Mike I am using a dual servo saver setup, and they are all metal (from Golden Horizon) The bearings are brand new. Very little on this truck is old. In fact the only "used" things on the truck would be the MM motor and ESC. All bearings on the truck are brand new. Do you think the dual servo saver setup might be too stiff? I'm using dual black springs with this set up.

If you are using servo mounted servo savers then that is most likely the problem - they don't make those things stiff enough to handle the torque load your setup dishes out. I suggest finding a UE servo saver or even the Proline version(I have a couple around if you need one) - the bellcrank saver design is far superior to the old school 1/10 servo mounted pieces of crap. To verify whether or not the savers are the problem, simply remove them and replace with solid servo horns(try not to hit anything when testing). If the truck suddenly drives straight, then search for the savers mentioned above. :)

Mike I have dual bellcranks (all metal from Golden Horizon). Do you think the Proponents or UE designs offer better performance?

Metal bellcranks aren't directly the problem - soft servo savers are the likely culprit. The UE servo saver is part of the bellcranks and is superior to anything else made(it is a typical 1/8 buggy style servo saver setup). The Proline setup mentioned has been out of production(like the UE) for some time, but is also a bellcrank 1/8 style servo saver setup. Your truck is deserving of the UE saver if you can find one - servo mounted savers won't get it done for your beast. I have 4 UE savers, but they are each on different trucks and not for sale.

Can you use dual servos with the UE servo savers? I think I will wait till someone puts a UE servo saver up for sale on ebay. I had the chance to buy two or three as I was putting this truck together, and I'm now kicking myself for not getting one of them. I will just have to wait as usual.

Dual servos is accomplished with linkage - the bellcrank setup is largely the same as stock so it is no problem to use dual servos(although dual servos is not necessary - 1 good servo is the ideal setup).

Thanks Mike, as soon as I can get my hands on a UE servo saver I will install and I'm sure it will fix the problem. On to my next build. I just got my pair of Hot bodies 43t 8028 ring gears and that completes my parts list. I can now start my build. I will not do another complete build thread, but I will post pictures when I can.

Well I just bought a gen 4 UE servo saver and can't wait to install it:yes:

Congrats, those are to come by. How much did you pay for it if you don't mind me asking?

$95.00 US. I also got the spring pack from UE $12.00 on the way.
http://www.ebay.com/itm/160688343760...84.m1439.l2649

I have not heard back from UE on my spring package, is this common procedure? They took my money though. This is the first time I have ordered from them directly.

Yup, that's common. There is no more email or anything after Sam left the place and let Robin do everything. You'll get it though.

Thanks that's good to know.

Ok, I just got the time to swap out the steering linkage for the UE (gen 4) servo saver,and took the truck out for a spin. I still have the severe pull to the right. I now don't think it's the saver that is the problem. I am now thinking it's the 300k diff oil and locked slipper. At first I tried to run the truck with two servos, but I am now going to give in and just go with one. I know I'm stubborn, but when all the senior members in here keep saying just use one.........( I can here you guys saying I told you so). I just think all the torque is forcing the truck to the right under full acceleration. I'm really glad that I got the UE servo saver it just really looks great and you can tell what craftsmanship when into the design. So, guys what diff oil should I try to use? Remember I still want to be able to pop the front wheels up off the ground at will.
Thanks,
Mike.

Since you are running a thick diff oil, have you thought about the tires.
Is one side growing more then another?
Does it pull to one side at a low speed or just high speed?

Unfortunately
 

Unfortunately a lot of this hobby is trial and error. Even with the best advice from some of the most experienced hobbiests you have to try different things to find what will work best for your vehicle and your style of driving. With your severe pull under acceleration I would try going on the low end of things and work your way up. Losen your slipper just a tad, and put some low weight diff oil in your diffs and see if it all goes away. Even though the advice given to check your steering linkage did not resolve your problem it did give you a better look into exactly how well or not so well your steering was working. The UE Gen4 servo saver is the best one ever made for sure, and you are lucky to have one for your truck. It sounds like you have worked your way pretty much through all of the possible problems that your steering could have been giving you.

So I would go back to what I started telling you a while back. Your getting torque steer from your drivetrain because of the power your truck has in it. It could be a fault in your setup (sticky bearing, of bad toe adjustment, Etc), but I really do believe that you just have to play with your diffs until you get it where you want it to be. Are your tires taped and balanced? Are you using beadlock rims or just gluing your tires? If you have your tires taped and you are not seeing any ballooning, than that leaves your drivetrain itself as your culprit.

I think I remember asking you to try disconnecting your front driveshaft and just running it with rear drive and see what happens. Then try running it with just front wheel drive and see how that works out. That will give you a good idea how the front and rear wheel drive works independently so you can figure out if further adjustment is needed to run them together.

No it happens the moment I pull on the throttle. I have the tires double gorilla taped so they don't balloon at all.

Can you switch sides with tires for a test run and see what happens?

I'm willing to give anything a try.

I don't know why I didn't think of this but my tires are directional. I can't swap them for the other side.

Anything is possible
 

Well anything is possible, but honestly unless one tire is totally different from the rest I doubt that it would make much of a change for your particular problem. And even though the tread is directional you can still try swapping them around for a test. Even so as long as they are all the same size, and the weights do not differ more than an ounce or two I would find it hard to believe that it would change your driving experience to swap them around. The only way tires would affect steering would be if they were different sizes like they do with some oval track racing. They put small diameter tires on the left side to make the vehicle naturally want to turn left making it easier to steer through the turns.

What you have been describing as your torque steer issue would not be affected by the tires unless one side is balooning drastically. Alignment maybe, but this seems more like a diff issue where one side is receiving more power (rotation) than the other. You have to try whatever comes to mind after you do a little knowledge based elimination. Eliminate what you know for sure is not your problem, and make a list of what you do suspect, and then test that theory one by one until you have tried everything that you can think of, or the problem disapears.

Steering issues under power can only be caused by a few things. The servo is always the first place to look. Second would be the steering linkages to make sure that there is no slack or binding of any kind. If it operates smoothly by hand than it should do the same under servo power as long as you have the right servo for your setup. Next is the drivetrain itself. Closely examine each axle for any unusual binding due to a bad bearing or improper installation. The diffs are next in the line. Diff slipage is an individual descresion and you have to set yours up to match your expectations, but you still have to make sure that they are smooth as silk and have no binding what so ever. The last thing in the drive line is the transimission or center diff including whatever slipper you might be using. Make sure that everything is operating smoothly and easily as it should. I cannot think of anything else that will effect your vehicle in the way that you have described.

Have you noticed if it dog tracks any?
I looked back but no video to see.
Maybe something out of line in rear of truck as well.
Just things to look for that is simple.

I'm not sure what "dog tracking" is. Yes I still have not had the chance to get the video camera out to film this running.

Dog tracking is where the rear is out of whack.
The back of the truck runs out further on one side then the other.
It can cause all kinds of weird steering issues.

I have a question not related to my metal maxx. I am putting together my stock brushless emaxx (3908) and I am going to use dog bones for center drive shafts does anyone know what length the front and rear shafts are? I am using the stock plastic chassis and the stock transmission.

I don't know the actual lengths, but if you are looking for bones to use that will definitely fit:

http://204.186.93.64/NewE-Maxx-CenterDogBone.htm

Saves a job- Mike can custom make dogbones too, though he'd need the dimensions before he started, so...

Thanks Neil,
I found out that I needed a 60mm pin to pin for the front, and a 120mm pin to pin for the rear. I have both on the way. I already bought them before you posted, but as always thanks again.....
Mike.

Did you get the 120mm from kershaw design as well? I have been trying to find 120mm pin to pin dogbone for quite some time..

No I actually got a Ofna 40710 120mm dogbone.
http://www.ofna.com/parts.php?start=3600

I was told that Ofna measures their dogbones according to the overall length, not pin-to-pin. I might be wrong. Please let me know once you get the parts.

And as for the link on Kershaw Design, the dogbone is not 120mm.. it is only 114mm, according to Dan, the owner.

Yes, you are correct the 120mm measurement is end to end not pin to pin. It turns out that even with that I still had to grind the ends on my bench grinder and now the back drive shaft has just the perfect amount of play.

I just read this build from start to finish after, cmac, you referred me and I'm glad you did! It looks fantastic and has definitely motivated me to make my own Maxx :yipi:
Keep up the good work

Thanks so much. It was a learning process, but really fun. Good luck on your build, and let me know if you have questions. I don't know everything by a long shot,but I will be happy to help when I can.
Mike.

Yeah I've learnt a lot by reading builds like yours so hopefully my build should run quite smooth, much appreciated :smile:

Does anyone know if $299.00 for the Spider 8 diff set (on the UE web site)is for one diff or two?

Hi mate
It"s for two!

Pair
 

Yeh its a pair. Man do I feel lucky though, because I just scored a pair of those on here for $170. I could not have justified $300 when I need so many other things. They are the best 1/8th diffs for sure, but I would try to pick up a pair another way. Its your money.

I'm still trying to get my original Emaxx (3908) together and I'm trying to figure out what pinion gear to use. I going to use the stock transmission with HB Lighting pro diff's. I would like for this to be capable of at least Mid 50 mph. On the speed calculator I'm not sure which Traxxas transmission to choose. Also what pitch pinion do I need?

What motor, what voltage and what tires are you going to run?

For the speed calc, you're going to use the "E-Maxx 3905 1 speed or 2nd gear" option. I'd recommend running a 65T spur, you're going to need it to make up for the Lower ratio in the HB diffs and keep the pinion a normal size. Btw I run a 65t spur on my 3905/8 and I cant use a pinion smaller than about 18t with a castle motor because the motor will hit the trans case before the mesh gets tight enough. On 6s with a 2200kv, 24/65 gearing with the 3908 tires you'll be at 55mph before you factor any tire ballooning.

I'm going with MM 2200kv on 6s. Wheels will vary but I do have the stock wheels and tires. I also have several different aftermarket wheels and tires. Are the stock gears 32 pitch? Or something different.