ZRP Forged Conrods
Discussion
Tangs also help locate the shell radially during assembly. When I showed a dual tang cut rod to a friend who does engine and component machining for Ilmor, Cosworth and a number of BTCC teams, he said whoever produced them needs lining up against the wall and shooting.
If the bearing does move radially then the end of the tang will contact the bottom of the tang groove in the opposing half of the big end. As this gets shallower it can cause the bearing to nip in.
Dave
If the bearing does move radially then the end of the tang will contact the bottom of the tang groove in the opposing half of the big end. As this gets shallower it can cause the bearing to nip in.
Dave
Interesting you should say 'night and day' that is what we think about different quality rods.
We only use a stretch gauge for fitting our rod bolts where specified nowadays. I get the feeling not many engine builders use them, preferring a torque setting which does not relate to clamping pressure only friction.
http://www.hotrod.com/articles/using-rod-bolt-stre...
Peter
We only use a stretch gauge for fitting our rod bolts where specified nowadays. I get the feeling not many engine builders use them, preferring a torque setting which does not relate to clamping pressure only friction.
http://www.hotrod.com/articles/using-rod-bolt-stre...
Peter
Mignon said:
There is still not the slightest indication that what failed on the OP's engine was anything to do with the conrods.
We know this, i'd like to see this Gulf of difference he sees between one and the other.No doubt like you i've seen the finger pointed at the wrong component many many times and stuff covered over for ulterior motives. I had a customer recently bring me some rods he claimed were Arrows, they weren't, but he and many others would never have known.
The other thing the OP doesn't seem to realise is that he's just binned a set of £400 rods when he could have been scrapping a £1000 set of Arrows instead so he's saved £600. Half decent rods are so cheap these days that in some cases when they bear the brunt it's an advantage if other components survive.
As I stated earlier in the thread, I was not seeking to lay the blame of failure solely with ZRP and there were other contributing factors.
I, like many other people, have to rely upon the knowledge and skills of an engine builder. Unfortunately, in my case there was a breakdown in communication and certain concerns were not understood until too late in the day. Initially my understanding was that the builder had said that although not overly impressed with the quality of the ZRP rods, they appeared to go together OK and the only thing of note was how heavy they were, in comparison to the OE rods. Having spoken to him in person (after the failure) it appears he had concerns over the thickness of coating in the small end, the variation in material thickness along the length of the road and the oil way size. As I say, unfortunately these concerns did not reach me till it was too late, or else I would have taken his advise and not used the rods. I would have taken that decision based upon the fact I am paying the guy for his expertise and to simply ignore it would have been foolhardy.
It was his opinion that the overheating possibly contributed to the failure of the big end, although there was also concerns about thickness of internal big end surfacing and its wearing through before the bearing eventually spun.
Either way, there were several factors at play. For whatever reason though, had I not misunderstood third party information, I would have taken the builders advice and not used the ZRP rods.
In relation to the Arrow rods however, initial inspection shows the quality of finish far exceeds the ZRP. Obviously the checks that Mignon kindly wrote about would need to be employed to confirm their being so. Just the quality of packaging and the overall finish of each individual rod hints at a far better quality of product though. (I realise this is cursory inspection by eye and not how rod quality is checked!) I also bought my rods directly from Arrow so am pretty confident that they're genuine.
In relation to your final point though, it could be that a better quality rod would not have suffered a failure brought about by the short overheat? In which case, spending the extra on Arrow rods would have actually saved me several £k's in rebuild costs. That said, if my sister had balls she'd be my uncle. As I say, there were several things that led to the ultimate failure of the big end and no single thing I would seek to lay at the door of ZRP. Any questions over their (ZRP) quality are simply the opinion of the engine builder I used.
I, like many other people, have to rely upon the knowledge and skills of an engine builder. Unfortunately, in my case there was a breakdown in communication and certain concerns were not understood until too late in the day. Initially my understanding was that the builder had said that although not overly impressed with the quality of the ZRP rods, they appeared to go together OK and the only thing of note was how heavy they were, in comparison to the OE rods. Having spoken to him in person (after the failure) it appears he had concerns over the thickness of coating in the small end, the variation in material thickness along the length of the road and the oil way size. As I say, unfortunately these concerns did not reach me till it was too late, or else I would have taken his advise and not used the rods. I would have taken that decision based upon the fact I am paying the guy for his expertise and to simply ignore it would have been foolhardy.
It was his opinion that the overheating possibly contributed to the failure of the big end, although there was also concerns about thickness of internal big end surfacing and its wearing through before the bearing eventually spun.
Either way, there were several factors at play. For whatever reason though, had I not misunderstood third party information, I would have taken the builders advice and not used the ZRP rods.
In relation to the Arrow rods however, initial inspection shows the quality of finish far exceeds the ZRP. Obviously the checks that Mignon kindly wrote about would need to be employed to confirm their being so. Just the quality of packaging and the overall finish of each individual rod hints at a far better quality of product though. (I realise this is cursory inspection by eye and not how rod quality is checked!) I also bought my rods directly from Arrow so am pretty confident that they're genuine.
In relation to your final point though, it could be that a better quality rod would not have suffered a failure brought about by the short overheat? In which case, spending the extra on Arrow rods would have actually saved me several £k's in rebuild costs. That said, if my sister had balls she'd be my uncle. As I say, there were several things that led to the ultimate failure of the big end and no single thing I would seek to lay at the door of ZRP. Any questions over their (ZRP) quality are simply the opinion of the engine builder I used.
Edited by e30m3Mark on Saturday 9th December 23:41
Edited by e30m3Mark on Sunday 10th December 09:53
Nothing in the above points even tangentially at the rods being at fault. If the engine was over heating then there was a cooling system problem. If a big end bearing failed then there was an oil pressure or oil supply (surge etc) problem. No type of rod on god's green earth can stop a seized shell spinning. It sounds to me like an engine builder trying to point a finger away from himself and hoping the client will swallow it. He's the engine builder and he chose to use the rods - end of. If they weren't up to snuff then he would have rejected them not just moaned about it and shoved them in anyway. Experts don't get to turn round after the event and say maybe they should have done something different. They're being paid to get it right the first time FFS!
You need to find out what actually caused the failure because all you're doing at the moment is building it back in to the next engine but with a more expensive set of rods to destroy.
You need to find out what actually caused the failure because all you're doing at the moment is building it back in to the next engine but with a more expensive set of rods to destroy.
Edited by Mignon on Sunday 10th December 07:29
Were it not for the fact he (the builder) had expressed concerns before using the ZRP rods, I would most likely have agreed with you. As I said earlier, a breakdown in communication led to these concerns not reaching me. If they had, I simply wouldn't have risked using them whether those concerns were misplaced or not.
What I had noticed, the first time the car was driven on track, was the increased oil temp' from before the rebuild. It wasn't to the point where I had concerns, given that a new oil pump was fitted along with a baffled, increased capacity sump but before then oil temp' had always been consistent. With hindsight, is it possible that the big end had started to deteriorate and develop heat?
Whilst I think, this is a quote from an exchange with the engine mapper, who was there when the engine was stripped.
''There is no sign of detonation at all, even where the pistons have touched the head as the big end clearances went wide, indicating a good margin in my settings for the extreme conditions that occurred. The skirts are scuffed as expected, but not severely enough to have initiated the failure, that's limited to the big ends, which appear to have high spotted, probably because of uneven rod shape, subsequently worn through the surface and spun readily as the radial clamp force on them appears to have been inadequate. Assuming the oil supply has remained constant, that is simply down to the quality of the rods, which I think someone this end should have advised you against using.''
Just for clarity, this is just a discussion which I am trying to learn from. As I have said (a couple of times at least) I am NOT looking to lay blame solely on the ZRP rods. It's just a discussion and the rods, amongst other things, were just one factor.
What I had noticed, the first time the car was driven on track, was the increased oil temp' from before the rebuild. It wasn't to the point where I had concerns, given that a new oil pump was fitted along with a baffled, increased capacity sump but before then oil temp' had always been consistent. With hindsight, is it possible that the big end had started to deteriorate and develop heat?
Whilst I think, this is a quote from an exchange with the engine mapper, who was there when the engine was stripped.
''There is no sign of detonation at all, even where the pistons have touched the head as the big end clearances went wide, indicating a good margin in my settings for the extreme conditions that occurred. The skirts are scuffed as expected, but not severely enough to have initiated the failure, that's limited to the big ends, which appear to have high spotted, probably because of uneven rod shape, subsequently worn through the surface and spun readily as the radial clamp force on them appears to have been inadequate. Assuming the oil supply has remained constant, that is simply down to the quality of the rods, which I think someone this end should have advised you against using.''
Just for clarity, this is just a discussion which I am trying to learn from. As I have said (a couple of times at least) I am NOT looking to lay blame solely on the ZRP rods. It's just a discussion and the rods, amongst other things, were just one factor.
e30m3Mark said:
Were it not for the fact he (the builder) had expressed concerns before using the ZRP rods, I would most likely have agreed with you. As I said earlier, a breakdown in communication led to these concerns not reaching me. If they had, I simply wouldn't have risked using them whether those concerns were misplaced or not.
What I had noticed, the first time the car was driven on track, was the increased oil temp' from before the rebuild. It wasn't to the point where I had concerns, given that a new oil pump was fitted along with a baffled, increased capacity sump but before then oil temp' had always been consistent. With hindsight, is it possible that the big end had started to deteriorate and develop heat?
No!What I had noticed, the first time the car was driven on track, was the increased oil temp' from before the rebuild. It wasn't to the point where I had concerns, given that a new oil pump was fitted along with a baffled, increased capacity sump but before then oil temp' had always been consistent. With hindsight, is it possible that the big end had started to deteriorate and develop heat?
e30m3Mark said:
Whilst I think, this is a quote from an exchange with the engine mapper, who was there when the engine was stripped.
''There is no sign of detonation at all, even where the pistons have touched the head as the big end clearances went wide, indicating a good margin in my settings for the extreme conditions that occurred. The skirts are scuffed as expected, but not severely enough to have initiated the failure, that's limited to the big ends, which appear to have high spotted, probably because of uneven rod shape, subsequently worn through the surface and spun readily as the radial clamp force on them appears to have been inadequate. Assuming the oil supply has remained constant, that is simply down to the quality of the rods, which I think someone this end should have advised you against using.''
Just for clarity, this is just a discussion which I am trying to learn from. As I have said (a couple of times at least) I am NOT looking to lay blame solely on the ZRP rods. It's just a discussion and the rods, amongst other things, were just one factor.
Christ you don't half keep drip feeding little bits of information instead of just telling the whole story once properly. So the overheating was oil temp not coolant temp as we'd assumed, (and no of course it wasn't a big end bearing generating that heat), the engine had a new type of sump!! which you never said anything about before.''There is no sign of detonation at all, even where the pistons have touched the head as the big end clearances went wide, indicating a good margin in my settings for the extreme conditions that occurred. The skirts are scuffed as expected, but not severely enough to have initiated the failure, that's limited to the big ends, which appear to have high spotted, probably because of uneven rod shape, subsequently worn through the surface and spun readily as the radial clamp force on them appears to have been inadequate. Assuming the oil supply has remained constant, that is simply down to the quality of the rods, which I think someone this end should have advised you against using.''
Just for clarity, this is just a discussion which I am trying to learn from. As I have said (a couple of times at least) I am NOT looking to lay blame solely on the ZRP rods. It's just a discussion and the rods, amongst other things, were just one factor.
It's pretty clear that the small end bush, oil drilling or whatever it was you were on about previously has nothing to do with a big end failure and the verbiage from the mapper is little more than pointless guesswork with its "probably" this and "assuming" that it's clear the big ends in the rods hadn't actually been measured for the assumed uneven shape and no one knows if oil supply had been constant. And you haven't said how much higher this oil temperature was and nothing at all about oil pressure which is obviously key.
We're not psychic and I doubt you'll ever manage to tell a complete story about how and where the failure happened and all the bits that had been changed since the previous build that might have contributed, and we haven't seen a single photo to try and glean any clues but Occam's Razor says the chances are your new sump doesn't prevent surge properly, you dropped oil supply during cornering and you ran a big end. Same as has happened to a million other people over the years. Engine builder is covering his arse and the mapper wouldn't know one way or the other.
When you rebuild it the same but blow the Arrows rods up along with another crank and set of pistons then we'll know for sure.
I didn't have the full story from the outset so any drip feeding hasn't been deliberate.
The overheat was coolant. I merely noted an increase in oil temperature (compared that that seen under similar conditions on an earlier occasion). The sump fitted was one developed specifically for the s14 engine, with increased oil capacity and baffled against surge. I know you said you weren't psychic and your assumption in relation to the sump certainly confirms that fact.
The oil pump was also in good order and there was no hint of a drop in pressure.
I am not able to give exact readings (in relation to oil temp and/or pressure) hence my decision to swap to a Stack dash display in future which records these readings.
I do not have any photos yet, hence there not being any posted here.
Anyway, thanks for your input.
The overheat was coolant. I merely noted an increase in oil temperature (compared that that seen under similar conditions on an earlier occasion). The sump fitted was one developed specifically for the s14 engine, with increased oil capacity and baffled against surge. I know you said you weren't psychic and your assumption in relation to the sump certainly confirms that fact.
The oil pump was also in good order and there was no hint of a drop in pressure.
I am not able to give exact readings (in relation to oil temp and/or pressure) hence my decision to swap to a Stack dash display in future which records these readings.
I do not have any photos yet, hence there not being any posted here.
Anyway, thanks for your input.
Edited by e30m3Mark on Sunday 10th December 12:59
stevieturbo said:
datalogs of oil pressure during the racing ?
It was a few laps of Brands Hatch @ Deutschfest Steve and unfortunately I don't have anything relevant available. I merely noted that the old analogue gauge was reading higher in comparison to an earlier event in similar conditions. I have measured my ZRP rods for my Honda K20 stroker build. The big end and small end bores were identical to within a few µm.
Big end diameters only show properly when you tighten up the bolts to the recommended stretch. I have acquired a ARP stretch gauge just for my build. Very handy. I have found that you need a good percentage of extra torque over the recommended torque to get to the stretch. ARP also states that this is done on purpose to prevent stretching the bolts. Especially for high strength alloys like L19 and CustomAge625+ this is very important as they are tightened rather close to their stretch limit.
Here are my big end diameters in mm of the ZRP rods as measured with a Mitutoyo inside micrometer: (I was still practising while recording these values)
51,005
50,998
50,995
51,001
Be aware that accuracy and repeatability of my hand tools were on the order of the observed deviations at that time.
Little end diameters (measured and recored twice). This is done with a HHW precision inside micrometer.
21,985 21,989
21,990 21,992
21,994 21,995
21,995 21,995
I have only recored these on a spread sheet while I was practising with the gauges. It is not that easy. Measuring the crank in winter at 15C in the basement makes a rather large difference to repeating the measurements at 25C in the summer. I made sure I measured all components to be assembled at the same time. I got 3 grades of Kind XP bearing shells to be able to get the desired clearance. I even measured the thickness of the shells with a ball ended micrometer (Tesa-Switzerland) and found them very consistent. You cannot use a inside micrometer on the assembled block or rod wit the shells mounted as the tip of a conventional needle type inside micrometer scratches and deforms the bearing's surface. Separate measurements of shell thickness and steel solace of rod solved this. Afterwards, it was all checked with UK spec Plastigauge under as assembled conditions. I was a LOT of work.
My final build measurements are all on paper.
The crank was as consistent with all journals being within a few µm of each other. the OEM Honda K20 crank showed larger deviations journal to journal than the ZRP crank.
Steel rods have massive end caps. I cannot see how you deform these easily. They don't look that different from your arrow rods.
There is no "coating" to wear though at the big end of a con rod. The only thick "layer" is the steel backing of the bearing shell. If this was worn, you had no lube.
With the bearing shells mounted, the big end is not round anymore. The shells are designed to be wider horizontally than vertically. See King's info on their website.
I'd agree that this either a screw up of the builder or your sump system is s
te. It is very easy to get things wrong. Swapped big end caps from rod to an other (=big no no as their are matched and the big end is finished with the cap mounted and torqued. Didn't set clearance right, poor gauges etc.
Your sump kit sounds VERY suspicious. I this a tried and tested sump set-up? If you were the Guinea pig for this sump, then go figure.
Literally, it takes only a fraction of a second of reduced oil pressure on track with high revs and loads for the crank to work itself well though a bearing shell. No matter how good or bad the rod is.
A fair share of Honda K20a2 and Toyota 2ZZ-GE engines died that way on track in the Lotus Elise. They all of a sudden sound like a old diesel tractor after a cold start in winter. They all now fit sump baffles if you get that thing even near a track. No need to see the oil light flickering. A little lower than normal is all it takes. When the red light comes on while on the boil, it is usually too late already.
A properly build big end will not fail on track for a non-extreme powered build unless you have oil pressure issues.
Ii is your engine and your components. Why don't you post pictures.
I agree with the others you are risking to blow an other engine.
Big end diameters only show properly when you tighten up the bolts to the recommended stretch. I have acquired a ARP stretch gauge just for my build. Very handy. I have found that you need a good percentage of extra torque over the recommended torque to get to the stretch. ARP also states that this is done on purpose to prevent stretching the bolts. Especially for high strength alloys like L19 and CustomAge625+ this is very important as they are tightened rather close to their stretch limit.
Here are my big end diameters in mm of the ZRP rods as measured with a Mitutoyo inside micrometer: (I was still practising while recording these values)
51,005
50,998
50,995
51,001
Be aware that accuracy and repeatability of my hand tools were on the order of the observed deviations at that time.
Little end diameters (measured and recored twice). This is done with a HHW precision inside micrometer.
21,985 21,989
21,990 21,992
21,994 21,995
21,995 21,995
I have only recored these on a spread sheet while I was practising with the gauges. It is not that easy. Measuring the crank in winter at 15C in the basement makes a rather large difference to repeating the measurements at 25C in the summer. I made sure I measured all components to be assembled at the same time. I got 3 grades of Kind XP bearing shells to be able to get the desired clearance. I even measured the thickness of the shells with a ball ended micrometer (Tesa-Switzerland) and found them very consistent. You cannot use a inside micrometer on the assembled block or rod wit the shells mounted as the tip of a conventional needle type inside micrometer scratches and deforms the bearing's surface. Separate measurements of shell thickness and steel solace of rod solved this. Afterwards, it was all checked with UK spec Plastigauge under as assembled conditions. I was a LOT of work.
My final build measurements are all on paper.
The crank was as consistent with all journals being within a few µm of each other. the OEM Honda K20 crank showed larger deviations journal to journal than the ZRP crank.
Steel rods have massive end caps. I cannot see how you deform these easily. They don't look that different from your arrow rods.
There is no "coating" to wear though at the big end of a con rod. The only thick "layer" is the steel backing of the bearing shell. If this was worn, you had no lube.
With the bearing shells mounted, the big end is not round anymore. The shells are designed to be wider horizontally than vertically. See King's info on their website.
I'd agree that this either a screw up of the builder or your sump system is s
te. It is very easy to get things wrong. Swapped big end caps from rod to an other (=big no no as their are matched and the big end is finished with the cap mounted and torqued. Didn't set clearance right, poor gauges etc.Your sump kit sounds VERY suspicious. I this a tried and tested sump set-up? If you were the Guinea pig for this sump, then go figure.
Literally, it takes only a fraction of a second of reduced oil pressure on track with high revs and loads for the crank to work itself well though a bearing shell. No matter how good or bad the rod is.
A fair share of Honda K20a2 and Toyota 2ZZ-GE engines died that way on track in the Lotus Elise. They all of a sudden sound like a old diesel tractor after a cold start in winter. They all now fit sump baffles if you get that thing even near a track. No need to see the oil light flickering. A little lower than normal is all it takes. When the red light comes on while on the boil, it is usually too late already.
A properly build big end will not fail on track for a non-extreme powered build unless you have oil pressure issues.
Ii is your engine and your components. Why don't you post pictures.
I agree with the others you are risking to blow an other engine.
The bolts were ARP CustomAge625+ #300-6704,
they are 3/8" UHL 1.5".
In the end I settled for 0.065" stretch as listed in the ARP catalogue. Recommended torque is 60 ft-lbs. I believe I needed some 80 ft-lbs to get to that stretch. ZRP could not provide me a definite answer on what stretch to use for the CustomAge625+ bolts.
After consulting with knowledgable folks, I used the ARP catalog values. They are similar to the recommend stretch values for the L19 bolts provided by ZRP.
Given that L19 is almost as strong and stiff, just not as durable and more corrosion sensitive, that should work.
Process wise I zero'd the gauge, tightened them to 60 ft-lbs, measured stretch and the added 5 ft lbs at a time until desired stretch was reached.
The required torque was pretty consistent across all 8 bolts. At 60 ft lbs stretch was more like 4 thou. I did not take notes on this.
This is from memory protocol. I build this thing for myself. It is a hobby. If it blows up, I know who to blame. ;-) Me.
BTW, here were my first measurements of the ZRP crank journals. "Average" of three values 120° apart around the journal. All three values were the same down to a single µm, hence no standard deviation! I measured it up and down and back and forth. It was always the same. Spooky.
Crank main bearing journal diameters in mm. This was measured in March, so at slightly cooler temperatures. In summer, the journals gained a few microns. But this is well in line with the thermal expansion of steel. You'd expect some 5µm per 10°C for these diameters. This is the tolerance for bearing clearance as per Honda engine manual!
54.979
54.982
54.981
54.981
54.982
rod journals:
47.987
47.986
47.988
47.988
As the ZRP rods were as consistent, so all 4 rods run the same bearing shell combination. Measurements of rods plus shell thickness perfectly matched the plastigauge I did to check.
The mains needed three different sizes of XP shells in combination to get to the desired 40-45µm range due to crank case journal variation. The journals were hour class shaped and a couple of microns wider on their outside. As there is also a oil channel in the middle, in the end I settled for plastigauge to get all 5 uniform. With a uniform block, I would have gotten away with a single bearing shell size.
Overall I found ZRP Europe aka Drakos Engineering in Greece very responsive. I called them and had email contact. They answered questions.
In doubt about any features of the rods, you could have just returned them the rods for them to check, exchange for an other set or refund.
they are 3/8" UHL 1.5".
In the end I settled for 0.065" stretch as listed in the ARP catalogue. Recommended torque is 60 ft-lbs. I believe I needed some 80 ft-lbs to get to that stretch. ZRP could not provide me a definite answer on what stretch to use for the CustomAge625+ bolts.
After consulting with knowledgable folks, I used the ARP catalog values. They are similar to the recommend stretch values for the L19 bolts provided by ZRP.
Given that L19 is almost as strong and stiff, just not as durable and more corrosion sensitive, that should work.
Process wise I zero'd the gauge, tightened them to 60 ft-lbs, measured stretch and the added 5 ft lbs at a time until desired stretch was reached.
The required torque was pretty consistent across all 8 bolts. At 60 ft lbs stretch was more like 4 thou. I did not take notes on this.
This is from memory protocol. I build this thing for myself. It is a hobby. If it blows up, I know who to blame. ;-) Me.
BTW, here were my first measurements of the ZRP crank journals. "Average" of three values 120° apart around the journal. All three values were the same down to a single µm, hence no standard deviation! I measured it up and down and back and forth. It was always the same. Spooky.
Crank main bearing journal diameters in mm. This was measured in March, so at slightly cooler temperatures. In summer, the journals gained a few microns. But this is well in line with the thermal expansion of steel. You'd expect some 5µm per 10°C for these diameters. This is the tolerance for bearing clearance as per Honda engine manual!
54.979
54.982
54.981
54.981
54.982
rod journals:
47.987
47.986
47.988
47.988
As the ZRP rods were as consistent, so all 4 rods run the same bearing shell combination. Measurements of rods plus shell thickness perfectly matched the plastigauge I did to check.
The mains needed three different sizes of XP shells in combination to get to the desired 40-45µm range due to crank case journal variation. The journals were hour class shaped and a couple of microns wider on their outside. As there is also a oil channel in the middle, in the end I settled for plastigauge to get all 5 uniform. With a uniform block, I would have gotten away with a single bearing shell size.
Overall I found ZRP Europe aka Drakos Engineering in Greece very responsive. I called them and had email contact. They answered questions.
In doubt about any features of the rods, you could have just returned them the rods for them to check, exchange for an other set or refund.
Edited by Ive on Sunday 10th December 14:51
Hi Marko, exactly the same 80 ft lb torque we got when I helped a mate change 3/8th rod bolts from 2000 to 625 in a Cossie bottom end, worried us to death at first . We even checked stretch values the next day and they stayed the same!
I have seen a rod cease stretching at 5thou even though bolt was turned, we think the stretch requirement of the bolt exceeded the spec of the rod material, after a period of time the stretch reduced! A good reason to use a stretch measurement not a torque setting.
Peter
I have seen a rod cease stretching at 5thou even though bolt was turned, we think the stretch requirement of the bolt exceeded the spec of the rod material, after a period of time the stretch reduced! A good reason to use a stretch measurement not a torque setting.
Peter
ZRP themselves list .0065-.0070" stretch or 55 ft lbs for the L19 bolts.
7 thou for a 260000 PSI bolt is about the same clamping force as 6.5 thou for a 280000PSI bolt. The rod should be able to cope.
I also had to tighten them a few times to check clearances, journal diameters etc. Never observed any deviations from their behaviour.
Yeah, 80 ft lbs is rather a lot for a not that big of a bolt. The CustomAge bolts are also pretty heavy. These superalloys are pretty dense. Lots of Nickel and Molybdenum.
7 thou for a 260000 PSI bolt is about the same clamping force as 6.5 thou for a 280000PSI bolt. The rod should be able to cope.
I also had to tighten them a few times to check clearances, journal diameters etc. Never observed any deviations from their behaviour.
Yeah, 80 ft lbs is rather a lot for a not that big of a bolt. The CustomAge bolts are also pretty heavy. These superalloys are pretty dense. Lots of Nickel and Molybdenum.
Edited by Ive on Sunday 10th December 15:15
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