Want more low end punch ?

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lorraine

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We gave up running the beadlock type tire system a few seasons back and are now running the 180mm grp rims and tires that MCD use on their race buggies, The GRP soft and med compounds are true race tires and have massive hookup on 2wd 5Bs , The hex hubs need to have .100 taken off wheel side face so there is more thread out of rim face for wheel nuts, That's done. Now the large OD of these bad boys will make lower powered motors fall on their face even with the 16-58 gearing setup, Now the fix. HPI made 2 different tooth count upper gear for the inside of gear case, A 19 tooth for truck and a 20 tooth for buggy. You want to change to the 19 tooth for more low end and take load off motor and make the rollout right, DDM sells the 19 tooth in their Black Magic line of HD gears for the buggy tranny . You will never go back after running this setup
 
lorraine said:
We gave up running the beadlock type tire system a few seasons back and are now running the 180mm grp rims and tires that MCD use on their race buggies, The GRP soft and med compounds are true race tires and have massive hookup on 2wd 5Bs , The hex hubs need to have .100 taken off wheel side face so there is more thread out of rim face for wheel nuts, That's done. Now the large OD of these bad boys will make lower powered motors fall on their face even with the 16-58 gearing setup, Now the fix. HPI made 2 different tooth count upper gear for the inside of gear case, A 19 tooth for truck and a 20 tooth for buggy. You want to change to the 19 tooth for more low end and take load off motor and make the rollout right, DDM sells the 19 tooth in their Black Magic line of HD gears for the buggy tranny . You will never go back after running this setup
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No need to also change the idler gear so to maintain proper gear mesh backlash ?
 
No other gears in stack need to be changed out but top shaft gear, sounds goofy but true. Idler and diff gear are the same for BOTH setups. They take the MOD1 tooth profile and open it up a small bit on each tooth so a 19 takes up the same room as a 20. Hpi made this 19 tooth just for their short course truck so it would have more punch on short tight tracks. Look in Hpi break downs and see the 20 top for buggy and the 19 in truck. the idler and diff gear is same tooth count. I had both gears on bench and they are the same OD as each other and BOTH 19 and 20 mesh the same in case. It is strange that it does not scrub much speed off top end , but it sure wakes up the bottom end. This gear makes mid range much much stronger and that is what I think HPI aimed for. I put alot of these in the rovan buggies for the guy's and they love them. I use them as we run 180mm setups but in a stock buggy with the smaller wheels it wakes them up pretty nice . Perfect for backyard point and shoot.
 
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