How To Get The Fastest Frog.

[CR-01nut]

what is the fastest motor i can put in a frog without risking the gearbox?

i will be using the high speed gear set and full ball bearings.

i can not afford brushless at the moment.

[HunterZero]

what is the fastest motor i can put in a frog without risking the gearbox?

i will be using the high speed gear set and full ball bearings.

i can not afford brushless at the moment.

Well - any motor that will clear the right suspension trailing arm sufficiently will work (some fatter motors will be hit by the trailing arm, since the clearance on the motor looks like it was originally only meant for a 380 motor) - but for how long it will hold up is the question. In stock form, I wouldn't put much more than an RZ in there, without asking for constant trouble.

If you put mucho mambo on there, the rear diff is likely to separate and eat itself within a few runs, and you're likely to have constant problems with the dogbones (wearing out quickly on the original hex shafts without loads of AW or moly grease, and dogbones popping out on the re-release).

First, I'd recommend full bearings, and the rear UJ driveshaft set. The car should work fine with an RZ motor with this setup.

To solve the diff issue is a bit more involved. You could drill out one joint shaft, and tap a screw into the other, so you can use a loctited screw to hold the diff together, instead of the axle shaft. Or, you could go the super-expensive Thorp ball diff route, and see how one of those holds up to the power. Or you could forego the rear diff altogether, and replace with an original Brat spool (re-re Brat has the same diff as the Frog).

Another hurdle is that the Frog's gearing options are fairly limited. It's a fairly light car, so you could probably get away with using the smallest pinion/largest spur. There is a motor mount kit for it, that allows even more choice in pinion, but these aren't easy to find.

If you want to go the whole hog, then reinforcing the rear suspension arms/suspension mounts, eg with some formed carbon fibre, would help the suspension/driveshafts cope with the power.

- James

[acorn]

Another way to sort out the frog diff is to shim it properly. Of course the gear box plates must be in tip top condition and not bowing out. My runner frog is perfectly shimmed and runs a 13x2 motor with no problem. And do go for a set of UJ's.

Also, make sure there is no wear in the rear arms, the mounting plates and the holes in the gearbox plates where the arms locate. You don't want the arms flapping about.

In my experience, you cant really completely avoid risking the standard gear box, as its inherently flawed. Back in the day, my gear box lost the plot with the stock motor, let alone any modified motors.

But, get it right, and the Frog is a great car.

[CR-01nut]

after reading that i think i will go for a sport tuned or lightly modified motor. that should be fast enough for me after plodding around in the land cruiser for a few months now.

[acorn]

after reading that i think i will go for a sport tuned or lightly modified motor. that should be fast enough for me after plodding around in the land cruiser for a few months now.

Ooops didn't want to put you off.

Dunno how many cars you have, but if you have a few, how about getting a hot motor that will work in your other cars? Then if you kill the diff you can cheaply replace it, and / or give up and use the motor and esc in another car? No harm done then!!!

Not a bad idea to use a moderate motor though. Should still be quick enough for fun. Might still kill the diff in the end though !!!!

[CR-01nut]

yes i have a df02 but it is in no state to drive. some time after xmas i will get it the new wheels, tyres, servo, receiver, ESC, bearings, and motor it needs.

will stick a 15T in it and see what happens.

[retroman]

I have a vintage Frog, running a retro Schumacer Formula 17T stock motor, and a re-re Frog, running a sport tuned. Not yet had drive shaft, or gearbox issues on either.

The Frog is an excellent car. "No Guts, No Glory"

[HereBeMonsters]

If you can't afford brushless at the moment, have you seen the price of EZ-Run stuff?

[CR-01nut]

If you can't afford brushless at the moment, have you seen the price of EZ-Run stuff?

yes it is good value, but i cannot find it from a good UK supplier. so until then my wallet stays closed.

[HunterZero]

I have a vintage Frog, running a retro Schumacer Formula 17T stock motor, and a re-re Frog, running a sport tuned. Not yet had drive shaft, or gearbox issues on either.

The Frog is an excellent car. "No Guts, No Glory"

Perhaps the Frog is your Sunday driver?

Sport tuned is a fairly mild motor, not really much faster than a standard motor. And a 17T vintage motor is a long way off the power of modern motors with similar winding count.

I am not saying that The Frog will spontaneously combust with a superfast motor in it, but once you get down to the modern sub-23 turn modern motor range, then the maintenance required increases rapidly, and you will start to have failures more regularly, proportional to how silly a motor you put in there.

The re-re Frog will throw driveshafts if you run it hard on rougher surfaces. The rear arms can flex to a degree that the driveshafts bind and pop out. It's more likely to generate enough force to pop out the driveshaft with a faster motor, but it's quite possible to do it with the standard motor. Some re-re Frogs have faulty steering knuckles that come apart and require loctite or superglue to put them back together.

There is plenty of anecdotal evidence on the forums that this is the case.

However! With some simple mods and maintenance, eg regular checking of the grease in the driveshafts and making sure the rubber boots are in place, and properly shimming/maintaining the diff as it wears, will do wonders to significantly prolonging the drivetrain.

And it depends on how you drive, and where you drive it. Jumping the car can be very hard on the drivetrain, for example.

My vintage Frog had a Yokomo Turbo in it, and was OK with that. Then I put a Technigold in it which is almost equivalent to the RZ, and it lasted several more runs, but over time, apart from chewing pinions alarmingly quickly, it ate its differential and bent the gearbox side plates out. And it desoldered its MSC. I didn't have driveshaft issues, because I rebuilt them every two to three runs with fresh molybdenum grease.

- J

[CR-01nut]

i would not be able to put up with stripping my car down every few runs, so sport tuned motor it is.

[retroman]

Both my Frogs are fully ball raced, and as with all my cars, I flushed all the grease out the bearings, and then lightly oiled them. The front wheels spin for ages, and the gearboxes are lovely and free running. They both have plenty of grease in the drive shafts

If you do the above, and use really good quality battery packs, the sport-tuned will make for a lively frog.

[CR-01nut]

Both my Frogs are fully ball raced, and as with all my cars, I flushed all the grease out the bearings, and then lightly oiled them. The front wheels spin for ages, and the gearboxes are lovely and free running. They both have plenty of grease in the drive shafts

If you do the above, and use really good quality battery packs, the sport-tuned will make for a lively frog.

i will be having full ball bearings in my frog, but how do you get the grease out of them? the oil seems a very good idea to me.

[HunterZero]

i will be having full ball bearings in my frog, but how do you get the grease out of them? the oil seems a very good idea to me.

You blast them out with WD40 or motor cleaner, then bathe the bearings in some light oil. Will make them run more freely.

Only problem is with this trick, you'll need to keep adding the oil to them to make them last.

If you want bearings that are going to last, get some rubber sealed ones for the wheel axles.

- James

[CR-01nut]

You blast them out with WD40 or motor cleaner, then bathe the bearings in some light oil. Will make them run more freely.

Only problem is with this trick, you'll need to keep adding the oil to them to make them last.

If you want bearings that are going to last, get some rubber sealed ones for the wheel axles.

- James

Thanks

[retroman]

Yeah, that's pretty much how I flush my bearings. Generally I put them in a small plastic pot, with a screw top, pop the bearings in, and half fill the pot with white spirit. new bearings I will leave to soak overnight. Then shake the pot hard, and lovely free spinning bearings! I tend to oil them with Trinity Royal Oil.

Try the same trick with bearings that are full of dirt. You'll be surprised at the amount of filth that will be in the bottom of the pot! keep repeating the process until no more muck comes out, then check the bearing spins nice and free.

Rubber sealed bearings, I tend to pop the seal off one side, so they can be flushed and oiled. When fitted to the car, I fit the side with the seal facing outwards. I done this with my Associated B4.

Properly flushed, oiled, and maintained bearings can make a big difference to performance, and run time. Just ask anyone whos races 12th scale!!

[terry.sc]

Thread tidied, keep it on topic please.

As someone who used to race a Frog in the early 80s, the hottest motor buggies at the time ever saw was a 21 turn, so obviously the Frog could manage that. I must admit though after every race meeting I would rebuild the gearbox and reshim the diff each week to make sure it was 100% reliable on the track.