Hyper ST Pro Brushless clarification....

[shan75]

Hi Guys,

New to forum and first time poster.

Been out of the scene for a VERY long time, but recently got the bug again. Things have come a LONG way since my Tamiya days! Really loving the technology and the brushless stuff is nuts! Can't wipe the smile from my face when bashing with my HPI Firestorm.

However - I am getting sick of breaking the HPI and wanted something tougher without killing my wallet. Thinking 1/8 scale and after doing research, trawling through forums and waiting for a cheap car to appear on ebay - picked up an ST Pro.

I know - it's getting "on" a bit, but I checked with Ofna and parts are still being made and the hyper platform is repected as being tough. I am just bashing as well - so do not need the fastest/latest/greatest.

So - my question?

Now- I reckon I have read EVERY single post on ST Pro conversions out there and there seem to be a number of different battery placement configurations. This is my dilemma. I know that guys on this site have run both (I think a moderator owned two ST's with two different battery configs) - hence my post.

The majority seem to leans towards 1 x Lipo down the side of car opposite the motor and esc. Reported good balance and handling.

There are also other 2 x lipo configurations - often saddled at the rear after flipping the middle diff. Looks great and users also state good balance, handling and straight flying as a result.

Which is best and why? x1 to the side or x2 at the rear?

ONE battery is easier, but the runtime from 2 batteries is attractive to me.
Two batteries at the back though? Got to be unbalanced from front to back surely?

I am hoping someone can personally confirm the results of both configs and nudge me in the right direction.

So yeah - what is the best bashing config for the batteries in a Hyper ST Pro.

Thanks guys!

[shan75]

Anyone??

I know some of the mods here ran Hyper ST's in both battery configurations - would appreciate some advice!

Cheers!

[Thirdgen89GTA]

I don't have a Hyper ST. I've got a Jammin X1 truggy though, and while people recomended the single battery layout, no one told me I was crazy or that it couldn't be done with saddle pack style. My advice is to take ALL of your measurements and mock it up on the chassis. There will be drilling and countersinking of the chassis most likely.

Now that the truck is done I'm VERY happy with the saddle pack layout. Left to right is about as balanced as it can get, and the truck is actually balanced front to back very well too. The motor is already pretty close to centerline, so even though its nearly 416 grams, it doesn't have much polar momentum.

With twin 2S packs its slightly nose heavy. Steers faster under power. With twin 3S packs its a little less nimble, but the run time or speed benefits are why I'd run it that way. 3S 10,000mah is nice. But if you wanna go fast just change from parallel to series and go 6S.

The only annoying thing is making sure to label your packs so you only run them in pairs. I only have 1 pair of 2S, and 1 pair of 3S but when I get more I'll label them so I don't mix and match new/old packs.

If I did it again though I would have gone for custom battery trays to fit the batteries I do have better. since the trays are slightly too long and I had to do some clearancing to make them fit. I also installed stops to prevent the battery from sliding forward. If I had gone with custom sized trays I could have avoided that.

If you go saddle pack, you can make a rear ESC tray that will put the ESC between the two packs. I just finished the last revision to the setup which lowered the ESC and protected it better from lid impacts.

http://www.rc-monster.com/forum/show...t=30843&page=2

[shan75]

Awesome build. Was hoping to get some feedback on the saddle config - so thanks!

I was leaning towards 2 x lipo simply due to the longer "fun/run" times for bashing, but even so - would not do it if balance was way out of whack. Based on your commnets - with a bit of tweaking it works well. Appreciate the feedback!

Some good points about ESC placment. I purchased a MM along with a traxxas MM ESC mount. http://www.rcplanet.com/Traxxas_Moun..._p/tra5626.htm Should be well protected I think. Was a suggestion I read somewhere on another forum.

What about rear suspension? Any issues?

[Thirdgen89GTA]

Originally Posted by shan75

Awesome build. Was hoping to get some feedback on the saddle config - so thanks!

I was leaning towards 2 x lipo simply due to the longer "fun/run" times for bashing, but even so - would not do it if balance was way out of whack. Based on your commnets - with a bit of tweaking it works well. Appreciate the feedback!

Some good points about ESC placment. I purchased a MM along with a traxxas MM ESC mount. http://www.rcplanet.com/Traxxas_Moun..._p/tra5626.htm Should be well protected I think. Was a suggestion I read somewhere on another forum.

What about rear suspension? Any issues?

The nuts on the rear arm pins can be someone hard to get to. But a set of small/long needle nose pliers is usually all I need. I can grab the nut and unscrew the arm. It doesn't make it the fastest to work on, but it works.

If I went with a set of custom battery trays I'd save some space and it would be easier too. But thats more $$$ than I want to invest. The truck right now is pretty hard to upset side to side. Though I still need to work out the damping and small rhythm sections at speed can upset the back end. I should try filling the rear shocks with 50wt instead of 60wt to see if that helps.

But if you can fit them, it offers balance as good as it can get. If you look at all the purpose designed 1/10th scale electric off roaders they either use a single central battery or saddle packs. Just about anything thats converted from a nitro car uses a single pack for easy of conversion.

One of the things I really don't like is where the motor wires are, but thankfully with as low as they are now the chances of them getting hit hard in a crash are very minimal.

Just take your time, measure out your components and you should be fine. You'll hit some snags with a saddle pack that most people don't see because they didn't go that route. But nothing is insurmountable. My conversion took about 1 month to complete due to waiting for parts, and wanting to do it right. I had questions that needed answering, and some questions only popped up once I had the components in my hands.

This was also my first electric conversion, so going my own way made more questions. But I'm really happy with it. Its supremely fast, and runtimes are good when I want them to be. I think I get about 15-20m on the twin 4S and 3S packs in series. And with the 3S packs in parallel I can be out there for a long while. It tops out about 35mph right now with 3S power. Top speed has never been tested because I don't have a tire that won't fly apart at speed, and the front diff STILL unloads even with 100k center fluid.

[brian015]

I'm not sure that anyone is running two packs for longer runtime - that would add to your weight significantly. Most run two smaller packs for better weight distribution. One pack is a simpler layout and it only takes a minute if you have a second pack to change it out when you are bashing.

[Thirdgen89GTA]

Originally Posted by brian015

I'm not sure that anyone is running two packs for longer runtime - that would add to your weight significantly. Most run two smaller packs for better weight distribution. One pack is a simpler layout and it only takes a minute if you have a second pack to change it out when you are bashing.

Yeah, but it gives the opportunity.

I can run either my twin 2S packs in series for 4S at the track. And I often run the twin 3S in parallel at the track for runtime or when bashing. 6S for the most part is just plain to stupid fast with my combo. Its really only useful for the shock and awe bit.

With 3S I keep up with the nitro 1/8th buggies on the straights. They have a higher terminal top speed, but they don't have the room to use it, so the acceleration of the electric system offsets it. On 4S I walk away easily.

I have considered twin 4S packs in parallel, but that is too much weight and breakage will occur. The truck would settle in just at 11lbs with twin 4S packs.

Twin 2S = 9.8lbs
Twin 3S = 10.5lbs
Twin 4S = 11.0lbs

Or if you want kilograms the base weight w/o batteries is 3.751kg.

[Arct1k]

It was me - I has 2 hypers with one in each config.

I think it is personal preference. I couldn't tell much diffetence.

The single tray is much simpler and I'd do that next time.

[shan75]

Again - appreciate the input guys.

Correct Arct1k - you were the guy I was thinking of running both setups! Cheers for that.

This is my first conversion as well - so trying to be mindful about what I do.

So - seems like there are positive benefits for going both ways with the batteries. Obvious simplicity for the single battery, but added benefits in going for x2 lipos. Hmmmm.....need to think about this more I think.

As for diffs - 100K in middle diff and it still unloads? Damn.

I have read posts all over the web about different configs relating to diff oils (specific to Hyper ST mind you). To be honest - seems like opinion is all over the place! I have seen positive reviews (front/middle/rear) for 5K/20K/3K, 5k/10K/3K, 10K/50K/3K, 10K/100k/10K etc etc. Some people putting 140K+ into the centres. All over the place!
Did my head in actually. Settled for 10K/60K/4K for my Hyper Pro. Also bought a bottle 20K in case 60K was overkill.... Maybe I should have gone higher tho? Time will tell.

As for motor protection with the middle diff flip - I read somewhere that Mugen MB chassis guards fit nice onto the Hyper ST, so I ordered a set. They widen the body and provide impact protection as well as higher edges to prevent debris from getting into chassis.

Trying to cover all the angles I can with this car....bound to miss something though....

[Thirdgen89GTA]

Originally Posted by shan75

Again - appreciate the input guys.

Correct Arct1k - you were the guy I was thinking of running both setups! Cheers for that.

This is my first conversion as well - so trying to be mindful about what I do.

So - seems like there are positive benefits for going both ways with the batteries. Obvious simplicity for the single battery, but added benefits in going for x2 lipos. Hmmmm.....need to think about this more I think.

As for diffs - 100K in middle diff and it still unloads? Damn.

I have read posts all over the web about different configs relating to diff oils (specific to Hyper ST mind you). To be honest - seems like opinion is all over the place! I have seen positive reviews (front/middle/rear) for 5K/20K/3K, 5k/10K/3K, 10K/50K/3K, 10K/100k/10K etc etc. Some people putting 140K+ into the centres. All over the place!
Did my head in actually. Settled for 10K/60K/4K for my Hyper Pro. Also bought a bottle 20K in case 60K was overkill.... Maybe I should have gone higher tho? Time will tell.

As for motor protection with the middle diff flip - I read somewhere that Mugen MB chassis guards fit nice onto the Hyper ST, so I ordered a set. They widen the body and provide impact protection as well as higher edges to prevent debris from getting into chassis.

Trying to cover all the angles I can with this car....bound to miss something though....

It all depends on just how much power you are putting through the system. On 3S and 4S the front diff really doesn't unload all that much. Its crazy the power jump from 4S to 6S. Thats really crazy. I can control the power now without much of the software aids in the ESC. But I couldn't track it on 6S. Its just too much power. Though I make take it to the local track and set the TQ limiting to .6 or .7 and see if I can control it there. Would be funny to blast down the straights like mad. Except the end of the straight is a brick wall.

Truthfully I've been having alot of fun with my Mini 8ight. So much so that I'm considering buying a Mini E-Revo VXL so I have that too at the indoor track.

[shan75]

Yeah - well - no indoor tracks near me unfortunately. Outdoors bashing only so strength is really important to me. Bigger is better outdoors...

Soooo...

Decided to make life hard for myself and go with the saddled lipo config. I figure I can always reverse it back to 1 x lipo it if I am not happy. If I do it the easy way with single battery from the start and I get the truggy operational - I will never be motivated to mod it again. So yeah - will do necessary tricky chassis mods now for diff flip I reckon.

I started stripping the car down, flipped the diff and visually it appears like the front chassis brace is definitely going to get in the way of the Castle 2200kv I have on order!?!

I know other guys with this config have used the 2200kv castle combo, but yeah - while I cannot confirm for sure as engine is not here yet - I am pretty certain it will get in the way.

Scanned through the forums and there is some mention of the space limitations at front, but no real mention about having to mod chassis braces with a 2200kv motor?

QUESTION - can someone who has flipped the centre confirm for me what else needs doing in the front? Arct1k if you read this would appreciate your input as I know you have done this! Already thinking maybe I should have followed your original advice mate...

2200kv castle is approx 75mm long and 41mm wide - from my rough measurements - engine will hit that front brace. Am I going nuts?

Comments I read about flipping the diff on the hyper mentioned grinding chassis for centre diff gear clearance, but have read no mention of anything else?

Looked at all the pic's I can - hard to tell what other peeps may have done.

Grind the brace for clearance?
Shim the engine so it is angled way from the brace?
Alter the diff mount slighty? Not real keen and changing drive train alignment tho...

How the heck to you guys do it?

Appreciate any input on this.

Cheers.

[Arct1k]

Yes you have to mod the brace. It's only a few mm in one area.

I just used the Dremel sanding drum.

[magman]

Originally Posted by Thirdgen89GTA

Would be funny to blast down the straights like mad. Except the end of the straight is a brick wall.

That would not be good for sure. I was showing off one day in a campsite with my mbx5t on 5s and lost focus for a sec and wham...bathroom wall jumped out at me. Not to much damage considering the speed of impact

[shan75]

Thanks Arct1k - thought as much.

Again - appreciate the input.

Cheers!