Tamiya Dark Impact Noise on turning

[Hullstorage 0]

Hi all,

Well i finally completed my Tamiya Dark Impact.

I have a slight proplem with the car though.

On a hard lock there is clicking noise think may have something to do with drive rods.

Any ideas??

thanks

simon

[mike_o 35]

Check front drive shaft position. If you did not follow step 14 of the manual precisely (fit the diff sponges correctly), the drive shafts will not be well seated in the wheel axels. The Dark Impact is particularly susceptible to this, especially if you set the steering for a wide throw.

[TA-Mark 195]

Lower the front suspension by using a different set of holes for the dampers. High amounts of ground clearance don't work on the DF03.

Notice that the dogbone is not parallel to the lower arm. As the weight lifts off the suspension, the distance between the outdrive cup and axle cup increases. On the most extreme setting for the dampers that gives the highest ground clearance, the front and rear dogbones can spit out from the drive cups, and the dogbones are easy to loose.

[speedy_w_beans 4272]

Something that happened on my Dark Impact a few times was the front diff cups cracked and chipped on the outer edges by the dog bones. I eventually figured out that the front suspension allowed too much compression, putting a lot of stress on the front diff cups and causing them to chip while rotating. There was a lot of lever arm force multiplication going on between the end of the dog bone and the part of the shaft that contacted the cup. Adding spacers to the shock shafts limited their travel and helped with the problem. Try adding some fuel line to part of the front shock shafts to limit their travel.

I never had any problems with the rear diff cups cracking or chipping, but I did have to rebuild my rear diff several times after putting in a higher power brushless system. I latched onto someone else's idea to use the front diff cups in the rear as the diff rings mate to the cups directly without needing CA glue or plastic holders. Using front diff cups in the rear worked fine.

So, check your sponges in the diffs as mentioned, and take a look at your suspension travel to make sure you're not putting any stress on the edges of the drive cups (both front and rear).

-Paul

[TA-Mark 195]

Something that happened on my Dark Impact a few times was the front diff cups cracked and chipped on the outer edges by the dog bones. I eventually figured out that the front suspension allowed too much compression, putting a lot of stress on the front diff cups and causing them to chip while rotating. There was a lot of lever arm force multiplication going on between the end of the dog bone and the part of the shaft that contacted the cup.

You will find that the dogbone/CVD has come out of the drive cup and jammed causing the outdrive cup to chip. Seen it happen more than once. The 'pad' is plenty soft enough to absorb all of the force from the suspension as the bogbone pushes into the outdrive cup as the suspension compresses. The dogbone chipping the front drivecups is more common due to the steering making the distance greater between outdrive cup and axle drive cup at full steering lock and the dogbone coming out of the drivecup (but not so far that it spat the dogbone completely).

Adding spacers to the shock shafts limited their travel and helped with the problem. Try adding some fuel line to part of the front shock shafts to limit their travel.

DO NOT DO THIS EVER! Limiting the suspension in this way will shift all the weight of the buggy and the landing as the damper stops functioning (loads up on the fuel tube) to the damper tower. This tears off damper towers. Again, seen people do this, seen them tear off both the front and rear towers, and on more than just the DF03. The tub of the buggy must be able to bottom out.

You can limit the total length of the damper by fitting an o-ring inside the damper body. This has the same effect as lowering the ride height or moving the damper to another set of holes.

[speedy_w_beans 4272]

For all the driving and hits to the wall my son put on the Dark Impact, we only lost a front dogbone once and in that instance he also cracked a shock tower.

I should clarify that I only added enough tubing for when the dog bone started contacting the edge of the cup. Also, the tubing was loose on the shaft, not tight. The chassis still had significant motion, but at that point the fuel tubing was starting to make contact with the shock body. I suppose an off-angle landing could put a some stress on the shock tower, but fuel tubing doesn't provide an instantaneous load like a plastic spacer will. No, I didn't put a lot of fuel tubing on the shock shaft -- that wouldn't have worked very well as you pointed out.

Seems like an off-angle landing would be the worst case scenario for tearing off a shock tower -- without anything on the shock shaft, the spring retainer should hit the shock body hard and transfer a jolt to the tower. With a small amount of loose tubing, an off angle landing should push the spring retainer into the shock body through the fuel tubing, and since that's a soft material it should take the harshness of the jolt out of the impact and reduce the peak load the shock tower sees. The car starts to correct its roll as forces start going through the fuel tubing before max shock compression... It's kind of like a progressive spring.

I think you have several good observations about the dog bone not being parallel to the bottom arm and also how extreme steering affects distance... Limiting droop with an internal O-ring is a great idea. I'd probably still have something on the shaft by the spring retainer to control peak impacts and max compression.

-Paul