| Author | Message | ||
| arthur chambers (Art355)
Intermediate Member Username: Art355 Post Number: 1264 Registered: 6-2001 |
Ben: Not only would I replace them, I'd try to find a better spec bolt of the same dimensions. | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 240 Registered: 5-2001 |
ok, thanks everyone, you have managed to scare me into spending $ for new rod bolts, hope your all happy now  I will buy new rod bolts, but Im giving them it in all pennies, so there gonna earn it. | ||
| Jere Dunham (Questioner)
Member Username: Questioner Post Number: 332 Registered: 1-2003 |
Ben, You said you do not mind spending money on a performance item. The rod bolts in a Ferrari engine are performance items. If they break, the engine stops performing!!!!!!!! Seriously, if they have been stretched any at all, replace them. I did not on an engine rebuild I did on a muscle car years ago and lived to regret it. Within two weeks, one of the bolts let go and spit the rod out the side of the block at 5000 rpms. And for as little as what those GM bolts cost then, I should have been shot. I considered shooting myself. | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 238 Registered: 5-2001 |
ok what companies and part numbers | ||
| peter james moran (Pjm)
New member Username: Pjm Post Number: 43 Registered: 3-2002 |
Replace, replace, replace. You don't have to use Ferrari bolts - there are companies that make better bolts that meet specification for less money. | ||
| JohnR. (Rivee)
Junior Member Username: Rivee Post Number: 178 Registered: 1-2002 |
Sean, Very Funny,... but true Rivee | ||
| philip (Fanatic1)
Junior Member Username: Fanatic1 Post Number: 102 Registered: 2-2003 |
Richard has a good point...as do a lot of you...I really enjoy this board, however, when I read threads like this, I realize how very little I know..............but it's fun to learn!!! | ||
| Richard Ham (Hampappy)
New member Username: Hampappy Post Number: 5 Registered: 2-2003 |
Part of my job is defining tightening specs for the bolts on engines, so here we go again. Apologies in advance if this annoys anyone! If a bolt is specified to be tightened only with a torque, then it is not loaded fully up to it's yield point. It's not posible to do this using only a defined torque. This means it can be used again. If you need to use a bolt efficiently because of space or weight reasons or whatever then it is normal to tighten with a pre-torque followed by an angle. This means that it is normally taken over it's yield into the flat part of the load deformation curve. In this way you get about 50% more load. Then it can be dangerous to use it again, if it is taken well into its yield. Most 10.9 quality bolts fail after stretching about 5% of their clamp length. However even using a pre-torque and angle you can use a bolt many times. We do this all the time because the tightening spec is made just into yield and no further. I guess it boils down to that if the bolt is specified for torque only, and it isn't damaged (diameter necked down or thread pitch looking greater anywhere)then it can be used again. Although this would give me the willies on my ferrari engine, so would 625$. I would use them again. Custom made bolts sound a bit dodgy. Normal production bolts have rolled threads, which greatly increase their strength. hope this helps and apologies again | ||
| Sean F (Agracer)
Junior Member Username: Agracer Post Number: 86 Registered: 2-2003 |
Ben, You're not paying $612 for the Ferrari Bolts. The bolts are $5 each. It's the yellow box they come in that cost so much money. Don't you know how hard it is to make cardboard that color yellow? ;) | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 234 Registered: 5-2001 |
Thanks for all the advice, I have always replaced rod bolts in the past so I dont have any experience using old bolts. Anyhow I am going at noon today to match up an ARP rod bolt. The tech yesterday said the 184-6001 should fit, and its only 79$. If it happens to not work, ARP said they could custom make bolts but you have to talk to the factory direct, and they said its more expensive, Im sure its still less then 1/2 the price of a Ferrari bolt. | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 488 Registered: 6-2002 |
Ben - we share your pain. However, do you prefer a little pain, or a big smack up side the head? It's a metallurgical / mechanical engineering thing. When brought to the proper torque specification, all bolts will "stretch" a calculated amount. With rod bolts, this stretch provides a "preload" that prevents the nut from coming loose, and acts as a "spring" to keep the rod-cap at proper dimensions/clearance on the crank journal. Unfortunately, the material used for these bolts is not "plastic." When the nut is removed, the bolt will not return to its original length. It stays at the stretched length. The next time you torque them, they stretch again. However, the strength of the bolt has been compromised as it has been stretched like taffy. As others have suggested, you will probably get away with it. Most mechanics do. Me, I prefer a good night sleep, and for $624, that's the cost of two nights at a fancy hotel. If a little thing like worrying about when they will let go doesn't bother you, then heck, it's the Four Seasons for you. Jim S. | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 233 Registered: 5-2001 |
I have an appointment tomorrow. ARP said that maybe the 184-6001arp bolts will fit, so Im gonna try it. I refuse to spend 621$ on rod bolts. I just wont do it, I dont care if I have to re-invent the wheel , I will find anouther way. Paying 621$ for only 16 bolts just pisses me off. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 486 Registered: 11-2002 |
I have re-used them only when I could not get new ones quick enough. Worked fine. Kinda like buying insurance IMO. | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 232 Registered: 5-2001 |
Willaim- are the bolts and nuts you re-use on a ferrari motor? | ||
| William Badurski (Billb)
Junior Member Username: Billb Post Number: 163 Registered: 6-2001 |
Guess I'm just lucky. Reused rod bolts and nuts all the time. No failures, many years and miles of use. Run the Daytona to redline all the time. If the bolts are damaged, that's different. | ||
| Mitchell Le (Yelcab1)
Member Username: Yelcab1 Post Number: 514 Registered: 11-2001 |
I replaced rod NUTs, reused rod BOLTS. Main bearing caps are held by studs so i only replaced the hardened washers. | ||
| Sean F (Agracer)
Junior Member Username: Agracer Post Number: 85 Registered: 2-2003 |
Call Norwoods in Dallas. They talked about ARB bolts in the 308 engine rebuild write up in last months Forza magazine. | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 231 Registered: 5-2001 |
ARP doesnt show a Ferrari listing, anyone know of which one interchanges with a ferrari rod? | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 488 Registered: 4-2002 |
The rod bolts are some of the heaviest stressed parts in any engine. And their failure mode is (also) rather exciting--they lurk around for any amount of time--until you get it on, take it up to red line--and whango--they let go--taking the entire engine with them {block, rods, crank, pistons, bores, valves}. This would be more of a $15K rebuild than a $6K rebuild. These bolts are torqued to ~1/2 their rated load. They need this kind of tension to join the bottom cap to the rods so that cap/rods do not separate as the pistons decelerate towards TDC (point of greatest tension in the con rods). At his instant, these bolts are operated AT their rated load, (not a good percentage, at). Use new ones. (Although ARP is a fine substitute) | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 230 Registered: 5-2001 |
I dont mind spending money on a performance item, but slays me to spend that much on rod bolts. | ||
| Bob Campen (Bob308gts)
Member Username: Bob308gts Post Number: 498 Registered: 9-2001 |
I would check if ARP makes a replacement set first | ||
| Mark (Markg)
Member Username: Markg Post Number: 440 Registered: 2-2001 |
ALlWAYS replace rod and flywheel botls; main cap bolts not a bad ides either; these are one-torque only specification bolts.... | ||
| '75 308 GT4 (Peter)
Advanced Member Username: Peter Post Number: 2647 Registered: 12-2000 |
$624 or +$6000 for a rebuild (if it lets go)? No choice here dude... | ||
| Ben Millermon (Brainsboy)
Junior Member Username: Brainsboy Post Number: 229 Registered: 5-2001 |
My Ferrari manual says you have to replace the rod bolts and nuts, no choice. Has anyone re-used the old bolts before? I know why they should be replaced, but that was when I was working on american cars and they cost 65$ a set. At 624$ a set for a ferrari, Im tempted to use the old ones. Anythoughts |