Just bought 2 more savages.

[Jam Racing 1]

going to a 52 spur will change your initial gear ratio from 3.5 to 3.71 , thats using a 14 tooth clutch bell for instance

 

[Smokey7]

What is the stock clutch bell? I think I have a 15 and a 16 here.

 

[Jam Racing 1]

to get the ratio divide the spur by the bell and see eg: 52 divided by 15 gives a 3.46 initial


https://www.hpisavageforum.com/threads/hpi-savage-gearing-and-transmission-info.13970/

Perhaps a read through these gearing threads will give you an idea

 

[Smokey7]

I understand the math of the gearing. I'm wondering if I will have a better bashing gear ratio. In my mind I think id get a better holeshot with just a little less top speed.

 

[Jam Racing 1]

I understand the math of the gearing. I'm wondering if I will have a better bashing gear ratio. In my mind I think id get a better holeshot with just a little less top speed.

that is only concerning the transmission, you have to also figure in the differential ratio as well as tire size which will affect gear ratio also.....

so I would have a couple of clutch bells available and try it out... a smaller gear in the bell with give a bit more punch off the line, a larger one will add speed which can be useful to control wheelies for example...

 

[bifftit]

use Nitrotane 30% at my house
Made by VP

 

[Smokey7]

Does the extra percent nitro make that much difference. Do I need to add or delete shims to run it?

 

[X]

Does the extra percent nitro make that much difference. Do I need to add or delete shims to run it?

I know it's not the answer you want..... But it depends on the engine. You almost certainly have to change heat ranges on the glow plug. The only thing you can do is look for other peoples setups that have worked and go from there. Even then, it can vary from engine to engine a little. If you can't find that, you'll have to experiment.

 

[J.LO's SAVAGE X]

On hpi big block of. 4.6 i use standard medium plug and have used all nitro contents and no problems, I know hpi well enough, other motor manufacturers, I don't. And running 3 shims in head

 

[Smokey7]

My 25 has 5 shims and my 21 only 2. I had been running a OS medium 8 plug for several gallons. Then only could get McCoy 59 so that's what I got now. The 21 is in the truck now with that mc59 plug and 2 shims runs real good I think.

 

[J.LO's SAVAGE X]

if you want try removing a shim, should be good. make more power, I think here on the forum there is info on running 3 shims on the 25 with no problems, more power! some one may chime sometime reading this. all the help is good here.

 

[Smokey7]

I pulled my 25 down to 3 shim it seems to have much more compression now. So how do shims nitro content and plugs change or work together in the 21 and 25? I'm looking at it like decking a jug or a tuning tool.

 

[J.LO's SAVAGE X]

well I'm not sure I know compression is raised, and cold medium and hot plugs help deal with detonation like in timing

 

[Smokey7]

Ok so a hotter plug fires earlier and a cold later? How would one use that when adding more nitro. Example add 10% nitro add a shim or increase a plug heat range? Or both. Or is it remove a shim and change plug? Or is it leave stock plug stock shims and observe behavior. What do these act like when not set up properly?

 

[J.LO's SAVAGE X]

well I know on my f 4.6 I actually didn't have to change a thing, i jumped to 25% and took out shims and ran three. and yes I think you have the scenario. if your motor doesn't run right then check a medium cold plug then cold but I think it should run fine, just a slight retune I'm thinking

 

[J.LO's SAVAGE X]

I have 4 f 4.6 hpi engines all the same shim count and fuel,,,,,, no problems.

 

[J.LO's SAVAGE X]

when you change nitro content you don't need to add a shim or take a shim

 

[J.LO's SAVAGE X]

when not acting right, they will spit and sputter and bog

 

[bifftit]

4.6's i never changed anything. lrp, losi 454, and picco , the same.
novarossi, i had to add a shim

 

[Smokey7]

All great info guys. I really appreciate the help guys. I will give it a go tomorrow.

 

[Smokey7]

So now that I got this 21 running super sweet. Geared it 52/15 and wheelies everywhere. New slipper pad aluminium shoes throttle opening fully head shims at 2 20% nitro mc59 plug I just destroyed my rear diff. Its only got front wheel drive. Anyone want to tell me how to upgrade this.

 

[J.LO's SAVAGE X]

yes buy the 29/9 set up shimmed, that's what I did. tougher and haven't had any issues since. and I put in 50,000 front and rear!

 

[Jam Racing 1]

yes buy the 29/9 set up shimmed, that's what I did. tougher and haven't had any issues since. and I put in 50,000 front and rear!

Just keep in mind if you go that route you will require 2 sets.... I am still running the original sintered set in my basket case parts truck and it is holding up to an axial 32....

 

[bifftit]

29/9 =3.222
43/13= 3.307
I run mobile1 20/50 in my differentials and my gear preference is 3.30

you might try getting the newer spider gears or going to hotbodies hardened internals if your going to run such low gearing. i don't like wheelies, myself, its hard on the drivetrain.

 

[Smokey7]

I don't have a large area to run in so the low gearing was a experiment. I like the snap its got and I have to try a spittle for wheelies but it will do them everywhere. Looks like I need to tear the diff out and see what I broke. Then decide what to upgrade. I don't think I want to mess with that ratio too. I'm happy with the ratio I have now. What's stock in them now?

 

[bifftit]

I would venture to say you thrashed the spider gears inside the differential cup. you may only have 2 spider gears in that cup, and if thats the case, you could put the 4-gear upgrade in it
to find out what you have, you need to pull the plates off and have a looksee

 

[J.LO's SAVAGE X]

The new trucks come with 29/9 and the gears are cintered and the gears are deeper cut for more engagement and strengh. That's why I upgraded