Boom_Stick

Hey all,

Just wanted to report how my Genny did at track yesterday. I had only two problems which one was fixable on the spot, and the other requires an order. Before I go into detail about what broke, I want to talk about how it did before the problems. Just for some information I did not get the Genesis to run races with, I got it more as a backyard thriller. I am a tweaker though so anything I can to do improve the truck I will. I normally do this by reading what others suggested/tried/thought of, but most importantly what I feel the truck needs to suit my driving style (*Or lack there of) . I came from on-road racing with RS4's at our LHS. I did pretty well there, but it was nothing like an official racing event. More like 20 or 30 of us running 1/10th scale nitros on a large parking lot with cones as our race track. I did goto a couple of HPI events and did well there, but I enjoyed more of the parking lot style. So enough about my boring on-road background as this is a Monster Truck forum, and even more so a CEN MT forum so lets get to the Genny.

Engine:
That NX-76 did a great job. I sill have the truck running a little to rich as this was its first true day of some strong running after the solid break-in. I took my time with the break-in and it took me 10 tanks and a few days. It was a very slow day at the track yesterday and the only person there with a truck close to class was a young kid with a Savage. He was far from timid with his truck and it was his first day with his new .28 at the track. We got some racing together and it was blast. Down the long main straight we were pretty even. I had more power, but I had to break sooner going into the corner. The NX-76 would really throw down the power when I hit the gas and I was very happy with it. Each time I went to start it after cool-down it fired right up almost instantly. It ran strong through most of the tank. When the tank got very low it would shut down. I figure it might be back pressure related so I starting to look for a check-valve to see if that will help keep the pressure up.

Suspension/Handling/Driving:
In the backyard this truck seemed to handle almost too well. It was perfectly at home in large areas and was easy to predict. At the track however it was terrible. It was not a HUGE track, but a nice size. The problem was that the truck needed entirely too much turning room. The radius it needed to turn was more like a semi-truck's. After a couple of laps I learned to counter it by drifting it through the corners. This isn't the fastest way around a track, but was loads better than trying to drive the truck through the turns. With the way I had to drive this truck it really hurt my line ups and landings for the jumps. It was uncommon for me to hit the jumps properly, but very common to watch my genny flip end over end after my horrible attempt at the jumps. The more time I had with the genny on the track the better I got with it, as will anyone. The problem was that even as the day went on and I got better controlling the beast it was still mediocore at best. If I had to give an honest pct of what was driver and what was truck I would say something like 60% driver error and 40% improper setup(truck). I will say, there were a couple of great things that had me smiling about this truck even with me driving like a drunk man. #1 Reverse! I am not used to R/C cars/trucks with reverse and it was really funny the first time I used it at the track. People were impressed with the trucks size and speed but when I was able to reverse out of trouble and hop right back into the little bragging rights race I had going on with the Savage, people were kinda "Woo'ed" or insert word close to that of your choice. Nobody thought my Genny had reverse, so when they saw me spin a donut and take back off there were pretty happy. Now the #2 thing that had me happy is something I never had before with an R/C. I was able to drive over and through ANYTHING!! When I landed completely off and ended up in another section of the track, this truck had no problems what so ever in driving over the barriers to get back on course. It was a great feeling knowing that I could pretty much fix anything accident and get back on track short of landing the turck on its roof.


The two problems:

#1 This first problem was caused by a terrible attempt at a jump due to lack of control of the truck. I hit the ramp sliding and landing pretty goofy (But on its wheels). When it did land I saw some fluid squirt out of the back of the truck. It turned out the heads of the left rear shocks popped off and shot the fluid straight up in the air. This had me pretty confused because they are threaded and there was no visible damage to either the tower of the shock or the head. So I got some shock oil, filled it back up and back to racing I went. Didn't have the problem again.

#2 This is the problem that ended my day at the track. Again another terrible attempt at a jump due to lack of control I had a terrible landing. I ended up breaking the right front upper suspension arm. After checking the truck there was no other damage, so when I got home I ordered some nice metal replacements of New Era. What I found sorta funny about it, is that when my wife took me into our LHS to purchase this truck I made a comment while looking it over "All of this plastic has to go, I'm sure I will be replacing this". I just figured with such a heavy truck that it wouldnt too long until they were replaced.


Configuration Changes/Learnings:

For the lack of steering I have decided I will try a few things. I will be replacing the stock 144oz steering servo with a HSR-5995TG High torque servo which over doubles the steering torque. I am open for servo suggestions and I did read about the dual servo steering conversion which I was considering. I figured I would see what the difference is using the new Hitech. The second thing I have just done is to change the tires. The stock tires are huge and heavy. I went with some Proline Crime fighters and some saucer rims. They are a lot smaller, lighter, and should give me a heck of a lot more traction. On the way home from the track I also thought of taking all of the shock spring spacers out to lower the center of gravity a touch. That and stiffing up the rear shocks a touch to help stop the 3-wheel turn (2 wheels at times). While I did the ordering for the upper and lower arms, I also ordered a new pipe. I am curious to learn what different pipe combinations run like with this engine. I already removed the baffles from my stock pipe and that did make a nice difference. On the exhaust note has anyone changed out the header? The stock header doesn't really look too good from the inside. If you have changed it which one did you drop in and did you notice a difference?


Summary:

Over I couldn't be happier with this truck. As time goes on and the more this RTR becomes more customized to me I feel that I can only become happier with it. Its fast, huge, and just plain out mean. If anyone has any suggestions for the truck or any tips overall on how I can drive it better please let me know.

The Real Dogman

hey Boom Stick, Good to hear you are happy with your GST!! You also might try fabbing some anti-sway bars I found them to make the truck more predictable when making high speed turns. My setup has me using 4mm in the front and 3.5mm in the rear.

I did build a header and rear dual exhaust, that generated buttloads more torque and speed. I am not running it now because I am test several Ideas I have for this truck but every once in awhile I will put it on for the fun of it.

And here a couple shots of my GPM suspension parts which have proven bulletproof under my extreme style of bashing while testing a cage I am developing

Boom_Stick

Dogman,

Thanks for the info! I think I will head to my bench and see what I can come up with for some sway bars. Anything that can aid in the trucks handling will make a huge difference in the "fun factor". I did have a question for you, I have only found one place to get GPM parts for the genny which is hardcoretrucks.com. The downside is that he is all ebay based, and does not have what I wanted listed (On Ebay). Is that who you use or do you know of another?

Thanks in advance

The Real Dogman

Boom Stick, Yes I use him exclusivley for my GPM Parts. I have sent him emails letting him know what I want and he will put it in his next order but he will only sell it on Ebay. He will then email you to let you know they are there. Almost always set up with "Buy It Now" And his prices are very reasonable!! So send him an email..You know CEN Is coming out with some aluminum parts too, they are supposed to be available in Feb 07..[link=http://www.cenracing.com/cars/gst/gstoption.html]Cen aluminum Hop-ups[/link]

Boom_Stick

Dogman,

Ahh thats pretty nice. I will shoot him an email on my next repair . I heard of CEN coming out with some hopups but didn't know when. Now I'm wishing I would have emailed him before I ordered from New Era. Any idea about New Era's parts? I hope I don't spend half a day doing touch up in order to get a proper fitting piece. Regardless on my next break I will use hardcoretrucks

The Real Dogman

the new era parts are nice but I think the GPM pieces look more refined. Alos the new era upper arms require you to use the oem turnbuckle and rod end. I like the GPM's better. You will have to do a bit of filing on the GPM arm ends to get as much articulation as possible, I have photos to show you were to file. If you go with the knuckles and c hubs I can also show you how to get more turning radius out of them. I also added some lexan washers to the arms to keep the wear down, since this is heavly used truck(I made the washers from some vacumn form packaging.)

Boom_Stick

Good to hear,

I noticed the need for OEM parts using the New Era and that the nice GPMs you have on yours didn't use them. Thats why I jumped on finding out where you got yours . I got another question for you. I have been reading some threads on here and your very up on the Nemmy/Genny's. With my GST I got a center lock block. I have been trying to find out exactly what it does, the difference it brings to the truck when driving, and how to install it. The downside is after everything I have read I have heard like three different explanations of its purpose. Could you help me out with that?

The Real Dogman

boom, flattery will get you everywhere here!![8D]

The lock block helps and hurts in someways. First thing the lock block in the center diff helps pull wheelies and launch abit harder, however, the rear break drive cup will wear faster. As a result the center lock will create more of a beast. Lock blocks in the rear and/or front diffs help if you want to stop torque steer on hard launches but creates ton of understeer so turning is comprimised. Locks in the front and rear diffs also help if you are hill climbing and drag racing, planting the power evenly. again the locks wear drive train parts faster.

You can tune the diffs using heavier or lighter silicone diff fluid.

My setup is great for all around driving styles. My center diff is locked my rear diff has 120,000 wieght fluid and my front diff has 90,000 weight. Seem to be very balanced for off road bashing and on asphalt parking lot high speed runs. There is acouple people that are setting up kinda rally style races here in Tucson which will include just that. Off road dirt sections with asphalt handling and speed jumping and turning, So I will see just how well this setup works. I do bash just on those types of surfaces almost daily so I should do well(Keeps Fingers Crossed)

Boom_Stick

Thanks for the good explanation,

I'm not too worried about the wear, I figure I got this truck to bash around so I'm expecting to replace parts. It sounds like something I may want to tinker with. If I don't come away from the track next weekend with more things to tweak/change/buy/build I may throw in the lock on the center diff to see the results first hand. Whats terrible about this GST is that its soooo tempting to set it up for racing. CEN makes it almost too easy with the powerplant they put in the truck. Short of the things I plan on changing/tuning its almost down to making the truck as light as you can and race it (Maybe its not that simple, but you get the idea).

Thanks again,

Going to play in the shop for a little

Edited to add: My wife loves your sig, she wants me to put something close to that in mine

jombo

Boom_Stick , i like your name. i actually have a boom stick barrel for my paintball gun lol[sm=lol.gif]. i just pulled it out and cleaned it.
good to hear the gst is going great. i havent broken any plastic except the shock and the piston. i did the same thing i took a jump at the track and all the oil flew out and i only noticed it because the truck was sagging to one side. the shock that blew was the one next to the exaust manafold. i added a metal heat shield and stuck it there with rtv silicone.

Boom_Stick

I just got done in my shop doing some touch up work on the genny since the run yesterday. Got some of the mud/grit off that I was unable to reach right after the run. While I was there I tried my idea removing the spacers from the shocks, and mounted my new rims/tires. It is a lot lower now, but now I am curious to see how the suspension will work when I get it all back together (Parts will be in this week sometime). I have to make a run to my LHS to get the servo I want. It may sound shocking but it is actually cheaper locally than some online shops.

So once I get the new servo in place, I will have to pick up a few nice receiver packs. For break-in and the first day of running I didn't think I needed one, but with this new servo its pretty much a must have. Anyways, more to report but I have to goto a New Years Eve party with my better half. Catch you guys in a few!

Jombo, you have a Gen/Nem?


PS> While drilling the body post holes in the body I just got done painting I just found out my steering tierod on the same link as the one with the broken upper arm is snapped ... I followed up with a quick ebay bid in efforts to get them in this week. Talk about over-looking something. I'm trying to think if it could have been broken while I was moving it around today, but that would have to be one hell of hit. I figure it was pretty much cracked through and all of my moving finished it off, sorta like a loose tooth. Anyways the Hummer body is looking sharp. I did a black base with a Purple Pearl fade for the windows/side stripe/front hood scoop. If/when I get a digi I will get some pix up.

Boom_Stick

Dogman,

What are your carb settings on the NX-76 and what temps are you seeing? I also saw you have different head on and I was interested in that as well.

Thanks for helping me out and HAPPY NEW YEAR!

The Real Dogman

Boom Stick, Happy 2K7.

Your carb setting are going to be different from mine since you are in a totally different climate than I am(In The Sonoran Desert). So you will have to tune for your area. Just make 1/8 turn drive it for at least 30 seconds then check it again. To Start out I tuned by temperature but as I got better and knew the feeling of the tune better I now tune for performance. When I first sterted tuning I was shooting for around 250-270 degrees. It seems to run better at these temps. But in summer tuning is a pain since it gets up to 115Degrees here, but it still can be done and run great!!

The head I use is a Nova products head found [link=http://cgi.ebay.com/CEN-Genesis-46-Nova-Head-rtr-FREE-SHIPPING_W0QQitemZ330067974799QQihZ014QQcategoryZ1 9168QQssPageNameZWDVWQQrdZ1QQcmdZViewItem]Here.[/link].

If you can't find your tie rods, I think I have about a dozen pair. I could send a pair to you.

I also use a [link=http://www.rchardware.com/]RCHardware N-Tune[/link] Dial, It helps alot for tuning quickly!!

Boom_Stick

Dogman,

I understand the difference in carb settings due to climate, config, etc.. I was just fishing for more information on what people run with this engine. I have never had an engine this big and I am always looking to learn as much as possible. Good call on the dial, definitely a purchase this week

Thanks again

jombo

quote: Boom_Stick Jombo, you have a Gen/Nem?

yes, on both accounts, i tuned mine after breakin. i put them on a stand and put them at full throttle untill they wouldnt die. what was happening was the low speed needle needed to be very rich, i tested it by pinching the fuel line. this engine needs a good 7 seconds before it starves of fuel. all you do is start it up, run it a little then pinch the fuel line. if it dies before seven-1000 its too lean on the lsn. the high speed needle i set by ear, if i can get a full throttle run with out it dying then its set pretty good then i fine tune the hsn with the temp gun. my temps are around 220- 235 start to finish. oh before i forget when you do set the lsn the idle will need to be adj too, the same goes with the hsn. you wont believe on how low you can get the idle after setting them properly. and if you find yourself hitting the throttle to clear her out its ok, the lsn may be a little rich but its better to be a little rich than lean and over heating.
just keep temps at 220- 250 and it will last for gallons.

notch

Yeah first thing I do is richen the bottom and raise the idle... keep it at 240 and you will be real happy... you will be happy with the smaller diameter rim ... less unsprung weight althoug I had to readjust the second speed slightly when making the change to a standard monster truck rim

Boom_Stick

Hey all,

I got my parts in yesterday from New Era. The lower arms fit perfectly, but the uppers were a little tight, nothing a little grinding couldn't sort out. After that I put the pipe on and I was able to modify the original pipe mounts to hold this one almost perfectly. My LHS got the servo I ordered in yesterday, so I will install that before I start my running at the track Saturday. FYI, I am still working on some sway bar rigs. I got a few complete, so I will test them out and see how they do.

To re-cap the changes so far;

New Parts
------------------------------------------
Pipe
Metal upper and lower suspension arms
Higher torque steering servo
Smaller rims/tires that are more "Race friendly"
Receiver Pack
Hummer H2 body
New header spring (A lot stronger to keep the seal tight)
Fuel Filter

Removal and Changes
------------------------------------------
Removal of some excess parts to decrease weight
Removal of the shock spacers to lower center of gravity
Change suspension setup for a lower center of gravity


I'll report back Saturday or Sunday to let you guys know how it did. Thanks for the words Notch, I hope the new rims/rubber help a good bit.

Boom_Stick

Good news (Kinda), but a few issues.

New Hitec servo (HS-5955TG)
I ended up going with this servo and it does one hell of a job! Turns the wheels just find sitting. Its very quick, and very powerfull. Its pretty much what the Genesis should have come with stock. I do have a problem with the new servo. I can not keep the servo arm screw tight. It keeps coming lose allowing the arm to come off the gears. Any suggestions on fixing this?

New Receiver packs (Team Orion 1600mah)
I haven't had much time testing these due to the servo issue as mentioned above. I hope to report how these due later on.

New Pipe from New Era
The new pipe is terrible. Its going right into the "Junk box". The pressure nipple hole is the wrong size. Once I sealed it, drilled and tapped a new hole to properly fit the nipple it still had the issue with not enough backpressure to keep the truck running. I should have known better with a $35.00 pipe.

So yea, any help with the servo arm screw would be greatly welcomed, because as of now I got a great servo that can't be used on the truck ...

PS> Even though we had great weather (Very odd temps of 67F for this time of year), all the rain from the day before had the track pretty much a bath tub. I declined racing today, so I hope it will be dry enough tomorrow to turn some laps.

The Real Dogman

Did you try blue locktight on the servo screw??

Boom_Stick

Yea,

I am thinking MAYBE red might do the trick? I never had a servo undo the screw soo quick. I put plenty of torque on it, and with blue loc-tite. Dogman, tell me you got another trick up your sleeve

The Real Dogman

Boom you got a pic of the setup so I can see it....is the arm aluminum??

Boom_Stick

Dogman,

No I don't, I am working on a getting a nice digi in a couple of days. My wife really wants one so I have been hunting. If I get one in a couple of days I will get some pics up.

gkcontra

sounds like your servo arm is moving a bit, are you using the screw that came with the servo or the old one? maybe the thread is slightly different. Also, what about end point adjustments, thee could be undo stress being put on the servo. And if not done yet, upgrade to an aluminum servo arm.

Boom_Stick

Thx gkcontra,

I am running the new screw with the new servo. I was thinking about the idea of a metal servo arm as an upgrade but didn't think that would aid in this problem. I sealed the screw in this time with some red loc-tite. I have yet to have a screw come out when I used red. Of course thats why I don't use it often as it can be a pain to get a screw out when you want to. I will also try the posistion of where i tie into the servo arm. Maybe move it a touch and see if either way produces better results.

So tomorrow I hope to find some time to try it out a little. I am dying to run this truck as its now all broken in, and in need of a nice performance tune. Just the couple of adjustments I made off stock made a huge difference.

timave

So do GST 7.7 take same hop up parts as the genesis or nemesis?