Subframe mount install
03-21-05, 12:36 AM
#1
Subframe mount install
Going to do it myself this time. Any specific instructionson how to swap out the subframe cushions or is it pretty straight forward? Where should I put the jack stands? Also can someone post the torque setting on the mounting bolts and the 2 subframe bolts? Thanks all.
03-21-05, 03:58 PM
#2
Pole Position
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By subframe are you talking about the rear for the anti-roll bar swap?
If you are, then there' should be (4)12mm bolts and (1)19mm bolt on each side. The 12mm takes ~80 lb-ft and the big one takes 95.
Here's an article I found in the Library: https://www.clublexus.com/index.php/...ew/2040/1/283/
If you are, then there' should be (4)12mm bolts and (1)19mm bolt on each side. The 12mm takes ~80 lb-ft and the big one takes 95.
Here's an article I found in the Library: https://www.clublexus.com/index.php/...ew/2040/1/283/
Last edited by Buttercup; 03-21-05 at 04:01 PM.
02-28-15, 12:46 AM
#4
Tonight, I found the correct number in a pretty random spot of the factory service manual, MA-17 in the section for mounting the seats and checking fluids.
The subframe bolts should be torqued to a much more reasonable 28 ft-lbs.Edit: I finally located the bolt on an appropriately mislabeled schematic, "Front Under Cover." Part #9011910679. Now to see if I can get it added to the Sewell order I just placed.
Last edited by t2d2; 02-28-15 at 07:17 AM.
03-01-15, 11:21 AM
#5
Lead Lap
The 8 bolts for the rear of the subframe are 43 ft-lbs. Part number 90119-10679
The 2 big bolts for the front of the subframe are 129 ft-lbs. Part number 52285-50010
Please note: All the subframe bolts should be replaced by brand new ones when you take them out. The bolts should also be re-torqued regularly (as per service manual).
The 2 big bolts for the front of the subframe are 129 ft-lbs. Part number 52285-50010
Please note: All the subframe bolts should be replaced by brand new ones when you take them out. The bolts should also be re-torqued regularly (as per service manual).
03-01-15, 02:41 PM
#6
Please note: All the subframe bolts should be replaced by brand new ones when you take them out. The bolts should also be re-torqued regularly (as per service manual).
03-01-15, 09:49 PM
#7
Lead Lap
Its cheap insurance to change the bolts because they tend to stretch over time
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03-02-15, 08:09 AM
#8
Ok, that explains that. I'm definitely siding with the SC manual. 
However, it raises a question I often wonder about: How important are torque specs, really? I've known and worked with plenty of engineers, and the idea that they would design things to work with only a specific number is rather humorous to me. (As is the commonly stated belief that their designs are beyond reproach (not approach!).) If something calls for 30 ft-lbs, I imagine you'll never notice a difference between 15 and 45... As long as you don't exceed the strength of the bolt, of course, which I may have at 65 ft-lbs on subframe bolts that call for 28 or 43.
But, you could say the same of the wheel studs, and they're likely to get stretched a lot more over time, being higher torque and changed much more frequently. And yes, wheel studs do stretch. I've seen it. Any bolt can stretch over time, but odds are that most of them are fine to re-use. If you see one that isn't, that's probably the right time to change it.
I read up a bit on caliper mounting bolts last week, and it would appear the real reason they're recommended replacement items is they get some sort of factory loctite, not because they stretch as commonly thought. Even without loctite, they work fine on repeated re-installations for many people. I have a hard time believing stuff like that is worth losing sleep over, unless you like spending an extra $10-20 every time you do maintenance on the car. The point being, factory recommendations are often not for the reason one might think. And they're often rubbish. Case in point, the factory torquing of our fuel filters.
Edit: Also, if the idea is that the subframe bolts are designed to stretch over time, then re-torquing them to spec upon reinstallation should be pretty much the same as replacing them. Why else would they recommend re-torquing regularly? The bolts must be able to withstand a fair amount of stretching, and we're not seeing a bunch of subframes falling off while driving...
However, it raises a question I often wonder about: How important are torque specs, really? I've known and worked with plenty of engineers, and the idea that they would design things to work with only a specific number is rather humorous to me. (As is the commonly stated belief that their designs are beyond reproach (not approach!).) If something calls for 30 ft-lbs, I imagine you'll never notice a difference between 15 and 45... As long as you don't exceed the strength of the bolt, of course, which I may have at 65 ft-lbs on subframe bolts that call for 28 or 43.
Its cheap insurance to change the bolts because they tend to stretch over time
I read up a bit on caliper mounting bolts last week, and it would appear the real reason they're recommended replacement items is they get some sort of factory loctite, not because they stretch as commonly thought. Even without loctite, they work fine on repeated re-installations for many people. I have a hard time believing stuff like that is worth losing sleep over, unless you like spending an extra $10-20 every time you do maintenance on the car. The point being, factory recommendations are often not for the reason one might think. And they're often rubbish. Case in point, the factory torquing of our fuel filters.
Edit: Also, if the idea is that the subframe bolts are designed to stretch over time, then re-torquing them to spec upon reinstallation should be pretty much the same as replacing them. Why else would they recommend re-torquing regularly? The bolts must be able to withstand a fair amount of stretching, and we're not seeing a bunch of subframes falling off while driving...
Last edited by t2d2; 03-02-15 at 08:33 AM.
03-02-15, 08:30 AM
#9
Lead Lap
Ok, that explains that. I'm definitely siding with the SC manual. However, it raises a question I often wonder about: How important are torque specs, really? I've known and worked with plenty of engineers, and the idea that they would design things to work with only a specific number is rather humorous to me. (As is the commonly stated belief that their designs are beyond approach.) If something calls for 30 ft-lbs, I imagine you'll never notice a difference between 15 and 45... As long as you don't exceed the strength of the bolt, of course, which I may have at 65 ft-lbs on subframe bolts that call for 28 or 43.
But, you could say the same of the wheel studs, and they're likely to get stretched a lot more over time, being higher torque and changed much more frequently. And yes, wheel studs do stretch. I've seen it. Any bolt can stretch over time, but odds are that most of them are fine to re-use. If you see one that isn't, that's probably the right time to change it.
I read up a bit on caliper mounting bolts last week, and it would appear the real reason they're recommended replacement items is they get some sort of factory loctite, not because they stretch as commonly thought. Even without loctite, they work fine on repeated re-installations for many people. I have a hard time believing stuff like that is worth losing sleep over, unless you like spending an extra $10-20 every time you do maintenance on the car. The point being, factory recommendations are often not for the reason one might think. And they're often rubbish. Case in point, the factory torquing of our fuel filters.
Edit: Also, if the idea is that the subframe bolts are designed to stretch over time, then re-torquing them to spec upon reinstallation should be pretty much the same as replacing them. Why else would they recommend re-torquing regularly? The bolts must be able to withstand a fair amount of stretching, and we're not seeing a bunch of subframes falling off while driving...
However, it raises a question I often wonder about: How important are torque specs, really? I've known and worked with plenty of engineers, and the idea that they would design things to work with only a specific number is rather humorous to me. (As is the commonly stated belief that their designs are beyond approach.) If something calls for 30 ft-lbs, I imagine you'll never notice a difference between 15 and 45... As long as you don't exceed the strength of the bolt, of course, which I may have at 65 ft-lbs on subframe bolts that call for 28 or 43.But, you could say the same of the wheel studs, and they're likely to get stretched a lot more over time, being higher torque and changed much more frequently. And yes, wheel studs do stretch. I've seen it. Any bolt can stretch over time, but odds are that most of them are fine to re-use. If you see one that isn't, that's probably the right time to change it.
I read up a bit on caliper mounting bolts last week, and it would appear the real reason they're recommended replacement items is they get some sort of factory loctite, not because they stretch as commonly thought. Even without loctite, they work fine on repeated re-installations for many people. I have a hard time believing stuff like that is worth losing sleep over, unless you like spending an extra $10-20 every time you do maintenance on the car. The point being, factory recommendations are often not for the reason one might think. And they're often rubbish. Case in point, the factory torquing of our fuel filters.
Edit: Also, if the idea is that the subframe bolts are designed to stretch over time, then re-torquing them to spec upon reinstallation should be pretty much the same as replacing them. Why else would they recommend re-torquing regularly? The bolts must be able to withstand a fair amount of stretching, and we're not seeing a bunch of subframes falling off while driving...
I think the torque setting for the supra may be higher because the supra subframe mounts have stiffer bushings and have the swaybar mounted to them.
03-02-15, 08:36 AM
#10
Now that you mention it, maybe I should side with the Supra manual on this one, since I've got Supra mounts and sway bar in place now. Interesting that the bolts themselves and what they thread into might not be the source of the torque specs in this case, rather the amount of force on the part(s) they're connecting.
03-02-15, 11:02 AM
#11
Lead Lap
Now that you mention it, maybe I should side with the Supra manual on this one, since I've got Supra mounts and sway bar in place now. Interesting that the bolts themselves and what they thread into might not be the source of the torque specs in this case, rather the amount of force on the part(s) they're connecting.
03-02-15, 11:07 AM
#12
I wish I had the right torque specs from the get-go, because trying to get 60+ ft-lbs out of those little 12mm bolts was a serious workout!
03-04-15, 10:20 AM
#13
However, it raises a question I often wonder about: How important are torque specs, really? I've known and worked with plenty of engineers, and the idea that they would design things to work with only a specific number is rather humorous to me. (As is the commonly stated belief that their designs are beyond reproach (not approach!).) If something calls for 30 ft-lbs, I imagine you'll never notice a difference between 15 and 45... As long as you don't exceed the strength of the bolt, of course, which I may have at 65 ft-lbs on subframe bolts that call for 28 or 43.
I'll say this as it relates to our situations. He helped his neighbor rebuild a racing transmission. Everything was torqued exactly to spec (torque and angle for most things). That trans has lived well beyond expectations and is one of those "unicorns" you hear legend of. Needless to say when the time comes for me to tear my motor down and build it back up, he'll be there measuring every bolt. I also pay closer attention to torque when I work on structural things or anything with a flange or gasket after talking to him. It all boils down to material sciences and yes it's important.
03-04-15, 03:25 PM
#14
SCereal, I hear ya, but aeronautics and gasket seating are much more extreme (in terms of tolerances) examples than simple bolt tension for holding solid objects together. Look at it in terms of these subframe bolts... The SC calls for 28 ft-lbs while the Supra calls for 43 ft-lbs for the same bolts and same mounting bracket, with the only apparent difference being the extra load the Supra sway bar places on the brackets. That tells us the SC bolts could just as easily call for 43 ft-lbs. Then, take into account that there's going to be at least a 10% margin of error built into any such spec -- again, because this is a much less extreme example than space travel -- and we're looking at anywhere from 20-25 ft-lbs up to 50-55 ft-lbs as an acceptable range for the exact same bolts.
The issue is that we see a torque spec as right and jump to the conclusion that everything else is wrong, when in fact many other figures simply haven't been tested and are likely every bit as right. Tightening to spec is of course the safest bet, but I bet your father-in-law knows what he's doing sufficiently well to improve upon specs in many cases.
The issue is that we see a torque spec as right and jump to the conclusion that everything else is wrong, when in fact many other figures simply haven't been tested and are likely every bit as right. Tightening to spec is of course the safest bet, but I bet your father-in-law knows what he's doing sufficiently well to improve upon specs in many cases.
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