View Full Version : TR4/4A TR4A Removing the old floor mount bolts?

07-24-2012, 08:20 PM
I've cut the heads off the old floor mount bolts and removed the the floor mount and plates. I've soaked the remaining threaded parts of the bolts for a couple of days with PB Blaster hoping to be able to remove them from the captive nuts with a vice grip. If this fails I'll have to drill the bolts out and clean up the threads with a tap. Anyone know what size tap or thread cleaner I should use?

07-24-2012, 09:55 PM
No but I feel your pain, the stubborness of those rusted on bolts kept me from doing a body off frame restoration on my 4A many years ago. After it became clear I would have to drill nearly every one out I cried uncle and removed the body panels but left the tub on the frame.

07-24-2012, 11:31 PM
From https://www.revingtontr.com/shop/catalogu...amp;PlateID=164 (https://www.revingtontr.com/shop/catalogue_page.asp?mscssid=LM6NT9NGUT4B8JJF22SG7P3 K6K5B1K45&CarType=TR4A&PlateID=164)
https://docs.google.com/open?id=0B2H2NJt34OffMjJhY2YwZmQtYzgxNC00ZTk0LTk1Y TUtZTIyZmU3ZTc1Y2M4

it appears that they are 5/16 NF.

07-25-2012, 05:45 AM
I have read on the forum before, that if you heat the bolts and nut up that the rust turns to carbon and then you might be able to get the bolts out, but I am not sure if its with a propane torch or oxy/ace torch and if you need to get them cherry red

as long as you dont catch stuff on fire might be worth a try


07-25-2012, 06:56 AM
I find that these combination drill and countersinks (https://www.reidsupply.com/sku/PTD-97604/) work great at getting a hole started when drilling out a broken bolt. Easy to get on center, but even if you initially miss the center of the bolt you can angle the drill down and "move" the hole and then slowly raise the drill back up while the drill is turning. You don't want to make this correction if you initially go to deep, or there is the possibility of breaking the end off. The key is to take your time. I usually use a #4 for this type of drill spotting.

07-26-2012, 06:23 AM
Have you tried tightening the bolt after letting it sit - sometime that can help break it loose. Heat, as mentioned, helps but watch the surrounding area of course.

07-26-2012, 08:26 AM
I bought the combination drill and countersink that Art suggested and I'm going to try that out on the rear mount bolts where I've cut the bolts flush to the mount . I had some luck with a front mount bolt that I've soaked with PB Blaster for 3 days.The heads are cut off these bolts to remove the plates and gain access to the threads.I cleaned the crud out of the bolt threads and hit the top of the bolts with a hammer to set up a vibration that would let the solvent seep in.I got one bolt to come out by turning a little one way then reversing a little then turning again. Had to use a vice grip to lock on to the headless bolt. Seemed to work for one bolt.I will see what happens with the others. :-) Karl

07-26-2012, 11:12 AM
Heat it up and touch around the exposed threads with a candle so that the wax melts into the threads. More heat then turn, reverse, turn. The wax will help get things so that they will spin more freely.

edit: Remember that when heating with a torch, the object that you heat will expand. So try to focus the heat on the threaded nut and not the bolt.

07-26-2012, 11:33 AM
After you get the hole spotted with drill & countersink, if the original screws are 5/16"-24, my charts show a letter "I" (0.272") drill for the final hole. Not a common size. 17/64" (0.266") is the common smaller size that should work for you. If you get close to the center with the spotting, chasing the threads should prove easy.

07-26-2012, 10:03 PM
Well I had great success with the PB Blaster and vice grip to remove the studs.You have to make sure the vice grip is on good and solid or you will just end up rounding off the threads. No heat recquired using this method. As for the drill and countersink on the bolts I cut off,I found that I could not get the 1/8 bit to bite very well into the bolt. I had a 3/16 bit handy so I drilled out the bolts with that followed by the countersink bit. Got the bolts out but I'm not sure how straight I was able to drill. Guess I will find out when I run the tap thru.