Help with Re-Re Tamiya FROG.

[calinthematrix 3]

Evening folks. I have built many cars over the years- and was an avid racer in the 80s. I have 4 Tamiya hornets, 3 Kyosho Ultima 2s, an original Ultima, a Lunchbox and now a re-re Frog that is DRIVING ME CRAZY. I always wanted a Frog as a kid so decided to pull the trigger on one as an adult. Everything seemed to go together great. On the first drive (pavement) it was ALL OVER THE PLACE. Stability was horrible. It was almost like driving without the steering rods connected. I have searched forum after forum and went over the build diagrams ten times. I can't figure out what is wrong. I can't imagine this is normal for a Frog! Is it? I have spent hours looking closely at photos from the web of many different builds. The front end looks exactly like everyone else! Any suggestions? I have bearings throughout and used the Tamiya RC Frog 2005 Assem Univ. Shaft kit to prevent the dog bones from popping out. Any suggestions? Help!

[Saito2 6686]

Hi, and welcome to the forum. The Frog does have a relatively short wheelbase which would aid in quick turning, but I don't think it would be much more "darty" than your Hornets on pavement. Here's a few things to check, although you may have already. Steering tie rod length: If they are adjusted too short, the resulting toe-out condition could make it wander. Toe-in aids straight line stability. Servo Saver: If the servo saver is loose on the splined servo output, improperly assembled or itself, just plain loose and sloppy, the steering would be erratic. Caster: The Frog is unique in the fact its caster angle is adjustable. Set up as the manual depicts should work well enough to start. If the angle is lessened or straight up (no angle, technically) or worse, negative, the front end could wander as well. Make sure the bolt and star washer assembly holding the pressed metal "front arm" to the "front suspension arm stay" together is adjusted properly and tight. You can play with this adjustment. I think the manual tells you to set the arm and arm stay at 90 degrees to one another (relying on the front kick-up to give some axis inclination). Rotating it back to give more positive cast might help (the opposite of rolling it forward, which would be negative caster akin to a shopping cart front wheel). Hope some of this helps.

[Hobbimaster 190]

13 hours ago, calinthematrix said:

Evening folks. I have built many cars over the years- and was an avid racer in the 80s. I have 4 Tamiya hornets, 3 Kyosho Ultima 2s, an original Ultima, a Lunchbox and now a re-re Frog that is DRIVING ME CRAZY. I always wanted a Frog as a kid so decided to pull the trigger on one as an adult. Everything seemed to go together great. On the first drive (pavement) it was ALL OVER THE PLACE. Stability was horrible. It was almost like driving without the steering rods connected. I have searched forum after forum and went over the build diagrams ten times. I can't figure out what is wrong. I can't imagine this is normal for a Frog! Is it? I have spent hours looking closely at photos from the web of many different builds. The front end looks exactly like everyone else! Any suggestions? I have bearings throughout and used the Tamiya RC Frog 2005 Assem Univ. Shaft kit to prevent the dog bones from popping out. Any suggestions? Help!

When you built it, did you use both springs in the front suspension? How about the rear dampers, can you compress both equally? It is hard to diagnose something like this without seeing exactly what it is doing. I have even had a bad servo that was not centering correctly. I would trim it to go straight, and the car would take off in the other direction.

[calinthematrix 3]

Thank you all for the replies. I ended up loosening the entire front end up and putting it back together. Still didn't help. Here's the weird thing.... I loosened the rear tires a bit (the nut holding them on the rear axles) and it fixed the issue! Apparently I may have tightened them too much as it was 330am when I got to this part of the assembly. The car now drives and handles the way it should! Now, onto the decision of my next build! Thanks all! Pictures attached!

[ruebiracer 1046]

17 hours ago, calinthematrix said:

Thank you all for the replies. I ended up loosening the entire front end up and putting it back together. Still didn't help. Here's the weird thing.... I loosened the rear tires a bit (the nut holding them on the rear axles) and it fixed the issue! Apparently I may have tightened them too much as it was 330am when I got to this part of the assembly. The car now drives and handles the way it should! Now, onto the decision of my next build! Thanks all! Pictures attached!

That makes total sense! It´s an issue with the old plastic wheel hubs, same on the Monster beetle. They bind the bearings, and if unequal tightened, you get weird reactions and steering moments from the differential! That´s why I also forbid my little nephew to change the tires on his MB himself. he was also tightening them too much…

Good, that you could fix this issue.

Br,

Matthias

 

[AJB123 107]

7 hours ago, ruebiracer said:

That makes total sense! It´s an issue with the old plastic wheel hubs, same on the Monster beetle. They bind the bearings, and if unequal tightened, you get weird reactions and steering moments from the differential! That´s why I also forbid my little nephew to change the tires on his MB himself. he was also tightening them too much…

Bind the bearings as in the plastic hub rubs on the bearing outer? If so, could it be fixed with a small washer between the hub and bearing? (Small as in outside diameter smaller than the bearing outer race's smallest diameter)

[ruebiracer 1046]

18 hours ago, AJB123 said:

Bind the bearings as in the plastic hub rubs on the bearing outer? If so, could it be fixed with a small washer between the hub and bearing? (Small as in outside diameter smaller than the bearing outer race's smallest diameter)

So far, I haven´t checked in detail where it binds exactly. I have a Hopped up Monster Beetle also with Re-Re cardans (besides the one I mentioned), but I drive aluminum wheels with aluminum wheel adapters. Can´t remember, if that was binding, too. I have something in mind, that the new cardans have a step turned for the inner bearing to Prevent binding the outer bearing seat. The original wheel axles don´t have that. The plastic wheel adapter should not bind the outer bearing, it is not contacting the full bearing diameter, when I remmber correctly. Guess I have to check my models.

Ideally a spacer between  the 2 bearings like on the TRF cars would be good, so a "prealoading" of the bearings would also be eliminated. (Prevent some drag and shorter life span).

Sorry, not near my cars at the moment, so I can not confirm my memories.