Tamiya Baldre

[pickleweasel]

Hi All, This is my first post so I apologize if this is in the wrong section. I have just built my first car a Tamiya Baldre, however, I am having problems with the ball diffs, I have read a few posts and have super glued both diff plates to teh plastic A7 plates to stop them spinning and used the included ball diff grease (only a small tube), I have also tightened the diff (BG4) as described in the manual, when holding both diff joints securely the diff pully doesn't/is very hard to move (about 2/3mm of the cap screw protrudes out of teh lock nut).

The problem is that the diff seems to slip quite a bit especially if I try and accelerate harshly. the car will eventually get up to speed however, I am unsure whether I should tighten the diff further, install a slipper clutch (i am running a stock motor) or shove loads of the AW grease into the diff (how much grease should you put on the diff, there is a thin film at the moment.

Any advice on any of the above would be really appreciated, I can probably do a video of the car accelerating so you can see what I mean if that helps?

[peetbee]

I'm sure others will be able to explain this better, but when the diff is in the car, I check how tight it is by holding the front wheels and one rear whilst turning the other rear. If it slips then I tighten it a little then repeat until it stops slipping. (if your motor turns when doing this then your front diff is loose!!)

It's worth bearing in mind that after your first run it will often need tweaking like this again.

I would recommend the slipper clutch even if you only have the standard motor as it does take a lot of stress off the drivetrain.

[dimblum]

Happy to help. I have been running a DB-01 Durga for the past year and had to work through the same fine tuning of the ball diffs. When set correctly, they will run extremely well

1. Super Glue works well to hold the plates, but the glue can break loose if the diff is overtightened.. You may want to check your diffs after several runs to make sure the glue is holding.. If its a problem, try scuffing the metal diff rings and the plastic surface with fine sandpaper before gluing it again. The glue will hold better.

2. It sounds like you got the diff tension about right, but it might still be a little on the loose side which is causing the slippage problem you are having.. I follow the same method of adjustment: with the diff removed, lock both joints and slowly tighten the screw until I can no longer turn the pulley with my hand. If the pulley still turns while the joints are locked, then the diff is still a little too loose - as soon as you can no longer turn it, its perfect! No need to tighten them further.. The screw will protrude a few millimeters from the lock nut, this is normal.

3. Only use the "diff grease" with your diff.. AW Grease or any other kind of grease can ruin your diff because it will cause it to slip incorrectly. Diff grease has a specific viscosity that allows the balls to grip the plate while being lubricated... You do not need a lot of grease for the diff.. Just enough to coat both plates and a small dab in each diff ball hole for your pulley (to hold the balls in place during assembly). The thin coat you have right now sounds correct.

4. Make sure ball diff grease was added to the balls of your thrust bearing. This is also necessary to ensure proper diff function.

I remember my diffs being too loose the first time I built them and had the same problem you did.. I also made the mistake of overtightening them and wrecking the diff balls (not good). I wish I would have tried the method in the instructions the first time.. It would have saved me a lot of problems... My diffs have been perfect since using the method mentioned above.. I have run a 17.5, 13.5 and an 8.5 brushless using the same diff tension.. They have all worked great and the diff has stayed in perfect condition

Some things you may want to consider for your diffs in the future:

* Get the TRF 501X metal diff joints to replace the hybrid plastic diff joints that come with the DB-01. They will hold up a lot better in the long run and you won't have to worry about any glue breaking loose.

* Trade up to some ceramic diff balls. They do not absorb heat and will not flatten. Your diffs will run smoother since the balls will not expand or shrink... You can also get the thrust bearing with ceramic balls as well. I got mine from JAAD Racing. Here are the links:

Diff Balls (12 per diff) - http://www.precisionrc.com/nv/car/product/...roduct_id=54309

Thrust Bearings (1 per diff) - http://www.precisionrc.com/nv/car/product/...roduct_id=53980

Hope this helps.

Dan

[94eg!]

Just to elaborate...

AW Grease is great for the tiny thrust bearing inside each diffs. They do not need the traction and their small size creates little drag from the super sticky grease. It will help the thrust bearing last longer as well.

In addition, you may want to take your diffs out and have another go at rebuilding them. The instructions are a little misleading in their assembly order, and it's VERY important to get the right parts on the right side. In one of the assembly instructions, the diff gets turned around. If you miss this, you will stack some parts on the wrong the side, and the diff won't stay tight once you start driving the car.

My buddy made this mistake on his rear diff. It seemed that no matter how much we tightened it, it would just come loose and start slipping after he started driving it. I disassembled the rear end and found the rear diff was built incorrectly...

BTW: The instructions specifically call for rubber cement on the diff plates, and not super glue. This allows for slight movement & expansion between the parts.

[pickleweasel]

Just to elaborate...

AW Grease is great for the tiny thrust bearing inside each diffs. They do not need the traction and their small size creates little drag from the super sticky grease. It will help the thrust bearing last longer as well.

In addition, you may want to take your diffs out and have another go at rebuilding them. The instructions are a little misleading in their assembly order, and it's VERY important to get the right parts on the right side. In one of the assembly instructions, the diff gets turned around. If you miss this, you will stack some parts on the wrong the side, and the diff won't stay tight once you start driving the car.

My buddy made this mistake on his rear diff. It seemed that no matter how much we tightened it, it would just come loose and start slipping after he started driving it. I disassembled the rear end and found the rear diff was built incorrectly...

BTW: The instructions specifically call for rubber cement on the diff plates, and not super glue. This allows for slight movement & expansion between the parts.

Thank you all for the replies

I appear to be having this problem, I tighten the diff up but it still seems to come loose when I start driving, not sure what I have done wrong though, the lock nut is on the longest side and everything looks like it should do (I think) I asked about 4 model shops in the gloucestershire area where to get synthetic rubber cement but none of them new what it was, do you have any recommendations on alternatives which are readily available in the UK?

[dimblum]

Thank you all for the replies

I appear to be having this problem, I tighten the diff up but it still seems to come loose when I start driving, not sure what I have done wrong though, the lock nut is on the longest side and everything looks like it should do (I think) I asked about 4 model shops in the gloucestershire area where to get synthetic rubber cement but none of them new what it was, do you have any recommendations on alternatives which are readily available in the UK?

Hmm.. The tension of the cap screw spins on the free motion of the thrust bearing. If the thrust bearing is binding, then the cap screw could work its way loose over time.. So the thrust bearing would be one thing to check.

If the nylon bushing on the lock nut becomes too damaged or worn, then the cap screw could also work its way loose because it can no longer hold the grip of the screw against vibration.

If the diff is overtightened, then the diff spring will become crushed and put excess force against the cap screw and thrust bearing (usually causing the thrust bearing to bend). This can also work the diff loose.

These are the first three causes I can think of..

When you say "loose" is the diff actually coming apart (eliminating the differential action), or do you just feel a lack of resistance when you turn the front and rear wheels by hand?

Dan

[94eg!]

The nut, nut holder and spring should be on the long side, and the screw and thrust bearing should be on the short side. If you look closely, you can see that the diff gets flipped over in the third asembly picture. This caused my friend to put the parts in the wrong side.

The only other thing I could think of is perhaps the foam inserts are pushing really hard on the head of the diff screw. As the differential turns, the friction against the red foam part may cause the screw to turn in the nut.

Try running the car with no red foams on the short side. If this fixes your problem, then you may have a weak lock-nut that needs replacing. Also try flipping the thrust bearing over. Perhaps the inner race is somehow dragging on the screw head or something...

[pickleweasel]

Well it appears that if all else you should go and read the instructions (again!), earlier on in the build I had made ball diff rookie mistake and mixed up teh long and short ends of the diff, only when I corrected it I forgot to switch the thrust bearing round, so 1 hour later and everything is working the way it should be, no diff slippage at all. only problem is now my battery is dead so I can't test it out properly.

Thank you all for your help an I am sorry this problem was down to user stupidity.

[94eg!]

Well it appears that if all else you should go and read the instructions (again!), earlier on in the build I had made ball diff rookie mistake and mixed up teh long and short ends of the diff, only when I corrected it I forgot to switch the thrust bearing round, so 1 hour later and everything is working the way it should be, no diff slippage at all. only problem is now my battery is dead so I can't test it out properly.

Thank you all for your help an I am sorry this problem was down to user stupidity.

YAY!!!!

I totally called it...

BTW: Rubber cement is similar to caulking. It's a flexible rubber type glue. In the states we have GOOP and Shoe Goo brands. You can usually get them in the plumbing portion of a local super store. Otherwise try the hardware store...