TRF501X build - Page 7

KingBob · #**121** 10-01-2007

Have been in touch with Rainbowten in japan, and they've provided these prices for 501x parts which aren't in their stock list. They get them direct from Tamiya basically.

Wing, part#: 1834018 = 1320yen
Sticker, Part#: 9494096 = 800yen
Universal shaft bag, Part#: 9404707 = 4800yen
Shaft bag, part#: 9404708 = 1160yen
ball bearing bag, part#:9404706 = 4800yen
Front shock shaft, part#: 9804292 = 330yen
Front Damper stay, part# 4304075 = 1200yen
Rear Damper stay, part#: 4304076 = 1560yen
Body, part#: 1824090 = 3100yen
Bottom-cover, part# = 1834019: 1740yen

bender · #**122** 10-01-2007

Quote:

Originally Posted by Fabs

"galling" as you call it only happens when both materials are the same, which isn't the case here. And if you use a decent driver, there isn't any problem with the steel screws. I've been running TRF cars for 6 years now and stopped stripping them screws when I got a Hudy driver.

Between my Evo 5, MSX and now the 501X I've stripped 2 HUDY drivers - I've never even worn out any other tools previously in my 22 years of rc racing - so don't tell me there isn't anything wrong with the screws

I replaced them with some better ones (with a deeper hex) and now have NO problems - I can even take them out with one of those crappy allen-keys

stegger · #**123** 10-01-2007

Quote:

Originally Posted by jimmy

These are all in the countersunk chassis I mean dcm, it is just things like the servo mounts (plastic), versus things like the alloy bulkheads. but all butted up against the carbon fibre

Anyway, drove it in the kitchen for the first time tonight! yay!
I am impressed with the bluebird servo I have to say, its rock steady and very quick - not as quick as my 2123 but quick enough.

I might be wrong here but i think it is called COLD WELDING and its an effect were by the steel and the alloy heat up and cool down at different temps

stegger · #**124** 10-01-2007

Thinking about it a bit more jimmy you say its happening only on the chassis screws it could also be the carbon absorbing moisture

I know some of us touring drivers used to boil some of the more brittle parts that had a higher carbon content in the plastics to make it less brittle

TRF_Tastic · #**125** 10-01-2007

Galling is not locaized to a single metal combination. Thread galling seems to be the most prevalent with fasteners made of stainless steel, aluminum, titanium, and other alloys which self-generate an oxide surface film for corrosion protection. During fastener tightening, as pressure builds between the contacting and sliding thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening is continued, the fastener can be twisted off or its threads ripped out.

I have been an aerospace engineer for over 15yrs and I have seen this happen many times, it is more apparent in single metal combinations but by no means localised to this, as I have seen it in disimilar metal combinations as well.

I do agree that a good driver is essential, however a good driver very rarely makes up for a poorly formed fastner.

TRF_Tastic · #**126** 10-01-2007

Quote:

Originally Posted by MattW

I suspect the "problem" might actually be that they have matched the screw head angle to the countersink angle on the chassis.

Now obviously this is what you should do - but it does mean that the screw will grip the carbon very tightly - which is why you struggle to get them out!!

Matt, I have never seen this happen on its own, however it could be a contributing factor to the problem, poorly formed fastner + galling effect + resistive surface friction from the fastner head.

Jimmy, the best way to remove the errant fastner is to drill the head off with a 3.1-3.2mm drill, (be carefull to just remove the head as you dont want to remove any of the shank, as this is what will provide you with the gripping surface) then remove all the other fastners, remove the bulkhead and then apply a liberal dose of WD40 or another penetrating lubricant and unscrew with a set of mole grips.

KingBob · #**127** 10-01-2007

Tamiya themselves say that you don't need threadlock on the metal into metal screws, perhaps there is a design feature of the thread that is designed to grip screws, to stop them vibrating out.

Chaz · #**128** 10-01-2007

Put some copper slip onto the threads, seemed to help me when i had this problem on my xray

Chaz

telboy · #**129** 10-01-2007

Quote:

stripped one screw .... with a new Hudy driver

Mine were stripped using a hudy driver too. people said how good they were so i bought one.....and stripped screws with it straight away.

I managed to get 1 screw out using an old set i got from cml, propper steel ones. I now use these all the time and haven't had a problem with them.

stefke · #**130** 10-01-2007

You guys are all complaining, but the screws on my ZX5 were A LOT worse.

But I think I'm f***'ed because I used Loctite on all my metal in metal screws.

HairySteve · #**131** 10-01-2007

I'm worried now!

I always threadlock screws into metal and I Z42'd all the screws into my TFR501 as I was building it. I had to get the top apart (to re-tension the belts, they were a bit tight) and it came apart fine but I haven't dared tackle the underneath yet. I've heard that heat is good when trying to undo stubborn screws, so I'll have a hairdryer on standby when I replace my screws woith some decent ones

As for the body being too low at the back, I thought this too, but once I fitted the undertray and the velcro strips they supply to hold the body on, the body was pulled out slightly at the back which brought the rear body down onto the rear mount. I was thinking I'd have to cut the body down at the rear too, but it all turns out good in the end.

I'm going to order some of those ti-ni shock shafts tomorrow (the Yok ones), I didn't make a very good job of building my shocks anyway so they'll come apart and get rebuilt properly with ti-ni shafts. I feel a set of B4 springs coming on as well.

-Steve

Fabs · #**132** 12-01-2007

Well, received my 501X yesterday and it was mostly built in 3 hours (BAR the electronics, but they're not going in before next week anyway). What took me longest was to get all the air bubbles out of the shocks, lol.

As for the screws, I tried tightening the first screw like normal and unscrewing it, and i stripped it

. However the fault isn't the screw's but the C/F of the chassis. I noticed that the chassis squeals when you tighten a screw. So what I did is do it by steps, tighten reasonably gently, unscrew, and so on until the screw isn't as hard to unscrew and it works. You'll notice that at every step you'll be able to screw the screw a tad more, like 1/8th of a turn more. I think this is due to the C/F compressing a bit. I have to say it has never happened to me with Tamiya, and it could simply be that batch of c/f that is like that.

Now I have to get the fooked screw out but all the others are easy to get off

.

Another point, I've never seen a kit with so many screws. It might be worth getting a complete set of Ti / Aluminium screws and save a fair amount of weight.

jimmy · #**133** 13-01-2007

I applied some grease to the cs holes like you suggest - of course my holes (ooerr) are already "used" so the friction is already less, but I appreciate what you say, and they felt easier to remove, less sticking.
I am sure it will help, but I don't think the chassis is really to blame, perhaps it is the cause of the really tight screws, but also the screws are simply not deep enough - deeper, better screws would not strip so easily, so it's a bad coincidence that these two factors are together. Shallow screws and very hard to remove! Nightmare!

I will advise people to apply a tiny ammount of grease to the CS chassis holes to help this problem, but also suggest replacing the screws if possible with deeper ones.

Fabs · #**134** 13-01-2007

well since then i changed most of my screws to titanium ones i had lying about and noticed something rather unusual on the steel screws: the heads are badly marked where it was in contact with the chassis. I just checked on my "old" TRF415 that has steel screws underneath, and the screws are hardly marked at all even after a lot of use.

Looking at a never used hole on both the 415 and the 501, I can see the countersinking is a lot neater on the 415, you can see the layers sticking out on the 501 chassis, so it could just be that the tool was in need of sharpening...

Fabs · #**135** 13-01-2007

On another note, anyone who knows the track at York can point me to a ballpark gearing for a 9T ?

Cheers

jimmy · #**136** 13-01-2007

Bah, winter is naff! luckily we almost had a bit of sun for 3 minutes today so we raced out and got some photos for the 501X review, nothing spectacular - hey, it was a manky carpark in huddersfield - but I can always add some more later I guess.

Vicky found it really hard to drive without spinning out, but it's just because shes mad! I thought it was good, green springs probably too soft though.