Drilling holes perfectly straight through both frame rails?

[ba123]

Ok, let’s hear your tricks. This would definitely have been easier with the engine out but I didn’t know that in my order of operations. Seems my life is full of parts with poor instructions but I guess that’s what keeps your brain working.

I removed my never used Duff Shock Hoops and putting on the newer towers and running their single Eibach shocks and need to drill the holes through the frame and the holes have to be IDENTICAL on the other side of the frame as the support bracket. Copies the boot holes from the tower.

I first drilled the holes on the outside:

I went one by one and put a bolt through the hole. These holes are tight and no room to get it wrong. Stressful.
Then, I put BOTH rear plates together and used those as a guide to help keep my bolts as straight as possible and I used my 1/2” bit to make an indentation on the opposite side and proceeded to make the holes with a series of bits.

Two holes are perfectly aligned. One is close, and the other has another hole right next to it so I’ll have to get in tight with an angle driver with the plate on the other side.

What would you have done to get the holes closer to perfect? I do think this worked as well as possible, but curious. The other side will be a little more stressful as there is less room beteeen the gram and pass side of the engine.

I plan on using the same guide but adding this little homemade drill guide I came up with (I need a different fitting and I’ll drill it out to 1/2”):

But I might need some longer bits for that.

I have a little portable drill press attachment thing but the spring tower is in the way.

Like this:

 

[ntsqd]

https://www.amazon.com/dp/B01JUZVNE2/?tag=classicbroncos-20

 

[ba123]

https://www.amazon.com/dp/B01JUZVNE2/?tag=classicbroncos-20

Wow, that’s not messin around!!! If only I had 100 of these holes to drill, I could justify that! I like the magnet idea, that would work great!

 

[67sport]

Good chance you can rent a mag drill like shown above. They are pretty common in the steel trades.

 

[Yeller]

https://www.amazon.com/dp/B01JUZVNE2/?tag=classicbroncos-20

TS you beat me to it lol. Bought mine at an auction many years ago, pays the price of admission every time I use it. It sure is a manly feeling tool to use There is no better way to ensure straight holes on a frame.

Before I bought the mag drill I’d spend a lot of time making a jig that would slide over the frame to locate the holes, or if I could only access one side I’d drill a thick piece of aluminum or steel to help keep the bit straight for plunging to the other side.

 

[ba123]

TS you beat me to it lol. Bought mine at an auction many years ago, pays the price of admission every time I use it. It sure is a manly feeling tool to use There is no better way to ensure straight holes on a frame.

Before I bought the mag drill I’d spend a lot of time making a jig that would slide over the frame to locate the holes, or if I could only access one side I’d drill a thick piece of aluminum or steel to help keep the bit straight for plunging to the other side.

Yeah, the aluminum hole jig is exactly what I’m doing but a couple holes were just barely off.

I LOVE the mag drill idea and will see if I can rent one, thanks for that idea @67sport otherwise, I’ll use the aluminum along with my little pipe jig and a little prayer.

I have an impact angle Dewalt attachment that’s only 1.5” deep so could prob get a short bit to improve a hole from the inside if I have to. That’s what I used to fix the two holes on the drivers side but plenty of room for that and a regular bit.

 

[jamesroney]

Yeah, the aluminum hole jig is exactly what I’m doing but a couple holes were just barely off.

I LOVE the mag drill idea and will see if I can rent one, thanks for that idea @67sport otherwise, I’ll use the aluminum along with my little pipe jig and a little prayer.

I have an impact angle Dewalt attachment that’s only 1.5” deep so could prob get a short bit to improve a hole from the inside if I have to. That’s what I used to fix the two holes on the drivers side but plenty of room for that and a regular bit.

I’ve never had any luck getting those thru-bolts straight.

Always ended up drilling a pilot hole from the back side, then use the pilot to guide the finish hole from the front side.

Mag drills are the spawn of Satan, and yeah, I’ve got a couple of stories. I never understood why the magnet was on a different cord than the motor. I know now…

 

[Lando375]

I thought I'd share my experience with the same the same thing you are working on. I installed the same shock towers and drilled the the holes perfectly straight by using a 2x4 with a pilot hole. Once bolted up, I Welded them to to frame. The backing plates looked horrible so I make some new ones.

I torqued the bolts down and the frame began to bend. I thought it was because the new backing plate was not supported by the frame enough. I made some larger ones and torqued them down. The new backing plate and frame began to bend.

I ended up welding the holes on the frame and in the shock towers. I'm very pleased the way it turned out. If I had to do it over again I probably would have enlarged the holes and welded sleeves for the bolts.

I've attached some pictures for you.

 

[ba123]

I thought I'd share my experience with the same the same thing you are working on. I installed the same shock towers and drilled the the holes perfectly straight by using a 2x4 with a pilot hole. Once bolted up, I Welded them to to frame. The backing plates looked horrible so I make some new ones.

I torqued the bolts down and the frame began to bend. I thought it was because the new backing plate was not supported by the frame enough. I made some larger ones and torqued them down. The new backing plate and frame began to bend.

I ended up welding the holes on the frame and in the shock towers. I'm very pleased the way it turned out. If I had to do it over again I probably would have enlarged the holes and welded sleeves for the bolts.

I've attached some pictures for you.

Wow, that is craziness! Thanks for sharing the experience! If you torque more than needed, it does make sense that it would squeeze the frame. It only needs to hold it in place securely.

As far as looks, my engine is already in and I can tell there is no way you will see these things, mine fit behind the frame rail and do not stick above or below, but I totally understand what you mean if they did. These plates are certainly thicker than they need to be.

I also like the idea of them welded, but my frame is already painted and the Duff hoops I had on there were bolted and my old towers were removed and all work done before it was painted so I’m not welding.

I stopped by Home Depot on the way home just now hoping I’d find a shorty 1/2” drill bit but they didn’t have one. Guess I’m gonna try with what I have and order one if I need it.

If I had access to both side, I would’ve put one hole as straight as possible right through and then bolted a plate on each side to make all the holes perfectly even drilling only one side from each respective side. Doesn’t make sense to drill straight through from one side if you have access to both (I guess unless you have one of those cool magnetic drill presses), but ok @JamesR, let’s hear a story. It’s gotta be a good (or bad) story if you’re calling mag drills the spawn of satan.

 

[ba123]

Ok, I took a little more time planning and tackled this testy side a little differently. I tried my little pipe flange setup but I couldn’t find the right fitting that would give me support so tossed that idea.

I started the same way I did the other side, by using the two plates as guides. I drilled the outside holes, all good, easy of course

Then, with the plates, drilled one hole through and pilot holes through for all the other 3. I then bolted a plate to each side and slowly enlarged those pilot holes. I was obviously going to get through, which I did, and if any hole wasn’t perfect then the hole in the bracket was either going to guide me to the right place or I was going to drill a little of the bracket.

Worked like a charm. Only one hole slightly enlarged but fantastic.

@Lando375 my brackets do hang underneath slightly but you can’t see them.

 

[Lando375]

Great job, they look good. I see you used the lower mounting holes. I used the upper holes because I plan on install a body lift. It appears you may be running a body lift as well. I don't have my body on yet so I don't know what kind of clearance I'm going to have with the body lift and the shock towers.

Could you post a picture of the clearance you have between the tower and the inner fender?

 

[ba123]

Great job, they look good. I see you used the lower mounting holes. I used the upper holes because I plan on install a body lift. It appears you may be running a body lift as well. I don't have my body on yet so I don't know what kind of clearance I'm going to have with the body lift and the shock towers.

Could you post a picture of the clearance you have between the tower and the inner fender?

Thanks! Yeah, that might be an advantage to putting it on with body on. I have a 3.5” suspension lift and a 1” BL. I used the top holes as well as the top of the bottom elongated ones. Instructions said to not go closer than 1/2” To bottom of frame rail and I went just above that and using those holes seems to me what would be the strongest.

I also dropped the axle with the armoring attached as far as it would hang to I could see max travel of suspension vs shock so I wouldn’t bottom out the shock or bottom will be both at the same time.

I have about 2” on the drivers side (this is a 76 with a lower driver wheel well) and about 3” on the pass normal side.

 

[Lando375]

Thanks! Yeah, that might be an advantage to putting it on with body on. I have a 3.5” suspension lift and a 1” BL. I used the top holes as well as the top of the bottom elongated ones. Instructions said to not go closer than 1/2” To bottom of frame rail and I went just above that and using those holes seems to me what would be the strongest.

I also dropped the axle with the armoring attached as far as it would hang to I could see max travel of suspension vs shock so I wouldn’t bottom out the shock or bottom will be both at the same time.

I have about 2” on the drivers side (this is a 76 with a lower driver wheel well) and about 3” on the pass normal side.

View attachment 906110

Fantastic! That helps out a lot. Thanks!

 

[73azbronco]

might consider drilling to next size up, and sleeve it, yeah, more welding cutting blah blah. Anytime I have considered bolting through a frame, unless I had a bracket which wrapped the frame, sleeving was only way to stop crushing the frame.

 

[ntsqd]

A low(er) buck way that might work is what I did (lacking a mag drill myself) when I needed to hole-saw some holes thru an angled plate using an HF tube notcher:

For holes in a flat surface that "guide plate" wouldn't be needed. I did that to guide the hole-saw specifically because of the angled surface that I was cutting thru.

On sleaving the frame, I only drill one side big enough for the sleave. I thru-drill at bolt size and then follow up with a hole big enough for the sleave on the near side. Use a sacrificial bolt to hold the sleave tightly in place and weld it to the frame. Easier to do, only need to weld on the easy to reach side, and it captures one side of the frame instead of relying solely on the welds. When it's not a problem to do so I make the sleave longer than the width of the frame so that it stands slightly proud on the near side. Makes the welding easier and you don't have to grind anything to get the bolts to sit flat.

 

[Madgyver]

gusset a pie piece on top of frame to mount to add strength. frame metal is thin and will tear off if it starts.
ask me how I know.

 

[ba123]

Great job, they look good. I see you used the lower mounting holes. I used the upper holes because I plan on install a body lift. It appears you may be running a body lift as well. I don't have my body on yet so I don't know what kind of clearance I'm going to have with the body lift and the shock towers.

Could you post a picture of the clearance you have between the tower and the inner fender?

Also, with yours, as you mentioned, you used the lower hole so your bracket is higher and the top will be higher as well. Your shock will need to be longer also because of that so hopefully you mocked it up and know it’s the right spot for your shock.

 

[Wild horse 75]

One way to sleeve a frame without having to weld to the frame is to weld the sleeves to the backing plate. The sleeves will still stop the frame from crushing but you won’t have to end on your painted frame. You will want to ensure the sleeves are just slightly shorter than the frame is wide so you will actually be clamping the frame. If the sleeve is too long the backing plate won’t contact the inside frame rail and you will only be clamping on the outside wall.

 

[bmc69]

I’ve never had any luck getting those thru-bolts straight.

Always ended up drilling a pilot hole from the back side, then use the pilot to guide the finish hole from the front side.

Mag drills are the spawn of Satan, and yeah, I’ve got a couple of stories. I never understood why the magnet was on a different cord than the motor. I know now…

We were boring some holes in largish new-construction vessel vertically, from the "bottom up", in to a large steel ring that would mount the azimuthing thruster. BIG mag drills, self feeding, and we were running running three at once. Hell..each ring (there were two) probably had 24 1" holes in it. Took two guys to lift each drill up to the ring, locate it and power it up...working off a scaffold.

Then the shipyard lost power in the middle of a drill cycle....

You talk about some fellas scattering out from underneath the stern of that boat in rapid fashion!

 

[ba123]

We were boring some holes in largish new-construction vessel vertically, from the "bottom up", in to a large steel ring that would mount the azimuthing thruster. BIG mag drills, self feeding, and we were running running three at once. Hell..each ring (there were two) probably had 24 1" holes in it. Took two guys to lift each drill up to the ring, locate it and power it up...working off a scaffold.

Then the shipyard lost power in the middle of a drill cycle....

You talk about some fellas scattering out from underneath the stern of that boat in rapid fashion!

That’s scary!