Connecting Rod Bolts

[KVH]

Can I re-use my existing connecting rod bolts on my TR4A and just use some Locktite?

My bolts look fine, and they are the self locking "place bolts" whatever that means. No tab washers. The flywheel bolts use the same name.

WOW the cost for new ones--$17 dollars each. I won't be cheap if you experts say to buy all new. Is it required?


[I'm imagining what kind of notice one would have of a connecting rod bolt becoming loose]

 

[rlandrum]

Any racer will tell you that the bolts stretch and deform after the first few torques, which causes them to have the incorrect torque settings. I reused mine on the TR3A. Even if they are 40+ years old, they'll hold fine. Replace only those that appear to be damaged.

 

[DougF]

Depending on the quality of the fasteners, they can lose 25% or more of their torquing strength after one use. I would look for other sources, $17.00 is a bit ridiculous but cheaper than a big hole in the side of the lock.

That said, I have reused fasteners inside the engine with no negative results...yet. But I have always had a backup long block just in case. The engine I am building now gets all new hardware.

It is good insurance to build it right the first time. They always seem to break when you are a good distance from home, at least further than your AAA towing range.

 

[Trick6]

I checked my rod bearings when I 1st got my TR6 home. As I was putting it all back together the rod blots would not torque up. So I checked the length of the ones I was tightening and the ones that I had not started. The bolts stretched. I ordered the ARP rod bolts and threw the old ones out.

IMHO, get new bolts and there will be no worries.

 

[TR6BILL]

I ordered the ARP rod bolts and threw the old ones out.

I hope you got the ARP bolts in before you threw the old ones out. Your rod may have to go to the machine shop for the ARP's to fit.

 

[Moseso]

My bolts look fine, and they are the self locking "place bolts" whatever that means. No tab washers. The flywheel bolts use the same name.

My understanding is that there are two different types of bolt used in this application. One is a more-or-less standard grade 8 type bolt, which is always installed with the lock tabs. These can be reused. The other type -- installed without lock tabs -- is designed to stretch when it is torqued. It is the "springiness" of this type bolt that makes use of the lock tabs unnecessary. This type of bolt should never be reused. It kind of sounds like that's what you've got. It's probably best to go with new ones.

 

[billspit]

Check with the varous sources for ARP rod bolts. I found a set for my Spitfire for around $50. It is highly recommended to replace them on 1500s, so I did. This engine has yet to be fired. Prior to that I had never replaced a bolt that wasn't damaged and have had no problems. Certainly if you are building a racing engine, you go with the best. The only bolts I know that yu cannot use are torque to yield bolts that are commonly used today if Fords. I seriously doubt that Triumph used those types of bolts in the 1960s.

Oddly enough, I replaced the cylinder heads studs on this enigine and snapped one when I torqued it down. These came from one of the big three. The crap you but today, may not be as good as the old stuff.

 

[Scott_Hower]

Personally, I would not reuse them. Nor would I trust anything I bought from the big three. ARP, Aircraft Spruce or my local CAT dealer is where I buy my hardware. McMaster Carr is a good source too.

 

[Trick6]

TR6Bill:

Right you are. The old motor got fresh rod bolts; replacements from one of the Big 3 and they torqued up just fine. I did check things as I reassembled the bottom end. That motor has been sold and replaced by another completely rebuilt bullet. I installed the ARP rod bolts in the new motor.

Thanks for having me clean that up.

Photos on the bottom end can be seen at the link below.

 

[glemon]

I have rebuilt a few motors and never replaced head studs, main or rod bolts, It may be good insurance, but if what you have is in good shape and torques down fine I wouldn't worry about it. But do use the loctite.

 

[TR6BILL]

Dave, at TRF, said it is a 50-50 call, replace or reuse. I reused. It is pretty rare to have a rod bolt fail on a street engine. That said, I am sure a hailstorm of different opinions will follow.....

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I am sure a hailstorm of different opinions will follow.....[/QUOTE]

I consider it insurance. Just my opinion based on previous knowledge and preferences. Not for everyone and possibly overkill, but that's just me.