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signats
07-23-2005, 03:54 PM
After breaking 2 wheels on the very first lap at a very rough, dust covered, cement hard clay track that has not seen any maintenance for the last year or so (since the club that ran it dissolved), it was time to attempt to mount the stock tires to a set of TC wheels that were collecting dust in my spare parts bin.

They ended up being about 3mm taller, and 3 grams heavier than stock, but the tread remains the same width at 24 mm.

I have used these same type of wheels with the HPI Rally tires at the same track without any breakage so I know they can handle the abuse.

I can't wait to test them out!

The white rims are stock next to my franken-tires:

bluegrooveracer
07-26-2005, 03:28 PM
did you use acetone to remove the tires and if so did the acetone ruin the tires at all as this has happened with losi mini t tires???

signats
07-26-2005, 04:41 PM
I didn't have the balls to try acetone on these tires, instead I pinched the tire with finger and thumb, and firmly pulled it back away from the bead, and then very carefully used an x-acto knife to pick and cut the rubber free from the wheel. It took about 3-5 min. per tire to get the rubber off the wheel.

They came off really clean and the bead was still in good shape, but as it turned out, in order to get them to fit the TC wheels nice, and smooth, and clean the bead had to be trimmed completely off of the tire with some sharp scissors.

After that I double foamed them (the stock foam + a HPI low bounce foam) and glued them.

The scrap rubber trimmings were put in a jar with some acetone and let it sit for a few days now. It didn't dissolve the rubber or anything, but I don't really want to open the jar just yet either, simply because I'm avoiding that nasty acetone stuff and as it turned out the pinch, pull, and cut method was much faster than soaking them off ever could be.

bluegrooveracer
07-27-2005, 02:20 AM
thanks for the input ,so just to confirm the actone didn't visibly weaken or distort or break down the rubber?? as i want to order a new set of tires and remove them thanks [just wanted to be sure]

.5x8
07-27-2005, 02:33 AM
as he said...he didnt use acetone

signats
07-27-2005, 03:10 AM
Ok I just took the rubber scraps out of the acetone and they are mush, just like the Losi mini tires, acetone will ruin them. Sorry dude :(

bluegrooveracer
07-27-2005, 03:47 AM
actually 5x8 he said he did use acetone, and thanks for the heads up signats

.5x8
07-27-2005, 04:01 AM
I didn't have the balls to try acetone on these tires

...see he didnt use acetone... read the second post...

bluegrooveracer
07-27-2005, 04:11 AM
no if you reread it you will see he test some scraps in acetone so yes he did and that is why i asked about the result of the acetone that he did use as stated in his 2nd post

BitHed
08-02-2005, 02:37 AM
...i love it when someone has the balls to try something new...thats how the BitHex's were 'invented'...Great post Signats..Thanks for the follow-up of trying the SCRAPS in the ACETONE too :D Good call...

signats
08-02-2005, 06:11 AM
I "invented" a center ball diff. today :) by combining (boneyard) parts from 5 different cars :eek:

Funny thing is.... it works like a champ :D

nismo4life
08-02-2005, 07:01 AM
hey, got pics?

signats
08-02-2005, 07:34 AM
No pics yet, this one works so good that I'm going to build another one from new parts.

Pics will have to wait 'till then....sorry.

signats
08-03-2005, 02:05 AM
hey, got pics?

Ball diff. pics for you ;)

signats
08-03-2005, 02:12 AM
With it in the car.

signats
08-03-2005, 02:17 AM
One more out side of the car.

.5x8
08-03-2005, 02:08 PM
thats crazee!!!!!! how much did it cost to build it? if you dont really know...what about a estimate?

.5x8
08-03-2005, 02:13 PM
maybe sometime soon someone can come up with center diff, but it is a slipper . so its direct pinion to diff gear, but it would probably be impossible without taking the thing apart.

signats
08-04-2005, 12:59 AM
thats crazee!!!!!! how much did it cost to build it? if you dont really know...what about a estimate?


What is really "crazee" is that every single part to make this came from my personal RC boneyard. :eek:


Since all the parts and materials were paid for long ago, and just sitting there not being used, the total price was 0 $ and 0 cents...... :D

I'm going to make another one with some new parts, I want to use a MIP mini-t ball diff(19$), so the diff can be adjusted without any disassembly of the buggy, also need a new mini inferno center diff gear(7$), the other parts can carry over (0$).

Parts list:

Mini-t ball diff.
Mini inferno center diff gear
Two 5x8 bearings or bushings
Two 8x12 bearings
Two RC18t upper shock spring collar


Tools:

Dremel roto tool with sanding drum, and small grinding bits.
11/2" long 2-56 screw and a 2-56 nut, and various washers.
Sand paper
Plastic weld glue
Breathing protection--dust mask
Eye protection--safety glasses

The diff in the pictures is a Losi diff, it works really well, but must be removed to be adjusted, so I consider it "set-able" but not really adjustable if you know what I mean.

The ol'e bone yard also contains a 3racing mini-t ball diff, I intend to try that one out as well............

signats
08-04-2005, 01:07 AM
maybe sometime soon someone can come up with center diff, but it is a slipper . so its direct pinion to diff gear, but it would probably be impossible without taking the thing apart.

The Losi xx4 has a setup sort of like this, the front and rear wheels each use half of the same slipper, but each side can slip independent of the other.

AFAIK no other car has ever used a system like that, before or since, and that buggy is considered by some to be the finest electric 4wd buggy ever.

Rumor has it that the Losi team drivers are even going to race the XX4 over the XXX4 at this years IFMAR world championships because the track is a rough one and the xx4 is better in those conditions.

Oh yea, the 5x8 bearings used in the CBD above are out right of an old xx4 diff. (most Losi ball diffs use the 5x8 bearings).

WhoMe
08-04-2005, 03:17 AM
Well Signats..youve gone and done it now. Time for a tutorial!

signats
08-04-2005, 05:26 AM
If you have the parts and tools and are a tinkerer by nature then this will be fairly easy to make.

Modify the Kyosho center diff gear:

Cut the center hub out of a mini infeno center diff gear with some wire cutters (notice how it forms a West Coast Chopper lookin' maltese cross :eek: )

Open up the center of the gear wit grinding bits until the sanding drum will fit.

Notice that there is a raised shoulder near the outer edge of the gear, use the sanding drum to remove all material out to the shoulder, use the shoulder as a guide to keep it perfectly round. Lets call this creation the "ring gear" since it looks like a ring.



Modify the mini-t ball diff gear:

The next step is dependant on which mini-t ball diff is used, idea is to chuck the diff gear in the dremel and spin it against some sandpaper until it fits inside the ring gear.

The most important part of this whole project is to get the diff gear absolutely perfectly centered when it is spinning on the dremel.

For a Losi ball diff, you would disassemble and clean the lube off of the gear and rings, set the balls aside for later, re-assemble the diff leaving out the diff balls and adjustment screw, in it's place insert a long 2-56 screw with a washer on each side of the diff and a nut to hold it all toghether. There has to be enough of the screw sticking out past the nut so it can be chucked in the dremel and the nut needs to be tight enough so the gear will won't slip when it hits the sandpaper. MIP and 3racing diffs are completely different and require different techniques to achieve proper results.

Chuck it, spin it and check to see that it is spinning perfectly true.

Check and double check that the diff gear is spinning true. Spin it against sandpaper until it fits inside the ring gear. Get it so that the parts fit just a bit looser than "snug", we will finalize the fit later, so this will do for now.


Assemble into Center Ball Diff:

Re-build the ball diff as you normally would, if it needs parts replaced this is the time, make it ready to go, but instead of using the standard Mini-t 5x9 bearings for the outdrives replace them with 5x8 bearings.

Note about bearings,the mini inferno center diff uses 6x12x4 bearings, the Mini-t uses 5x9x? bearings, to make this work a 5x12 bearing would seem ideal, searching ebay, tower, and google drew a blank, my conclusion is that if 5x12 bearings even do exist they are very rare, and may be too wide anyway.

My solution to this delima is to put a 5x8x2.5 (1/10th scale losi ball diff bearing) inside of an 8x12x3.5 (RC18t wheel & driveline bearing) effectively creating a 5x12 bearing.

Once the diff is assembled slip the ring gear into place, the mini-t ball diff is a few mm narrower than the mini inferno center diff, so I used the upper spring collars from a RC18t as spacers, they were inserted into the bearing holes in the center bulkhead before installing the diff., (collars need to have a little 3mm chunk cut out of them so they will fit).

Install everything back into the center bulkhead (ball diff, slipper, spacers, any shims being used) and check to see if everything spins free. If it dosen't spin free then it is time to adjust the fit.


The fit is critical to the success of this project, if the two gears fit together tightly then the ring gear is forced outward and will bind against the small slipper gear. The two gears (ring and diff) should fit together with very little friction, snug is too tight, but the two parts must be in contact with each other, looser is better, but they have to be touching each other, it is a delicate adjustment, so go slow and check it often by installing it into the center bulkhead along with the slipper gear/shaft, when done right the assembly will spin free and easy just like the stock center diff :rolleyes:.

Adjust the fit by using the dremel sanding drum on the ring gear, if there is any binding between the slipper gear and the diff, then remove the ring gear and make 5-10 "laps" around the inside of the ring gear with the sanding drum and check the fit again, go slow, you can always remove more, but you can't put any material back if you go too far. Repeate as necessary until the fit is acceptable (everything spins nice and free when assembled in the center bulkhead.

Glue:

I used plastic fusion, it is a plastic weld type adhesive, and very strong, something like 4000lbs/sq. inch, it is packaged in one of those double syringe applicators. Several companies sell similar plastic weld, or fusing products, I chose to use this stuff for it's strength and because it sets up relatively quickly, however the working time of this stuff is only about 3-5 min., so there is a bit of pressure to get the gears aligned before the glue starts to stiffen.

I'm certain that there are other very strong adhesives that can be used, and have longer working as well as curing times (jb weld anyone?).

To give the adhesive the best chance for success the surfaces were cleaned with IPA, and then lightly crosshatched with an x-acto knife so the glue would have something to "bite" into.


Dogbones:

Mini inferno dogbones will not fit into the drive cups on a mini-t ball diff, it is not the pins that are the problem, it is the size of the knob.

Since I was not using the stock plastic driveshafts they were carefully adjusted to fit, this time using a dremel cut off wheel. I have about 10 runs on them and they show no wear weakness. I do intend to modify some metal bones for future use.

Hope this helps anyone wanting to give this a shot!

signats
08-04-2005, 08:01 AM
Jesse James would be proud!

signats
08-04-2005, 08:09 AM
Wanna go for a spin?

signats
08-04-2005, 08:11 AM
5x8 bearing inside of 8x12 bearing.

BitHed
08-04-2005, 08:19 AM
...So Signats how is it working? any difference? It sounds great...I have essentially given up on getting my H8 to work at all...I am desperate for parts to make it run how it SHOULD run...

BitHed
08-04-2005, 08:21 AM
...bearings inside bearings...well whos a clever boy then ;D

signats
08-04-2005, 01:17 PM
...bearings inside bearings...well whos a clever boy then ;D

You are Bit :)

It is working very sweet, much improved stability any time one (or both) end(s) break traction, the buggy maintains fwd. momentum which seems to help the suspension work through the bumps better as well.

The car just seems to get around the track with a lot less drama ;)

Only time will tell about how durable it is....keeping fingers and toes crossed for luck :D

Pic of the dog bones, and spring collar.

.5x8
08-04-2005, 01:51 PM
Wanna go for a spin?

was the pic in this post a slipper??!?!? or front/rear diff?

signats
08-04-2005, 01:54 PM
was the pic in this post a slipper??!?!? or front/rear diff?

It is what it is, through and through.........it's the diff silly, ready for the dremel and sandpaper treatment. :eek:

NiMo
08-04-2005, 02:24 PM
Have you thought of checking the 3racing site lately?
3racing are soon to release front/rear and centre (or center in the US) diffs for the H8
Part numbers are:
Centre : MIF-047BU or MIF-047TI
Front/Rear : MIF-048BU or MIF-048TI
(BU=Blue TI=Titanium)

There is also an alloy Centre Bulk (for diff) MIF-039BU or TI

WhoMe
08-04-2005, 03:16 PM
Coming soon with CAD drawings. From the emails responses we have heard about on this forum it seems as if those ball diffs are still a ways off.

signats
08-04-2005, 03:22 PM
It took them about 8 months to get a mini-t diff out........besides I made this one by recycling stuff that was just layin' around so the price was really, really low. :D

signats
08-05-2005, 03:32 AM
[QUOTE=BitHed

I have essentially given up on getting my H8 to work at all...I am desperate for parts to make it run how it SHOULD run...[/QUOTE]


So what is the problem Bit? Reliability is my specialty ;)

BitHed
08-05-2005, 04:21 AM
...my center diff isnt giving ALL its power to the front and rear and i dont know why...its been like this for ages...i have lubed, un-lubed, greased, ungreased...you name it i have done it...the center diff just whines...I give up...

acsubie
08-05-2005, 04:32 AM
...my center diff isnt giving ALL its power to the front and rear and i dont know why...its been like this for ages...i have lubed, un-lubed, greased, ungreased...you name it i have done it...the center diff just whines...I give up...


Bit i'm having(been) the same troubles mate, been doing it for about a month now, and boy have i tried to figure it out, with little success...all my gears are basically new...im totally stumped...so Sig if you could, your diagnosis sir ;)

signats
08-05-2005, 05:13 AM
When you say it isn't giving all it's power to the F&R do you mean that the center diff is binding or is it slipping?

If it is binding, and the individual bearings have been checked to see that they spin freely, then the three screws that hold the center bulkhead halves together can be backed off by as much as 1/2 of a turn each, and that alone can help free up the center diff quite a bit (it sure did in my car).

Another thing that can bind it up is if the screws that hold the center bulkhead to the chassis are longer than stock, the outdrive bearings may get "cocked", the rear most gear cover screw has the potential to do this as well..........Also the front and rear bulkhead screws that hold the (F&R) bulkhead halves together can be backed off about 1/8-1/4 turn to free those diffs up too, and longer than stock screws used to hold the F and R bulkheads to the chassis can distort the plastic and internally rub on the diff gear mainly this happens with the front most and rear most screw nearest to the diff "blister" at each end, to fix this it necessary to open the case and trim away the distorted plastic with an x-acto knife.

If the power is being lost because of a slipping center diff. and it is not the slipper clutch causing the problem, and the all the center diff gears have been replaced then look for stripped drive cups where they mount to the output gears.

I sincerely hope you can find out what is F'd up and fix it, this buggy is just too good to let it sit and collect dust.

If I'm missing something or you can elaborate in greater detail, perhaps there are other things to check.........Good Luck!

BitHed
08-05-2005, 09:01 AM
...the motor spins, the pinion spins...there is plenty of power going TO the center diff...the center diff is somewhere LOSING that power to either the front or the rear and it is spinning and whining, ie not ENGAGING the front and rear diffs...Its so damn hard to explain...

...i will try the bulkhead screws backed off a bit...i have honestly tried every friggin thing else...

...in ALL honesty I would prefer to lose the center diff altogether and get the drivtrain rolling around a center SHAFT...basically the same as the 18T :o

signats
08-05-2005, 12:15 PM
If you want to see where it is loosing the power, then remove the gear cover, push down on the car until it is completely mashed into the ground (locking the wheels) and rotate the big slipper gear with your finger.

Follow the rotating components, if the center diff gear rotates, then look to see which driveshaft is rotating, follow the rotating components until the rotation stops, the slipping will be right there. because from your description it sounds to me like something might be slipping.

If you want to see what it is like to loose the center diff just gum (mmmmm gum) it up with silly putty, put a little gob of it between the spider and output gears, that way if you want to go back to having a center diff you can just remove the silly putty, and there you go!

signats
08-06-2005, 10:34 PM
Update on the ball diff; after about 15 runs the glue let loose, seems like it didn't like sticking to whatever material the Losi diff gear is made of.

It has been roughed up with the exacto, and re-glued using JB Weld.

Meanwhile the stock gear diff has been re-installed to do a performance comparison while the JB Weld sets up.

Oh and the stock tires just won't stay glued to the 1/10th rims, they work great for 8-10 laps and then the handling goes all to hell because the tires are flapping on the rims :( , I have given up on the stock tires ever working on the bigger wheels, C'mon Pro-Line we need some stronger wheels :D

signats
08-09-2005, 01:03 AM
...the motor spins, the pinion spins...there is plenty of power going TO the center diff...the center diff is somewhere LOSING that power to either the front or the rear and it is spinning and whining, ie not ENGAGING the front and rear diffs...Its so damn hard to explain...



My car started acting like this last night and it turned out that the rear diff had stripped, it made a high pitch whirring noise and would drive but the power was definately not getting to the ground.

Everything looked good visually, but when the wheels were locked and the spur gear turned by hand it was fairly obvious that the rear diff had stripped.

It happened right after I tightened my slipper a little, I heard faint clicking noises when the buggy was accelerating, and some screeches during a couple of big crashes, so I knew something was up. Then the clicking stopped and was replaced by a consistant high pitch growly-whiney noise.

The buggy still scooted along pretty good though, probably because the center ball diff forced the front wheels to pull it up to speed, it just took a little longer than normal to get there.

Did you ever find out what had gone wrong with your buggy Bit?

BitHed
08-09-2005, 01:05 AM
...nope not yet...THTAS the freakin' mystery..nothing has stripped..its all been replaced...The only thing left to do that you mentioned was loosening the front and rear gear box casings...Thats on my list of things to do for sure...Just got back from being outta town for 3 days so I will look into it again later on...Ascubie was having trouble too..wonder if he got HIS fixed...

WhoMe
08-09-2005, 01:51 AM
Mine did the same..it was a stripped outdrive.

holy_inferno
08-09-2005, 03:43 AM
I'm not good at judging whether my Mini Inferno is being inefficient/having lack of power in the front/rear, so what's the signs of it happening?

Thanks :)

signats
08-14-2005, 05:33 AM
If the driveline is binding the motor, esc, and batteries will get excessivly hot. This is something that should be fairly easy to check, simply remove the motor or pinion, and with the car on a stand, spin the tires to see if everything is free and smooth.

If something is slipping then you may notice a lack of acceleration, but the motor, esc, and batteries won't get smoking hot. The slipper clutch is a problem for a lot of people, and that is an extremely easy problem to diagonse and fix, it is tougher to figure out when an outdrive has stripped, when my car strips a front or rear diff. outdrive, it pulls to that side, almost exactly as if there was a wheel bearing that is binding/frozen, every time the car accelerates it pulls to that side, and if the car is coasting or off power it rolls straight and true.

When my rear diff stripped it made a gawd awful noise, like cats goin' at it, but the diff appeared to be fine, that is, until the outdrive gear teeth were examined under a magnifing glass and compared to a new set of gears, it was then that the rounded off profile of the teeth became obvious. The car drove OK like this, the acceleration was only slightly reduced (cbd ;) ), but it didn't want to rotate under braking in tight corners anymore, and it drove like it was a front wheel drive car.

holy_inferno
08-14-2005, 06:02 AM
Ok, thanks for the information...My Mini Inferno doesn't seem to be having any problems other than the fact that both my front knuckles are stripped/broken, and I don't have enough money for an aluminum replacement :(...My front tires are now all worn out, and soon it will reach up to the foam, makes for really fun street drifting though. :D

JuJuB
08-22-2005, 11:51 PM
If the H8 tires can be fit on 1/10th wheels, then I was wondering if 1/10th scale tires could fit on the H8 wheels. I'll probably try it.