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PostPosted: Sun Jan 16, 2011 8:08 pm 
Dirt Disciple

Joined: Sat Jan 15, 2011 6:55 pm
Posts: 23
hey
iv just signed up today with retro bike and left a post in the new comers section
so il get on with the reason for this post :

i am about to embark on rebuilding my well ridden dynatech MT4 ,
[img][img]http://i885.photobucket.com/albums/ac54/DSnV/P1020091.jpg[/img]
[img][img]http://i885.photobucket.com/albums/ac54/DSnV/P1020092.jpg[/img]

im not sure what year it is exactly but i read on one thread that if the serial starts with C then it is 92 ,mine does, so can anyone verify this point ?
a couple of points to take note of is that i read that allot of dynatech owners say all there lugs are alloy strangely on mine only the head tube and the bb shell is alloy the seat lug is steel ,
rusty steel lug
Image

the second point is that there are riveted bosses for the top tube routed brakes ,i have not seen it mentioned when iv been browsing so here are some pictures to explain what i mean ,this may give away its year

the holes for pot rivets ! :shock: :lol:
Image
Image

and the brake bosses :shock: :lol:
Image

it dosnt sound too great does it having pot riveted brakes !
this hapened when i was stripping the paint ,i must have broke the seal of the glue , the rivets held but they where always loose and could snap any moment but they never did thankfully , so this leads me too my next question .
has anybody had experience with this ? any recommendations of metal epoxy's ?

also i was needing advice on the directions to go concerning finishing the frame ,firstly , is it ok to powder coat these frames temperature wise ,i know some say yeah and some say nay so there is no consensus evidently but what would you the reader do ?

ideally i wanted to polish the entire frame/forks and laquer it but last night i found a hole in the seat stay (4mm x 2mm) that must of happened in one of the crashes i had (it looks like there is a crack coming from the hole ,this is just camera trickery thank bejesus)
Image

its not gonna look good when that has been filled so i may have to paint the back triangle , any ideas how to repair a hole like that ? i thought of back filling it with a bit of expanding foam and then body repair resin but any other suggestions more than welcome

for the components i am going to use xtr m970 throughout , i scrimped and saved to buy the bike as a teenager so the second coming is gonna be pimped up somewhat
i do still have the DX group of the original Mission i told you about in my first new user post , but il save that for another job ,
Image

now im just waiting on parts and making a final decision about the frame finish , do i go just three main tubes polished ?, or complete bike polished with the hole filled and covered wtih a sticker ? or im kind of fancying the idea of powder coating everything(frame ,stem,forks , seatpost ) jet gloss black and having the xtr group as it is silver with grey cables and solid white decals and all black wheels ,like a shadow on the hills , i dunno i keep having different ideas its hard to settle on one but im sure it will come .

oh berfore i forget , i need to get some transfers for the mt4 does anybody know anybody here on the forums ?

so to recap on advice i need
transfers ?
filling the hole ?
powdercoating or not ?
refitting brake bosses ?
and anything else you can think of

ta raa for now
Lee


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PostPosted: Sun Jan 16, 2011 8:36 pm 
Retro Guru
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Joined: Sat Sep 15, 2007 10:08 am
Posts: 1040
Location: Thatcham - Berkshire
....well personally I would go with Black with white writing but them I am biased (check my own steed)! Always liked the lugged Dyna's - I used to stare at them through the window of the Raleigh dealer in Winchester on my way to 6th form....


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PostPosted: Sun Jan 16, 2011 9:04 pm 
retrobike rider
retrobike rider

Joined: Sat May 29, 2010 3:44 pm
Posts: 1508
Location: Leeds
fuzzywuzzy wrote:


filling the hole ?
powdercoating or not ?
refitting brake bosses ?

ta raa for now
Lee


Welcome

Regarding the hole, I would say that a piece needs brazing in, that hole is quite a percentage of the circumference of the tube.

Powdercoating - i've a Dynatech (well more than one), that requires paint and i'm in quandry at the moment. Powdercoating is cured at 200degrees C and i'm not sure what effect it will have on the bonding. I'm after a US (broken rather than USA) frame so I can stick it in the oven.

brake cable bosses, loctite 414 and countersunk pop rivets will do the job.


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PostPosted: Sun Jan 16, 2011 9:13 pm 
Gold Trader
Gold Trader
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Joined: Wed Jun 20, 2007 11:19 pm
Posts: 7006
Location: Odense, Denmark
That's exactly where my MT3 developed a hole. And there's no way that's being repaired to ride again.


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PostPosted: Sun Jan 16, 2011 9:28 pm 
National & North West AEC
National & North West AEC
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Joined: Mon Nov 03, 2008 12:43 am
Posts: 8146
Location: Macclesfield Forest
Firstly welcome.

The C does indeed indicate a 1992 frame. The lug design, colour and cable routing matches up with this too.

In terms of powder-coating, I think the general consensus is that due to Dyna Tech be 'thermally bonded', the heat of the powder coating process would be sufficient to cause potential weakening between the tubes and lugs.

I have a knackered 1992 Diablo frame which I'm going to contact paininthe about so we can test this theory.

I'd be pretty confident that the cable guides for the rear brake can just be riveted back on. A dab of Araldite or Loctite 414 in addition could hurt I suppose.

But as dbmtb says, that hole in the rear stay is a major problem. If they were Cro-Mo stays like on the MT-3 then a frame builder could probably repair it with a brazed on patch or sleeve fairly readily. It'd be ugly though.
The MT-4 has a Ti rear triangle though hasn't it? You'd need to find a Ti frame builder to see what they think, but either way just filling a hole like that is asking for trouble further down the line.


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PostPosted: Sun Jan 16, 2011 10:23 pm 
Dirt Disciple

Joined: Sat Jan 15, 2011 6:55 pm
Posts: 23
high
thanks for the comments
the seat stays are magnesium molybdenum so they are steel
do you think the back end will fold up on me ?
i see what you mean about it being ugly with a chunk of steel stuck over the top of it , maybe i can fix it with some steel strength putty they manufacture
il look into it
i dont wanna see this baby die ,2 days ago i ordered a full xtr m970 group with hubs to go on it , because the back end is black all this time i hadnt noticed the hole, dang

il have a think


[/quote]


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PostPosted: Sun Jan 16, 2011 10:26 pm 
retrobike rider
retrobike rider

Joined: Sat May 29, 2010 3:44 pm
Posts: 1508
Location: Leeds
Just being doing a bit of research with the coefficients of linear expansion of the various materials involved in these frames. I would say powdercoating is a NO,

Titanium has a low coefficient of linear expansion which is equal to 5.0x10-6 inch per inch/°F, whereas that of stainless steel is 7.8x10-6, copper 16.5x10-6, and aluminum 12.9x10-6.

So nearly x3 much expansion of the Aluminium v Titanium.

The expansion alone of the two differing materials would pull (or seriously weaken) the joint that the risk is not worth it.[/quote]


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PostPosted: Sun Jan 16, 2011 10:30 pm 
retrobike rider
retrobike rider

Joined: Sat May 29, 2010 3:44 pm
Posts: 1508
Location: Leeds
Just being doing a bit of research with the coefficients of linear expansion of the various materials involved in these frames. I would say powdercoating is a NO,

Titanium has a low coefficient of linear expansion which is equal to 5.0x10-6 inch per inch/°F, whereas that of stainless steel is 7.8x10-6, copper 16.5x10-6, and aluminum 12.9x10-6.

So nearly x3 much expansion of the Aluminium v Titanium.

The expansion alone of the two differing materials would pull (or seriously weaken) the joint that the risk is not worth it


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PostPosted: Sun Jan 16, 2011 10:31 pm 
Dirt Disciple

Joined: Sat Jan 15, 2011 6:55 pm
Posts: 23
ovlov440 wrote:
....well personally I would go with Black with white writing but them I am biased (check my own steed)! Always liked the lugged Dyna's - I used to stare at them through the window of the Raleigh dealer in Winchester on my way to 6th form....


like the bike man its simple and elegant and yes that is the scheme i had in mind but with all black wheels tyres spokes and white dyna tech decals
thanks for sharing that

but its looking like my build has been selected for demolition at the planning stages if i cant repair the hole lol


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PostPosted: Sun Jan 16, 2011 10:33 pm 
Old School Grand Master
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Joined: Sun Sep 05, 2010 1:10 am
Posts: 4756
Location: Heathfield, East Sussex
Re powder coating bonded frames I eventually found the following info;

# Do not use chemical paint strippers! They will attack the epoxy resin that holds your part together. Acetone, alcohol and other solvents are okay, but they don't remove paint.
# Do not use heat! Some epoxies undergo glass transition as low as 150 degrees F or so. Keep it under 100 to be safe. If it is too hot to touch with your bare skin, it is too hot. That means no power tools (buffing wheels, sanding discs, etc.) and no heat gun paint strippers, etc

As for repairing Ti frames I bought a damaged Marin Team Titanium frame when I lived in Cambridge with the intention of having it repaired. It had already had several cracks repaired around the bottom bracket and now the r/h chainstay had cracked at the dropout weld. When I took it to one of the many companies serving the aircraft industry that abound in the city I was told that once anything manufactured from Ti starts failing then that is the time to replace it not repair - the frame has been hanging in my shed ever since... :cry:

This is why I don't use Ti handlebars because catastrophic failure is sudden and without warning. The same goes for carbon fibre - having witnessed firsthand a handlebar failing at the bombhole at the Malverns! There was also a TV documentary on the Lotus carbon fibre frames BITD showing Caroline Alexander (if memory serves me right?) consistantly breaking them...

Even early alloy frames were sold with a limited lifespan of just five years. That's why I stick predominantly with steel (I say 'predominantly' because I have a recently acquired alloy/steel Dynatech frame on the go... :oops: ), Reynolds in particular...


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