.

A few people have suggested this as an option – sourcing a different ratio diff for nicer open road driving. Unfortunately, my Vitesse sounds to have an incorrect diff (FD12062) - from a Mk3 Spitfire with I think a 4:1 ratio rather than the standard Vitesse 3.89 ratio. From what I gather a 3.89 with an OD would be a nice set-up. 

Edited December 4, 2021 by Jason C
Spelling mistake

[Jason C]

16 hours ago, RobPearce said:

When I fitted an overdrive gearbox to my first Vitesse, it was straight out of a scrap car. While it looked good, the mainshaft rear bearing was past its best.

Leads me to another question, I have sourced a second hand J-Type OD – are there typically items that should be replaced as a matter of course before installing to the gearbox? As these units are old, are most parts readily available? 

[glang]

I believe the usual diff change on a Vitesse 2L non OD is to a Spitfire 1500 item with a 3.63 ratio which makes first gear more effective and drops cruising revs although no where near as much as OD.

To fit your 3 rail gearbox with a J type OD isnt easy as this arrangement was only used on a few models and over a short time. I think youre going to need a particular adaptor plate to fit between the main case and the OD plus the corresponding mainshaft which is different from the standard D type version. Then the gearbox mounting is different and of course propshaft shorter...

Shouldnt be any problem getting the OD overhauled by a specialist. 

[RobPearce]

13 minutes ago, glang said:

I believe the usual diff change on a Vitesse 2L non OD is to a Spitfire 1500 item with a 3.63 ratio

Yes, a popular option because of relatively good availability, plus it's a good match. I have 3.63 diffs (and J-type overdrive) on all three of my Triumphs.