I'm in the process of changing my trans mount and I can't seem to get the two 18mm bolts off that attach the mount to the transmission! I'm using a breaker bar and I'm pulling so hard that I'm moving the whole transmission in the direction I'm pulling. I put some PB blaster on there last night in hopes that I can get them loose today.

I really don't want to snap these bolts. Any tips on getting these loose? I don't own an impact gun but I'm thinking of getting one just for this...

 

Impact.

 

x2. Beat me to it. Ingersoll Rand 231c is a great mid level impact, can be found for $120 or so online or at Northern Tool if you have one close.

 

Impact gun it is. Thank you!

 

Another option is to make sure anything damageable is out of the way and apply some heat via a blow torch to the bolts and try again.

An impact should solve the problem, but my Dad (who is a master of freeing frozen bolts) would tell you to soak it in liquid wrench/pb blaster and tap the bolts with a hammer for a bit. Just a little tapping, don't beat on it, and repeat, then give it a bit of time and retry.

I'd also consider replacing those bolts when you do get them out, especially if you've started to round them at all, with new stainless steel bolts from your local hardware store. And I'd use anti-seize on everything when you put it back together.

 

I was considering replacing them, great idea. However, it's my understanding that the use of a grade 8 bolt would be better in this application. Perhaps it doesn't matter in this case? I'm not so sure.

 

Just make sure that whatever you use is at least the same strength as the old bolts. If the old ones come off and they're still in good shape afterward, there's no problem re-using them.

 

Welp, still can't get these off. I tried everything (heat, more leverage, PB Blaster, impact) I could and they just wouldn't budge. I'll be taking it to a shop to see if a professional can get them loose. For now, I just put the cross member back and hope for the best unless anyone else has some unique ideas?

The mount doesn't appear to be in terrible shape, but I have the new part just sitting around now. Very frustrating indeed...

 

What kind of compressor? I bought a Harbor Freight impact and at first it couldn't even break my lug nuts free, let alone removing the axle nuts. It turned out it was my regulator either bring inaccurate or clogged.

I wild bet a beefy impact will remove those in a few zips.


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If they are that tight, I'm guessing they have already been messed with at least once, and somebody cranked them in hard. If I recall correctly they are into aluminum, and typically anything into aluminum does not have seriously high torque specs. Either that, or someone put a lot of red loctite on them, and now they may need a little more heat to remove.

Mine were 20 year old factory originals when I did them, and I don't recall them being very difficult to get turning (just as a comparison). How much heat did you apply?

Are they rust-fused to the steel plate that they are holding up? If so, you may want to clean them up around the heads with a wire brush to help the penetrating oil get in there.

Impact is still probably best and will get it out with less chance of snapping something. Almost any local shop could probably get them started out for you for a modest amount.

 

If there's nothing nearby that will be damaged, give it more heat.

I was having trouble getting my steering knuckle off the ball joints and was on the verge of grabbing the sawz-all when gave it a last try with a second blowtorch (and 2nd human using it)and viola - it came apart.

 

Derp - double post

 

It looks like this (not my XJ, but mine is 2wd like this one). I don't have any rust on it either, the area looks clean. The bolts go into this adapter bracket that's attached to the transmission. You can see one of the bolts in this picture and it's right below the speed sensor, so I didn't want to apply too much heat to it.

I didn't have an impact before this so I bought one from Tractor Supply. It's rated at 450 ft/lbs. I tried it on my lugs which are at 100 ft/lbs and it took them off no problem. The torque spec for these transmission mount bolts is 55 ft/lbs, so either it's been removed before and torqued too much or it's fused.

Probably more heat and a better impact would work, which is why I just came to the conclusion that a professional should do it. I love my jeep but I can't spend hours trying to get two bolts off!

 

I stole your photo.....

 

If it has been previously covered in red loctite, it will take significant heat, and some time to allow the heat to migrate the length of the bolt.

I have a 450 impact and a 1200 impact. I find that 450 tends to be right on the border line for bigger stuff. Usually if I'm going after something for the first time my 450 impact won't get it and have to use the larger one (which gets almost everything). But then after the initial work is done, the small impact works on everything.

Loctite tends to absorb torque which also reduces what the impact is capable of.

If you a get a chance, follow up, and let us know how it turned out.