hpi pro d

i got a pro d second hand a awhile ago other than getting some alloy parts its sat on my shelf and ive done nothing with it since 

recently i decided to do a budget rwd build with this chassis using mostly stuff i had lying around.

starting with the diff i used the front ball diff and used this in the rear ratio is 2 . 4 to 1

next was assembling the rear end and adding some nice alloy bits

then to the front for this abit more work was needed the standard arms would not allow enough lock so for the moment im using modified arms done by the previous owner mst Y arms will be added soon as they will fit and are cheap at $10aud  . i used some type c upper arms and mikuni knuckles i already had new parts include some mst axles and a x limit sliderack.

to fit the rack all original holes in the bottom plate where filled in with resin and after some measurements and trail fittings to see if i had the geometry i was after two new holes where drilled and the rack bolted in place .

 another thing i needed to do to allow the rack to give full sweep was to channel out a section in the front bulkhead

more than decent lock













 all together , shocks are yeah racing purchased for $24aud using the 4 hole faster compression piston in rear and standard 4 hole  piston in front none of the yeah racing springs were of use as there to stiff , r2 hobbies green are in the rear , fronts are a medium unsure of origin








sticking with the budget build theme im using basic electrics i already had a ezrun esc and unsensored 9turn motor sanwa servo and a mst gyro

using the standard 87 t spur the motor hit the servo and didnt allow enough adjustment a 25 pinion was the smallest i could use and i couldnt get a fdr i was after so a 92 spur was used this with a 23 pinion gave a 9.6 fdr but the motor is still at full adjustment i plan to add a larger spur in future space permitting.





after the first test run it felt pretty good one thing that did happen was the chassis crabbed in one direction but not the other with a little playing around i found that either adding a lot of weight to the chassis opposite of the motor lessened this also not adding weight and pre loading the rear shock stopped it , not wanting to do either the esc is now on the opposite side to the motor as you can see above now theres no crabbing at all .

also to give some more rear grip ive angled the rear arms by spacing up the toe block .













driving it now it feels stable and has good drive, with the battery in it has a slight rear weight bias . pretty happy with the end result and looking forward to changing to a sensored motor soon.

a short on board video of the pro d showing the steering rack i now run 26mm wheels up front , hex hubs are 3mm with 8 offset rims giving zero scrub and 75deg of lock