old_man
NAXJA Forum User
- Location
- Loveland, Colorado
A right angle chuck for your drill and stubby drill bits.
-
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Interesting Motor Mount Problem
- Thread starter cjohnson
- Start date
jeepsrock
NAXJA Forum User
- Location
- LA California
Well here is an update to my mess.
I got bolt 1 and 3 out with the ez outs and the bolt thread is fine.
Bolt two on the other hand is really messed up. The ez out did nothing and almost broke. I tried progressiviely larger and larger drill bits to try to salvage the situation and honestly things may have gotten worse.
I stopped with a 5/16 drill bit and it seems that i can see the threads perfectly on one side of the hole but on the other side the drill bit killed them. So i know i basically have two options now - either use a helicoil or tap it one size larger. Whats your guys recommendation ?
Thanks
pete
I got bolt 1 and 3 out with the ez outs and the bolt thread is fine.
Bolt two on the other hand is really messed up. The ez out did nothing and almost broke. I tried progressiviely larger and larger drill bits to try to salvage the situation and honestly things may have gotten worse.
I stopped with a 5/16 drill bit and it seems that i can see the threads perfectly on one side of the hole but on the other side the drill bit killed them. So i know i basically have two options now - either use a helicoil or tap it one size larger. Whats your guys recommendation ?
Thanks
pete
5-90
NAXJA Forum User
- Location
- Hammerspace
I'd go Helicoil, but if you don't have a good centre, you're going to have to field modify the engine mount bracket anyhow (as you will if you overdrill/tap the hole to the next size up - should be 7/16"-14, I'm thinking.) And, I'm not sure if you can get screws in the next size up only one inch long - so you'd DEFINITELY have to use washers!
This illustrates why there are so many lengths of drill bits - and I keep a set of "screw machine length" drill bits around - just for cramped jobs like this. Screw machine bits and a right-angle drill will get you into some amazing places...
5-90
This illustrates why there are so many lengths of drill bits - and I keep a set of "screw machine length" drill bits around - just for cramped jobs like this. Screw machine bits and a right-angle drill will get you into some amazing places...
5-90
jeepsrock
NAXJA Forum User
- Location
- LA California
Well it seems either way i have to drill a 25/64 hole in the block. After that i can either tap it with a 7/16 tap like you suggested or use the helicoil kit.
Can you explain why a helicoil would be better than just tapping it and trying another larger screw ? Why wouldnt a screw be available in an inch.
pete
Can you explain why a helicoil would be better than just tapping it and trying another larger screw ? Why wouldnt a screw be available in an inch.
pete
5-90
NAXJA Forum User
- Location
- Hammerspace
A Heli-Coil is useful beacuse it would allow you to use the same size screw.
As far as "not being available in an inch," there is usually a minimum length in which they bother to make a certain diameter of screw. For instance, you can get 1/4"-20 screws with 1/2" underhead length, but you can't get 5/16"-18 screws easily in anything shorter than 3/4" Following that pattern, figure that 3/8"-16 screws will have a minimum underhead length of either 3/4" or 1", and 7/16"-14 screws would have a minimum length of 1" (unlikely, I think) or 1-1/4" (more likely,) but I'd have to check.
It's the same sort of standard that governs the threaded length of screws - if the shank is three "diameters" long or less, it's fully threaded. If the shank is more than three "diameters" long, they only thread three diameters' worth, unless you specially order full-thread screws. For instance, a 1/2" screw 1-1/2" long or less will be fully threaded, but 2" or longer will only be threaded for 1-1/2" of its length.
If you can get a 7/16" screw to work (probably with a stack of washers...) you'll end up needing to "clearance drill" the engine mount bracket - meaning that the hole will now need to be at least 25/64" or 15/32".
Simply stacking a batch of washers under the screw head would look a little shonky - but it's up to you. One or two can usually be hidden - six or so (which is what you'd probably need) gets ugly.
5-90
As far as "not being available in an inch," there is usually a minimum length in which they bother to make a certain diameter of screw. For instance, you can get 1/4"-20 screws with 1/2" underhead length, but you can't get 5/16"-18 screws easily in anything shorter than 3/4" Following that pattern, figure that 3/8"-16 screws will have a minimum underhead length of either 3/4" or 1", and 7/16"-14 screws would have a minimum length of 1" (unlikely, I think) or 1-1/4" (more likely,) but I'd have to check.
It's the same sort of standard that governs the threaded length of screws - if the shank is three "diameters" long or less, it's fully threaded. If the shank is more than three "diameters" long, they only thread three diameters' worth, unless you specially order full-thread screws. For instance, a 1/2" screw 1-1/2" long or less will be fully threaded, but 2" or longer will only be threaded for 1-1/2" of its length.
If you can get a 7/16" screw to work (probably with a stack of washers...) you'll end up needing to "clearance drill" the engine mount bracket - meaning that the hole will now need to be at least 25/64" or 15/32".
Simply stacking a batch of washers under the screw head would look a little shonky - but it's up to you. One or two can usually be hidden - six or so (which is what you'd probably need) gets ugly.
5-90
needsrepair
NAXJA Forum User
- Location
- Michigan
I often use an engraver for broken bolt removal. I have a chicago pneumatic that has worked for years. I also have a cheapie thats useless. If the bolt isnt bottomed or froze too bad this method works good. Get on the bolt at an angle so the tip bites in and then walk the bolt around until its out far enough to grab. With many repairs of this type finesse is needed. Sometimes penetrating oil is needed, or a little heat and wax. After the area is heated up a little the wax will suck down into the threads. Dont go wild with the heat. When removing broken bolts dont be in a hurry. If your using an engraver or using a chiesel method as mentioned above try going back and forth, dont be in a hurry and force it. It may not appear to be moving at first but work it back and forth before moving on to the next method.
rickoregon
NAXJA Forum User
- Location
- Burns, Oregon
Hey, some good ideas in this thread for bolt removal!
Regarding bolt length, Mcmaster.com has 7/16" - 14 bolts in 1 inch lengths, grade 5 (120,000 psi tensile strength). Even have them down to 3/4 inch length. Downside of ordering there, however, is that minimum purchase for this size bolt is a pack of 50 (cost is $8.60 for a pack). Fyi, Rick
Regarding bolt length, Mcmaster.com has 7/16" - 14 bolts in 1 inch lengths, grade 5 (120,000 psi tensile strength). Even have them down to 3/4 inch length. Downside of ordering there, however, is that minimum purchase for this size bolt is a pack of 50 (cost is $8.60 for a pack). Fyi, Rick
jeepsrock
NAXJA Forum User
- Location
- LA California
I am gonna try to find a helicoil kit today and try to take care of this, bc i need my car back on the road.
A few things interesting to know is that my driver side rubber mount is cracked in half, maybe thats what caused the stress to begin with.
The second thinng is that the stock engine mount bolts that sheared off are grade 8, i find it interestin that they didnt use grade 5 like you guys recomend.
Pete
A few things interesting to know is that my driver side rubber mount is cracked in half, maybe thats what caused the stress to begin with.
The second thinng is that the stock engine mount bolts that sheared off are grade 8, i find it interestin that they didnt use grade 5 like you guys recomend.
Pete
jeepsrock
NAXJA Forum User
- Location
- LA California
Well guys after a night of major cussing at the jeep, last night i believe i finished the job.
I ended up using the helicoil, and boy is that a little intresting device as i never used one before. Anyways i replaced the other sides bolts also as they are probably stressed from the engine hanging on them for a while. I used 3/8-16 grade5 1 inch bolts with a washer (like suggested above). I also found that the driver side rubber mount was seperated into two pieces which i replaced with a new part from pepboys.
I really hope this holds up for a while bc ,to be honest with you this was an annoying job aswell as a knuckle buster. I drove the jeep today and it did well.
thanks for the help guys
pete
I ended up using the helicoil, and boy is that a little intresting device as i never used one before. Anyways i replaced the other sides bolts also as they are probably stressed from the engine hanging on them for a while. I used 3/8-16 grade5 1 inch bolts with a washer (like suggested above). I also found that the driver side rubber mount was seperated into two pieces which i replaced with a new part from pepboys.
I really hope this holds up for a while bc ,to be honest with you this was an annoying job aswell as a knuckle buster. I drove the jeep today and it did well.
thanks for the help guys
pete
micklongley
NAXJA Forum User
- Location
- Salinas, CA
Hey Chip, Did you ever get this figured out? what was your solution?
Mick
Mick
