Which gearbox?

[nuttinnew]

Just a thought to help compare, the Polo was available with a 100bhp 1.9tdi and 5sp box so it could be worth finding out the ratios for that.
I think the reason that BM boxes were not discussed more earlier on was/is their lack of availability, they've never been the most common model about because on the normal 3yr/10k/yr deals they don't pay back the extra cost over a non BM 1.4.
While that test (I'll have a full read in a mo) says you can end up a gear lower than usual, if that means in fourth rather than fifth then you'd still be using standard A2 fifth gearing (tyre wear would make more of a difference), so it would make more difference psychologically than anywhere else.
Has anyone got graphs for a remapped 75? While a vnt can help, a map could well make more difference to the curves.
dan, the FSI is quoted as 127 vmax, and if they're like the 1.4s seem to be...
I've only ever had a BM for a short while, not long enough to get fully used to it, but at times when it perhaps sounded like it was struggling with the gearing, the speedo showed it wasn't. The 1.4BM was certainly a better match than the 1.4tdi 70bhp (my normal steed at the time) or the current 1.2tdi (as far as I non BM & BM use the same ratios) which is marginal even without passengers etc.

 

[timmus]

The cost of the 6-speed conversion seems to be rising, though. He now likes to do it with the gearbox out of the car ...takes the cost up to £1700!

Sorry, that would be my fault.

 

[Zoltar]

Looked into the JDD Bluemotion gearbox as I do a lot of motorway miles on my commute to work, I cruise at around 70mph whilst keeping up with traffic. While I see the benefits (cost/mpg) of keeping speeds down ensuing low rpm, personally sticking to 60mph is too slow for my route with trucks bearing down on me in a little aluminium car!

Even at a law abiding 70mph the car is doing 2,600rpm and at 80mph it’s about 3,000rpm, both of these are far too high to cruise comfortably (especially first thing in the morning!) and the fuel consumption drops quite a bit too.

I would love the 6-speed conversation as done by a few members here, like they said, it is the ultimate solution to the A2 gearbox woes. But, this is too money for me to justify the cost of fitting it, so another solution was needed.

The JDD box would allow me to cruise at 70mph (2,000rpm-ish) and still have decent MPG, it may even allow me to cruise at 80mph with good mpg. Sure you will agree that cutting down any time on the daily commute helps lubricate the work day a little!

The trade off is losing the close ratio box which gives the car it’s nippy feel (more so on the remapped TDi’s) After driving a Polo BM it felt to me that gears 1-4 were effectively the A2’s 1-5 gear compressed into 4.
Hooley’s graph shows that 4th in the BM box is not far from 5th in the A2 box. It means that you will have 4 gears to play around with for everyday motoring and a 5th motorway/A road gear above 60-65mph. I am sure there are a few members here who still remember when 4 gears were standard and 5th a luxury anyway!

Yes, you did have to rev the car more before the next gear change but this was not a problem for me, the gearing feels like you had dropped 2-3 teeth from the rear sprocket on a motorbike, in that you lose the acceleration though the gears and had to rev a little more before the up change, thus spacing the changes further into the rev range.

On the JDD box I had thought about changing the final drive to the shorter A2 one which would give the 0.659 'longer 5th' setup and space the remaining gears to it nicely(would be nice to see this graph Hooley), if I didn’t do so many motorway/a road miles, this would be my choice.

However I am looking to eek out much mpg as I can from the daily commute, if you do 15000 miles a year, the cost would be (@1.48p diesel) :

55mpg £1834.
60mpg £1682
65mpg £1552

I average 55mpg so if I can raise my mpg by 10mpg(fitting the JDD box) that would save nearly £300 a year, thus giving me return on the gearbox in just one year!

Even a 5mpg gain would take two years for the return. Remember I was going to change the clutch anyway, so the gearbox has cost me just £250 extra.

I agree with Timmus about the VW 6 speed gearboxs that would just give 6-speeds over the same range as 5, I did not follow this route as I wanted a larger spread and not a closer one.

The JDD box will not be for everyone but it suits my needs(hopefully!!!)


BTW, the gearbox linked is the one I bought, I got a good deal as he was only around the corner from Stealth

 

[MikeMarsUK]

... sticking to 60mph is too slow for my route with trucks bearing down on me in a little aluminium car!
...

HGVs are usually limited to either 50, 56, or 60mph (note these would be the true figure not the indicated figure). If you find that you are being overtaken by HGVs, I would suggest comparing your indicated speed to a GPS to see how much it differs.

 

[DJ 190]

As I have intimated ... my A2 is running "sweet as a nut" at the moment, so I think things shoyld be left as they are! (I have just "touched wood" LOL! The kind members on this great A2OC would, I'm sure, allow me to drive their cars to assess the improvements and/or drivability that has resulted? (That would be Tom (Timmus) in Lancaster and "Zoltar" in Cambridgeshire) ..... Nevertheless, this thread has proved to be SO interesting! The total outlay to change the gearbox would appear to be only £500 - £600 .... and with the potential to replace a worn clutch, too! Who knows, you Guys might even come up with another suitable box, with even better ratios! It is such a pity that you can't find a way to fit a 6-speed box! (Years ago, it was quite common for people to mate almost anything together .... Triumph Bonneville engine into a Norton frame <Triton> , V6 engine into a Ford Escort) What is so difficult with this gearbox thing? That thread about 6-speed gearboxes (Skipton) starts "I am the proud owner of a 6-speed gearbox" .... what DID happen with that?

David

 

[timmus]

Looked into the JDD Bluemotion gearbox as I do a lot of motorway miles on my commute to work, I cruise at around 70mph keeping up with traffic. While I see the benefits (cost/mpg) of keeping speeds down ensuing low rpm, personally sticking to 60mph is too slow for my route with trucks bearing down on me in a little aluminium car!

I agree with MikeMars, here. If you're cruising at a true 60mph, lorries cannot be bearing down on you. A true 60mph is my default cruising speed and I'm overtaking lorries almost continuously.
Having purchased your TT alloys (thanks again, they're in superb condition!), I noticed that you opted for 205/45/16 rather than the 205/50/16 that would have been my choice. 205/50/16 would have resulted in your speedo being bang-on, whereas with 205/45/16 the speedo over-reads slightly, meaning that you're actually only doing 58mph when the speedo says 60.

The JDD box would allow me to cruise at 70mph (2.000rpm-ish) and still have decent MPG, it may even allow me to cruise at 80mph with good mpg. Sure you will agree that cutting down any time on the daily commute helps lubricate the work day a little!

Even with longer gearing your consumption at 80mph will not be much better than it is now. Aerodynamic drag increases as the square of speed, meaning that your engine will drink to overcome the large increases in drag whatever you do with your gearbox.

I have driven a friend's Bluemotion and it felt gutless compared to mine but still managed to pull the gears with only 75bhp, I don't think a remapped engine will have any problem with these ratios.

The trade off is losing the close ratio box which gives the car it’s nippy feel (more so on the remapped TDi’s) After driving a Polo BM it felt to me that gears 1-4 were effectively the A2’s 1-5 gear compressed into 4.
Hooley’s graph shows that 4th in the BM box is not far from 5th in the A2 box. It means that you will have 4 gears to play around with for everyday motoring and a 5th motorway/A road gear above 60-65mph. I am sure there are a few members here who still remember when 4 gears were standard and 5th a luxury anyway!

Yes, you did have to rev the car more before the next gear change but this was not a problem for me, the gearing feels like you had dropped 2-3 sprockets from the rear on a motorbike, in that you lose the acceleration though the gears and had to rev a little more before the up change, thus spacing the changes further into the rev range.

If I may be so bold as to say so, I think you need to move away from comparing the characteristics of this gearbox installed in a Polo BlueMotion. Your observations of the 'box within that car have little relevance to how it'll feel once installed in an A2. The biggest difference here is that the Polo runs on much smaller wheels.

As I mentioned in a previous post (bottom of page 5), the 5th gear in the JDD 'box will feel like a 0.613 ratio once installed in an A2. Doing this bit of maths provides a much more realistic assessment of the JDD's character for its proposed purpose. 0.613 really is very long; too long if you ask me.

When I'm just pootling about in my A2, trying to keep my urban fuel consumption down, I change up at about 2200rpm. If I change much earlier than this, I find that the engine revs fall too much and the engine ends up spluttering a bit. Remember, a spluttering, stressed engine will consume more fuel.
Once mated to a JDD 'box, in order for your engine to avoid falling into this region after a gear change, you'll have to change up no ealier than 2750rpm - and that's when you're eco-driving!! Believe me, there's nothing 'eco' about that, especially when your engine is cold! For all that your car will certainly save you money once you're motorway cruising, in all other driving circumstances your fuel consumption will go up. Imagine doing 2600rpm in 3rd and still being unable to change up. Added to that, the overlap between gears will be so small that the 'driveability' of the car will really suffer; you'll no longer be able to change gear to stay within the torque wave as your speed fluctuates during urban/cross-country driving.

From both an eco perspective and 'driveability' perspective, I cannot urge you enough to reconsider this mod. An average 23% increase between each gear is just too much and I fear you'll live to seriously regret this.

On the JDD box I had thought about changing the final drive to the shorter A2 one which would give the 0.659 'longer 5th' setup and space the remaining gears to it nicely(would be nice to see this graph Hooley), if I didn’t do so many motorway/a road miles, this would be my choice.

This sounds like a better idea, but is a lot of work to achieve in practice. The ring gear on the differential is driven by a gear at the base of the gearbox's output shaft. Together, they make the final drive. So, in order to put the A2's final drive into the JDD 'box, Vince would have to do a lot of dismantling to access the base of your current gearbox's output shaft as well as the base the the JDD's output shaft in order to transfer the 'first half' of the final drive, resulting in a huge labour bill. This photo should help to visualise what's involved...

However I am looking to eek out much mpg as I can from the daily commute, if you do 15000 miles a year...

Any savings from having a longer motorway cruising gear (which won't be that great if you're cruising above 70mph) will almost certainly be cancelled out during all other driving conditions.
If your car spends most of its time on the motorway, then you're a prime candidate for the longer 5th. Yes, you end up with an unusually large gap between 4th and 5th, but at least the hassle is contained to just one gear change rather than all of them!

The JDD box will not be for everyone but it suits my needs(hopefully!!!)

Ehh.... I suspect otherwise. :S

If you've definitely ruled out the common 'longer 5th' setup because you want to keep the spacings even, then consider the EXB 'box. It provides an even increase of 7.2%-10.9% depending on tyre choice. Ok, your motorway cruising revs won't be reduced as much, but I bet it returns better combined fuel economy and won't totally sacrifice driveability.

Tom

 

[spike]

There is a 6 speed box which has potential. Its the 02S (based on the 02J) with code GQM. The negatives are that it does not have a compatible speedo drive system which means replacing the front gear casing with one from an EWQ box, driveshaft flanges are 100mm (not 108mm) and also need changing and the overall 6th gear ratio is only 3.5% taller than the EWQ box.
Things like the starter and flywheel mounting appear to be compatible.
I guess it would be fun on cross country runs but offer little advantage on motorways.

As Tom indicated, aerodynamic drag is related to the square of the speed but BHP is proportional to speed cubed, so upping the cruising speed from 70 to 80 mph will have a significant effect on fuel economy

Cheers Spike

 

[DJ 190]

Tom ..... ever thought of going on "Mastermind"? Your specialist subject? Well, the Audi A2, of course! LOL!

David

 

[timmus]

Tom ..... ever thought of going on "Mastermind"? Your specialist subject? Well, the Audi A2, of course!

Haha! Thank you, David.

 

[dan_b]

@Zoltar, have you already completed the box swap?
I was going to ask why you'd not gone for the longer 5th option and maybe just slow down a bit to 65mph?

 

[Zoltar]

Hi Tom,

Thanks for your input into this, I am truly grateful of another point of view and with all your recent experience of gearboxes, I welcome and respect your options.

I agree with MikeMars, here. If you're cruising at a true 60mph, lorries cannot be bearing down on you. A true 60mph is my default cruising speed and I'm overtaking lorries almost continuously.
Having purchased your TT alloys (thanks again, they're in superb condition!), I noticed that you opted for 205/45/16 rather than the 205/50/16 that would have been my choice. 205/50/16 would have resulted in your speedo being bang-on, whereas with 205/45/16 the speedo over-reads slightly, meaning that you're actually only doing 58mph when the speedo says 60.
Tom

I have a sat nav on my dash to tell me true speeds(OEM looking Sat-Nav in your A2 using your Smartphone and a Dock.) I know my speeds are out by about 3mph over @ 70mph. Even at a true 60mph I still get trucks behind me, I know they should not be there(HGV limited to 60mph)but they are. Besides as an ex-biker even if there were no trucks around or behind me I don’t think I am wired up inside to cruise at 60mph!

Even with longer gearing your consumption at 80mph will not be much better than it is now. Aerodynamic drag increases as the square of speed, meaning that your engine will drink to overcome the large increases in drag whatever you do with your gearbox.Tom

I am aware of this “it may even allow me to cruise at 80mph with good mpg” I know that sticking to 60mph(or low as you can) is the best for out and out MPG but I do not drive at that speed and 70mph is my mark so I need to find the best solution for those speeds.

If I may be so bold as to say so, I think you need to move away from comparing the characteristics of this gearbox installed in a Polo BlueMotion. Your observations of the 'box within that car have little relevance to how it'll feel once installed in an A2. The biggest difference here is that the Polo runs on much smaller wheels.Tom

Strange you keep saying this? His wheels which I just checked out this lunchtime are 185/60/15. My current setup is 215/45/16.

Car Tyre size Overall Tyre Diameter

Polo BlueMotion

​

185/60/15

​

603mm

My Car

​

215/45/16

​

600mm

Standard A2 SE

​

185/50/16

​

591mm

He has not changed the tires for a different size and looking online confirms that 185/60/15 is standard on the BlueMotion. As such they are almost the same overall tyre diameter as an A2?

The Polo BlueMotion(using more or less same engine) is heavier with less power(75-80bhp) but the same torque(180Nm) as my remapped A2(not seen dyno graphs of BlueMotion for curves), the turbo in the Polo will help low end grunt but it can’t be much more than the grunt you get from a remapped A2 engine?

I do not have any problems with the gearing, I went for a drive again(in the Bluemotion) at lunch just to confirm I was doing the right thing after reading your posts.

Also my driving style may be different to yours, I always change around the 3,000rpm mark anyway so the drop will not affect me too much (again the biker in me!)

I know that I will be sacrificing things like cruising at 60mph in 5th as the revs will be too low to pull as this speed but that is the compromise.

Ideally I would get the 6 speed option like you but I cannot afford that and as such, I will have to live with the benefits/compromises that the JDD box will bring.

I agree that 0.613 really is very long but again for the money I am spending on this I can’t complain/want too much.

About 80-90% of my driving in this car is motorway so I just need to find a way to save money doing 70-80mph and this is the cheapest I could find/think of.

Without driving like a saint(to keep mpg low) this is the best option I can see for me personally, but if there is another(cheaper/easier) way then I am more than happy to listen to that option.

The reason I didn't go for the 5th upgrade was I wanted a gearbox with less miles on it than mine. The one I bought has only done 8,000 miles, this is a big plus point for me.

Please keep up with input everyone....what a great sounding board this site is!


Plus, it seems this thread has quite a few views already and I am guessing people will want me to go ahead with the JDD box as a test!! Sacrificially lamb!!

I'm going to try and make an A2 meet this year sometime, you are welcome to drive it and see what you think of the JDD box

Just found this :Autocar review

"It takes a while to get used to the wide gear ratios, and to trust the change-up light which wills you to let the little engine lug. Once you train youirself, spectacular fuel mileage is simple."

A few reviews say the same thing, that ratio are high but you get used to them, also my friend was unaware that his ratios were different to standard and never thought to complain about them.


Thanks

 

[MikeMarsUK]

... I know they should not be there(HGV limited to 60mph)but they are. ...

The only vans I can think of which go over 60 are the light ones (Lutons & so forth), under the 7.5 tonne limit.

... and I am guessing people will want me to go ahead with the JDD box as a test!! Sacrificially lamb!!
...

Absolutely It will be an interesting experiment. It's a pity you can't just drop a 6-speed box in there instead without having to look at the final drive.

 

[dan_b]

Absolutely

Hi Tom,
Plus, it seems this thread has quite a few views already and I am guessing people will want me to go ahead with the JDD box as a test!! Sacrificially lamb!!
Thanks

 

[timmus]

Strange you keep saying this? His wheels which I just checked out this lunchtime are 185/60/15.

You're absolutely right. I'd never actually checked, so worked with the size of my Polo's tyres... VW have clearly increased their size since I was a Polo owner.
However, this doesn't affect the maths; you're still increasing each gear by an average of 23%, and the following still remains true...

Once mated to a JDD 'box, in order for your engine to avoid falling into [the splutter] region after a gear change, you'll have to change up no ealier than 2750rpm - and that's when you're eco-driving!! Believe me, there's nothing 'eco' about that, especially when your engine is cold! For all that your car will certainly save you money once you're motorway cruising, in all other driving circumstances your fuel consumption will go up. Imagine doing 2600rpm in 3rd and still being unable to change up.

It seems that your priority here is increased fuel economy, but yet you're changing up at 3000rpm and regularly doing over 70mph. You're looking to defy the laws of physics; you can't continue to drive like you do and expect tangible increases in economy. As Spike stated earlier...

...aerodynamic drag is related to the square of the speed but BHP is proportional to speed cubed, so upping the cruising speed from 70 to 80 mph will have a significant effect on fuel economy

When you consider that MikeMars was averaging over 70mpg when his A2 was factory standard, you can see that driving style is way more influential than gear ratios. Increasing your ratios will never compensate for a heavy right foot.

I agree that 0.613 really is very long but again for the money I am spending on this I can’t complain/want too much.

You're right, you can't want too much. But, from my reasoning, I'd suggest you'll get barely any increase in fuel economy and that the driveability of your car will take a serious retrograde step.

When the purchase and installation of the 0.659 5th gear will cost less, is known to provide tangible benefits in fuel economy for those of us who do mostly motorway miles, and has a much lower impact on the overall performance of the car, I can't see the sense in fitting the JDD 'box. Yes, I like the idea of spacing the gears evenly, but...

I'm happy to be proved wrong, by the way.

Tom

 

[Hooley]

Absolutely

+1
I'm VERY keen to find out


J

 

[Zoltar]

It seems that your priority here is increased fuel economy, but yet you're changing up at 3000rpm and regularly doing over 70mph. You're looking to defy the laws of physics; you can't continue to drive like you do and expect tangible increases in economy. As Spike stated earlier...

When you consider that MikeMars was averaging over 70mpg when his A2 was factory standard, you can see that driving style is way more influential than gear ratios. Increasing your ratios will never compensate for a heavy right foot.
Tom

Not looking to change the universe standard model just yet!

I am getting 55mpg driving like this now with the OE gearbox and sticking to 70-80mph, if I can get more mpg using a different box(driving the same way) then it must be worth a shot....no?

After all, VW Group when thinking of a way to make their cars more economical put this gearbox into a car that has less power/torque than mine and weights more?

Surely if increasing the ratios would have such a detrimental effect on economy and drivability then they would of gone down another route to increase MPG??

Also when I asked about the 5th gear upgrade, the parts alone came to over £300 then the labour on top to fit it.

To be fair, I do not know 100% how that car will on the JDD box, but my reasoning is......if the heavier Polo(less Bhp/Nm) can handle it then a lighter remapped A2 surely must too?

I will find out on the 2nd of April(date it's booked in for the work)

 

[MikeMarsUK]

... When you consider that MikeMars was averaging over 70mpg when his A2 was factory standard, you can see that driving style is way more influential than gear ratios. Increasing your ratios will never compensate for a heavy right foot.
...

Driving conditions are also significant, I am lucky enough to have a long enough daily drive so that my MPG is not compromised by the time the engine takes to warm up, and also the 30% 'city' driving I do is fairly free-flowing with only a few stops. Most people are not as fortunate as me.

As a very crude rule, dropping your speed by 10mph will typically improve your instantaneous mpg by about 10 also (both aero drag & mpg are non-linear, but pretty much by fluke the relationship roughly works at A-road speeds).

Regarding speed vs. mpg + the effect of the higher top gear... obviously dropping speed will make a bigger difference than anything else, due to aero drag. But Zoltar should also see an improvement due to being in a more efficient area of the map, provided he is in the same gear that he would have previously been using.

For example, cruising on the motorway in 0.613 5th at 70mph will use about 8-10% less fuel than cruising at 70mph in the 0.75 5th as you can see from the BSFC map. On the other hand, if at 50 mph he is now in 4th instead of 5th, then MPG will drop due to the increase in RPM. So it very much depends on his exact driving conditions to whether his mpg will improve or drop (very much like the 5th gear mod which has similar trade-offs).

 

[spike]

Not looking to change the universe standard model just yet!

I am getting 55mpg driving like this now with the OE gearbox and sticking to 70-80mph, if I can get more mpg using a different box(driving the same way) then it must be worth a shot....no?

After all, VW Group when thinking of a way to make their cars more economical put this gearbox into a car that has less power/torque than mine and weights more?

Surely if increasing the ratios would have such a detrimental effect on economy and drivability then they would of gone down another route to increase MPG??

Also when I asked about the 5th gear upgrade, the parts alone came to over £300 then the labour on top to fit it.

To be fair, I do not know 100% how that car will on the JDD box, but my reasoning is......if the heavier Polo(less Bhp/Nm) can handle it then a lighter remapped A2 surely must too?

I will find out on the 2nd of April(date it's booked in for the work)

I love it. You've done your homework and are prepared to take a calculated risk that the JDD box will work for you. (The fatter torque envelope of your remapped engine should really help here)
As with other members who did the same with the first 6 speed and high 5th gear conversions and passed on their experiences, this is how the continuing development of the A2 progresses. Can't wait for the next instalment.

Wonder who will be first with a more conservative EXB box conversion.

Cheers Spike

 

[MikeMarsUK]

... Wonder who will be first with a more conservative EXB box conversion.

Cheers Spike

Yes, this discovery process is very exciting I'm hoping that someone will find an easier way to do it with a 6-speed box ... Kane326 managed it, but it was a big job from the look of it.

 

[DJ 190]

"Spike", you wrote this :- There is a 6 speed box which has potential. Its the 02S (based on the 02J) with code GQM. The negatives are that it does not have a compatible speedo drive system which means replacing the front gear casing with one from an EWQ box, driveshaft flanges are 100mm (not 108mm) and also need changing and the overall 6th gear ratio is only 3.5% taller than the EWQ box.
Things like the starter and flywheel mounting appear to be compatible.
Well, say you went ahead with that box . Why couldn't you change the 6th gear in THAT box, for a taller ratio, just like A2OC members do with their gearboxes? (0.651 or 0.681 < mine > ) That way, you'd have 5 gears for general use plus a real "overdrive" for motorway cruising! Now, even if you needed TWO gearboxes to make a suitable hybrid to mate with the A2, (and these boxes seem to be typically £250 - £300), then you would be looking at about £700 - £800, including labour, to fit that 6-speed box ... I gather that the required front gear casing and driveshaft flanges would come from the existing A2 box? Is that right? That would result in an even lower cost! Hey, please always excuse my ignorance if I DO get things wrong! It is just my active mind at work! LOL!

David