What is the best distrabution to have on a rock crawler? I know with sum sports cars (porsche) they put the tranny in the back to make the car even as far a weight I think the numbers are 60%front and 40% back. So what would be best for a crawler front heavy/ back heavy/ weight centered? any thoughts will help.
Keith

I DONT KNOW WHATS BEST BUT MINE IS 50 50........WITHIN LIKE 40 LBS

most would agree that nose heavy is better. Usually you are climbing, not descending. But on those descents, it can get weird...

I've searched for the same info also. It seems like everyone likes 50/50. I understand the theory that more weight up front is better to help you climb vertical stuff because once the front tires are over the top you have the weight up front to help hold the front end to the ground for traction but I have been wondering how a rear engine vehicle would do on verticals. My thinking is that if the front end is light, it would be easier for your spotter to pull the front end to the ground while climbing. Does anyone have experience with a rear engine rockcrawler on verticals?

I like 50/50 because most of the time if im gonna go up something I will probably end up coming down it later that day.

My next project will be 60/40 or even 65/35. Backwards rolls hurt. And the spotter can grab the strap when you go downhill.

I think its probably more important to get a low center of gravity with a slightly forward weight balance, my theory is you apply throttle going uphill so you need a bit more weight there than downhill when you are only on the brakes, besides you can always lighten up on the brakes and ride it out then. either way the lower the cg the better.

Originally posted by ChinLei
Does anyone have experience with a rear engine rockcrawler on verticals?

Just because the engine is in the rear it DOES NOT mean the weight has to be distibuted unevenly (toward the rear). That's all I can say about that :)

Read carefully what bigdude said and start thinking outside the norms. What other wieght can you put up front? We have thought about this many times and always decided it would take more work than the benefit you'd get. Which way were you thinking about facing the engine? You need room for the tranny and tcase and if you invert the engine the driveshafts will spin opposite directions. That's all I will say, the rest will need to be figured out by you. Good Luck

Originally posted by bigdude


Just because the engine is in the rear it DOES NOT mean the weight has to be distibuted unevenly (toward the rear). That's all I can say about that :)

The rear-engined mud racers are almost all lower to the ground than are the front-engine cars. Mid-engine is kind of the current trend:

http://www.truckworld.com/Shows-Events/00-Essex-Junction/mud-23-400.jpg

Stole that off www.truckworld.com


TEX

Yeller is 70/30 front/rear. Going up is awesome, coming down can get your attention. There are a lot of obsticals that I back down, then it feels just as good as going up. But I don't compete.

Originally posted by jeepguru7
Read carefully what bigdude said and start thinking outside the norms. What other wieght can you put up front? We have thought about this many times and always decided it would take more work than the benefit you'd get. Which way were you thinking about facing the engine? You need room for the tranny and tcase and if you invert the engine the driveshafts will spin opposite directions. That's all I will say, the rest will need to be figured out by you. Good Luck

Just another thing to toss into the pot to ponder, what about a reverse rotation marine motor:D

We came up with several ways to accomplish this but I'm not saying anything til we decide if it's something we might persue.

Originally posted by Madmarx


Just another thing to toss into the pot to ponder, what about a reverse rotation marine motor:D

The only thing I will say is that driveshafts spinning in reverse direction can be corrected VERY easily and effectively.

All I know is that I really really hate REAR heavy rigs :flipoff2:

I am going for 60/40, low CG, 102" WB. I think there is going to be a LOT of new tech and thinking in this next season of rockcrawling......

About the rear engine stuff....if the motors facing the other way....just run portals with normal centers ( not flipped ) then everything runs the correct way! You can move almost everything to the front more then. People, batteries, gastanks, seats, cages, etc. Sorry if I gave away anyones secrets!

Originally posted by bigdude


Just because the engine is in the rear it DOES NOT mean the weight has to be distibuted unevenly (toward the rear). That's all I can say about that :)

Hey Forest Gump, you got sumpin' you wanna say?

I did everything I could think of to get the half the weight on the rear axle, I set the drivetrain (BBC and sm465), battery, winch, tool box, fire extinguisher, seats, everything ...as low and far back as possible, and I just hit 50/50 .
This thing climbs great and handles like a quadracer...In fact I've been giving motocross track "thrill" rides lately : )... it is really spookey how fast I can go and still be comfortable, It has a "neutral" feel, going fast or slow.
I haven't been out west yet, so, I can't say how it would do out there, but, I think it will do fine.

Sprung or unsprung? There can be a couple hundred pound difference between a front and rear axle and suspension.
I'm 60/40 front bias and don't have a lot of room to move anything back so it's pretty much going to stay there. It works pretty well, I'd like to lower everything but also can't get good uptravel and low ride height without drastic reconstruction.

I really don't know what's going to work best but my guess is this:
Keep it as low as possible (this is where alternative motor locations can be cool since it could let you drop the seating position and maybe some other heavy parts)
I'm guessing no worse than 60/40 front, since we do have to go down hill sometimes.

Next question, what about good weight bias for going fast? I know a lot of desert trucks are running with the motor way back so they have to be 50/50 or more to the rear. Any numbers on what flies the best?