Turbo Optima Re-Re Transmission

[sundevil67]

When I roll it back & forth by hand, the belt moves & the gears seem to go in the right direction..but it sounds like the spur gear is getting knocked loose under any power...seems like the gear cover/body clip is all that's holding it in place, which doesn't feel like the same way it was done way back when...though I only had an Ultima Pro and a Turbo Mid SE, which both had ball diffs, so this is a bit different. Before I tear the whole transmission apart, wanted to see if anyone had any theories...I'll retain some dignity in the fact that I haven't built one of these in 30 years and got this far without help...

https://vimeo.com/479301611

[coxbros1]

yup cover holds it on....or clip if no cover

[XLR8]

Maybe the slipper clutch is too loose?
The clutch is something new for re-re Optima and Ultima, your vintage Ultima Pro didn't have this feature.

[sundevil67]

Maybe the slipper clutch is too loose?
The clutch is something new for re-re Optima and Ultima, your vintage Ultima Pro didn't have this feature.

Woah...I feel a little silly now...That sounds like it might be a winnah...I think part of it has to be that it's taken me a year to get this thing together. The gorgeous weather motivated me to speed things up. I do (now) recall that adjustable on the other side ... Pretty much the same result as a ball diff that's too loose I guess...but this is easier to adjust. I'll report back. Thanks for the fast replies!

[sundevil67]

OK, I'm losing my patience here! I pulled off the counter gear shaft & everything moves very smoothly without the Spur & pinion attached. Nothing appears out of place. I can get it to drive forward a few feet before the gears lose contact. Reverse never works. I don't think I need to tear apart the belt drive or any of the other gears & the problem is somewhere in this slipper clutch & spur.

Video Clips Here

One thing that I'm not clear on - what is that wrench for in this step? The box wrench tightens that outer nut no problem ..

[GoMachV]

If the slipper is slipping, you will be able to visually see that the nut on the left side of the car is stationary when you apply power. If the nut is turning during the slipping, the issue is inside the trans case.

[Champ85]

Watching that video, I can see the entire slipper gear and shaft lift up when it's grinding. I outlined it in green with arrows in this picture. Are you sure you installed the ball bearing on that side of the gearbox housing in step 3? And the spacer in step 4? Without the spacer, the ball bearing will slide out of the housing and allow the whole slipper shaft assembly to wobble up and down.

[sundevil67]

Watching that video, I can see the entire slipper gear and shaft lift up when it's grinding. I outlined it in green with arrows in this picture. Are you sure you installed the ball bearing on that side of the gearbox housing in step 3? And the spacer in step 4? Without the spacer, the ball bearing will slide out of the housing and allow the whole slipper shaft assembly to wobble up and down.
1.png

Unfortunately, I think this might be the problem. I'll find out for sure exactly what's missing or incorrect, but ... I don't remember having to pretty much tear apart the entire car to troubleshoot the tranny! Now I am having trouble even getting the thing apart and am really discouraged. I don't know how I'm ever going to get these 2 screws out ... or really how does anyone secure 2 spots while turning the driver. There were a few spots during this build where it felt like I'd never be able to proceed without a 3rd hand or really tiny fingers...

[XLR8]

I can feel your pain brother.
I'm relatively new to the Optima series (built my first car only a couple years ago). My initial thoughts; although the aluminum chassis parts form a really cool exoskeleton, they also make repairs and maintenance much more difficult than with the later plate-based cars.
More than other car, the Optima is one that you'll want to build correctly the first time. The benefit is an extremely fun car to drive.

[sundevil67]

I remember rebuilding the transmission on my old Ultima Pro in a weekend without a hitch when I was 14. I can cope with not being able to play sports like I used to because I'm older, but I never expected my R/C skills to have declined the same way! I definitely have a helluva lot less patience, that's for sure. It's like the plastic parts are more delicate than they used to be...In this particular case, I don't know if I've stripped the insides, but I really don't know how the heck I'm going to get the rest of the rear end apart. If I had a LHS with an employee who was born after I got my 1st Optima series R/C, I'd be tempted to bring it down there & just drop it off. I really don't want this to be one of those sad, partially built new kits for sale cheap on eBay

I can feel your pain brother.
I'm relatively new to the Optima series (built my first car only a couple years ago). My initial thoughts; although the aluminum chassis parts form a really cool exoskeleton, they also make repairs and maintenance much more difficult than with the later plate-based cars.
More than other car, the Optima is one that you'll want to build correctly the first time. The benefit is an extremely fun car to drive.

[sundevil67]

I'd meant to link to this sad video that's got me stuck now.

[sundevil67]

SOS... I don't know where to go from here. The counter gear shaft seems to have too much play, until I tighten the nut on the spring on the other side...Then it's nice & tight, but the then counter gear doesn't mesh well enough with the spur to make the go-go.

I also found a teeny aluminum ball in my gear cover...should this worry me? No idea where that could have come from.

[sundevil67]

Meh. I'm still doing something wrong in the slipper but I can't rebuild it again. I give up. Shouldn't I be able to mail this thing to someone who can do better?

[GoMachV]

Ok so clearly it’s slipping and the only place it can slip is the slipper assembly. The first thing I would do is remove the cluster gear and remove the slipper nut, spring, and special washer. Remove the slipper shaft and disassemble. Look for signs of things not fitting together properly. As much is it sounds like it’s been slipping, you might be able to see a shiny spot somewhere. I would then reassemble the slipper carefully making sure the pads are in place properly and install the special washer, spring, and nut to the spec shown in the manual. Now- before you put the cluster gear back on, spin the drive train and see if things are smooth. If there is any binding you have to have something inside the case assembled improperly. Most common cause would be the spacer being out of place, but if you installed the holder properly it shouldn’t fall. Report back after this and let us know if the drivetrain is smooth or not.

[XLR8]

This is a complex slipper assembly so maybe it will help to look at an exploded view.