ZRP Forged Conrods
Discussion
rachaeljf said:
Thanks 227, so you think these rods are ok for a non race engine? I was about to reject them but when I look at photos in other eBay listings I see the same machining marks, so I can see mine are not a one-off fault (I doubt the advert photos are of *my* rods!).
If you read the whole thread it's explained in there, but I would put them in a road car after I'd checked them as well as I could and they were better than what came out.
Look carefully at the bolt seats, I spent a long time (2 years plus) in dialogue with a Chinese steel rod manufacturer suggesting changes to the design (which have now been incorporated in all the rods they make) . Some of these were dimensional, others to do with design fundementals. The rods I have made are to the improved specification and I have had them comprehensively tested by a contact within Ricardo's. They passed the testing and were described as adequate for the use I would be putting them to which is fairly extreme. The one recurring problem I have experienced has been machining of the bolt seats which has varied from acceptable to poor (less than 50% contact area). This can be resolved by careful lapping or machining but it shouldnt be necessary.
Dave
Dave
DVandrews said:
Look carefully at the bolt seats, I spent a long time (2 years plus) in dialogue with a Chinese steel rod manufacturer suggesting changes to the design (which have now been incorporated in all the rods they make) . Some of these were dimensional, others to do with design fundementals. The rods I have made are to the improved specification and I have had them comprehensively tested by a contact within Ricardo's. They passed the testing and were described as adequate for the use I would be putting them to which is fairly extreme. The one recurring problem I have experienced has been machining of the bolt seats which has varied from acceptable to poor (less than 50% contact area). This can be resolved by careful lapping or machining but it shouldnt be necessary.
Dave
That's good information, do you mean that the bolt seat was not at 90' to the threaded bolt hole or just a bit rough?Dave
Edited by 227bhp on Monday 31st July 12:39
227bhp said:
That's good information, do you mean that the bolt seat was not at 90' to the threaded bolt hole or just a bit rough?
The bolt seat appeared to have been finished manually with a file, probably to remove burrs, the resulting seat was neither flat nor perpendicular to the bolt centre line.Edited by 227bhp on Monday 31st July 12:39
Dave
227bhp said:
e30m3Mark said:
A quick update.
Although all was well for a while, a couple of cooling issues contributed to an eventual failure. 20/20 hindsight is a wonderful thing but I wouldn't use ZRP rods again.
Why not? Can you specifically attribute the failure to a conrod?Although all was well for a while, a couple of cooling issues contributed to an eventual failure. 20/20 hindsight is a wonderful thing but I wouldn't use ZRP rods again.
The Farndon rods have the oil way to the little end and a groove in the little end bush to help oil movement. We noticed the aftermarket B rods, whatever make, did not have the oil drilling to spray oil from the big end onto the thrust side of the bore so we had them incorporated when we worked with NMS detailing the rods we wanted.
On a slightly different tack, little end pin diameter, current practice A series is to put smaller ID pins in to save weight. We stripped an engine that had started to kill number four piston from det. All the little end pins evidenced wear which we feel may be the area for load is too small compared with the OE size load area? These are Omega pistons so would be surprising if pins soft, they filed same as all the other Omega ones we have seen as well as OE pins.
Peter
On a slightly different tack, little end pin diameter, current practice A series is to put smaller ID pins in to save weight. We stripped an engine that had started to kill number four piston from det. All the little end pins evidenced wear which we feel may be the area for load is too small compared with the OE size load area? These are Omega pistons so would be surprising if pins soft, they filed same as all the other Omega ones we have seen as well as OE pins.
Peter
Stock BMW S14 rods don't have an oil way from big end to little end, nor do my Arrow S14 rods.
If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
stevesingo said:
Stock BMW S14 rods don't have an oil way from big end to little end, nor do my Arrow S14 rods.
If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
They must have some oiling hole in the rod? It's usually a drilling for splash feed, not the rifle drilling you mean.If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
If you go back to P1 and click on the link it shows one in the pic (with oil hole).
The builder was given the rods to examine and he passed and fitted them, he can't really go back now and point out they are substandard. IF there are holes missing then he should have noticed, it's an hours job to drill some in. The buck stops with the builder, not the components, that's what you are paying him for.
That's the problem when you are the customer with little knowledge (and little interest and memory) you take what's given, people will always blame something else as a get-out-of-jail-free card when an expensive failure occurs.
227bhp said:
They must have some oiling hole in the rod? It's usually a drilling for splash feed, not the rifle drilling you mean.
If you go back to P1 and click on the link it shows one in the pic (with oil hole).
The builder was given the rods to examine and he passed and fitted them, he can't really go back now and point out they are substandard. IF there are holes missing then he should have noticed, it's an hours job to drill some in. The buck stops with the builder, not the components, that's what you are paying him for.
That's the problem when you are the customer with little knowledge (and little interest and memory) you take what's given, people will always blame something else as a get-out-of-jail-free card when an expensive failure occurs.
In truth, there was also some breakdown and/or miscommunication which is why I'm taking a more philosophical stance than maybe I would otherwise. As you say though, as a customer with little knowledge one is dependent on the expertise you're paying for. If you go back to P1 and click on the link it shows one in the pic (with oil hole).
The builder was given the rods to examine and he passed and fitted them, he can't really go back now and point out they are substandard. IF there are holes missing then he should have noticed, it's an hours job to drill some in. The buck stops with the builder, not the components, that's what you are paying him for.
That's the problem when you are the customer with little knowledge (and little interest and memory) you take what's given, people will always blame something else as a get-out-of-jail-free card when an expensive failure occurs.
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