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Auto to manual swap: Those damn bolt holes

3K views 12 replies 8 participants last post by  frijoles 
#1 ·
Alright, sorry if this isn't necessarily deserving of it's own thread, if that's the case, then I will gladly delete it, just let me know. I was gonna ask this in the H22 swap thread, but I kinda felt like this was a topic that deserved it's own thread, due to the fact it could really be for either swap.

So, what methods have you all used to secure that transmission mount OTHER than drilling holes in the firewall? I was planning on just welding the bracket in place, but after about five seconds of looking at it in place, I realized that the area I wanted to weld it to wasn't flat like I thought it was. It's still possible to weld it, but I won't be able to make it as water tight as I originally thought, and I won't have as much area welded, which worries me in terms of strength.

Now, I know most people drill all the way through, and put a nut on the other side, but that really isn't very... sound, in my opinion. I've heard of people ripping shit up doing that, which is no good at all, and I don't want that. There's also the fact that you now have four more sides in your frame that weren't there before. If I was gonna do that, I'd just as soon weld some nuts on the inside piece of metal, anyway, which would be a bit safer, but that still leaves the fact that there are holes there, that I don't think are necessarily ideal.

So, then I considered, a small adapter plate, some studs on it, bolt to the auto holes, but studs for the manual holes. Which would work, more or less, but now the mount is 1/4" out further from the frame than it was before. Maybe not a huge amount, but it is something.

I've seen some other people use other methods, but not many. So, I would like to know if anyone has done anything different, or what products you might know of to use.
 
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#2 ·
Custom mount or drill the holes, those are pretty much your choices.

If you wanted a really nice install you could drill the holes oversize, slip a thick steel tube through, cut it to length, and finally weld it in place. You could also weld the nut onto the tube so you don't need to mess with holding it while you tighten the bolt.
 
#3 · (Edited)
What makes you think that the drill through and bolt/washer/nut method is not going to be secure?

I ran that swap on the H23a for 2.5 years daily driven not weekend warrior status.

And right up until the accident nothing tore or ripped or cracked.

the frame is tougher than you think for what its designed for.

You are over thinking the process. Dont make it harder or more complicated for you down the road than it is.

MustardCat was there for my swap and even he knows it works just fine, he was the one who put in the foot pedals, because I am too big to get under there....lol.


...If you wanted a really nice install you could drill the holes oversize, slip a thick steel tube through, cut it to length, and finally weld it in place. You could also weld the nut onto the tube so you don't need to mess with holding it while you tighten the bolt.
^^^^ This is what I would do..
 
#6 ·
I didn't potato. I mean, sure it will probably work "fine", but Honda didn't do it that way.

I actually have something I'm going to try and I think it will work pretty well, but we'll see. I just don't like drilling holes in things that don't need holes. Anywhere rust can happen is bad, and also putting the stress on the outside of the frame pulling in just... I don't like it. But I think my solution will work nicely. We'll see.
 
#9 ·
got the engine out of mine after 1.5 yrs done the swap, the holes drilled throught fender have elongated, thinking get a steel plate inside wheel wall drill holes get the bolts through and weld all 4 nuts on the plate, and weld plate to the metal if possible, any suggestions?
 
#12 ·
You could probably use an AK-47 to make the holes if you are afraid of drilling in that location. Just be careful what is behind the target area before shooting it. The benefit might be it leaves some steel in place by piercing, then you can fold the shredded bits over and weld them a bit.
 
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