i think i found what our cars are ripping off. it is a hpi rs4. tell me if these look compatible.[img][/img]

I have one of the VH-X5 buggies. The engine ran good for a couple of days then started doing what he says. The engine is cheap in my opinion, just put an OS .18 in it, fixed the problem!

Keith

check out how similar the assembly is. the diffs are the same.
http://www.hpiracing.com/graphics/instr/10251/10251.pdf

The diffs on that buggy have springs inside, on the spider gear shafts... They look quite different, but I think can work on our buggies by swapping entire differential housing.
This also has a lot of plastic chassis parts where ours are aluminum.

i think the gears are a direct fit dude. i think this is what smartech ripped off. tell me if you think the gears in the pic will fit.

The pinion gear looks different, but still may work. As long as all the gears share the same bearing O.D. and don't exceed max diameter, they just might work... If someone wants to try it, post back here! I think it would be better to get the whole diff assembly, so in case the gears don't work, you can retrofit the whole works to the Smartech...

The diff housing is attached to the a-arm holder.. so i think it would be necessary to transplant both diff housing and a-arms, The complete rear assembly. some of the small diff gears works according to naturefreak that posted in here a while ago, maybe arond page 50 somewhere. and i think the a- arms on those cars are shorter than on our buggies as the car is not as wide as a buggy.

finally got an e-mail from rcworld today. parts should be here today!! yes!! I can fix my buggy in 5 minuits after i get them. Oh and ill try some of thoes parts. they do look simalar. the c-joints have a few extra screw holes I dont have on my speedy tiger.

thank you. there is no lhs where i live, so i have to buy them to try them, and i cant afford to waste money if they don't work. they make longer arms like that for a truck version. that would be cool. those diff gears in the picture sure look similar to me. i wish i could try them.

If i get a chance ill run down there today. give you results tonight. that is if the girlfriend will let me.

those girlfriends sure get in the way of having fun

I use HPI gears in all the diffs on my Vanguard. They are a direct fit, and an awsome upgrade. They should also fit the 1/10th buggies. Funny thing is even though the buggy is bigger, most of the inside parts are the same as the 1/10th!

great! thank you for the info. i would sure like some aluminum knuckle arms. if i can get the c hubs to fit, the knuckle arms will drop right in. i can always make arms to fit the c hub. the arms are easy to make.

I tried hpi mt2 diff parts in my winner sport, didnt fit..

when did you try? which parts did you try? that makes me sad

ooh you tried mt2. im talking about rs4. im relieved

i guess that is the truck version. the gears do look similar though

are those hpi gears? i tried the driving gear. the shaft were thicker than the smt. went to my lhs to try to find something that fits. but he werent wery helpful...

those are mt2 gears

Trail..... how much fuel do you have through your engine? i would not mess with stuff like changine compression, cuz they make the engines with that much compression for a reason. when you increase the compression that much (it dosent seam like alot but it is) you change the timing of the engine. and your engine may be experiencing pre detonation, which is where there is so much compression that the methane ignites by just the compression. that is why when you use extra washers it runs better. oh and also. how long have you had that particular gallon of fuel. because when you open it one of two things will start to happen. 1. the alcahol in the fuel will draw water. 2. the nitro, which is what keeps the alcahol from igniting too early, evaporates.

i have a gallon through. i am using fresh gallon. a thousandth wont make that much of a difference i don't think. but i can always machine a different head. i odnt mind experimenting. the engine is not pre igniting or pre detonating. it doesn't sound chocked up. when it runs it runs great. now it is tuned good. it is rich on the hsn but it still gets hot, but it runs good now, and it is really fast. when i get it tuned perfectly i will take the other washer off, and i expect a performance boost. and for ignition timing i could delay it by putting a colder plug in it, or by putting more head shims, or put a shorter plug. my fuel is new, so that is not the problem. i got it tuned ok, so that is not the problem either. to solve the over heating i could put a huge cooling head, and i would have the preformance boost, and still have head temps down. what cooling head do i buy?

i know a thousanth dosent sound like much but when you start messing with it and ther is already a very small ammount between the piston and the head it is alot. im not saying dont experiment, that is great, but i would make some bigger cooling fins or more fins to get rid of some of that heat. the reason i say it might have pre detonation is cuz it is running hot, but also the more compression you have the hotter it runs.....

yep it runs hotter with higher compression so its probably just a matter of getting the temp down with a better cooling head. smt cooling heads arent very effective, when you compare with more expencive engines. perhaps you should install watercooling and a radiator

that would be awesom!!!!!!!!!! ok get a mini radiator and instal an elctric fan then make a head with a water chamber and a little mini water pump and that would be awesome!!!!! lol

the cooling fins are already a radiator. i dont need a fan because of the air blowing over it from driving