reuse head bolts and rocker bolts?

[jas98]

hi, can i reuse head bolts and rocker bolts on a vs v6?

i have in the past reused them on another vs and a vt but im not sure weather it is a must or is there a way to tell if i need new ones?

for the rocker bolts can i go to the bolt place and get them to meassure them and supplie me with some? or are they a special bolt?

 

[kiwicon]

Head bolts are TTY (torque to Yield) meaning they are slightly streached when they are tightened down.. if you reuse them you can stretch them beyond their yield point causing the bolt to break.. so you SHOULD REALLY get new ones...

 

[jas98]

thats what i thorght butbthe gregorys manual ( just found it) says to cleannhead bolts and reuse with some locktight. but dont reuse the rocker bolts......

 

[Immortality]

Both are TTY bolts as mentioned above and should be binned once removed.

Go down to your local engineering shop with some sample bolts and get the equivalent cap screws (grade 12.9) and hardened washers to suit, also ask for the correct torque specs for these bolts. Grade 12.9 is as good as (if not slightly better) entry level ARP head bolts and they are re-usable.

TTY bolts are generally easy to identify by their torquing instructions. Regular bolts will be torqued to X spec (sometimes in steps), TTY bolts are similar but the last step is normally to further turn the faster Y number of degrees.

All bolts stretch when torqued, it is this stretching of the fastener that provides the clamping force between the 2 mating surfaces. A regular bolt (if not over torqued) will stretch within a set limit and when released will return to it's original length, this is known as elastic deformation. TTY bolts on the other hand when torqued are stretched beyond the elastic deformation point to what is known as plastic deformation and will not return to it's original length once released. It's quiet an interesting subject but can get very involved if you are at all interested in engineering. The ARP catalogue has some good info about it.

 

[gossie]

New ones are best.

 

[jas98]

ok weired how the gregories says just to clean bolts up snd reuse but replace the rocker arm ones haha

so are the rocker arm ones a 8.8 grade bolt or 12.9? as id like to get reuseablr ones. csn i use 8.8 grade??

 

[Immortality]

Grade 8.8 is you basic high tensile bolt. I'd just use 12.9 all round.

 

[jas98]

thanks. also book says to use lovktight on head bolts. should it be locktight or thread sealer? do any of the bolt hokes open into coolant pasages??