any tips on adjusting the brake on a nitro 4-tec?

[benbishop98]

Hey everyone. I, like the rest, would like to get the most out my braking system. So when I have the side plate off to adjust the pads I get it where I think I want it. Then after it is all put back together it is way to tight. So I take it all apaet again and loosen them. Then as you can guess it is not as tight as I would like it. How fo you guys go about this? Any suggestions eould be great.
Thanks
Ben

[Snook Man]

I adjust the adjustment screws so that there is a few mm’s of free play between the disk and pads. I also add cut ink pen springs between the pads to keep them from dragging the brake disk as a precaution. The springs between the pads will also ensure that the brake post arm snaps back/returns to center without hanging.
The fine tuning is adjusted with the linkage rod from the servo horn to the brake post arm with a piece of fuel tubing or spring to suite me for the sensitivity I want.

[Monte_1977]

Hey Snook...You wouldnt happen to have any pics would you?

[AnthonyV]

Pics would be great. I just replaced my old pads/disc and the brakes still dont seem right. Basically i pushed the car by hand and then hit the brake to feel how well the brake was working. Before replacing the disc/pads I had to allow 50+ ft of room to slow down if I want to go over 40mph. I screwed the 2 pad screws all the way in then backed them both out 1.5 turns. There is a bit of drag at neutral but the brakes are still feel super weak and i havent even tested them out on the street yet. Doing the same test with my HPI rs4 you can tell that the 4tec is much easier to push by hand when the brake is applied.

[cenracer1]

I have pretty decent brakes on mine and they are set as the stock setup.. Over 50 feet from 40mph is a bit excessive and they should be better than that. I found the easiest way for me to do it was adjust the pads so they are just touching "evenly" this is important! then back off the screw about 1/8 turn. put it all back together then your adjustment will be in the linkage from the servo to the brake lever. I use a small piece of fuel tubing and a spring to keep tension on it, but still allow some feel. The radio is the final adjustment.
From around 40-50 mph it will stop in around 20 feet or so.. faster than that I cannot guarantee as the tires (I run foams only) may not get enough grip or the surface is uneven and the car will skip a bit.. Your stopping distance can very greatly at 70 mph.. can be anywhere from 50 feet to 100 feet.. I've replaced enough front ends finding that out.

[Snook Man]

Here’s the brake setup with just the chassis stiffener and the rear top brace so you can see the springs between the brake pads.
Just adjust the screws so there are a few millimeters between the pads and the brake disk. The springs will keep pressure against the pads so the brake does not drag and will also force the brake post arm back to the neutral position.
If the pads and disk are in good condition with just a couple millimeters of clearance between them and the linkage is adjusted correctly, even a weak servo should lock up the tires easily.
I use a light weight spring instead of the fuel tubing on the servo linkage rod to have more control/feel of the brake input and to prevent flat spotting the tires due to locking up the brake.





It’s a good idea to add the springs in between the pads of any RC that has a mechanical brake system.
Also due to the location of the 4Tec brake, if you have any leakage of fuel/oil from the engine, the disk can easily get saturated with it and you will loose a lot of braking power.

[AnthonyV]

Thanks for the information and pictures. When installed the new pads/disc I did not have the chassis stiffener installed. Everytime i would install everything back with the stiffener it would cause a slight amount of brake drag at neutral. Ill try these tricks out and hopefully my braking gets better. My old disc was a bit on the damaged side... im guessing fuel may have damaged it and cause it to become brittle and glazed.

Ive been messing with my erevo and havent had a chance to test out the new brake disc/pads. Thanks for the stopping lengths... that should give me a good idea to how ive got things dialed in. Isnt there a larger brake disc thats available for the 4tec 3.3?

[benbishop98]

Awesome, thanks for the pictures. I was wondering how you put the springs between the pads, on the screws!!!! Duh, I guess I would have figured that out eventually. I'm going to the basement to do that to mine right now.

[AnthonyV]

I finally got to run the car today with the new pads/disc and it stops quite well now. There is a slight drag when at neutral... but i'm very happy that I can stop the car now. It took a few times adjusting the disc/pad gap but it worked. Just for future reference, I tightened the 2 pad screws all the way down then backed them out roughly 2 turns each. For fine tuning I used the brake rod. One thing I should have down was sand down the inner pads with a 100-120 grit sand paper for a bit more bite.

[highrpm666]

Great idea with the return springs between the pads, gotta do that myself! I have found that the brake disks for the tec load up with fuel and oil very quick and the whole area should be kept very clean if you need or use the brakes a lot. I have a large area to run mine and still sometimes have trouble getting her shut down in time to keep her in a single piece. I also scuff my pads and soak the disk in alcohol to get good bite at the sacrifice of feel. I'm truthfully only on my second disk in a decade, once oil soaked they don't wear till sterilized and adjusted just right... A good servo will help gobbs, I have used many different from the 2018's all the was to fancy $$ hitec Dig. MG's and I think I found the permanent solution with the 2075. Its a very stout unit for being plastic geared and the speed and torque are overkill for the application(plus, I spill fuel all over the car all the time even though I try soo hard not to, the tec is a messy fueler, easy to have accidents). I've never damaged one myself but, I did have a buddy destroy a 2075 gearset when his VXL bandit became one with the curb on 3s. Those pesky VXL bandits are hard to repair when vaporized! lol. I apologize for the hijack, I have a 4tec problem and love discussing them when possible. The 4tec thread needs more activity and I babble from a lack of anyone discussing this great if not the greatest traxxas basher ever. Anyone considered fabbing a slotted metal/alum disk? I have thought of it for years, just never tried.. I have enough old lower chassis I could make a few.. I have hand slotted the stock disk before and all it did was collect oily debris, never tried cross-drilled though.. could be interesting to toy with... Another factor is the length or presence of fuel tubing on the linkage, Its not really needed but improves feel having it there. Mine all have the tubing cut in half for more precise feel and quicker bite.. I have tried removing it and it makes the brakes touchy and induces drag when the trigger is released if the linkage is properly adjusted(many people do this regardless, I tend to like some feel because I do run a home made street course and have a beautiful grape soda lathered outdoor track a few miles away that is private(CORRC) but located in an old Target parking lot and has no fence or anything to keep the bashers out except the occasional club member seeing you from the indoor track up the street).

Back to the subject, The brake adjustment my seem tough at first but after multiple adjustments, it takes just a few minutes to access and you will come up with your own way too. And it gives you a chance to inspect, replace, or adjust the rear belt and access the differential for service. Easy way is to remove the top left rear shock nut, remove the top left rear brace screws, the left shock tower screws and the left side rear bulkhead lower chassis hardware and the rear long course threaded screw that goes through the engine mount. remove the left rear lugnut/wheel and from there you just wrestle the entire left side of the rear bulkhead out of the car noting the position of the rear belt tension cams, the diff is removable at this point also.. It becomes second nature after a while. From there getting to the brake for parts replacement is cake.

Kirk B

AND Try some grip compound on your tires too, I have "jack the gripper" from when I raced 17.5 TC, Its a miracle in a can! Another way to strengthen braking power. I even slather it on drift tires to challenge myself with faster longer controlled drifts.. Or the stock slicks benefit greatly from regular applications and really come to life as a usable tire(I like the stock tires, despite the lack of grip they put up with 70+ mph cruising better than any set I have ever glued myself and wear out evenly and for me have never failed at speed). Self glued tires seem to explode no matter what brand, insert or glue leaving you with another snapped shock tower or cracked front diff case when the car goes airborne at terminal velocity..

[highrpm666]

I forgot to mention, a digital caliper 6" or so is a priceless tool for rc. I measure everything and double check a lot. You could actually figure out exactly where the brake pads need to be tightened to as a mm gap reference point for quick changes. Note this in your maintenance log or however you could to re use the info whenever. I have home made setup sheets for the tec, simple but effective and helpful when u cant rememaber what your camber, droop setting were, etc. And harbor frieght has nice dig calipers under $10 on a sale day, likely cost $15 not on sale. With this tool you can verify the pads are perfectly square before getting it together unsure of accuracy and even contact on the rotor.

[cenracer1]

I forgot to mention, a digital caliper 6" or so is a priceless tool for rc. I measure everything and double check a lot. You could actually figure out exactly where the brake pads need to be tightened to as a mm gap reference point for quick changes. Note this in your maintenance log or however you could to re use the info whenever. I have home made setup sheets for the tec, simple but effective and helpful when u cant rememaber what your camber, droop setting were, etc. And harbor frieght has nice dig calipers under $10 on a sale day, likely cost $15 not on sale. With this tool you can verify the pads are perfectly square before getting it together unsure of accuracy and even contact on the rotor.

+1 for the calipers.. I don't touch my cars without it.. learned to live by them when flying helicopters.. close isn't an option with them.

[AnthonyV]

I have thought about making a metal slotted disk brake... but I just dont have time. I got so sick of the braking issue that I ended up buying a XO1. Here is a good thread... to bad the disc has been discontinued: http://www.rcuniverse.com/forum/m_60...tm.htm#6070015