mugen mbx5-truggy.

[jollyjumper]

this one is for all mugenite's:

Originally Posted by tony1034

Here are some build tips for guys putting together a MBX5T (or buggy)


The biggest tip would be prepping the diff cups and double-gasketing them. Using like 3 different grit sandpapers (I use emery cloth) you want to sand the cups until they’re smooth as glass. I use 320 grit, then 800 grit and finally 1500 grit. Place the paper on a perfectly smooth table and hold the cup on the paper. Swirl it around in a figure 8 pattern. The idea is to get the cup perfectly smooth and flat. When you go up to 800 grit, you’ll quickly see the plastic get very shiny smooth. If you didn’t go long enough on the 320 grit, you’ll clearly see it. I then do a quick run with the 1500 grit and they’re dead straight. What this does is ensures the cup won’t leak against the ring gear or spur gear. Most people blame the leaky Mugen diffs on the o-rings, but 95% are at the cup (just take two cups and face them together and see the light in between them as you rotate them face to face). Remember, the cups are not machined, they're molded. Then double up the gaskets (Part # C0257). I use my screws 2mm longer than the manual and tighten up. They’ll NEVER leak from the cup (Tip comes from Chad Bradley).

I also have thicker 5mm (S5) o-rings for the out drives. These are tighter than the stockers. The real key is to use grease on them (the thicker S5 o-rings or the stock S5 o-rings) and in the slot on the outdrive shaft. Of course, do NOT use the small S3 o-rings.

I use the stock Mugen brake linkages so I put a slight z-bend in the upper rod to get it fit right. You won't be able to easily adjust the rear brake bias with the z-bend, but remove the small 2x10mm screw and twisting it is very easy. I usually get it set right and then adjust the front in or out. I know most guys love the Kyosho linkages. If you’ve had the Kyosho, you may like it and want to fit them on the Mugen. The Mugen uses fuel tubing where the Kyosho has those little springs. I’d like to change mine over to try the springs, but don’t have a Kyosho to see how it goes. Maybe someone else that switches can post pics.

The kit should also have shims to get the ring & pinion mesh set. They go outside the 8x16 bearings on each side and just add pressure to get the ring gear closer or further away from the pinion. They are 14mm x 16mm by .1mm thick. On the buggy, I always used two on the diff cup side to push the ring gear away from the pinion. But I've heard that the new 46/10T ring & pinion on the MBX5T doesn't need them. Regardless of what anyone else uses, always check the backlash on your car.

The rest of the car goes together like butter. New shocks are SWEET!

Best regards,

Tony P.

This post has been edited by tony1034 on Aug 18 2006, 04:58 PM

Originally Posted by tony1034

OK, so let's put this shock end issue to rest. I just measured the shock bodies, shafts and springs from my X5T shocks and my old MBX5 shocks. I also measured the shock end hole depth.

DATA ....LOL

Shock Rod End Hole Depth - 11.15mm

MBX5 Front Shock Body - 42.33mm
MBX5 Front Shock Shaft - 52.63mm
difference - 10.30mm
Rod end to top of shock body height: -0.85mm
Shock Spring - @70mm

MBX5 Rear Shock Body - 54.06mm
MBX5 Rear Shock Shaft - 64.71mm
difference - 10.65mm
Rod end to top of shock body height: -0.50mm
Shock Spring - @90mm

MBX5R/T Front Shock Body - 47.33mm
MBX5R/T Front Shock Shaft - 59.63mm
difference - 12.30mm
Rod end to top of shock body height: +1.15mm
Shock Spring - @75mm

MBX5R/T Rear Shock Body - 59.05mm
MBX5R/T Rear Shock Shaft - 71.65mm
difference - 12.60mm
Rod end to top of shock body height: +1.45mm
Shock Spring - @100mm

So.....If you screw the rod ends on all the way on the old MBX5 shocks the piston, locknut and shock shaft are below the end of the shock body by a very small amount. The piston would be very noticable down in the body and if you looked at it from the side, you would not see the nut or shock shaft.

But on the MBX5R/T shocks, the piston would be noticably below the end of the shock body, the top of the nut would be about flush and the tip of the shock shaft would be above by a very small amount (1.15mm in the front and 1.45mm in the rear). You might just barely see the top of the nut looking at it from the side. So obviously I did not get my shock rod ends on all the way because my pistons are flush with the top of the bodies and the nut and shaft completely poke out and compress the bladder. I will have to thread each rod end on several more turns to get them correct.

In looking at the old shock shafts and the new ones, the way the threads are cut into the shaft is different. On the old MBX5 shocks the threads are cut all the way, nice and deep until they end. But on the new shafts, the threads are nice and deep at the tip, but then gradually taper off as they go up the shaft. This makes the shafts much stronger and less prone to breaking. +1 for Mugen. BUT...it will also make tightening up them rod ends a tough son of a beech them last few threads...LOL :brickwall

Everybody that didn't get the ends on all the way like me, happy busting out the pliers and twisting the skin off your fingers ....HAHAHA

Best regards,

Tony P.

Originally Posted by tony1034

Servo-saver issues with blowing servos:

Some guys have been having issues with the servo-saver locking up on the MBX5T and MBX5R (use same servo-saver). Before assembling the servo-saver with the spring, make sure the upper plastic piece slides up and down the tube smoothly. The fit is a bit snug on this new tube/plastic. I polished my servo-saver tube and then use a dry lubricant (Dow 557 from mcmaster.com). You can also use some graphite. Don't use any lubricants that contain oil such as WD-40 as dust will adhere to it and bind it up. Then make sure that the servo-saver works. It should cam over if you try to turn the wheels and hold the servo link. Finally, make sure you set your EPA (both left and right) with the arms level. I set mine for maximum and then back off two clicks on my M8.

Enjoy!

Best regards,

Tony P.