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Heat treat questions

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Hi Dave, the straps hold the tank down, under the tank are rubber buffers,overtime they compress and leave the straps a bit loose in the holes.Additionaly, it is possible that the weight of a full tank of fuel bouncing a bit on the buffers can chew up the thread.Similarly, the boot floor leaves a bit to be desired in terms of rigidity and it can flex too. I used oillite bearings because they had the collar on them--Fwiw---Keoke
 
Mostly it depends on how, and with what you welded these with. since they were gas welded (do you mean gtig? if so you have no problem) then the penetration is unlikely to be deep, and you may have a 'interface' of hard material and the substrate with a grain structure that can cause crystalization within the disparate metals.
I would think repeated annealing of the areas in question would be useful.
You should 'draw back' the the parts by heating them to a dull orange color and then sticking them into dry sand to cool very slowly, this should be done twice, at least.

Just my .02

Cheers!
Dave G.
 
So - Just replace the buffers under the tank, & the pads under the top straps to tighten up the tank in it's straps. I don't think the tank was loose when the cars were new. I replaced the pads & there is a good half inch of compression on the hold down straps & T bolts. The tank only weighs about 80 pounds full. High density foam, when compressed, seems to hold the tank in place very securely. I agree that low quality or worn out foam might let the tank bounce around & wear the T bolt mounts. It might also rattle a bit on the bumps. The preload/buffer compression should be enough to stop bouncing. Also, if the tank is not securely pulled down, water will get in through the hole in the bottom of the floor & cause rust.
D
 
Whew Whee yall are something, it ain`t the space shuttle weld it back togther, recut the threads, use a good self locking nut and washer and a little sealer on the hole and go on with life.
 
Lin, /ubbthreads/images/graemlins/iagree.gif-Keoke- /ubbthreads/images/graemlins/lol.gif
 
o.k. wise one .. what type of sealer /ubbthreads/images/graemlins/grin.gif

(and yea .. I think we beat this one into the ground /ubbthreads/images/graemlins/hammer.gif )

Cheers,
John
 
[ QUOTE ]
o.k. wise one .. what type of sealer /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]
We can have another thirty posts for that! I’ll vote for bonded washers.
 
Hi Ed,

The original tank had some repair done in the past along the front lower edge and there were some rusted panels in the boot floor in the same area. It was obvious that the original chaulking between the floor panels and frame had fallen out and let the water get in between the metal. The back edge where the shroud meets the floor was in good condition but rust could have been a contributor to the T bolts wearing away. I picked up another original BJ7 tank that had been dry stored for many years. No rust damage on that one and I flushed and sealed it with the Hirsche gas tank sealer for good measure.
 
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