bobbyb323

I actually found a way to fix the loose left steering arm. The 4mm shaft is smaller than the 4mm hole in the bearing. I measured in with calipiers. Also, the bearings are loose and move in the arm. That's where the movement is. I pulled the bearing out of it. Put a piece of copier paper 1/8 x 1" over the hole in the arm and forced the bearing in. I put two pieces of paper on the other bearing and forced that in too. I then poked the paper out blocking the holes in the bearings. I took another 1/8 x 1" paper and put it through the center of both bearings then put the shaft through it and put the e-clip back on. It's tight as a drum now and moves freely. I then soaked the assy in 3 in 1 oil the lube. There is zero loose play in it now. The servo save side has minimal loose play so I'm not too concerned.

Marv

iTrader: (2)

Good one bobby!

Thanks for posting that fix!

Marv

iTrader: (2)

Inch to MM Small Numbers Conversion Chart

bobbyb323

That fix is not for worn bearings but pooring designed parts the bearings go into.

Marv

iTrader: (2)

Maintenance Tips - from the HPI Web Site

NOTE: These tips are "dated" when it comes to motors, batteries and diffs, but for general maintenance in other areas there's some useful data...


Maintenance Tips

5VoltDetonator

Interesting, I've had my Sprint 2 Drift since Xmas of last year. I've glue gun locked the rear, put a one way on the front, shocks have bladder, new servo, esc and now have 10.5 motor. Also I dremeled out some notches on my steering arms to give it more steering. Also I got about 3 oz led on front bumper. This is the best car I own as far as thing not breaking. It seems to go out and drift come home and rarely need repairs.

Untill a couple weeks ago, my left front wheel was bouncing all over the place. I check the bearings they seemed fine but the steering arm that holds the bearing seemed like it was wore out. I replaced it and it was still doing the same thing, jumping all over the place. The only thing I could figure out was that it seemed like the dogbone was too short. Seemed like it was coming out of the axel and making it wobble and was not staying where it needed to be. I could figure out what to do but I thought if the dog bone were longer or not able to move back and forth it might stop.

So, all I did was cut a piece of round plastic off a parts tree ( you know the extra plastic that parts come attached to ) I cut a piece about the size it seemed like the dogbone was too short and I simply stuck it in the axel the comes out of the left side of the front one way then I put the dog bone end in. No more wobble.

I'm going to read what you wrote again, I think we fixed the same thing. So basicly you put a paper wrap around the outside and inside of the bearing to shim up the play? I think maybe my dog bone not being able to wobble is also holding the bearings together and giving them less wobble room?

Marv

iTrader: (2)

Everyone has their own voodoo.

5VoltDetonator, you may consider trying this for the dog bones -

BUT - Don't get "married" to the 'O' ring fix for dog bone slop - It has drawbacks.
I have a better one coming.


What you need:
HPI #6819 'O' Rings



Some people use (nitro) fuel tubing and just cut off a piece to fit.

Going to hard plastic isn't such a good idea it can bind and cause other issues = as the suspension works up/down, the dog bone needs to slide back and forth. The 'O' rings/fuel tubing apply pressure yet compress (to a point). You don't want the dog bones don't bind - on turns especially.

Stuffing 2 'O' rings in the front on each side is pushing it.

I get wheel hop/dog bone bind on tight turns.

However, I also trimmed my C block stops to turn tighter = this may be contributing to the bind issue.

I noticed that there's a lotta slop in the left diff shaft. I might have to shim that puppy later on.


Found it...

5VoltDetonator

Funny I was looking for O rings when I did this but could not find any in my stuff, ok I will stop at local hs and get some now. Cause your probly right, even though so far it is ok I rather make it bullet proof

Marv

iTrader: (2)

How to Clean a Brushless Motor

Novak's brushless motors can easily be cleaned.
Watch this short how-to video to learn the steps.

Uploaded by NovakElectronics on Mar 29, 2010

+ YouTube Video

Marv

iTrader: (2)

Turnbuckle Wrench Upgrade

Got one of these for the 4mm turnbuckles?


You might want to upgrade to one of these -


Available at a reasonable price from -

ZORO TOOLS

and

DRILLSPOT

Marv

iTrader: (2)

FRONT BELT TENSIONER MOD

I have no idea where I saw this picture on the web, some UK site - but when I saw it...

I thought to myself, "That's a great mod for a front belt tensioner!"



If you look close enough, you can see that the owner uses what looks like a smaller toothed gear on the main shaft for the front belt drive (must be a drifter) and he made an extended tensioner arm out of aluminum and mounted a main shaft pulley to it.



Here is my simplified version of that other guy's mod.

PARTS NEEDED:
Thick CA
HPI85016 Pulley Set
2 - 3x6x2.5mm Sealed bearings - If you bought the 10 pack to do the belt lift mod, you have these already.
1 - M3x18 Allen Head Screw
1 - M3 Lock Nut - Dubro 2101
2 - M3 Flat Washers - Dubro 2109
2 - HPI72111 M3x5x.2 shims

*Optional - I swapped out the OEM M3x8 Phillips screw in the front tensioner for a Dubro 2122 M3x8 Allen head screw backed by a Dubro 2109 flat washer.
These are so much easier to deal with than Phillips head scews (IMO).



TOOLS NEEDED:
File
Sand paper
Tapered Reamer
Allen wrench for the M3 Allen head screw
5mm wrench for the M3 lock nut
Jewler's saw - to cut the protrusion on the pulley


Glue the side to the main pulley section - WITH THE PROTRUSION FACING OUTWARD.
Rotate the side with the protrusin to speard the glue as you install it.
Let the CA set up a bit for a strong bond.

Rough cut the protrusion back to about the shouldered step for now.

Alternating sides, ream out the ends for the bearings.

NOTE: The bearings are going to be a PRESS FIT into the pulley - So do NOT over ream either side.


What I did was to measure the diameter of the beaing = .239 inches.
Then I taped off my reamer at .225 inches.
I reamed til I hit the tape and then, ever so carefully final reamed until I could feel the force when trying to push the bearings in.
Once I had them started I did the final press in a bench vise.


If you're feeling lucky you can try drilling out the pully.

BUT drill it UNDERSIZED for the bearings - for the press fit.

NOTE: The bearings are going to be a PRESS FIT - So do NOT over drill the hole.


The final length of the protrusion should be .05 inches - So file/sand it down carefully and squarely.

When you have the pully hole finished and the protrusion trimmed to the final length press fit the bearings into each end.


Take your front tensioner off the car.

Remove the screw that holds the bushings (or bearings - if you upgraded) assembly from the arm.

Thread the M3x18 Allen head screw into that hole.
Install one .2 shim, then one M3 flat washer, then the pulley - with the protrusion facing the arm.
Next install one M3 flat washer, then one .2 shim, then the M3 lock nut.
Holding the Allen head screw to keep it from roating with your Allen wrench, tighten the lock nut - snug, then back it off a scoatch at a time checking for free rotation of the pulley.




Reinstall the tensioner on the car.

TADA!



There will be a little more adjusting movement - just in the opposite direction - Because the newly geared pulley/tensioner is taking out belt slack before being adjusted.

This should also provide more front belt life.

The modded tensioner also raises the belt up and away from the lower portion of the belt which has been raised with the belt lifter mod.

Oh, and it clears the VTA driver figure. Well, it clears mine just fine.


All voodoo is welcome here. If you have a fix, mod or upgrade for the HPI Sprints by all means post it.
Including what you did, how you did it and the parts you used (parts numbers) will greatly help other Sprint owners.

Marv

iTrader: (2)

10/05/2012 = I found part of my wheel hop issue...

The drive cups (gear differential shafts) on the diff are all loosey goosey and flopping/wobbling around = Causing the dog bone to flop/wobble = Causing the wheel to hop.

And the bushings were loose in the diff housing.

I have a spare back up diff that's never been used and I checked it = same problem, but not as pronounced due to being unused.

Now that I think about it, my RS4 Nitro had the same problem back in 2000.
Go figure.

I took that one apart; I upgraded the B070 bushings to 5x8x2 bearings (5x2x2.5 should work as well) & I shimmed the drive cups.

I used a variation of bobbyb323's fix to tighten up the bearing to diff fit = I used a 5/16" punched out circle of a zip lock bag (the same size I use for my center link ball cups) to shim each bearing.

I just placed it over the end of the diff hole, pushed the bearing in and trimmed the excess inside and out for each side.

Now the bearings are snug in the diff and the ball cups have a much better fit.


The rear diff has the same issue, but it's less noticeable because there is no steering action/stress going on.


PARTS USED
HPIZ694 Washer M5x10x0.5
HPIZ852 Washer 5x7x0.2mm
Zip Lock bag

Vostok 7

So I did this yesterday using SAE parts. I don't have a LHS and the hardware stores around here are notoriously devoid of anything "unamerican". I did some looking and found the closest SAE equivalent to an M3 is a #6-32 machine screw, and 35mm is a dead ringer for 1 1/4". I ended up using a 1 1/2" because I got both and didn't pay attention to which one I grabbed. I used three #6-32 lock nuts. So far the mod seemed to work fine, the big difference is the screw is slightly bigger in diameter so I had to drill out my graphite top deck very slightly to fit, and the lock nuts are also a little larger in diameter and thickness so you have to be careful about tension, but so far it seems to work fine. Since the lock nuts are thicker, the arm ends up a few mm higher than it would be with the stock pivot/spacer, I don't know if this is going to be an issue or not.

Just wanted to post this up as an alternative if anyone has issues finding metric hardware.

Marv

iTrader: (2)

Better Dog Bone Slop Fix - WIP UPDATE: 10/07/2012

Don't get "married" to the 'O' ring fix for dog bone slop - I have a better one coming.

My fronts are done with the new fix.

Just need one more piece to do the rears, take pics, draft the walk through & then I can post it all - probably mid-week.

Marv

iTrader: (2)

Excellent way to improvise, adapt and overcome, Vostok!

Thanks for adding your "americanized" (LOL) version!