Longer 4th and 5th gear & strengthening ATV gearbox

[dan1300r]

Does anyone have any info on what I need to do to have longer 4th and 5th gears (or just 5th) in my ATV box? Not looking to change final drive as I've heard of the 4th 5th mod being possible without changing this and want the same lowdown pull in 1-3. I would like to do this when I fit my diff - also can anyone point me in the right direction for uprated bearing cases for a stronger box and where to get seals, or anyone that would do all of the aforementioned? Thanks

[PR23M3K]

ATV box has a ratio 0,851. If you need longer 5th gear just put the gear from 8P, AEB or AYZ box (ratio 0,740).

[dan1300r]

Sounds good, I saw someone on here quote that they changed their 5th and dropped their RPM from 3100 at 70mph to 2750.. Just wondering if this would be the gear that did that or if anyone has any idea where my RPM would be at 70 if I did this.

[Jimmy B]

Does anyone have any info on a gearbox from the 1W / Seat Terra engine at all - the vehicle was a 1390cc diesel. With the torque produced by a diesel engine and with it being geared for a larger engine would it be any stronger? 

Maybe a mix of ATV / 8P and the 1W box gears'd work out ok? A longer 3rd and fifth?

- Jimmy

[PR23M3K]

Here is data for almost all Polo gearboxes, with a help of a gear/speed calculator (that is easy to find online) you can check what is the impact on speed.

[Nick_S]

Seat terra came with a cem box, no stronger than others because its a late 1 litre polo box

[dan1300r]

Here is data for almost all Polo gearboxes, with a help of a gear/speed calculator (that is easy to find online) you can check what is the impact on speed.

Excellent info.. very clear, I'll lose 409RPM at 70mph and at 6700RPM I get a road speed of 172mph instead of 150. I'm currently swallowing 5th gear with ease so will be interesting if the aerodynamics will let it go that far hehe

[z3i]

172mph.... wow!
not that this is relevant or helpful, but the other day i was driving a new bmw 120d and at 70mph the revs sit at 1850rpm... lol
thought it was interesting haha

[dan1300r]

172mph.... wow!
not that this is relevant or helpful, but the other day i was driving a new bmw 120d and at 70mph the revs sit at 1850rpm... lol
thought it was interesting haha

I run a mk6 Golf 2.0 TDI GT and it's at 1800rpm at 80mph, you get to 140 (on a good day) and ifirc it's still only at around 3200rpm but it won't pull any more.. Maybe if I shape the front like a knife blade it will do 250mph lol.. I wish I could make my Polo a 6 speed 

[physicsfool]

I will be popping an 8p 5th into my atv box. Make the A road driving a tad more easy going.

Where would I best source such a gear?

[dan1300r]

I will be popping an 8p 5th into my atv box. Make the A road driving a tad more easy going.

Where would I best source such a gear?

I'll second that question - I fancy trying the 8p 5th too, just hope there's not too much of a gap from 4th, at least you can change 5th gear with the gearbox fitted if you don't like it.

[z3i]

Thought about this and had the same thoughts as above. if you try this martin post your results as im sure many people would be interested

[physicsfool]

Ay lad, you had a mosey at the state of my diff! Need to sort that before I refit the box

[z3i]

Ay lad, you had a mosey at the state of my diff! Need to sort that before I refit the box

is it bad? lol did you ever see mine? looked obliterated. took it too a specialist and they said, its normal, just fit some genuine cv seals. so i did, and it worked!
might be worth taking yours to a gearbox specialist just to check tolerances?

[vee-dub90]

In my gearbox it is believed to have a longer 5th and supposed to be at 2750rpm at 70 but I haven't tested it because I haven't had the gearbox fitted to my car yet haha!