Pede Tranny Gearing (Small spur, Large pinion)

[oxyjansen]

I'm going to preface this post by saying that I've done tons of research, but this is something I've not come across;

I'm working on a Marx Powerhouse pressed steel dump truck with all custom suspension, and drive train.

My issue is a spacial concern. I'm using a Pede tranny on a scale rig that sits somewhere around 1/12 scale. I'm trying to drop the spur height to fit the tranny in without cutting the body.

I've seen suggested crawler gear ratios of 7.25 using a 87/12 set up with the Pede tranny. My curiosity is if I get an adapter (assuming part #3693???), and a 72 spur gear with a 10 pinion adding up to 7.20 ratio does it matter so long as the ratio is the same?

[treys1]

As long as you have the right ratio it does not matter how you get there pinion / spur combination wise.

Where problems arise is if your spur and pinion are not physically large enough to properly mesh together. You can always notch the motor slots some to get a little closer, but at some point the motor will start to hit the trans.

[oxyjansen]

Good point. Do you have any idea how much of a difference in diameter there is between a 87 and a 72? I also saw spurs in the 66 range, but the big question is will they fit? I don't have an assortment of these around to play with right now unfortunately.

I wonder if it'll be more cost, and time effective to just cut into the bed? Playing with some of this stuff for fitment can be such a PITA! LOL

[RiceBurner]

You can always get a gear reduction unit to get down low enough to pull that cool a$$ rig

[slim_chance]

I really dont have any tech help to add but I couldnt resist saying what an awesome freakin cool rig your building. Brings back the younger years when I always wished my old metal toy trucks could operate under their own power. I cant wait to see where this goes! Sorry for the interruption we now return to our regularly scheduled programming.

[slim_chance]

Oh just had a thought. Could you move the trans up into the back of the cab and hide it with interior stuff? Then put a transfer case at the point you where going to place it in the first place?

[oxyjansen]

Glad you guys like the build. I'll be putting up a thread on the 1.9 scale forum, as this is going to go on for a bit. Keeping the tires under the fenders is turning out to be alot of work!

I had thought about doing a transfer case, but the 1 issue I see is that I would only be using one output shaft on the tranny. Now, if someone tells me its not a big deal it'll be come a great way to end some of the issues. The tranny does fit into the cab pretty well.

A link to my other builds

RC Photos by oxyjansen | Photobucket

Two metal trucks:

[JBailey]

It wont be a problem running off of one granny output to the t-case, people do it all the time with trucks they're putting a full interior into. Oh and that is a sweet project I look forward to your build thread.

[oxyjansen]

Thanx for the compliment.

But, what about running off 1 output on the tranny itself?

I actually just went down and did some measuring:

I'm using Slash 4x4 diffs, which are a bit large. Mounted directly to the frame they hang down 2". If I drop the Pede tranny thru the frame and make a mount for it I can hang it 1.5" under the frame and have 1/2in clearance more than the diffs. The tranny housing has to be cut down a bit to fit into the frame rails, but it looks like it'll work.

This is going to be a moderately articulated suspension, so its not going to be climbing Everest any time soon! LOL Ground clearance issues in this case shouldn't be too big of a deal. I guess it'll end up more like a real 6x6 dump than anything else. During the mock-up I dropped it down like a low rider, and it looked awesome! I may have to get another one to build!

I'll post when the build thread is up, but I'll try before the weekend.

[slim_chance]

It would be fine to run of one trans output as long as the diff is locked. Thats what most scaler guys do when they add full interiors to their rig

[oxyjansen]

Perfect. That will give me the ability to do some cool 2wd rigs in the future.

I have some Tonkas I thought might do some great wheelies with a stock Pede set up!