58041 Frog rebuild

[Max Power]

Hi TC members.

I thought it might be a bit of fun,(and a bit of a learning experience for me) to post some pictures of my newest project as I rebuild it. It's an original frog that I intend to make into a cheap and fun runner.

First impressions are that it is a good candidate for a rebuild. I bought the car from America. I gave it a quick run around the yard to see how it went, and the Kyosho motor seems quite punchy. The car has some slop in the rear suspension, some screws are not the right ones and of course the shell will have to go, but all in all its a great car for what I want it for. I will upload more pictures as I rebuild it

[OldSchoolRunner]

Hi TC members.

I thought it might be a bit of fun,(and a bit of a learning experience for me) to post some pictures of my newest project as I rebuild it. It's an original frog that I intend to make into a cheap and fun runner.

First impressions are that it is a good candidate for a rebuild. I bought the car from America. I gave it a quick run around the yard to see how it went, and the Kyosho motor seems quite punchy. The car has some slop in the rear suspension, some screws are not the right ones and of course the shell will have to go, but all in all its a great car for what I want it for. I will upload more pictures as I rebuild it

For sure document your rebuild I will be watching! I have one too that i bought 6 -7 years ago and it has been sitting there waiting for me to rebuild it too.

OSR

[Percymon]

Looks like it should clean up nicely. A lick of paint on the wheels, some fresh tyres and a new body = sorted !

[Max Power]

All stripped down and cleaned now. The bearings and screws are soaking in 'Inox' and I have undercoated the chassis in preparation for a colour change. I feel a little uncomfortable about rebuilding a classic Tamiya in anything but Box Art, but I didn't sand the chassis, so hopefully at a later date I can strip the paint off again to return it to original. I have already completed the shell while I was waiting for the post man to deliver the car. I won't post any pictures of the shell until the chassis is ready for it, but I will tell you that it's a polycarbonate Brat shell.

Thanks for looking

[Max Power]

On close inspection, the diff gear teeth are quite worn. I didn't hear it skip when I drove it, but is was only a quick run.

Here are some pictures of the gears.

[Max Power]

I have added some silicone sealant to semi-permanently lock the diff. I don't know if this is considered dodgy, but it seems like it should be ok to me. I didn't clean the gears, so hopefully the silicone makes more of a mould around the teeth of the gears than a glue.

[Max Power]

I got the Dremel out today and gave the alloy parts a bit of a polish. I have also posted a photo of the front wheel axles. Maybe I haven't seen enough old R/Cs, but have you ever seen axles with this much wear? They should be replaced, but I will use them for the time being (along with the diff gears) as I am trying to make this a cheap runner.

I also reassembled the shocks. I found the them really interesting, apart from being beautifully made, they have a diaphragm on one side of the piston, I think this is to slow the rebound? They also have what looks like progressive rate springs? Although I have read the shocks are too stiff, I think they are a great example of why Tamiya was the best in the business during the eighties. I have left off the preload spacers for the moment and used 30wt oil in them. They do feel a little overdamped, what grade oil do you guys use?

Oh, and yes I realize the springs are upside down.

[ap6318]

I got the Dremel out today and gave the alloy parts a bit of a polish. I have also posted a photo of the front wheel axles. Maybe I haven't seen enough old R/Cs, but have you ever seen axles with this much wear? They should be replaced, but I will use them for the time being (along with the diff gears) as I am trying to make this a cheap runner.

I also reassembled the shocks. I found the them really interesting, apart from being beautifully made, they have a diaphragm on one side of the piston, I think this is to slow the rebound? They also have what looks like progressive rate springs? Although I have read the shocks are too stiff, I think they are a great example of why Tamiya was the best in the business during the eighties. I have left off the preload spacers for the moment and used 30wt oil in them. They do feel a little overdamped, what grade oil do you guys use?

Oh, and yes I realize the springs are upside down.

I have tried the original shock with 25wt oil and a set of re-re shocks 25wt and the originals are so much more suited to the Frog. The squishy tyres do most of the dampening on the frog and it's still a pig on the track. Mad Racer is a bit of an expert setting up the Frog to handle with Yeah Racing 70mm shocks but if you want to keep it true vintage running stock wheels/tyres the original shocks with 20-30wt oil will do you well.

Look forward to doing some Frog bashing with you soon!

[HunterZero]

Maybe I haven't seen enough old R/Cs, but have you ever seen axles with this much wear?

Yup, exactly the same thing happened to my Frog BITD before I replaced the plastic bushings with ball bearings. If anything, mine were worse, I had to replace mine because the wheel wobble became too bad.

Other points of wear are all the aluminium pressed suspension parts. The holes for the rear arms and front screw pins wear badly. The more the front suspension wears, the worse the steering accuracy becomes until it is undrivable.

Diff doesn't look too badly worn. Are the small spider gear teeth worn to a point? If it skips, it's easy to fix with some 5mm shims. What you've done to lock the diff effectively makes it the same as the original Brat which had a spool instead of a diff. This is perfectly acceptable for running off road on loose surfaces, not so great for high grip surfaces though.

If you are going to use the original hexagonal shafts, make sure that the rubber boots are in good condition (not dried out and hard). Thoroughly clean out the drive cups, and pack plenty of molybdenum grease in there. Don't run the car without the rubber boots, and secure them with zip ties like the manual says to stop grit getting in. The original cups/shafts wear out really fast if these precautions aren't taken.

- James

[Max Power]

Hi Mark, thanks for the input, I will try some 25wt in them. As far as tyres go, for a start I'm going to use some original Brat/f150 ones. they aren't exactly what I would call squishy, so I guess I will have to see how it runs when finished.

Hi James, thank you for all of that valuable information. At a glance the diff gears look ok, but they have lost a fair amount of meat, and yes the spider gears are looking a tad pointy The old axle boots have started to rip, I had a look for some new ones but decided to buy some universal drive shafts instead. The old hex drive shafts look pretty good so I will keep them for when I return this to an original Frog

[Max Power]

Oops, first stuff up of the build . I built the gear box last night, only to find it too tight. I thought to my self, it could probably only be one of two things, a bad bearing or my gunked up diff. Can you guess what the problem was? It's obvious to me now, and I feel quite silly for not thinking of this when I originally siliconed up the diff. When I originally applied the silicone to the diff gears, I left the diff on it's side to set, the weight of the gears by themselves was not enough to compress the silicone fully, and the diff ended up slightly wider than standard, and this made gear box too tight.

I removed the silicone from the diff, and as seen in the pictures it came out easily, and in single pieces. I took this opportunity to do the right thing and clean the gears off, as I should have done in the first place. This time I rebuilt the diff as I would normally, with ceramic grease, even though I don't intend for the diff gears to be moving, if the new silicone fails and I don't notice straight away the grease will be their to do its job. I then assembled the gear box before the silicone had time to set. I left it overnight and it now seems good, the gear box turns freely and the diff is locked

I also refilled the shocks with 25wt oil (thanks for the advice Mark) and I am happier with the feel of them now. The chassis paint has been curing for a few days, so I can now start on the chassis assembly (yaaay!)

[ap6318]

Hi Mark, thanks for the input, I will try some 25wt in them. As far as tyres go, for a start I'm going to use some original Brat/f150 ones. they aren't exactly what I would call squishy, so I guess I will have to see how it runs when finished.

The Brat tyres will make you cry on dirt but come into their own on bitumen. I run the original spikes on dirt - the difference is incredible.

The other option is the Frog hex adapters with modern wheels and tyres - if you go that way, make sure you run 2" or 2.2" fronts as well because the little fronts with big rears upsets the balance and handling in a big way

[Max Power]

The car is starting to take shape now. I raided my blue RC10L for its servo saver and made some thicker steering tie rods. I think I will have to change out the Kyosho motor for a different one though, as I gave the electronics a test last night and the motor would not run. I tried a 21 turn motor with the speed control, and no problems, then I tried the Kyosho motor with a Novak speed control and it worked, I then tried the original set up again and it worked, but the motor did not run at anywhere near the RPM as it did with the Novak. The brushes look good, as does the commutator, I don't know how many turns the Kyosho is, so I am thinking that the motor may be too low a turn for the speed control.

Now I just have to wait for the universals to arrive, so I can finish it off

[Percymon]

Great progress !

I found a spare ORV chassis under my office desk today (i'd wondered where it had gone lol!) so i'm looking at how many parts i'd actually need to make a Frog from it.

[Max Power]

Great progress !

I found a spare ORV chassis under my office desk today (i'd wondered where it had gone lol!) so i'm looking at how many parts i'd actually need to make a Frog from it.

Hi Percymon. Are your creative juices flowing? If you need ideas, I always like the Frog Scorchers!

[Percymon]

Hi Percymon. Are your creative juices flowing? If you need ideas, I always like the Frog Scorchers!

I have enough projects without another one, but if i already have 80% of the parts then why not - a few other things to complete first though !!

[Max Power]

The universals arrived yesterday, so I finished it off last night. I replaced the motor with the 21 turn, and all is now well. I am really pleased with the result, it was an enjoyable, hassle free, and cheap build. I have four more cars waiting for some attention at the moment, but this one jumped the queue, I appreciate other manufactures, and other types of R/C, but I will always like Tamiya buggies most! Only one more question, is it a Frog or a Brat?

Thanks for looking

[Max Power]

[Max Power]

[metroplex]

Great job! It looks fantastic! Makes me want to start a new project...

[RichieRich]

I disassembled my original frog and rebuilt it so many times I could probably do it blindfolded. Great work, it looks fantastic.