Manco Dingo Torque Convertor or TAV2?

[XXXStevemanXXX]

I am working on a stock 8HP Manco Dingo that needs attention to the torque convertor. I am missing one of the metal rods inside the shoe driver in the driver pulley, so I am about to order up some new parts. We installed a TAV2 kit onto another 8HP Dingo and it works great, but some minor differences I note is the Driven pulley is only a 6" on the TAV2 and its a 7" on my Dingo.

Would you guys clean up the stock Comet 30, order a new belt and shoe driver for ~$60, or should I also convert mine over to the TAV2 for a couple more dollars to get everything brand new and not use the stock jackshaft setup? I am not sure if I will lose performance or speed with the TAV2 over the stock Comet 30 with 7" Driven pulley?

 

[landuse]

Either way would be fine

 

[itsid]

well first, you can also get a 7" driven
in case you want.

the 7" just shifts the ratios towards torque and has a slightly wider range... that's basically all the difference.

low ratio
for a 6" 2.7:1
for a 7" 3.13:1

high ratio
for a 6" 0.9:1
for a 7" 1.12:1

ranges: 6": 1.8, 7": 2.01.

So if you keep the stock sprocket ratios, a 6" is slightly slower on take off, but has a better top speed.

you could even compensate for that by adding a few more teeth to the axle sprocket,
then all that's left is the slightly wider range the 7" has to work with.
(but seeing how most TCs rush into high gear.. I'm not sure that's really important)

'sid

[EDIT]
assuming a 388 dingo (22" rear wheels, 9T jackshaft sprocket, 54 axle sprocket)
let's ask my calculator ...

6" driven:
KartInfo by kartcalc.net:

[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 55.88 cm | 22 in[/B]
[I]Total weight[/I]: [B] 180 kg | 396.83 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 8[/B]
[I]Asummed HP[/I]: [B] ~8[/B]
[I]Torque[/I]: [B] 15.82 Nm | 11.67 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 6:1[/B]
[I]TC type[/I]: [B]  series 30 6" driven[/B]
[I]Lowest ratio[/I]: [B] 16.2:1[/B]
[I]Highest ratio[/I]: [B] 5.4:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 256.28 Nm | 189.02 ft lbf[/B]
[I]Min Wheel Torque[/I]: [B] 85.43 Nm | 63.01 ft lbf[/B]
[I]Acceleration[/I]: [B] 2.89 m/s² | 9.48 ft/s²[/B]
[I]Top Speed[/I]: [B] 70.22 km/h | 43.63 mph[/B]
[/INDENT]
[B][U]PROBLEMS[/U][/B]
[INDENT][B]You might burn your clutch/belt![/B]
[B]Gear ratio too high![/B]
[I]Suggested final ratio[/I]: [B] at least 6.4:1[/B]
[/INDENT]
[/FONT]

adjusting the sprocket to 60T instead of just 54 makes that a final ratio of 6.67:1

[FONT="Verdana"]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 6.67:1[/B]
[I]TC type[/I]: [B]  series 30 6" driven[/B]
[I]Lowest ratio[/I]: [B] 18.01:1[/B]
[I]Highest ratio[/I]: [B] 6:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 284.92 Nm | 210.15 ft lbf[/B]
[I]Min Wheel Torque[/I]: [B] 94.92 Nm | 70.01 ft lbf[/B]
[I]Acceleration[/I]: [B] 3.22 m/s² | 10.56 ft/s²[/B]
[I]Top Speed[/I]: [B] 63.2 km/h | 39.27 mph[/B]
[/INDENT]
[/FONT]

7" driven:
KartInfo by kartcalc.net:

[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 55.88 cm | 22 in[/B]
[I]Total weight[/I]: [B] 180 kg | 396.83 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 8[/B]
[I]Asummed HP[/I]: [B] ~8[/B]
[I]Torque[/I]: [B] 15.82 Nm | 11.67 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 6:1[/B]
[I]TC type[/I]: [B]  series 30 7" driven[/B]
[I]Lowest ratio[/I]: [B] 18.78:1[/B]
[I]Highest ratio[/I]: [B] 6.72:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 297.1 Nm | 219.13 ft lbf[/B]
[I]Min Wheel Torque[/I]: [B] 106.31 Nm | 78.41 ft lbf[/B]
[I]Acceleration[/I]: [B] 3.3 m/s² | 10.83 ft/s²[/B]
[I]Top Speed[/I]: [B] 56.43 km/h | 35.06 mph[/B]
[/INDENT]
[/FONT]

 

[XXXStevemanXXX]

Thanks for the calculations, Sid. I think I should stick with my 7" Driven, because it is a heavy kart with big 22" knobbies and needs all the torque she can get. I see the TAV2 is also listed as a 10% overdrive, and I am not sure if my stock Comet 30 does the same ratio in High , or is he going to beat me in top end speed by 10% due to his overdrive...

 

[itsid]

SO basically you haven't read what I said

No, a 7" driven does NOT provide overdrive.. in fact it doesn't even provide a 1:1 high speed ratio. (line 9)

You can adjust a 6" driven TAV with a bigger sprocket to get about as much torque as it had with the 7" driven (second part of the calculation)

And yes a 6" driven will still beat a 7" driven in top speed because of that missing overdrive, even with slightly adjusted gear ratios.
(compare the performance part of all the calculations)

'sid

 

[Johnnyboy]

Assuming there is nothing wrong with the rest of the tc, I would just replace the shoe assembly for <$30. Comet torque converters will last forever with some basic maintenance (new springs, new buttons on driven, etc when needed)

 

[XXXStevemanXXX]

I did fully understand your post. The big, giant, heavy kart came with a 7" Driven pulley and replacing it with a 6" is going to REDUCE wheel torque, thus making the kart slower to take off, but it can attain a higher top speed.

If the sheaves were not rusty on my stock Comet with 7" Driven, I would just replace the driver and driven, but the TAV2 kit at $80 and includes both pulleys, belt, and cover which is way, way cheaper.