mk4 gear change

[tshirt2k]

What is your issue with the gearbox? Do you spin easily in lower gears? Want better cruising speeds?

I'm going for a vr6 final drive on a 16v box. Basically a vr6 box that will fit a 4cyl. It will reduce cruising revs by around 300rpm. Will reduce wheelspin in the lower gears by lowering axle torque. This should aid acceleration.

You could go for a diesel ctn box but I worked out, that it wouldn't be that suitable for my engine. If it were a g60 then yes.

All depends on how easy you want it? A box swap or get internals changed?

That's why I changed 5th gear as it was easiest and cheapest to do now and I could get more relaxed cruising revs.

[Dan_GTi8v]

Ah yes I guess it would help knowing my issues  I get a lot of wheel spin in low gears and when at 70+ it feels like the engines working harder than it should be, id like to cruise at lower revs basically. I think the box I have now is a dpa

[tshirt2k]

Same as me then. A lower final drive would suit you then. But if the box is being split, you may aswell get an LSD.  That's what I'm waiting for. Already have a spare dpa to get built.

You could try a diesel/g60 5th to give you a more relaxed motorway drive. Those gearboxes are designed for a higher reving lower torque engine so that's why it feels highly strung on the m25.

I ideally wanted a 0.755 5th from a CTN box which will give 70mph @ 2900 rpm and 158mph @ 6500rpm.

But I've got a 0.769 5th from a g60 which should give 70@ 2950 and 155 @ 6500rpm

Top speeds will only be reached if the car has enough power to over come the drag.

[Dan_GTi8v]

Looking like I may have to go the same route as you then, I better get swatting up on gearboxs :p so when finished your going for just changing the final drive, or final drive and 5th?  I may end up getting a diesel box anyway then I can play around with the dpa and see what I can learn :p

[Dan_GTi8v]

Have you looked into the ASD diesel box at all?

[tshirt2k]

Asd has similar ratios to a 16v box but a low final drive and an even longer 5th.

Go into the gearboxman website and download calculator. Put the ratios in and see if it works. Personally I think it would be to long and lazy. You may have to do alot of changing up and down the box to get it moving swiftly. 5th would need changing to the 16v ratio as it tops out at a theoretical 170mph.

I'll be changing final drive along with an LSD. I can always change 5th if i need to as I already have it. Only takes about an hour to change.

[Dan_GTi8v]

ASD looks pretty good for what I want I think, same as my box I have now in 1st-3rd and a longer 4th and 5th. I just need to work out where the final drive comes in, I dont have excel so cant use the gearboxman sheet and have to use some tool i found on google, its saying I'd get 180 in 5th at 6000rpm

1st 39mph
2nd 66mph
3rd 98mph
4th 118mph
5th 180mph

Not sure how accurate that is though cant see myself doing 100 in 3rd Though if I put in the DPA ratios it seems pretty similar to what I can get atm

[tshirt2k]

I'll put up a graph for ya. Or you could get OpenOffice free 

[Dan_GTi8v]

Thinking I'm going to go for ASD box with a mk4 shifter just deciding on the towers. With the box out do you think it would be worth it at all fitting the newer 02j tower or stick with the mk3 type 02j tower I alraedy have?

also this will all fit gearbox end without any mods right? cables will be the right length etc? shifter im looking at has the ball type end links

[tshirt2k]

This is how the gear speeds will be. 5th will be Waaay to long and i'd change for a 16v one.



I did max revs at 6500 and 195/50-15 tyres. Your car may not be able to pull 6500rpm in top.

This is using Quaife calc

Gearbox:-  ASD
Tyre:-       195/50-15
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Top Gear gives 29.811 MPH/1000 RPM and a top speed of 193.770 MPH at 6500 RPM

Engine speeds in top gear:-
    30 MPH = 1006 RPM   40 MPH = 1342 RPM   50 MPH = 1677 RPM   60 MPH = 2013 RPM
    70 MPH = 2348 RPM   80 MPH = 2684 RPM   90 MPH = 3019 RPM  100 MPH = 3354 RPM

Top Speed in 1 gear = 42.101 MPH
    And changes into 2 gear at 3829 RPM dropping 2671 RPM
Top Speed in 2 gear = 71.468 MPH
    And changes into 3 gear at 4373 RPM dropping 2127 RPM
Top Speed in 3 gear = 106.218 MPH
    And changes into 4 gear at 5114 RPM dropping 1386 RPM
Top Speed in 4 gear = 135.017 MPH
    And changes into 5 gear at 4529 RPM dropping 1971 RPM
Top Speed in 5 gear = 193.770 MPH
******************************************************************************************
Gearbox:-  ABF
Tyre:-       195/50-15
-------------------------------------------------------------------------------------------
Top Gear gives 21.914 MPH/1000 RPM and a top speed of 142.444 MPH at 6500 RPM

Engine speeds in top gear:-
    30 MPH = 1369 RPM   40 MPH = 1825 RPM   50 MPH = 2282 RPM   60 MPH = 2738 RPM
    70 MPH = 3194 RPM   80 MPH = 3651 RPM   90 MPH = 4107 RPM  100 MPH = 4563 RPM

Top Speed in 1 gear = 36.129 MPH
    And changes into 2 gear at 3829 RPM dropping 2671 RPM
Top Speed in 2 gear = 61.330 MPH
    And changes into 3 gear at 4373 RPM dropping 2127 RPM
Top Speed in 3 gear = 91.151 MPH
    And changes into 4 gear at 5114 RPM dropping 1386 RPM
Top Speed in 4 gear = 115.865 MPH
    And changes into 5 gear at 5287 RPM dropping 1213 RPM
Top Speed in 5 gear = 142.444 MPH
******************************************************************************************