TC Bros Hardtail Help

memyself

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So my welder is a dumb fuck. He welded up my hardtail and it looks great very straight except one problem. He had a piece of pipe exactly 8.5in wide stuck between the axle plates held in place with the axle and nut. Ok seems all good. I get the frame home and knock out the pipe, of course, the plates squeeze into 8 1/4 wide. Let me guess he rushed it and it heated up too much and the they warped? Well anyway how can i remedy this? How do i get the plates to 8.5? I cant get the brake caliper bracket in to save my life? Can i have someone machine 1.4in off the bracket? If this isnt 8.5 is it going to mess up the geometry or anything. Please help.
 
Warping and welding go hand in hand. What happened was the frame sprung on you when the pipe was knocked out. There may not have been much he could have done depending on the hardtail design and where the welds needed to be placed. The problem may not be that he rushed it, but that more welds needed to be placed on the inside of the tubes than on the outside. You should take it back to him and he should be able to to use a straight edge to determine where the tubing warped, and use a torch to apply heat on the opposite side which will pull the sides back out again. I'd be willing to bet that both sides start to bend in after the rearmost upper and lower braces that go between the two sides. Some heat applied just to the rear of those four welds (on the outside of the tubing) should bring it all back out. He'll (or you'll) probably need to use the cutting head of an oxy acetylene setup (without pressing the oxygen lever!!!) so he can localize the heat in small spots.

If none of that makes any sense, use a jack, pry bar, or whatever you need to use to push the sides apart to get the spacer back in. Then heat the tubing (with the rosebud tip) by the four welds that hold the upper and lower braces until they are red hot (heat to bright red, more than dull red, less than orange). Try to heat them all evenly if you can. Then let it all air cool. Once it's totally cool, pound the spacer out and the frame should spring much less.

Also, I would fix the frame vs machining the bracket.
 
No need to go through all that heating etc. Simply place a small scissors type jack(lots of cars and small trucks use them) in between the axle adjusters and slowly crank it out until you are a little(about 1/4") past the measurement you need.Should spring back to what you need.Have built many frames and have done this with no problem,have even had to do this on stock bikes at times,no big deal.I wouldn't go heating on the frame with a torch unless you know EXACTLY what you are doing.You could easily make things much worse.Hope this helps.not nice to call your welder a "D.F." though.
 
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These guys are right no heat-if you dont have a jack small enough go to home depot and buy an 8 inch or 7 inch swivel bolt with eye lits on each end, cut the eye lit in half and as you spin the inside bolt both sides either expand or contract-put it between the plates spin in out + a 1/4 more than you need. These type of bolts expand equally so one side wont be out greater than the other-I use them all the time to spread various parts some. It will cost no more than 4.95
Good luck
 
Hmmmm..."crickets chirping"....OP...where ARE you?!!! You are WELCOME for all of the responses...3rd post and he's a flamin'...
 
Just out of curiosity, why are you guys so against using heat? Heat from the weld was what caused the internal stressing to begin with. By heating the other side, you are just balancing it out. You could actually lay a weld on the outside of the tubing (then grind it off) to create that balance, but if you use a torch you don't have to grind. And heating the whole weld joint to bright red (if using mild steel) and letting it air cool will normalize the joint making it stronger. That will take care of the internal stresses and brittle areas caused by the weld. I've done some reading about building small aircraft frames out of thin-walled high-carbon steel and they all normalize the joints with a torch after welding to remove internal stresses just as an extra measure of caution and to make sure the joint is as strong a possible.

Maybe you are against it because you think it would take too long and a jack or threaded rod with nuts would be easier. :shrug: It would only take a couple of minutes with a torch. Maybe I'm more used to fixing warped plates where you can't always cold bend them straight so I think of the torch first.
 
The (possible) issue is alignment, I would want some lines or a straight edge to watch as I spread (bent) the tail so that I know it's not all coming from one side (very likely). Then again 1/4" isn't very much.
A plain old chunk of threaded rod with nuts and washers should be plenty enough to do the spread. I am sure I don't know enough to comment about heating and normalizing this particular combination of Yamaha's frame metal, TC's hardtail stock and whatever the welder chose for rod. I don't recall the OP mentioning what METHOD his welder used, perhaps that is not relevant here?
 
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I,ve always been told never to heat steel unless you know exactly what your doing. Can do more harm than good. In my experience, red hot heat tends to make steel brittle. I've seen where guys have heated front end components, like tie rod end lock nuts,(something I never do), come back loose, or even cracked. You're actully changing the metal at a molecular level. That's why steel always breaks right next to weld, and not the weld itself. How can you know what you're actually doing? I was told years ago by an old time welder, straighten it cold if you can. I'd rather see steel bend than break. Just my 2 cents.
 
I've done alot of bending frames to get rakes I wanted. The older 57 straight leg frames had chrome molley tubes but the heads and bends were made of cast. Alot of people would cut those off and weld on new stearing heads. If you dont have alot of experience with heating metal to bend them properly and not remove the structural integrity then dont start with a newly built frame. Most people heat steel until is red hot and of course it bends great-but you can be sure it will crack at that location especially if the frame ride is rigid. The key to doing this is to heat the area evenly so it just becomes very light brownish orange-then use a mechanical device to pull or bend it slowly the direction or shape you are looking to achieve. Then let it cool in the normal air. Your steel will still have great strength.

Hope that anwsers you question

Chris
 
... In my experience, red hot heat tends to make steel brittle. .... You're actully changing the metal at a molecular level. That's why steel always breaks right next to weld, and not the weld itself. How can you know what you're actually doing? ....

Heating mild steel to red hot is not what makes it brittle. It's rapid cooling that will make the steel brittle. Hard but brittle. That's why you shouldn't quench it in water or oil. You need to let it air cool with little or no air circulation. The reason welds break right next to the weld is that the cool metal around the weld pulls heat away from the hot spot too quickly. Another good reason to heat them later and remove the brittle spots. You can know what you are doing by researching hardening, tempering, annealing, etc, and learning a little about metallurgy.

... Most people heat steel until is red hot and of course it bends great-but you can be sure it will crack at that location especially if the frame ride is rigid. The key to doing this is to heat the area evenly so it just becomes very light brownish orange-then use a mechanical device to pull or bend it slowly the direction or shape you are looking to achieve. Then let it cool in the normal air. Your steel will still have great strength. ...

Yeah, you don't want to heat the part to red hot then mechanically bend it. I was saying heat the part to normalize the metal and remove the internal stressing. In the situation of this hardtail, if he were to apply concentrated heat to the outside of the tubing as mentioned before, he would not need to mechanically bend anything, the heat itself will do that.
 
Not to highjack the post, or bump up a very old post as well but my tc hardtail had did the same thing. It is about 8 1/4 wide measuring from the inside of the plates.

I have opened the rear with a sissor jack as stated in this post to about 8 3/4 up to 9in inches , did this mutiple times and and it has not moved. I also heated up the frame rails and the axle plate with a blow torch and did the same.

Should I have to use something hotter to heat the steel?
Also, how long should I wait after I spread the rear open? I didnt wait to long not more then a couple of minutes.
 
Hi Gmorrone,
don't need to heat it, you ain't getting past the frame's elasticity, is all.
If it springs back to 8-1/4" when you spread it to 9" spread the bastard out wider?
Start at 9-1/2" and see how that goes.
Spread it by 1/2" increments until it springs back to the width you need.
 
Thanks for the quick reply. I'll try that first thing tomorrow and let you know how it goes. I was just weary of opening it with the jack too much.
 
okay so I got the rear of the frame to 8 1/2 put on everything and it needs about 1/4 inch to fit the spacer.

I know this may be a dumb question but should I just continue to space the rear of the frame to fit the spacer, or is it not wise to go past the 8 1/2 that it is suppose to be at?

Here are some pictures

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disregard the attached , thats was before.
 

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I use a 3/4" all tread with two nuts and wahsers and turn them out way past where the need to be and it'll spread right out for you had to to my voodoo ventage one yesterday that way
 
Well I'm only asking because I can get the rear wheel with the spacers in the rear axle at 8.5 perfectly. But I cannot get the chain adjusters on as well. By measuring the adjusters I need 3/16 more per one spacer . Therefore my rear has to be opened to about 9-9.1 to fit the rear.

I'm just wondering if this is okay since it's suppose to be at 8.5 and that's what everyone is doing. Idk if something is wrong.
 
Hi Gmorrone,
you sure you ain't putting the adjusters in backwards?
The thin sides go to the insides eh?
 
I have used them all HEAT JACK ALL THREAD....All work its just how bad its out. I would say 5 out of 25 Hard tail kits I installed were out and maybe it was the vendor or bent in shipping whatever.
Most of the time it comes up a little over a 1/4" out and I would use the ALL THREAD method for that and go past the 1/4" and when you tighten all up it will come back. One trick I have used is while welding up one and NO JIG measure up all of what you are putting in there and make up a spacer and put it in before welding just like a jig and you will not have to go threw this. HEAT WELDING of any kind can twist most metal and if its a premade kit measure the cross piece before you start I have had some come from the vendor not the right size.
HINT HINT!!! have you ever noticed the cross piece only tacked in and not completely welded:thumbsup:
 
Well thanks you all for the help. I stretched the axle a little too far then end up using the rod with bolt method. Got it to 8.5 added some 3/4 washers and now it tightens up nice and good and sproket is pretty much lined up. Just one problem the chain adjusters are off center of the holes in the hardtail. Anyway to fix that?
 
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