Hi, I just baught my first cen product. it is the gst 7.7. I love it but i am having tough time with the braking system. Is there a way i can adjust the braketension on the truck directly or do i have to use the radio? if i had to use the radio can anyone give step by step instructions? all the answers are appreciated. thanks you guys. I am still new to the nitro worls and ireally want to get into the hobby!!!

I am assuming that your brakes are not working, rather than stopping too hard.

The GST brakes are good once they are set up.

there is a shaft coming from the throttle/brake servo that goes through two loops. On that shaft there should be two clamps.

Turn on your radio and receiver so that all the servos go to a neutral position. Then undo the clamps and slide each so that they are snug against the loops (away from the servo) and retighten.

Hope that makes sense.

thank you very much for your reply. I will work on it tonight. The rod that is going through the 2 loop looks different from the one i have on the truck. I will take a picutre to show you what i have.

here are the pictures, again thanks for your help

aaah right, they changed it on the GST ( I have a Genesis... older model of GST)

so, same thing applies, just move those collars away from the servo so that they are tighter against the loops.

If you are just bashing and you want SERIOUS brakes, just remove those two little springs. If you just leave the collars and the plastic bits you will be able to do stoppies. The brakes are that good.

Any more questions just ask here. This used to be a very busy section of the forums... dunno what happened.

hey dustin,
thank you for your help it worked just like you said. hope i am not bothering you with too many questions but i am new to nitro and especially cen racing. Ihave something else i want to ask you. what is the secret for tuning the gst 7.7. I cant get it to tune right. another thing. I noticed when i push the truck by hand while the engine is off, i noticed that it feels like it is locked in place. i cant push it back and forth at all. if i push hard enough enough the tires will drag. is the transmission locked or it is just a feature on the truck? If i put it on the stand the tire will spin no problem. and whatsup with the shifting?? why am i not hearing the 3rd gear. it feels like it goes from 1st to 2nd. maybe i am hearing the 2nd and the 3rd. hope i am not asking for too much. thanks in advance for your reply.

No problem with the questions. If you bothered me I'd just ignore you lol.

as for the wheels not "freewheeling", Mine wheels fine both ways, you should check your gear mesh at the pinion. Take a piece of regular printer paper, rip/cut it into an aproximately 1" wide strip, then wheel it between the pinion and spur gear. The paper should pull out wrinkled, but not ripped. http://www.youtube.com/watch?v=g5SWwdxOuCw

Check out this thread and the link in it to see how to adjust the 3rd gear shift. http://www.rcuniverse.com/forum/m_74...tm.htm#7440030


For tuning: I am assuming you have done the break in procedure as in the manual? Once it is broken in You just need to tune the high end needle, then the low end. I have posted the NX76 recommended settings below.

There are TONS of threads on here and tons of videos on Youtube on how to tune a nitro engine.

A big help in tuning the GST engine is putting a check valve in the line from the exhaust pipe to the tank. This helps stabilize the fuel pressure and makes tuning more consistent.
http://www3.towerhobbies.com/cgi-bin...?&I=LXEYG3&P=7

Some of the Biggest tips to nitro newbies are: Make sure your glow ignitor is FULLY charged!!!! Also, after the first few break in tanks, CHANGE the glow plug. Also, if you are having tuning issues, change the glow plug.

When you fire up the truck, let it get up to operating temperature before doing any tuning. Only turn the needles 1/8 turn at a time. Often that's all it takes.


I suggest you get an infrared temp gun. They are cheap and well worth it.

Recommended engine settings:
Top end: 3 ½ -4 turns out
Bottom end: Flush – 2 turn out from flush
Idle: 1mm gap
Recommended engine temp: 250-260 degrees Fahrenheit
Refer to these settings if your engine is not running properly. This will give you a good starting point.

Again, feel free to ask more questions.

hey thank you very much for your quick response. I ordered the check valve. I should get it in a week or so. i will check the gear mesh today and see what happens. as far as the 3rd point shift on the trany. the thread was great but for a newbe like me "lol" it was way too advanced,haha. what set screw is he talking about. when i looked at the truck. was there like an aluminum ring with two holes and then when i turned it i found like two screws. is this what he was saying. if yes which screws?? i looked at the manual it shows the assembly and all but it doesn't point at which set screw!! you think you can help me with that. again you have been very helpful thanks in advance

hy dustin,
i think i know what my problem is exactly. I put the truck on a stand. i started spining the two back wheels. the front wheels didnt move at all and i notcied the spur and the engine gear didnt do anything neither. then, i tried to spin the front wheels. the front wheels didnt even move it looked like they were stuck i pushed little harder it sounded something inside the trany like it is grinding. could i have blown the transmission? what could it be it is a two weeks old truck. I cant beleive the trouble i am going through. I havnt see what this truck is capable of. please help!! thanks again

ok, i took the whole front end of the truck just to get to the front diff. The diff is working fine. then, i took the front drive shaft that is conneced to the trany directly and i rotated it. it wont rotate. it is stuck. so far i think the brakes are sutck they wont release. i cant assume it is the trany yet because the rear wheels are spining just fine and the trany is not grinding at all. so now the question how do i release the brakes? please let me know if you have any sugestions. thanks in advance. sorry to bombard you with my problems. summer is near and i want to have some fun. my friends are bashing but me.

To see if the brakes are binding, just turn it upside down and see if the brake discs wiggle freely.

If it drives fine, odds are the trans is fine, but it's just a matter of taking everything apart and see what turns and what doesn't. I would just take the trans right out and check the rear diff, and if it turns then inspect the trans.

Also, if you are just bashing, I would open up the center diff (inside the transmission) and replace the gears with the solid locker that should have come with the GST. This ensures that there is power to the front and rear wheels at all times. It won't turn as smoothly, but it will have more traction.

Refer to the CEN diagrams while you are ripping it apart and get familiar with all of the parts.

Don't worry, once you've disassembled and reassembled it a half dozen times, you will understand how it works entirely.

BTW, The adjustment for second gear is 5 full turns out
Third gear is 7 to 7.5 full turns out

look at the CEN diagrams for the 3rd gear clutch. There are two "Set screws" that you musnt touch, then there are the two adjustment screws for the 3rd gear shift. Don't turn more than 1/8 tun at a time and eventually you will get it shifting.

But I would really worry about getting it tuned first, and making sure nothing is binding. THen once it's going good, get the third gear adjusted.

you're right the brakes were the problem. somehow the front were stuck the only thing i had to do was to release the brake collar and i am back in business. i am just going to reassemble the whole front end lol. i will let you know what happens with the tuning thanks

I know this post is really old but could anybody tell me what that other servo next to the throttle/brake servo is used for? im currently restoring one and previously had it running without issue and it does not have that servo.

Its use to shift the trans.
Edit. It’s used for shifting into reverse.