What's the best gearbox for a 16vT?

So, what would be the best off-the-shelf gearbox for a 16v Turbo? Been thinking about the CTN TDi boxes, but not sure on the ratios, anyone got any ideas?

Been told for mine it would be too long on the ratios by numerous people, i hit full boost at just over 3k last time i drove it but its been a long time since i been out in it.

Im using a CTN, It removes the "throw in the seat" feel but you can just hold it in a gear and thrash it for ages with no need to change.

This may help

G60 box

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TDI box

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It would be great to get some similar cars running down the pod and compare their 60ft and 330ft times with the different boxes.
I know it wouldn't exactly be scientific but it would be interesting anyway.




I'm keeping an open mind on this one.

The longer ratios look pretty good, especially 1st gear as VW always make 1st to short IMHO. But 40 in first is nice, but not too long and easily hitting 60 in second is spot on. Providing you have enough bottom end torque to get away in the first place!

SensibleDave wrote: Providing you have enough bottom end torque to get away in the first place!

I think this is the main point tbh.

If you have torque to burn "cough cough Junkie" then you will still be pushed back into your seat.

I think in a lightweight car like my engine in a mk1 that i want to do then it would warrant it, 1st and 2nd are spot on but then the rest start getting too stretched i think.

Open mind still on it too, may just have to try someday.

Oh my favorite suject!

Have you seen this page it gives a lot of info on different ratios etc.

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I guess it depends on a lot of factors, tyre traction, driving style, vehicle usage ie daily or toy and what your prepared to sacrifice or trade off really.

I'd say use the box your used to driving ie the standard 16v box and see where it lets you down and then make a choice based on that information. Every engine is different and gives torque or response in one area more than another so it's really a case of trying things out although you can make a good guess at what would be a good choice.

ctwg60 wrote:Oh my favorite suject!

Have you seen this page it gives a lot of info on different ratios etc.

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I love it! The first link pointing at content that I wrote!

Crazy.... wrote:But 40 in first is nice, but not too long and easily hitting 60 in second is spot on. Providing you have enough bottom end torque to get away in the first place!

You so the reason I was asking about the longer TDI box was to use it in conjunction with the stroked 2042cc engine I was talking about the other day.

That's some good tabulated info Flusted, is that a website or an excel document that can work that out for you?

mrbeige wrote:So, what would be the best off-the-shelf gearbox for a 16v Turbo? Been thinking about the CTN TDi boxes, but not sure on the ratios, anyone got any ideas?

So you wrote that page and your asking us!!

OK I'll get a bit more in depth then. You have to work back from the available traction at the front wheels this can be guesstimated once you have an at the wheel plot for a for your torque curve and you know at what revs the wheels lose traction in say 2nd or 3rd, you then punch the numbers into a spreadsheet to tell you exactly at what torque the wheels are breaking away. I'd say much above 2000ftlbs at the wheels is enough to cause the wheels to breakaway with standard pressures. Another thing to consider if you just want to swap a box is to get one with the bolt in drive flanges as the breakaway torque dialed in with these gearboxes is far better that the early push fit flange boxes which has next to nothing after 80,000 miles.

This information of torque at the wheels can also give you some idea of the acceleration you can expect with a particular box. I can supply a spreadsheet to allow you to work all this out for yourself if you like!

EDIT heres the quaife gear speed calculator which is excellent for comparing ratios.

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I think i "may" of stole that info from CTW on rado forum

Personally i am gonna give the Standard ABF box a go... mainly because i have 2 sat in the garage lol

I had the CTN box on my Golf G60 and although it was nice to have the longer ratios it just wasnt as fun as the standard G60 golf box past 3rd gear... took all the fun out of driving the G60, thats just my opinion though. maybe different with the top end power of the 16vt

I think a compromise between the 2 would be good though

Shaggy wrote:I think a compromise between the 2 would be good though

I agree that the CTN is a great box for a cheap swap if you want traction, but it isn't perfect for a 200bhp/lbft engine, but the only way to get the perfect ratios is a cog swap either VR ratios or a mixture of diesel 1 & 2 for traction and 16v 3 & 4. Which is what I'm currently working on a the moment purely as experiment in finding the right ratios for drivability and QMT's.

Gearbox choice is a massive decision.
I think as ctwg60 says I am going to wait to see how my new engine behaves with my current box.
See where I feel let down traction wise and take it from there,rather than try a "one box fits all type solution."
Ideally you would want to do it at the build stage when your putting your new engine in but I think i'll wait and see how the engine performs.
Don't want to change too may variables at the same time.

ctwg60,didn't you say to me once that from 3rd gear onwards the ctn gearing is pretty close to standard g60 gearing?

Its nowhere near G60 gearing, its the 1st and 2nd that are very VR like though.

No I think I said a CTN is like a CBA (G60 box) but fitted with a diesel 3.1 FD the actual gear ratios are very similar so the drop between gears remains the same. If you have a look up at flusted's tech post you will see what I mean.

On the final drive side of things which way makes it accelerate quicker and vice versa?

im using 02a with vr6 clutch plate, my old 020 had **** gear selection and slipped at 2000 revs, now the gear selection feels slotted and doesnt slip, 6th gear would be a benifit me thinks