Hello 01 3.8L here,

I am new to the forums but I am familiar with the help these websites can provide. Recently my Crankshaft Positioning Sensor went bad. I went through the repair not fully understanding what a TTY bolt was. Came to find out that the harmonic balancer bolt needs to be changed.

Unfortunately I am unable to find this bolt anywhere, Chevy, autozone, Napa, you name it.
An employee at autozone told me the bolt was a M16 x 2.0. I am assuming I will need to find a bolt at a hardware store. I just don’t know where to look.

Any help or knowledge on the thread/pitch/length would be greatly appreciated. I tightened the bolt as much as I could and drove the car home. I am nervous to drive it anywhere else with the cloud of catastrophic destruction over me.
Please help!

 

You need to know the length. M16= 16mm outer thread diameter and 2.0=2mm between treads. Any hardware store will have a bolt section If you are going to try this get a grade 8 or Cap screw grade and the washer. You also want to put lock tight on the threads before you install it. The below one is from Amazon. It is 60 MM long (about 3-3/8") Most hardware stores will have bens and you can buy one at a Time. Tractor supply sells them by the pound.
https://www.amazon.com/Dorman-423-760-M16-2-0-Metric-Screw/dp/B0033YHOGI/ref=sr_1_8?crid=2RFOGNT05F6TT&keywords=M16+X+2.0+C ap+screw&qid=1694916852&sprefix=m16+x+2.0+cap+scre w%2Caps%2C98&sr=8-8

https://www.amazon.com/Threadlocker-H-271-Permanent-1-69-Fl/dp/B0BQDVF3VF/ref=sxin_17_pa_sp_search_thematic_sspa?content-id=amzn1.sym.afd9c6b4-b179-4d6a-8ad1-7056a39c01ab%3Aamzn1.sym.afd9c6b4-b179-4d6a-8ad1-7056a39c01ab&crid=2X2RO8H5MDVSP&cv_ct_cx=lock%2Bti ght&keywords=lock%2Btight&pd_rd_i=B0BQDVF3VF&pd_rd _r=6f83eb65-6354-42df-a9ef-e74f15bd6cd2&pd_rd_w=IVTol&pd_rd_wg=b1m7Q&pf_rd_p= afd9c6b4-b179-4d6a-8ad1-7056a39c01ab&pf_rd_r=XSTA2FY4A69J69MQGV1J&qid=1694 917362&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&spre fix=lock%2Btight%2Caps%2C109&sr=1-4-2b34d040-5c83-4b7f-ba01-15975dfb8828-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9zZWFyY2hfdGhlbWF0a WM&th=1

Call the dealers and get an original one if you can. They built the 3800 all the way up to 2009 they may still produce the bolt.

The main reason engineers use a TTY bolt is because they do not have enough length for bolt to properly expand and contract. This can cause the bolts to stretch over time. The longer bolt now means that it is looser. With the lock tight I do not think it would come loose soon. It could last for years.

When you tighten a TTY bolt in a way the bolt fails right at the end of the tightening. The they metal then becomes very spring like. This allows whatever the bolt is holding to expand as much as it wants and never get loose. Problem is the next time you tighten it you now pulled the "spring" as long as it can stretch.

 

https://www.ebay.com/itm/392498251018
This is the only bolt I found. This is the same bolt but used. No other options I am seeing look the same

 

I have done some digging. Come to find out 1998-2002 Camaro and firebird 3.8L have a different harmonic balancer which also has a slightly different bolt. Upon further research you apparently CANNOT buy a NEW bolt or balancer. Plenty of other posts around the internet about this issue. Even websites specifically list compatibility with pre 97. Rock auto just does not have sections for these parts post 97.

So I guess my next question is can I just put a 99 balancer and bolt onto my motor?

 

I can not say from personal experience. I used Car-parts.com to check compatibility of parts. So I just search for my car parts and see what models it shows will work. In this case the site is showing 1995-2004 3800's harmonic balancers are interchangeable. I am not 100% sure about the bolt, but I would think that you would use the bolt with the balancer it was design for just verify the crank is threaded deep enough to work.

I do know used TTY bolts should go to the scrap yard and have zero value. Your better off with a grade 8 bolt (Grade 10.9 metric) and lock tight. Use a paint market to make a line on the bolt and the pulley so you can see if it starts to loosen. If it does remove clean re-apply lock tight and retorque. I would torque it to about 250 lb/ft of torque. That is the low side of the spec for that bolt. After that whenever you change your oil take a peek and see that the line of paint is still straight.

Sorry I aways think in SAE so Grade 8 is the strongest high volume bolt. The metric equivalent is 10.9. It should be right on the head of the bolt.