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Old 11-18-2006, 08:41 AM   #796
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I've actually taken all these precautions, and still had at least 1 servo die(a Z590). However, I've had the same servo in it now for a few weeks(another Z590), several runs, and it seems to be fine...knock on wood. I believe all these precautions will work, so as suggested, just get a throttle servo that is overkill, and it should be fine.
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Old 11-18-2006, 04:05 PM   #797
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Default throttle servo theory

I have a theory about the throttle servo failures.

First, I have an 8ight, and I have not had any servo failures.

But I can tell from the elongated holes in the body that the chassis flexes quite a bit. When the chassis flexes, it must put a lot of strain on the radio tray (top deck). The part of the radio tray that runs past the throttle servo is tiny... not really capable of taking any kind of load.

My theory is that this is making the throttle servo itself a 'stressed member' of the chassis. The servo gets 'compressed' as the chassis tries to bend down in the middle, and 'stretched' as the chassis bends the other way.

I wonder if this load being transmitted through the servo is breaking the circuit board inside or something?

Possible experiments to run:

1. put some sort of strong (steel or aluminum or carbon fiber) bracing around the throttle servo to transmit load around the servo instead of through it.

2. take out the screw that holds the radio tray to the chassis behind the throttle servo. Without that one there, the tray can no longer transmit chassis bending load through the servo. However, the unsecured rear part of the tray might bounce around and cause the same or other problems. Actually, without that rear screw, the throttle servo is carrying all the 'load' imparted by the weight of the receiver battery... might be worse than carrying chassis bending loads.

It is just a theory, but when looking at the 8ight compared to other buggies, the main thing that looks different to me is that the radio tray doesn't 'wrap' around the throttle servo, but rather only bypasses it on one side with a very thin piece of plastic. All those other things that can kill a servo (hitting the chassis, vibration, incorrect EPA, etc.) shouldn't happen any more on the 8ight than on other buggies.
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Old 11-18-2006, 06:56 PM   #798
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www.tkocompetitiondev.com for Losi Ceramic clutch bearings and other parts.
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Old 11-18-2006, 07:27 PM   #799
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ok, i was just wondering. I really like the car, and I think the design is amazing, just want to make sure I can work through these issues. So is it only the throttle servo that people are having trouble with?

What servos would you reccommend (non digital if possible)
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Old 11-18-2006, 09:33 PM   #800
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Quote:
Originally Posted by Peter Martin
www.tkocompetitiondev.com for Losi Ceramic clutch bearings and other parts.
The bearings from TKO are the best in the business, hands down, his ceramic clutch bearings are stellar. I can't wait to see how crazy free the car gets with his ceramic drivetrain bearings.

Ok,

Ran an entire race today without a servo failure. I run a JR 8800T with the rubber grommets supplied by JR. I shimmed the servo with the Losi servo shims, replaced the Losi fuel tubing with a more pliable Venom fuel tubing. I also used a softer rate throtte return spring trimmed off.

I checked the temp of servo everytime I came off the track and it was cool to the touch so I didn't bother with the temp gun.

The car felt good, but there is room for improvement. What is everyone else doing for indoor setups?

-Seann
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Old 11-18-2006, 10:20 PM   #801
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Quote:
Originally Posted by Panther
What is everyone else doing for indoor setups?

-Seann
indoors? you mean....besides wearing a seperate oxygen supply?
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Old 11-19-2006, 08:21 AM   #802
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Can anyone tell me if the TKO o-rings will stop the shocks from leaking? A little electric motor spray along with a shim seemed to fix it for the time being.
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Old 11-19-2006, 08:48 AM   #803
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Yeah My losi is a servo eater to.I have burnt 2 590`s and a friend of mine has bent 2 650`s.Itrs not do to heat either our engine temps were running around 150 175.Its was 60 degrees out last night.We always made sure that all of our epa adjustment were correct and that the servo didn`t have any strain put on it.We also don`t use the brake we only use it to open the carb.WE run dirt oval and brakes arre just not important and not needed.
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Old 11-19-2006, 10:05 AM   #804
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i am looking at getting an 8ight but from reading this thread lots and following on the Sgrid ever since people have been getting them and racing them, i am a little weary about it. i have heard of the servo problem, the leaking shocks problem, the clutch problems, the starter box problems, and a few little things aswell. my question is, can someone post up some building tips for someone to take into consideration when building an 8ight? is there anything that should be avoided or added that isnt in the manual? also, what parts should i order when i order my 8ight, or what wears out quickly or the quickest?

thanks guys
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Old 11-19-2006, 12:49 PM   #805
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Well, the servo issue, while not comepletely sorted, seems to be greatly reduced by using the rubber spacers that come with all servos to reduce vibration. I heat shielded mine with some thick double stick tape(the type with a foam core). Since then, the Z590 has been fine.

With the shocks, I just let the lock-tite set up and dry for 24 hours, no problems there. Mine haven't leaked any more than average shocks, I checked a few days ago and they were nearly full(I lost maybe 2-4%)

The clutch issues are no more then an average clutch. My front bearing(standard clutch size) let go, and I didn't catch it in time(was really focused on trying to sort a traction/steering problem, turned out it was my tires). You can go back a few pages and see the pics. While it looks terrible, it really was just one bearing that caused the whole failure. From what I'm told, clutch bearings can last from half a gallon to maybe 1. Mine lived almost 2, so not bad really.

As far as the starter box issues are concerned. I set up my old, cheap universal Ofna box once, and it's been perfect ever since. The only mod to the car, was opening up the flywheel hole a bit, took me 5 minutes with a dremel...piece of cake!

Only parts I would stock up on is normal wear and tear stuff. Clutch shoes/bearings, maybe an assortment of diff lubes, ect... I ordered the King Headz shoes, a local uses them, and they work VERY well. I found the larger bearings for the clutch at A-main for a really good price. 10 for $10!...can't beat that. The other bearing is the same size that's in most other clutches, your LHS should have those.

Take your time, follow the instructions, and read through the posts, you'll find lots of helpful info to get it race ready. So far, 3 or 4 locals have converted, after seeing mine and a few others run the track...you won't be dissappointed.
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Old 11-19-2006, 02:19 PM   #806
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Troubleshooting seems to be the "in" thing with a new car; we're all test-drivers of sorts. On that point, I'm having some serious trouble with mine. A link to my post here, if any veterans could possibly lend a hand I'd be mighty greatful

Help! Nitro engine revs super high on startup!
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Old 11-19-2006, 04:10 PM   #807
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Dont know if this has been mentioned but.... Clutch bearings need to be cleaned before installing them. You need to spray out all the lube that comes in a new bearing then install. If not the lube can sling off into the clutch bell and cause extra clutch slippage, creating heat and premature wear.

Clutch bearings are a high wear part. They should be checked after each run for smoothness and replaced at the first sign of a grit feel. I replace mine after 1 hour of run time no matter what they feel like and have yet to have a bearing blow out.

It seems the servos that are dieing are either cheapys or airtronics. Ive been running a 9000s and have 3 gallons on it with no sign of wear. A friend of mine has a 8800s with almost the same amount of time and is working great. Has anyone killed a highend servo that wasnt an airtronics or 40 dollar servo?
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Old 11-19-2006, 04:29 PM   #808
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I'm running an airtronics and have had no problems. I think the chassis space is so tight that clearances and adjustments that we didn't have to consider before are coming into play. I just trimmed my spring shorter, used the rubber gromments (I always thought this was a non-negotiable in nitro) and made sure that the servo case was above the chassis plate. I can't see any way that this car is damaging servos when other cars didn't (they did, otherwise we wouldn't hear stories about runaways).
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Old 11-19-2006, 05:34 PM   #809
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I raced at The Farm 2 this weekend, and I had problems with my rear bearing in my clutchbell today in a 45 min. main. My Dad couldn't believe it since we really havn't had any problems with it.

Yes, I have killed a non-airtronics servo, a high-end digital, high torque & speed Ko-Propo servo. A couple of them, not sure if it had to do with the car though, since I have had problems with them before.
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Old 11-19-2006, 06:40 PM   #810
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Quote:
Originally Posted by Walt
My theory is that this is making the throttle servo itself a 'stressed member' of the chassis. The servo gets 'compressed' as the chassis tries to bend down in the middle, and 'stretched' as the chassis bends the other way.
I wonder if this load being transmitted through the servo is breaking the circuit board inside or something?

Possible experiments to run:
It is just a theory, but when looking at the 8ight compared to other buggies, the main thing that looks different to me is that the radio tray doesn't 'wrap' around the throttle servo, but rather only bypasses it on one side with a very thin piece of plastic.

Walt, I think you are absolutey right on this one. I was screwing around with my 8ight tonite, and noticed that the chassis does flex an exhorbitantly large amount in the middle towards the front of the car. And it looks as though the front brace could be the culprit. I think the aluminum one would help, but that would change the handling too much. I think the location where the brace bolts to the top plate needs to be relocated or the top plate needs to be made of carbon fiber instead of a composite material.

With the throttle servo, the radio tray not wrapping around does contribute to the problem, all of you that read this, try flexing your chassis and watch the servo, it moves with the radio tray instead of being isolated. Maybe the radio tray being made into a 2 or 3 peice modular unit? But still only requiring 4 or 5 screws to take out?
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