Gearing turbo sled for 660ft for drags

[rx1 fern]

Hi guys , just looking to see what you would recommend for gearing my sled for 660 feet snow drags. I have a turbo rx1 with a 144 track that is 2 1/4 finger track with 8 tooth drivers and I am running 25/38 gearing right now . I am thinking of gearing down to 24/38 or even a 23/38 . Just wondering if that would be too low of gearing as I have 8 tooth drivers and that is like gearing down also . Just want to see what you guys think is a good gearin set up . Thanks for the help and opinions .

 

[mbarryracing]

I like gearing down so it uses all of the clutch ratios, but the increased torque down low will cause it to spin the track significantly more and cause slower acceleration off the line so you will have to compensate accordingly.

 

[rx1 fern]

So what gearing do you run on your sled and what size of track . Thanks

 

[mbarryracing]

I run stock Apex 24/38 gearing with a 136 1.25" track for the trail and for 500ft snow drags.
There are differences in opinion on whether it's faster to run higher or lower gearing, but here is my take... right, wrong, or indifferent...
Most say to gear up so you go faster, but that doesn't always mean it will go quicker... You may be able to do 125MPH but I can beat you going 112 MPH if I get to the finish line quicker.
Since your drag racing and not doing speed runs... pick your poison.
Also some will say run taller gearing so you can spin the track faster to compensate for spinning, but that never worked for me with grass drag racing for sure. And not sure how much spinning you get with a 144?
I only run the gearing that will provide the MPH speed at the finish line that my heavy apex can realistically with the HP i am making and the traction I can get... hence I don't wastefully OVER gear.
Lower gearing provides more torque off the line without adding additional stress and heat in the belt. Taller gearing tends to slip the belt more and starts the ball rolling with creating heat and more slipping, etc. Fact is taller gearing is harder on belts, track or trail for this reason.
Lower gearing help achieve closer to full shift out of the clutches at the finish line, which when you think about it... it fully utilizes the finished angle of the secondary helix so the belt isn't slipping...
The issue is controlling track spin off the line. A balancing act between traction / friction with the snow and maximum acceleration... Taller gearing will do that at the expense of belt slippage, but you can do it with lower gearing thru HP management via stepping the boost in, ramping the ignition timing, etc.
It's enough to blow your mind, trust me.
Figure out the MPH you want to shoot for in 660ft, then gear for that initially, keeping in mind that your 144 paddle track is heavier with more wind resistance, and be realistic with yourself on the MPH.
I'd try 23/38 and check for clutch shiftout at 660ft and any signs of belt slippage.
Just my 2 cents.

 

[Vectorboost]

im running 24/38 in my mcx vector was thinking about putting the stock 22/38 back in will that make it quicker out of the hole or will slow it down because of track blow out and just plan track speed? 80% trail riding ,never seem to use the top end very often.Thoughts?

 

[rx1 fern]

So mbarryracing you recommend me go 23/38 even though I have 8 tooth drivers . Changing driver size is also like gearing down too . Yeah the 144 is a big track to be turning , that is why I want to gear the sled down too . I notice you run stock gearing on your sled , but you must still have 9 tooth drivers on with the 1.25 track . Thanks for the help guys . I just want to know if 23/38 gearing with 8 tooth drivers is too low .

 

[mbarryracing]

Test it, like anything else, it's the only way to tell with whatever HP level you are running.

 

[rxrider]

Like mbarryracing says, there's only one way forward and that is testing, tuning, testing, tuning, tesing and then more testing. And it's neverending, belive me.
You will learn a lot about Your sled in the process.
What Works for you may not work for others and the other way around.
There are just too many variables in play to copy another guys setup.

 

[rx1 fern]

I think I'll try the 24/38 first since I have 8 tooth drivers and a big lug track in a 144. I think 23/38 would be too low . Just my opinion . But trial and error is best way to find out. So putting 8 tooth drivers on , how much does it lowering the gearing ratio. Thanks

 

[sledracer]

Maybe a gearing calculator will help.

http://www.turboaddictionparts.com/cata ... lator.html