My IFS Bomber Build

[*Old*]

Originally Posted by DenisLM

I use Axial spider gears and it work great. I run open front and rear diffs in my yeti with 1mil wt and is far away from locked but works great for my objectives (U4)

Thanks Denis,

I'll see how these go and replace with the Axials if/when they blow.

[*Old*]

Finally fixed my steering knuckle issue.

As stated above, the VP 12mm hub was frozen on one my knuckles. The hub was so tight against the knuckle, that I couldn’t fit anything in between to pry it off. I think my problem was I put too many shims on the backside of the knuckle, that the pin was too tight against the knuckle. Won’t be doing that anymore.
Once I was able to get the VP hub off by destroying it, I noticed that both bearings were completely destroyed and the outer bearing ring was frozen inside the knuckle. This was the biggest PIA to date in my whole RC experience. No joke, it took me a good week to figure this out. I would spend about an hour each fighting this thing.

Figure I document how I got this all off since I didn’t see anywhere in the search, and I know I can't be the only one that have- or will- go through this.

So here is the hub stuck on the axle. As you can see, there is no room between the hub and the knuckle to stick anything in it to pry it off.




I removed the screw and worked in a tiny screwdriver between the opening to try and pry it open wider. The aluminum hub is pretty soft, so doing this will dent up the hub pretty bad, essentially ruining it.
As I widen it, I was able to fit in a small pry bar to get some good leverage on it and broke a large chunk off. I could then fit in the small screwdriver between the knuckle and hub to get the hub off.



Here it is off, with the blown bearing. The other side bearing is also blown as well. This explain the “death wobble” I’ve been experiencing.. Thought it was from the bent Dlux shafts, but nope. Although I’m sure the bent shafts didn’t help.




I pulled off all remaining pieces of the bearing that I could, but it left the outer bearing ring stuck inside the knuckle on both ends.
The interior larger one was easy to remove, as I just used a small flat screwdriver and tapped it out. But the outside smaller bearing was a bitch!! This was the one that gave me problems for days!





So of course I tried everything I could think of and put some cosmetic dents on my VP knuckle and the darn thing just wouldn’t budge. Then it dawned on me, that the bearing ring is made from steel, while the knuckle is made from aluminum!! Light bulb!!! Aluminum and steel expands and contracts at different rates with heat and cold!!!

So I put the knuckle in the freezer for an hour and then used a heat gun on it and tried prying it out….nope!, didn’t work.

Then I put it back in the freezer and tried heating the arm of the knuckle, avoiding direct aim at the bearing…nope, didn’t work either.

So froze and tried again with a solder iron on the arm…again, no dice!!

Tried these methods above several times during different nights…no dice

Last try, before I go buy another set… This time, I put the arm in the freezer, with an old steel finish nail punch wedged inside it. The punch is tapered and course, so it only contacted the the bearing ring. I was hoping it would act as a heat sink making the bearing stay colder longer.

This final try I decided to use your standard propane torch to quickly apply heat. So I had it in the freezer for a few hours and then put this thing in a vice and torched the arm for about 5 - 10 seconds.




I then took it off the clamp and pulled the punch out and used it to the pound the bearing out from the backside. Just one single tap on the bearing and the freaking thing dropped right out!!



I know I can’t be the only one that had some bearing troubles like this…I hope this helps someone.

[*Old*]

So now I'm able to complete my open front diff mod with 20Million wt silicon diff putty.

Ofcourse I documented this change b/c that's what I do

Here is the complete parts to make the change.

Axial # AX80002 (Plastic carrier) this is included in your kit and holds the
Axial locker
Axial AX30381 - drive cups/output shaft for open diff
AX31135 - 92mm axles
AXA1162 - Orings
AXA1393 - Eclip
AX30385 - gasket
HPI spider gears - 86014. this comes complete with shaft and shims.
or you can go Axial route with:
AX30390, AX30170
Gravity RC 20Million Diff silicon









I start by putting the one larger gear on the diff. On the carrier, be sure to put the O-ring on both sides and then put the shim on.


This 20Million Wt silicon is pretty neat stuff. It is very thick, not too sticky, and can hold whatever shape you make it for a while, but will eventually self level out.


So I put in the output shaft and the gear and clip it in the place with the Eclip. I will say, this Eclip fits on loosely. I didn't give me that satisfying click sound. It just slipped on. I hope it stays.
I pack it in the silicon as much as I could and then installed the shaft and side gears and packed in more silicon till it's level.



Here it is all put together.




Just a comparison pic of the Axial output cup and the Dlux. The Dlux is much larger.



After putting the tires on, I spun the rear by hand and held one of the the front tires and was able to hold it with out too much effort while the other spun.




So now I'm off for a quick test on some rocky terrain and my next post will have my thoughts on them...

[SCREAMER]

I thought it was pretty common knowledge that the Axial spider gears are made from that brittle powdered metal and that's why guys were searching for a stronger alternative. It would be much easier to just run Axial parts for continuity's sake but from all of my research, I found HPI gears were supposed to be a significant durability upgrade. There's no other reason to run mismatched parts unless there's some kind of benefit. Several posts in the Yeti forums, several posts with guys building monster trucks, all running HPI. That's why I chose them to begin with. Who knows.

[*Old*]

Just got back from my test run with the open diff and 20M wt silicon.
Didn't go anywhere fancy yet, just the wooded area in my neighborhood.

First on open grass field run - Much improved handling compared to full locked. The truck would stay more planted on cornering with descent speed, but I could still easily flip it if I'm throttling too hard.

Then to the rock garden - these are small rocks with a lot of traction, so I think a 2WD rig could probably get through, so I purposely was trying to get it into situations where only one front tire would be grounded and it would not spin in this situation, like a true open diff. But when I was driving it like I usually would, it performed about the same through this terrain - easy.




In this pic below, is a small ditch at the bottom of this steep hill. The hill is probably about 70-75 degree angle. The ditch is muddy, so very low traction. I purposely stuck it in there and tried reversing up the hill. It took some effort, a lot of turning back and forth, but it managed to get up and out.
I tried this with a locked front and it had about the same amount of trouble.






Tried a really steep loose dirt hill and could only managed to get halfway up it. My sons locked front rigs was having the same issues as well, but got up higher. So definitely a disadvantage here.





Here is a quick video I took, however, my phone ran out of memory, but I did it in slo mo and you can see how the open diffs react while trying to climb the larger rocks:

https://vimeo.com/user63077290/open-diff-test

I still need to run this in some real trails to fully test it, but first inclination is it's an improvement in high speed handling, but you give up some of the crawlability - not much though. I don't think I'll be bending any axles with it open like this though, which may be a good trade off???

[SCREAMER]

Great video. I can tell that front diff is a lot better than what I have right now which may as well be empty of oil. I need to get mine in.

[bilinvic]

Thanxs for the vid....it has me convinced that I will go with a locked front and rear for now when my B2B build starts.

[SCREAMER]

I was going to suggest that for yours, Bil. From what I've seen of your driving style in your videos, I think you'd hate an open front. I spend a lot more time going faster with Qwiksilver and rock bouncing my way up an obstacle which is why I can benefit from an open diff and not notice too much of a loss when crawling. It is definitely a trade off though like Old stated. I can't wait to see the other B2Bs get built. I have a feeling this rolling chassis is going to be a very versatile platform.

[*Old*]

Originally Posted by bilinvic

Thanxs for the vid....it has me convinced that I will go with a locked front and rear for now when my B2B build starts.

I want to try this some more on other trails with larger boulders and see, but as of right now, I'm leaning towards putting a locker back on the front as well. Although I just destroyed my Axial locker
I do a mix of both high speed and slow crawl, depending where I'm at, so I'm just not sure yet.

I did put an order in for a few sets of the Lockedup RC Yeti front locker since it's on sale which makes it under half the price of Axials. I have their FI spool in the back, which I like, so I'm hoping their Yeti fronts FIs are just as good. I'm planning to use them Front and Rear on the B2B.

[DenisLM]

Originally Posted by SCREAMER

I thought it was pretty common knowledge that the Axial spider gears are made from that brittle powdered metal and that's why guys were searching for a stronger alternative. It would be much easier to just run Axial parts for continuity's sake but from all of my research, I found HPI gears were supposed to be a significant durability upgrade. There's no other reason to run mismatched parts unless there's some kind of benefit. Several posts in the Yeti forums, several posts with guys building monster trucks, all running HPI. That's why I chose them to begin with. Who knows.

I read the same and got some HPI gears and my experience was exactly the opposite, look how strong are the HPI gears are:



Yes, all 8 gears broke down during one U4 race. imagine how happy I was that day.
I don't recommend HPI gears even for my worst enemy...
I repeat: DO NOT USE HPI GEARS!!!
Or use it and gamble lose the race in the last lap...
Maybe if you guys just trailing or crawling that should hold, but serious U4 race, not at all.

The axial ones that I put after this POS HPI, still running great in my Yeti (exactly one year ago). That means at least 16 U4 races and countless backyard bash.

[SCREAMER]

Wow, that's the first HPI spider gear failure I've seen but that is pretty conclusive. It's just so weird to have read so many times from different sources that HPIs are better. Maybe you had a bad batch but if I had your experience I'd do the exact same thing. Guess we can all just cross our fingers. I'm not tearing mine apart until it fails. If it does I'll definitely post up.

It looks like just the 4 large gears failed. Maybe you had them shimmed to tight? I used no shims in mine and they feel plenty tight.

[DenisLM]

Originally Posted by SCREAMER

Wow, that's the first HPI spider gear failure I've seen but that is pretty conclusive. It's just so weird to have read so many times from different sources that HPIs are better. Maybe you had a bad batch but if I had your experience I'd do the exact same thing. Guess we can all just cross our fingers. I'm not tearing mine apart until it fails. If it does I'll definitely post up.

It looks like just the 4 large gears failed. Maybe you had them shimmed to tight? I used no shims in mine and they feel plenty tight.

I guess most of the guys in the Yeti forum try to use it for crawling or trailing and some backyard bash. U4 is waaaay harder in the truck. All the Yeti U4 locals here in WA uses axial and no problems. (They break other stuff, but the spider gears are good )

All gears failed, the small ones lost a teeth, but the big ones broke in half.
Even if I put all the shims I had in my drawer this should not happen. Gears should not break in half. They should wear out, like the axial ones do.

In my opinion the best upgrade for the diff aren't the gears, get the GCM diff cup and use the axial gears. As I said it is working great for over a year beating it like no tomorrow.

[*Old*]

Denis,

I can't see your pics for whatever reason, but thanks for the heads up man. Good to know.

If I stay with the open diff, I'll let run these till they go Boom! and then replace with Axials. Hopefully, they won't take out anything else with it


Btw, the GCM diff cups look beefy!! Didn't know they existed until you mentioned them. Wow.

[DenisLM]

Originally Posted by *Old*

Denis,

I can't see your pics for whatever reason, but thanks for the heads up man. Good to know.

If I stay with the open diff, I'll let run these till they go Boom! and then replace with Axials. Hopefully, they won't take out anything else with it


Btw, the GCM diff cups look beefy!! Didn't know they existed until you mentioned them. Wow.

I fixed the pictures.

The GCM diff cup is great. kinda pricey, but worth for sure.

[dpcardoza]

Originally Posted by DenisLM

I fixed the pictures.



The GCM diff cup is great. kinda pricey, but worth for sure.

I wished I would have known too. Could have bought that and the f1 lunchbox for cheaper and had the versatility to make it an open diff in the future


Sent from my iPhone using Tapatalk

[gbean]

I just ordered three GPM cups yesterday. Hope they're ok.
I just realized my error in buying the cheap Chinese version... LoL

sent from the Upside Down

[*Old*]

Originally Posted by gbean

I just ordered three GPM cups yesterday. Hope they're ok.
I just realized my error in buying the cheap Chinese version... LoL

sent from the Upside Down

Where did you get them from? I did a quick search and they're no where to be found.

[dpcardoza]

Originally Posted by *Old*

Where did you get them from? I did a quick search and they're no where to be found.

http://www.tinytrucks.com/viewitem.php?productid=85



Sent from my iPhone using Tapatalk

[gbean]

Originally Posted by dpcardoza

http://www.tinytrucks.com/viewitem.php?productid=85



Sent from my iPhone using Tapatalk

^ These are the GCM cups you want.

I ordered two GPM racing cups direct from the manufacturer... Hopefully for a simple part that Chinese stuff is ok. We'll find out.

sent from the Upside Down

[*Old*]

Originally Posted by gbean

^ These are the GCM cups you want.

I ordered two GPM racing cups draught from the manufacturer... Hopefully for a simple part that Chinese stuff is ok. We'll find out.

sent from the Upside Down

Thank you Sir! I just put an order in for 2 of them.