2000-2001 dohc connecting rod bolts

[ian1976]

Didn't realize these are tty bolts till assembling .Says in my manual 19 ft lb and 75 degrees but Was told and saw on these forums 31-33ft lbs . Any one reuse them or know where to get them . Thanks in advance.

[ian1976]

Found 8 of them delivered for 21 dollars. I had an experimental rod laying around and played with it as i have one of the harbor freight digital torque meters and once one of the rods bolts hit 32 ft lbs could not get anymore out of it .Twisted it around about 1 1/2 more complete turns and stayed at 31 ft lbs spiking up just a little till she snapped. Other side went to 34 ft lbs and held for a half turn then she went down to 32 and again about 1 1/2 complete then snap. If anyones going to reuse I think the 31ftlbs that Oldnuc threw out there is spot on.

[DJKrohn]

I think that's why it's important to do the 75 degree method, because I've noticed the same thing with those particular bolts - that they'll just start turning and turning without added resistance.

[OldNuc]

The process is called torque to yield for a reason. Put them back in and using a decent torque wrench take them to 31ft-lb. That 75 degree turn is relying on the thread pitch to apply an accurate stress on the bolt. The FSM manual 19 ft lb and 75 degrees turns into about 32ft-lb if you wanted to just run a new bolt in and hit yield point but this is tough when the usual good calibrated torque wrench is hard pressed to hit 32ft-lb reliably. As you have now discovered the used bolt will be fine at slightly more than the 32ft-lb or 19ft-lb +75 degrees. This exercise was worked through in a much earlier post. As the entire process has maybe an accuracy as to final stress on the bolt of 15%-20% the 30-31ft-lb should be sufficient without reaching plastic deformation.

[ian1976]

I did get the new bolts ordered as I ordered the tranny input output and oil pressure relief valve so this weekend was out anyway. But I was absolutely shocked how much that thing stretched befor she went. I forgot to add earlier the rod had spun pretty good so she had been hot . I was thinking it was stripping the whole time and then when she snapped I under stood at that point TTY bolt hits it predetermined clamp force and stays there to the point of complete failure. Next question is do you think that aftermarket suppliers match oem yield on there bolts. Now that I did my little test kind of makes me wonder how consistent a cheaper aftermarket TTY bolt would measure up to a genuine bolt. I ordered felpro for the head and have had good luck with felpro but next time I do an engine I think I will use genuine .

[OldNuc]

There are no more OEM genuine bolts. They use aftermarket and rebag them. FelPro head sets are good. The rod bolts will be good if you buy from a named supplier. Get a real angle indicator as the 75 degrees is critical. There is a relatively narrow range of stress where the elastic elongation effectively terminates and this is before the plastic deformation range starts. It is this narrow range of maximum stress that TTY fasteners are stressed to as it is beyond elastic and before plastic. This provides the maximum rigidity of the fastener. Once you are in the plastic range the stress on the bolt actually decreases until it separates.

If you have rods that spun a bearing have them checked for size, round, twist, and bent before assembly or you may be doing this overhaul again.

[ian1976]

Thanks for the reply's Oldnuc. I'm the person that had the rods honed. I called the shop and he said he knocked .0001 .0002 out of each rod on a machine to make sure the were round and true . I had #2 and #3 that had left a little material on the crank but the engine wasn't cored at the wrecking yard for knocking it was cored for blowby and had 110k miles when the car was wrecked. The machine shop was the one who told me cracked/fractured rods couldn't be rebuilt unless oversize bearings were available to make up the missing material on the rod and thats why when i got them back from him and seen that they had been worked i was concerned. When i did plastigage it my largest oil clearance was .0018 and the rest were .0015-16 . The rod bolts I ordered are from GMpartsdirect and showed a gm part # but from what you say its an aftermarket rewrap . Again thank for all your knowledge and input.

[DJKrohn]

Those rod bolts are hard to find. I've always had to get them from the dealer. Fastenal doesn't know what to do about them. I once had the ARP part number for them, it was actually for some kind of old Ford 4 cylinder car from the 70's I think. I have no idea if ARP still makes that bolt.

[OldNuc]

GM Parts Direct is selling quality parts whatever the source and I suspect that there are some of these odd fasteners at Vintage Parts as that is where GMPartsdirect gets them from if they can. There are bearings with a 0.002 increased base shell thickness to deal with ground out rods.

The accuracy of plastigauge really concerns me but it is a major PITA to actually measure oil clearance.

[ian1976]

Ok Oldnuc now i'm worried if that machine shop is just lazy/stupid/dishonest or all above. Inspecting a visual on them can't see any discoloration as they are all nice and clean now . My clearances that i checked with plastgage aren't 100% accurate but are under the .0021 high end spectrum and definintly under the .0025 max. I'm here unsure how hot these things got and if i take them to another shop and get them set for oversize i'll be into the rods another 50+ bucks and whatever the new bearings are and i've still got rods that were hot but no bearing spin on the rod itself just the crank side . Would you put this motor together with these tolerances and rods w/new bolt ?Do you know of anyplace that sells brand new rods that would eliminate a lot . Thanks again for your input . Ian

[OldNuc]

I believe new rods are nonexistent. I would just use them as is. The only other option is to dig up a set of good used rods and go with those. I would shoot ShawnV a PM and see if he just happens to have a set that have never been cooked.

You can solve the high clearances by using a 5w-40 100% PAO synthetic oil. With a new engine you can get change intervals out into next year with no problems.

[ian1976]

Well then I think i'll run what I have on hand even though the clearances aren't perfect and run the 5w-40. If this car was ever going to see any real abuse i may be a little concerned but my 20 year old son will use this thing for the next decade.....seriously . He's 20 ,lives at home, never really wanted to drive but has a license and is a homebody thats getting his teatching AA and is the most laid back person you will ever meet and my 85 year old grandmother drives more aggressive than him. I drilled the 3/32nd on the pistons 6 holes and will wait for the OPRV and the new bolts and get it together. Again I do thank you for your time.

[OldNuc]

You should be OK with what you have in hand then.

[jimbo1490]

Hey folks,
I know this is a pretty old thread but I've got some new info that some may find helpful so here goes my revival...

First a little background:

I'm rebuilding the DOHC out of my 2000 SW2 (after a PCV hose broke on me and I burned 4 exhaust valves, but hey, it had 290K miles on it) and in the process of finishing up the short block I realized I could not torque the rod bolts. Yes I know, TTY but you can use them again torqued to 31 Ft-lbs , blah blah blah. The thing is they won't reach that torque! After ~300 in lbs they just keep spinning without getting any tighter 😬 (And no, I'm not dumb enough to keep on twisting until they snap off; I know very well what failure looks and feels like without taking it to that point.) This is not good, my friends. Would YOU trust those bolts??!! I certainly do not! As most of us know, new OEM bolts are made of unobtainium😁

So I got to thinking, there must a another engine out there that uses a rod bolt that will work in the Saturn 1.9 engines. (The bolts are M8 x 1.0 x 45mm high grade steel, for connecting rod use) As it turns out, there is! Many VW and Audi engines use a connecting rod bolt of identical dimensions. This same bolt is used in a wide range of engines by VW/AUDI, both gas and Diesel, natural and pressure aspirated making more power and spinning as fast or faster than a Saturn 1.9. They are widely available and will probably always be so given the production numbers for these engines.

P/N 045105425, or 045-105-425

Disclaimer:

This is not an endorsement of this part as interchangable with the Saturn OEM rod bolt so use at your own judgement and you assume all associated risks.

I will be buying a set of these and using them in this build.

Jimbo

[Waiex191]

Nice! I was still able to find a set in 2017. The '99 also uses the TTY bolts.