Go Back   RCCrawler Forums > RCCrawler General Tech > General Crawlers
Loading

Notices

Thread: Question from the drawing board....

Reply
 
LinkBack Thread Tools Display Modes
Old 01-08-2010, 09:44 AM   #1
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default Question from the drawing board....

I'm in the process of making a new chassis from scratch specifically for my crawler, with the intent to get the weight all as low as possible, to do this, I'm considering widening the chassis to fit my saddle pack in on either side of the transmission (to keep it balanced). I know I've seen narrowed chassis kits but never seen anyone say anything about widening it.....what advantages and disadvantages will I run into with this if I do widen it by about an inch on either side?
dhyde79 is offline   Reply With Quote
Sponsored Links
Old 01-08-2010, 09:53 AM   #2
RCC Addict
 
Join Date: Apr 2009
Location: Anderson
Posts: 1,332
Default

The main reason for not widing the chassis is the gates are only so wide. There are a few that run it wider than stock but 2" is a lot!

-Jason
KrawlOff-Road.com is offline   Reply With Quote
Old 01-08-2010, 10:11 AM   #3
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

......I'm not sure I understand.....the chassis right now is considerably skinnier than the axles/wheels, I'd assume as long as I keep the TVP's inside the tires I shouldn't be effecting the ability to clear gates, since it's gotta clear the wheels/tires/axles through the gates before the body ever gets there....

as far as 2", that was just a number off the top of my head, I'd really have to slap the driveline on the table and put the 2S 6000mah saddle pack on either side of the tranny and get the measurement there.... I'm just thinking I recall the battery being about 1" thick on either side....
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 10:17 AM   #4
Rock Crawler
 
Join Date: Jan 2006
Location: SUPERMOTO heaven
Posts: 695
Default

a wider chassis will hang up on rocks more often.

You may be better off trying to keep the chassis skinny and mount the battery on the front or rear axle.
engineerjoe is offline   Reply With Quote
Old 01-08-2010, 10:33 AM   #5
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

battery's too big to mount to either axle, besides, I'd have to mount on BOTH axles (it's a saddle pack setup) and each side is 45mm x 69mm x 29mm and only an 8" lead from side to side, mounting to axles isn't an option.....the other idea I'm toying with is putting them low in front and rear chassis over the driveshafts....
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 11:02 AM   #6
20K Club
 
Harley's Avatar
 
Join Date: Jul 2004
Location: Sending illegals home one Hayabusa at a time.
Posts: 22,981
Default

Get a new battery! Don't sacrifice such performance gains by using a crappy battery. New Lipo's can be had for cheap.

Narrow chassis will give you less hang ups, uses less material (lighter) and gives better shock mounting options.
Harley is offline   Reply With Quote
Old 01-08-2010, 11:25 AM   #7
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

Quote:
Originally Posted by Harley0706 View Post
Get a new battery! Don't sacrifice such performance gains by using a crappy battery. New Lipo's can be had for cheap.

Narrow chassis will give you less hang ups, uses less material (lighter) and gives better shock mounting options.
yeah, you probably should read up instead of just the last line genius, it's a brand new 2S3P Maxamps 6000mah Lipo, because of the overall config of the rig I get about 45-65 minutes depending on how much throttle I use....moving back down to a smaller lipo isn't going to happen.

as far as a narrow chassis giving me less hang ups, if I've been running proline rock sliders and haven't gotten them touched yet, I'm sure I can step the chassis out to that width and be fine.

as far as lighter....I'm using delrin for the whole thing and moving to that from stainless steel sheet...the weight difference will be drastic regardless of which, and all of the extra weight will be at the skid so it'll still be down low, and not matter as much.

more shock mounting options? please elaborate on this one, because I'm not sure I follow how I'm going to lose shock mounting options by putting the TVP's wider, I'm already aiming to get the shocks back inboard of the TVP's so that won't be much of a problem.....I genuinely don't see how that would get me more options by moving the plates inward....
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 11:41 AM   #8
20K Club
 
Harley's Avatar
 
Join Date: Jul 2004
Location: Sending illegals home one Hayabusa at a time.
Posts: 22,981
Default

Quote:
Originally Posted by dhyde79 View Post
yeah, you probably should read up instead of just the last line genius, it's a brand new 2S3P Maxamps 6000mah Lipo, because of the overall config of the rig I get about 45-65 minutes depending on how much throttle I use....moving back down to a smaller lipo isn't going to happen.

as far as a narrow chassis giving me less hang ups, if I've been running proline rock sliders and haven't gotten them touched yet, I'm sure I can step the chassis out to that width and be fine.

as far as lighter....I'm using delrin for the whole thing and moving to that from stainless steel sheet...the weight difference will be drastic regardless of which, and all of the extra weight will be at the skid so it'll still be down low, and not matter as much.

more shock mounting options? please elaborate on this one, because I'm not sure I follow how I'm going to lose shock mounting options by putting the TVP's wider, I'm already aiming to get the shocks back inboard of the TVP's so that won't be much of a problem.....I genuinely don't see how that would get me more options by moving the plates inward....


Not saying the battery you have is bad, just that a smaller lipo that fits in a better place that won't require a larger chassis is a performance gain.

My chassis has a 1" skid and was a noticable difference from my previous 2.5" wide skid.

A narrower chassis will give you more shock mounting options by allowing the inward angles to be adjusted without interfering with the chassis plates i.e. spacing the shocks closer or further from the chassis plates.

I have a lot of chassis designs under my belt, several in mass production, thousands sold. I been in this same boat once or twice.
Harley is offline   Reply With Quote
Old 01-08-2010, 12:17 PM   #9
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

The only reason going to a smaller lipo would be a bad thing for me is when I'm only getting 45 minutes of runtime out of 6000mah, a 3000would get me 22, and i'd be lucky to get over 10 minutes out of a 1500mah pack, 1500 being the largest "small" pack I've found I don't wanna buy 4 batteries to be able to play for an hour... (3 high torque servos and a 10T puller and battery goes very quick on me)
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 12:50 PM   #10
Rock Crawler
 
Join Date: Jun 2007
Location: oVER ThErE
Posts: 600
Default

If your not going to compete then build it. Seem like your more worried about run time over performance. Build it and try it.
Sinastir is offline   Reply With Quote
Old 01-08-2010, 01:03 PM   #11
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

Quote:
Originally Posted by Harley0706 View Post
My chassis has a 1" skid and was a noticable difference from my previous 2.5" wide skid.

A narrower chassis will give you more shock mounting options by allowing the inward angles to be adjusted without interfering with the chassis plates i.e. spacing the shocks closer or further from the chassis plates.

I have a lot of chassis designs under my belt, several in mass production, thousands sold. I been in this same boat once or twice.
1" wide skid? I'm guessing you're running MOA and certainly not an axial transmission..... as far as moving the shocks around, I'm planning on having that much flexibility, except I'll be doing it inside the tvp's instead of outside of em....then again, on axial axles you only lean em in so far....currently my shocks are all running nearly vertical....on both my 14" WB AX10 and on the wife's 12.5" WB AX10....and for what we have around here to crawl, they're working pretty well, mine's just excessively top heavy due to the chassis that a friend cut out of 1/8" stainless sheet
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 01:12 PM   #12
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

Quote:
Originally Posted by Sinastir View Post
If your not going to compete then build it. Seem like your more worried about run time over performance. Build it and try it.
close, I'm considerably more worried about not having to buy $399.95 worth of batteries to match my current runtime, as well as having to change the batteries out after each run, than I am about actual runtime. (@ maxamps 1290mah 2S packs would fit on the front axle, 1550s wouldn't so, I'll use them as my basis, to make the same battery capacity as my 6000mah I'd need 4.65 1290's so, I'll say 5 batteries at 79.99 each)

as far as build it and try it, I'm wanting to, but, wanting ideas on what I'll run into as I come outward with the chassis that don't consist of "buy a different battery instead of changing your width".

I understand it'll be a little more prone to hanging up on stuff, but, like I've said previously, I don't think that'll be as much of an issue because of what the rocks are here to crawl, and at worst, I'll be putting some built on rock sliders on it so I can minimize hanging up on stuff.

what else would likely change with it? (I'm thinking if I can widen enough to get the batteries on the skid, I can keep EVERYTHING down because I can mount ESC and radio on the sides as well and then nothing should be higher than the top of the transmission as far as weight is concerned)
dhyde79 is offline   Reply With Quote
Old 01-08-2010, 01:15 PM   #13
I wanna be Dave
 
Join Date: Nov 2006
Location: spring hill TN
Posts: 2,959
Default

Man My Super running 2 35T motors 2 high torque servos pulling around 7 inch tall tires will run a hour beating the hell out of it on a 3200MAH pack.
My 2.2 pulling 2 40t handwounds and 1 high torque servo will run every bit of 40 min. on a 1300MAH pack.

AS for the question you asked about what would be the draw backs to running a wide truck.
I agree with Harley a wide chassis will hang up more and does not give as many shock placement options.
joesbruiser is offline   Reply With Quote
Old 01-08-2010, 01:21 PM   #14
20K Club
 
Harley's Avatar
 
Join Date: Jul 2004
Location: Sending illegals home one Hayabusa at a time.
Posts: 22,981
Default

Quote:
Originally Posted by dhyde79 View Post
The only reason going to a smaller lipo would be a bad thing for me is when I'm only getting 45 minutes of runtime out of 6000mah, a 3000would get me 22, and i'd be lucky to get over 10 minutes out of a 1500mah pack, 1500 being the largest "small" pack I've found I don't wanna buy 4 batteries to be able to play for an hour... (3 high torque servos and a 10T puller and battery goes very quick on me)
Wow your run times seem REALLY short with that setup for running a 6000 pack. Even with 3 HT servos and a puller I would expect double that amount :?
Harley is offline   Reply With Quote
Old 01-08-2010, 01:37 PM   #15
Rock Crawler
 
Join Date: Sep 2009
Location: Abbotsford BC
Posts: 563
Default

thats some short runtime. im running nimh 4500 sub c's with a 35t, 2 high torque servos and ive yet to run it completly dead, the longest ive run is 2 1/2 hours steady. granted a puller will draw more current, however it shouldnt be that bad. you may have another issue fighting you, is the drivetrain binding up, or is the lipo cutoff on your esc set quite high??? just a thought. id look into why your runtimes are so short before going further.

the wider chassis issues have been covered here, i also vote just build it and see how it works. worst case you need to build a narrow skid plate to bring it back to a stock width
Sharkey is offline   Reply With Quote
Old 01-09-2010, 12:59 PM   #16
Quarry Creeper
 
Join Date: Sep 2008
Location: Kuala Lumpur, Malaysia
Posts: 372
Default

One more voice on the run time issue. I run a very average 55T on a 2150mAH 3S 1P LiPo and get 80 to 100 mins. every time. And the battery fits easily on the rear axle.

And for what it's worth, I also agree that a narrower chassis is preferable.

Cheers.
Terranaut is offline   Reply With Quote
Old 01-09-2010, 01:25 PM   #17
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

I'm running 3 cs-170 333oz servos Holmes 10T puller, bec, and mamba max, and the truck's geared for moderate wheelspeed (16/84), so, I'm not sure what my major drain is unless I've got my lipo cutoff too high, it's not lasting, i'm somewhat torn thinking it might be partially due to the weight too....
dhyde79 is offline   Reply With Quote
Old 01-09-2010, 01:59 PM   #18
I wanna be Dave
 
Join Date: Nov 2006
Location: spring hill TN
Posts: 2,959
Default

Quote:
Originally Posted by dhyde79 View Post
I'm running 3 cs-170 333oz servos Holmes 10T puller, bec, and mamba max, and the truck's geared for moderate wheelspeed (16/84), so, I'm not sure what my major drain is unless I've got my lipo cutoff too high, it's not lasting, i'm somewhat torn thinking it might be partially due to the weight too....
How much weight?
I am really curious to why you would not have any more run time than that.Maybe its just your driving style.

I know my Super was about 14lbs running 2 35t motors and the 2 servos that made 400+ OZ at 7.2 volts through 2 CC BEC's
joesbruiser is offline   Reply With Quote
Old 01-09-2010, 02:19 PM   #19
Rock Crawler
 
Join Date: Sep 2009
Location: Abbotsford BC
Posts: 563
Default

Quote:
Originally Posted by dhyde79 View Post
I'm running 3 cs-170 333oz servos Holmes 10T puller, bec, and mamba max, and the truck's geared for moderate wheelspeed (16/84), so, I'm not sure what my major drain is unless I've got my lipo cutoff too high, it's not lasting, i'm somewhat torn thinking it might be partially due to the weight too....
lipo cutoff should be 3.0 volts per cell. that gearing is kinda high, however i dont see that being the issue
Sharkey is offline   Reply With Quote
Old 01-09-2010, 02:29 PM   #20
Pebble Pounder
 
Join Date: Mar 2008
Location: Amarillo
Posts: 181
Default

13.7 lbs right now (hence building new chassis plates and trying to slam the weight lower) and the cutoff is either at 3.2 or 3.3, I read somewhere that said that I should set a bit higher for protecting the battery's sake...I do need to go through and re-lube everything...but I don't think there's that much resistance in the driveline.....
dhyde79 is offline   Reply With Quote
Reply



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 01:16 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO ©2011, Crawlability, Inc.
Copyright 2004-2014 RCCrawler.com