Replaceable Hardware (nuts/bolts)


  #1  
Old 05-30-23, 02:38 PM
M
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,914
Received 27 Upvotes on 21 Posts
Replaceable Hardware (nuts/bolts)

Curious why the manufacturer states to replace certain nuts and bolts when replacing parts but not others. I'm having the rear seal replaced on my 2011 TL and there are about 30 bolts highlighted in the procedure for replacement, but others that are not. In general, is it typically the hardware that is under more stress and higher torque that should be replaced? How critical is it that said hardware is actually replaced? I have a feeling that they won't replace any of it, because they never have in the past unless I specifically ask, and even then there have been times when they haven't. This is a very labor intensive job and I want to ensure it is done by the book, which is why I am having the dealer do it.

Here's an example (subframe):





I just counted, and there are 21 bolts and 6 nuts that the manual says to replace. Curiously, most of these are engine mount, transmission mount and subframe bolts. None of the transmission mounting bolts or torque converter bolts or drive plate bolts get replaced.
 

Last edited by mossman; 05-30-23 at 03:11 PM.
  #2  
Old 05-30-23, 04:04 PM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 9,745
Received 1,210 Upvotes on 1,098 Posts
Exactly, hardware that see stress, suspension, engine mounts, brakes are typ called on to be replaced more so because when used the locking patch is disturbed so torque could be compromised more so than the hardware is degraded, they usually have higher grade hardware in those areas.

To each themselves but I have never replaced anything that didnt look suspect, have re-applied Loctite a few times.
 
  #3  
Old 05-30-23, 04:13 PM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
One guess is the nuts and bolts in question are not a good grade of steel. They stretch when they were originally torqued. If removed and used again in the same location, the second stretching might result in the bolt breaking or the threads in the nut stripping.
 
  #4  
Old 05-30-23, 05:29 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,440
Received 4,050 Upvotes on 3,633 Posts
The hardware that calls for replacement are called "torque to yield" fasteners.
It's a fastener designed to be tightened once only. Replaced when removed.

The bolts actually stretch in location and cannot be used reliably again.
 
XSleeper voted this post useful.
  #5  
Old 05-30-23, 05:37 PM
M
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,914
Received 27 Upvotes on 21 Posts
I've heard of TTY bolts. So my next question is, if I pick up my vehicle after service and find that they didn't replace any of these bolts, do I have basis to fight this and to have them redo the job? Seems like I do since the service manual specifically says to replace them. I'm anticipating a "it isn't necessary", "we never do that", "we've never had a customer request that", "those are only recommendations", and "we have never had any issues before" blah blah. Sure, not that you know of or have taken the time to investigate the cause of a failure. I wouldn't be making such a big deal out of it if it wasn't directly related to the engine and the transmission, and many of them cannot he replaced after the fact without disassembly a bunch of things. For $1700, they should be doing everything to the book, washing my car, and buying me a steak dinner 😄

 
  #6  
Old 05-30-23, 05:49 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,440
Received 4,050 Upvotes on 3,633 Posts
There should be no excuse for a dealer to not use the correct parts.
Not sure how you'd know or could prove they weren't reused or changed.
 
  #7  
Old 05-30-23, 08:19 PM
M
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,914
Received 27 Upvotes on 21 Posts
Many of them I'd be able to see after the job and it should be obvious I would think. Also, I asked them to return all the old ones 😉
 
  #8  
Old 05-31-23, 12:05 AM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 9,745
Received 1,210 Upvotes on 1,098 Posts
Torque to Yield (TTY) fasteners are used in many modern engines. When torqued properly, they provide better clamping force than standard fasteners.
TTY fasteners are typ internal for engine/powertrain related, suspension/chassis use higher grade bolts, 10.9's.
 
  #9  
Old 05-31-23, 05:11 AM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
Glad someone spelled out TTY because when I was in school it meant a teletype machine. Can anyone share if TTY hardware has a special Society of Automotive Engineer marking or how a consumer knows he is purchasing a TTY fastener?
 
  #10  
Old 05-31-23, 07:33 AM
A
Member
Join Date: Aug 2015
Location: USA
Posts: 1,097
Upvotes: 0
Received 124 Upvotes on 107 Posts
not sure why there recommending replacement but its likely for other reasons other than being TTY which is most common for head bolts. it may just be due to being more prone to rust and corrosion or may have a locking nut like swagged nut that is only 1 time use, or the new bolts may have loctite already applied to them.
 
  #11  
Old 05-31-23, 12:00 PM
M
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,914
Received 27 Upvotes on 21 Posts
Seems like it may be a corrosion thing. I spoke with the service manager this morning and he said they don't replace bolts unless they are specifically one time use/TTY. I asked why the service manual would say to replace them and was given the "I'm not sure which manual you're looking at", and "ours doesn't say that". I guess I'll let it go. I just hope everything works properly once it's all put back together.

FYI, I have subscriptions to Alldata and Prodemand and they both contain the same diagrams pointing out which hardware to replace with the caption "courtesy of American Honda Motor Co." underneath 🤷
 
  #12  
Old 05-31-23, 03:18 PM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
Mossman, this is from post 1. "Curious why the manufacturer states to replace certain nuts and bolts when replacing parts but not others." Why didn't you show the service manager that document? How would one order correct "replace" bolts identified in diagram of post 1 at an auto parts store?
 
  #13  
Old 05-31-23, 04:19 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,198
Received 1,947 Upvotes on 1,747 Posts
You would replace TTY because they might look like these otherwise.

 
  #14  
Old 06-01-23, 08:29 AM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
XSleeper, thanks for the response, but it didn't answer my question. I could replace the bolts identified with "replace" in diagram in post 1 with anything from a SAE grade 1 to 8 with grade 1 the least expensive. How do I order the correct one and least expensive?
 
  #15  
Old 06-01-23, 10:08 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,198
Received 1,947 Upvotes on 1,747 Posts
I wasn't replying to you.
 
  #16  
Old 06-01-23, 11:39 AM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 9,745
Received 1,210 Upvotes on 1,098 Posts
10.9 as noted is the norm.

 
  #17  
Old 06-01-23, 06:05 PM
M
Member
Thread Starter
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,914
Received 27 Upvotes on 21 Posts
I'm lost 😄.
 
  #18  
Old 06-02-23, 04:54 AM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
The auto manufacturer specs the bolts in diagram of post 1 with "replace" because they know that bolt will stretch at assembly when torqued as specified. I want to get replacement bolts at a auto parts store because I don't want to pay a higher price at a dealer. Majority of counter people I have encountered are number chasers, not technicians. The parts guy at a dealer would give me bolts with a part number on the bag (not on the diagram) and nothing about the torque (on the diagram). The guy at the auto parts store grabs the correct size bolts (on the diagram) from a bin because I didn't speciify a grade because the auto manufacturer didn't specify a grade. How do you know you have the correct "replace" fastner? Mossman, you didn't answer my question in post 12.
 
  #19  
Old 06-03-23, 05:54 AM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,294
Received 308 Upvotes on 273 Posts
Finally found an answer for bolts. TTY bolts have a controlled yield zone (machined area between head and beginning of threads where diameter is less than the thread OD) to make it easier to torque the bolt into its elastic region. Bolt in photo of post 13 is not a TTY bolt because it has no controlled yield zone but has been torqued beyond its elastic limit as evidenced by the change in distance between threads. My conclusion is these "replace" TTY bolts should only be obtained from the car manufacturer's dealer because the car manufacturer is only one to do the calculations that speced these TTY style bolts. Still searching for how a TTY nut is identified.
 
  #20  
Old 06-03-23, 09:40 AM
A
Member
Join Date: Aug 2015
Location: USA
Posts: 1,097
Upvotes: 0
Received 124 Upvotes on 107 Posts
head bolts are commonly available at most any parts store I don't really see the need to go to the dealer for those but for other specific engine subframe or mount bolts probably a good idea to go to the dealer since we do not know if they are TTY or not unless you could get the grade and specs off the bolt then places like fastenal and other places that have a large assortment of fasteners could possibly be used to source an equivalent bolt.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: