Gearing Explanation Please

[dobboy 231 2 Cars]

Wondering if someone can try explain to me how gearing affects the performance of the car.

 

I currently have a GTI6 with a 1.9 box fitted, but have a VTS box sitting.

 

I've read a lot of threads on here saying that the VTS box is much better suited to the 16V, but i don't really understand how/why.

 

Just now, 1.9box pulling away, 1st gear doesn't last an incredibly long time (although i have noticed a very big difference between mines and a 16V 6-speed i've been in, with 1st in the 6speed not lasting long at all). Distance wise i would say my (1.9) 1st gear would cover three, four, five, times the road compared to the 306 6 speed.

 

Out of 1st into 2nd, the rev's maybe drop (i'm guessing) to about 4.5krpm, but the car continues to pull right up to 7kRPM.

 

And so on......

 

The kind of performance i'm getting is new to me so i'm bottling it giving full whammy 4th/5th at the moment and i've never had it on the motorway yet.

 

But thinking about it, and my current gears being longer than the VTS box, does that not also give me the benefit of being able to go down the gears to slow down without whisking an egg with the left hand?

 

Would a 16V with a VTS box be quicker to say 100mph than the same engine with a 1.9 box?

 

Or, over the course of say a straight mile what box would be the quickest?.

 

Has anyone had the 1.9, swapped to VTS, and then regretted it/swapped back?

 

Or is it a clear cut decision that the VTS box is much much better all round, get the overalls on?

 

Even better if anyone's got any in car videos of a 16V with a VTS box going flat out up the gears?

 

TIA

 

 

 

[petert 554]

Deathly silence? I'll have a go. I'm sure others know this and can add more.

 

Unlike power, gear ratio multiplies flywheel torque. Thus if you had 200Nm at the flywheel, with a 4:1 cwp and a 0.8:1 5th gear, your axle torque would be 200x4x0.8, which equals 640Nm. You can thus see that lower gearbox and cwp ratios will accelerate a car faster, but won't improve top end speed.

 

If you have closer ratios, the engine won't fall off it's power band (insert the word torque for correctness) and will accelerate the car better. However, for something like a 0-100 or 400m time, it's possible that you may need to do an extra gear change, which may negate the time made up by lower ratios.

 

Further more, many think that revving an engine unnecessarily effects fuel economy. This is not true. A perfect example of this is an Mi16, which can comfortably deliver 41mpg despite having a 4:43:1 cwp.

 

Your engine with a standard 1.9L gearset & cwp is a dog. A VTS box is very similar to an Mi16 box. If I were you however, I'd go one step further and fit 4.06 cwp into your 1.9L 8V box. You'll have a grin from ear to ear and your fuel economy will remain the same.

[welshpug 1,626]

fitting a 1.6 gti box is an easier way to a 4.06, however I cannot agree that fuel economy is not affected.

 

theres far more to it than a final drive ratio, theres gear ratios to consider too, yes a 4.4 will be shorter overall in the lower gears as the first two are typically identical, however 4th and 5th are a lot longer.

[dobboy 231 2 Cars]

PeterT, thanks for your response, I think I've got what your saying.

 

But to add to the above.

 

Last night I took another member (Ams) out for a spin. He has a 6-speed Pug1off car. I told him about this query prior to setting off on to his local roads which are A roads and motorway interlinks.

 

Anyway, I gave it full throttle up through the gears on several occasions, and he noted that my revs fall to around 4.5-4.8k between the first few gears, and that there is no flat spots at all.

 

Ams has followed the bits and bobs I've done to my car and always said i should get a VTS box, but after being in the car he was surprised with how well my combo worked.

 

(He did wonder if something had been done to my box prior to me buying it.... which I doubt)

 

I've asked Ams to post what he thought/seen/heard as I was busy watching the road.

[allanallen 528 2 Cars]

I think you're missing the point petert made about gear ratios/torque. Your car may well not drop off the boil but it'll still be a dog as it's pulling the higher ratio.

 

Your 'arse dynos' may think the cars rapid with the 1900 box but you're comparing it to nothing. Drop a 4.44 final drive in your box and see what your dyno reads, it'd blow your mind

 

At the end of the day if your happy it doesn't really matter what everyone else thinks but..... A shorter box will really liven the engine up and it will be faster, you're missing out.

[dobboy 231 2 Cars]

Thanks Allen, yeah I am happy with it, but if your saying it clear cut that the VTS box is much better I'll swap it over.

[Ams 23 1 Cars]

Dobboy just wait till I fit the VTS box, then you'll be able to actually experience and compare the difference. For reference here's Shooter Mcgavin shifting through the gears with the same setup BUT with a VTS box:

 

 

So although the 1.9 setup doesn't feel "bad" to you the VTS would certainly be a step up once you've experienced it.

Edited August 2, 2014 by Ams

[dobboy 231 2 Cars]

Thanks Ams, yeah I can hear the difference.

 

Now to build up the will to do it.

[dobboy 231 2 Cars]

I think i now understand how the gearing works (by comparing it to a 5 speed bike, i.e. the gear ratios on the VTS and 1.9 box are similar (back wheel of a bike), but the final drives are different (pedal/crank side of the bike), with a bigger FD/crank of the bike being easier to initially turn/accelerate.

 

I've got the following boxes/options

 

BE1 1.9 box on car at the moment

BE4? VTS box

and also an additional BE3 box that i don't know if it's a 1.9 or 1.6 box.

 

 

My car is predominantly road use, so with what PeterT say's about a 4.06 would this be the ideal option for me? (although i'm not too fussed about fuel usage) or is the VTS box still regarded as the better option?

 

 

Next question is if the spare BE3 i have turned out to be 1.6 box, would the FD/CWP from this BE3 fit into my current BE1 box?

 

(I'm thinking i'd manage to remove my BE1 easily enough myself, then i could get local gearbox place do the FD/CWP swap for me, and it also means i don't need to change my current clutch arrangement.)

 

TIA

[Anthony 1,000]

I agree with what's been written above - the 1.9 box just doesn't suit 16v engines.

 

It's certainly better on a GTi-6 than an Mi16 thanks to the torquier nature of the engine, but with a shorter box it will unquestionably feel far more alive and willing.

 

My personal choice for a road car would be a 1.6 GTi gearbox (similar ratios to your current box but with the 4.06 FD Petert mentioned) as that gives you a nice close ratio box, but a VTS gearbox works well too and gives a taller 5th to lower the cruising revs for a given speed on the motorway, just the ratios aren't quite so tightly spaced. Others will prefer the VTS box to the 1.6 option, but I'm sure all will agree both will be better suited than the 1.9!

 

With regard the clutch, personally if it were me I'd spend a little time and money swapping over to BE3 rather than messing around trying to keep the existing BE1 setup - the clutch action is far nicer on BE3, and BE3 gearboxes and related parts (clutch cables, release bearings) are more readily available.

 

With an F reg, you should have the later pedal box so should just need a BE3 pedal, BE3 clutch cable and BE3 release bearing to change over (and a BE3 'box of course!). The clutch friction and pressure plates are the same.

[dobboy 231 2 Cars]

Thanks Anthony,

 

Next question is what's the easiest way to determine if my spare BE3 box is 1.6 or 1.9 ?

 

Do the number of teeth on the CW in the diff housing vary between 1.6 and 1.9?

 

 

Also, i don't need to worry about push/pull element of things (i hear talked about) at all?, and my clutch (mi16 iirc) can stay put?

 

(I think i'm currently push)

[Anthony 1,000]

Apologies, I was talking about BE3 push clutches (as used on 205 BE3's).

 

BE3 pull clutches (as on the VTS box) won't work with your current clutch, but it's easy enough to convert to push.

 

As for the spare box, whip the diff cover off and stamped on the crownwheel will be a couple of numbers. Divide the larger by the smaller and that'll give you the FD ratio which will give you a big clue as to what the gearbox is.

[welshpug 1,626]

the xsara is a pull clutch so you need the arm and fork from a push clutch unit, your BE3 1.6 box would be a good donor.

[petert 554]

We didn't have 1.6L GTi's in Oz, thus 4.06 cwp's are rare and we have to build a box. We have heaps of 3.94:1 cwps however. I'd just fit a 1.6L box if you can't be bothered rebuilding your 1.9L box. Go for the close ratios. You won't regret it.

[allanallen 528 2 Cars]

Ideally I'd be swapping the f/d in your current box to shorten it up but off the shelf I'd go for a 1600 box

Edited August 7, 2014 by allanallen

[dobboy 231 2 Cars]

Thank you all for info/help. Think I know what to do and what I need now.

 

Also spoke to SOS at Fallirk whilst getting wheels rebalanced/weights moved away from calipers, and he says go for 1.6 box too, and he'll do it in a few hrs for me if I want. He told me about checking CW numbers in diff housing too on my spare box to confirm if 1.6 or 1.9.

 

I was also there to get car geometry done but as my tyres have rim protectors he thought there was a chance of maybe chipping my newly refurb'd wheels with his clamp things so decided not to get it done.

 

So will suss out spare box, put my old wheels on, prob get him to do box, and get geo done after its in.

 

Thanks again all

[Dizzee stuff 33 1 Cars]

I have used both gear boxes and would say the 1.6 box is better for track work an sprints and the VTS box for road an occasional track work.

[dobboy 231 2 Cars]

Thanks Dizzee, is there a distinguishable difference between them?

 

If you were sat in a car would you be able to tell right away which box was fitted between the two?

 

I take it judging by how nice your car is that it only hits the track rarely, therefore what box have you settled for?

 

Would the 1.6 box be a bit of a pain to live with normal road driving?

 

TIA

[Dizzee stuff 33 1 Cars]

Thanks Dizzee, is there a distinguishable difference between them?

 

If you were sat in a car would you be able to tell right away which box was fitted between the two?

 

I take it judging by how nice your car is that it only hits the track rarely, therefore what box have you settled for?

 

Would the 1.6 box be a bit of a pain to live with normal road driving?

 

TIA

The only true way to find out what gear box you have has already been said above, as you say the car will rarely hit the track so for this reason I chose the VTS box a little easier for me to live with. I think the question you need to ask yourself is what are you going to use the car for and go from there.

[allanallen 528 2 Cars]

The difference between a 1600 box and a vts box at 70mph is about 200rpm

[dobboy 231 2 Cars]

I've just checked my spare be box and it says "16x65" on the diff CW.

 

So the diff/FD is 4.062. I.e from a 1.6

 

This box came off a track car that i have no info at all on, and I think someone has been in at it before as I can see instant gasket.

 

How do I go about checking/disregarding that this isn't a 1.9 box with FD already changed to a 4.06?

 

I'll post a couple of pics tomorrow and I'm hoping someone can tell me where to position levers and I can mark, spin, and count?

[dobboy 231 2 Cars]

I seem to have exceeded my alloted server space and can't post any pictures in the topic section.

 

With reference to the post above I've temporarily added 3 images to my profile page, on my CJ.

 

http://forum.205gtidrivers.com/index.php?app=garage&do=view&id=596

 

Could one of you gents have a squint and advise what I should do to determine what gear ratio's it has?

 

 

Also, (from memory) this clutch fork looks very like what I have on my car (BE1) at the moment, has this been altered from the oringinal BE3 set up?

 

TIA

[Anthony 1,000]

How do I go about checking/disregarding that this isn't a 1.9 box with FD already changed to a 4.06?

To be honest it doesn't really matter either way - the only real difference between a 1.6 and 1.9 box is the final drive and sometimes a shorter 1st ratio on the 1.6 (as Miles said earlier, they're often the same)

[dobboy 231 2 Cars]

Anthony, can you tell me anything about the clutch fork etc from the pic? (i forgot to take a pic of the clutch cable brackets)

 

If all is well with the box in the pic, is this suitable (with addition of a release bearing) to be put straight on just now? (and i only need a BE3 pedal and cable?)

 

If so, does it look as if all the bits are there that i would need to strip off it if i decided to use the VTS box? (and i only need a bearing, BE3 pedal, and cable?)

 

 

Or does it look like its been altered already to suit all my BE1 stuff?

 

(sorry for the Q's but i don't really know what i'm looking at)

 

TIA

[dobboy 231 2 Cars]

I think you're missing the point petert made about gear ratios/torque. Your car may well not drop off the boil but it'll still be a dog as it's pulling the higher ratio.

 

Your 'arse dynos' may think the cars rapid with the 1900 box but you're comparing it to nothing. Drop a 4.44 final drive in your box and see what your dyno reads, it'd blow your mind

 

At the end of the day if your happy it doesn't really matter what everyone else thinks but..... A shorter box will really liven the engine up and it will be faster, you're missing out.

 

And that was/is the case AA, actually can't believe the difference it made.

 

I'm sure it'll be a major contributing upgrade should i ever get a driving ban! lol