Tuesday, 20 January 2015

Ball Diff vs Gear Diff

I noticed that my Mid does not work well with gear diffs on loose sandy low traction surfaces , which cause the car to spin out on power while cornering.

On muddy surfaces or grass, the gear diff works great. So I decided to switch back to ball diffs, for this coming 8th Feb 2015 race. One of the problems with the ball diffs is it gets gritty by 10 packs, and you have to open the gearboxes and rebuild the diffs. There are 2 main causes of the diff getting gritty so quickly, one is dirt getting in the drive line, and the other is, even  if there is no dirt, ball diff greases break down ,turn black and form deposits. I recently bought a synthetic grease from ACE hardware ,called Super lube. I am now using this as my ball diff grease, and I will seal the driveline properly. In theory this grease will take much longer to degrade.

I opened my driveline yesterday and discovered sand in my gearboxes, and traced the entry points to the front belt cover edges. The front lower belt cover lifted from the chassis, and the one under the upper deck has also formed a gap. since the rest of the belt covers form a rather tight seal, when the belt moves, it forms a vacuum of sorts that sucks the sand inside.
I am now rebuilding the LWB with synthetic grease in the ball diffs and will reseal the driveline, hopefully I will succeed ,and get back the awesome handling as seen in the video of the last post. I want to get my LWB working to a level that it can challenge the Durangos and ZX6s.
Last night, on the 21st Of January, I rebuilt my LWB driveline, and I find the diffs to be smoother compared to before, thanks to the SUPER LUBE grease.
I set my front diff noticeably tighter than the rear, with the rear slipping a bit. I did this to make the car stable on acceleration and braking. This will make the car understeer a little, a car that understeers a little is easy to drive under pressure. Right now I use 10 Degree ZX5 caster blocks, and find steering to be a lacking at the very tight turns, may go back to 7 degrees depens on this weekend's testing.

Sunday, 9 November 2014

11-Nov-2014, all paid off !

The car was incredible with the 7 degree caster blocks. I was finally able to drive it really well and keep with modern cars. The tail wasn't swinging anymore.

Friday, 7 November 2014

Adding caster to front

I have changed back to ball diffs, because the geardiffs don't seem so smooth. Since I did not have enough parts to rebuild a rear ball diff, I made some improvements to the standard kyosho rear ball diff.
I got a 8x16x5 bearing, and got my machine shop to make a 16mm sleeve with 19.8mm outer diameter.

The bearing slides into the geardiff casing

This ball diff is now very smooth.
I also used Lazer ZX-5 7 degree c hubs with 3racing ver2 ZX-5 alloy knuckles. I had to grind the c hubs in the fronts to make sure it will fit into the arms without binding. I am in the process of making a ZX arm that will be a direct fit with ZX-5 c hubs.
7 degree caster blocks with 3 degrees in the arm mounts equal 10 degrees total. this should improve handling. However I find that steering throw is also reduced.
Assembled parts. The front CVD is 3racings 65.5mm and upper turnbuckle is now 50mm.
Grind the c hub below the angle mark. With my new arms which will be ready next week, no modifications will be needed.


Wednesday, 3 September 2014

Ready for racing - 2014

After cleaning up. Some sand went in the front gearbox and made its way to the back. I changed new gearbox so that it will hold better on the chassis.

Serviced LWB next to my SWB

Monday, 25 August 2014

Built a SWB Optima Mid - finally !

This was my brother's old Turbo Optima Mid, that was in pieces.
I have a LWB ,but I missed driving a SWB, so I decided to rebuild one with some upgrades.
My Own Made associated B4 slipper compatible layshaft. More is available for sale.

The loose parts layed out

The front & rear ball diffs and rear gearbox innards. Notice my own made hard PEEK gear. I have more for sale.

Semi completed

Assembled gearbox and slipper.

With 2.2" wheels

Kyosho GP10 strong steering parts.

Incomplete rear end

Grinded arms, flipped, to make sure CVDs exit straight

semi complete

Recently completed with Mid SE decals

This is a video of this car running, hadn't had a chance to test it offroad yet.
After the ball diffs get gritty I will install gear diffs to cut down maintenance.
next build, my Old Lazer ZX !