std rods:shotpeening and ARP bolt question

A

Anonymous

Guest
Hi,

Jobi Joba, i think you have put blame elsewhere instead of looking at yourself. To be specific you have slung crap onto PAR about their rods, whether it is justified or not is not my point in this post.

Who has built your engine?? Did you put it together or did a 'professional' engine builder? Whoever did put the engine together did not do their job properly and you deserved anything that could go wrong to the engine to go wrong. But please don't put blame on anyone else. It might sound harsh but is true.

It doesn't matter who built and put the engine together, the fact of the matter is that the engine was NOT blueprinted during the assembly stage. Yes, blueprinting does take more time but it will find any small defects early on which could then be addressed.

You will find that any serious engine builder (and for that matter any serious mechanical workshop) will blueprint everything along each step of the way.

It doesn't matter that items are made for a specific engine you still need to blueprint and double check the items that are going together.

I don't know what work you do but sandpapering the piston pin (gudgeon pin) bush in the small end of the conrod is a vary bad idea and not professional at all. I'm sure you have heard of honing the cylinder walls, this is the same method that should be used to hone and remove a smidgen of material from the piston pin bush.

I'm sorry but you have yourself to blame, or the engine builder for not doing their job properly.


I personally don't use the PAR rods in my engine as they weren't avaialable when i needed forged conrods, i went with ARGO connrods. These too don't have the oil hole from the big end, you will find that most forged conrods won't have them either. Oh and did you expect that all conrods are made the same? Did you ask for the weights of the rods before purchasing them? You mentioned they were heavy in your post. My ARGO rods are 120grams lighter than the stock rods for comparison.

The piston pin bush is deliberately made slightly smaller so that the engine builder can hone the bush to the exact specs to fit the piston pin being used.


Ivan
 
W

Websnowbo

New Member
Not my business really as i have nothing to do with PAR but all that you have described on here is false!

Small end bearing's NEVER come finished, i'm not sure if they are already pressed into the PAR rods when they are delivered but even so they will need to be honed to suit your gudgeon pins. You never SANDPAPER bushes!!! Even the tiniest amount can be removed using a small end honer and evenly! Sandpapering will have high points and low points!

Also i VERY much doubt the noise you are getting is from side movement on the rods, especially at the tolerances you mention. I have ground loads of crankshafts and the tolerance on the side cut is huge.

I disagree with everything you have stated and feel it is very selfish stating PAR problems on an open forum.

PAR could hold you liable for everything you have said.
 
campbellju

campbellju

Moderators
Staff member
Before everyone flames Jobi to death. I am in a similar position to him except my engine is not quite back together yet. I appreciate Jobi talking about this in an open forum as I have experienced similar problems to date.

I bought my rods new/2nd hand from robinsongtir who purchased them directly from PAR and never fitted them but it does put a different spin on warranty/support for me.

My/Our aim is not to flame anyone else or PAR but to find out what has gone wrong for Jobi so I/others don't end up in the same position as him.

Firstly Ivan, chatted to you before on the yahoo forum many moons ago and have a lot of respect for what you say and the things you've done with PAR and for the general good. Websnowbo, sorry, don't really know you.


Small end bearing's NEVER come finished, i'm not sure if they are already pressed into the PAR rods when they are delivered but even so they will need to be honed to suit your gudgeon pins.
Click to expand...
Can't comment really, it surprised me and the engine builder but didn't phase the machine shop. Whatever the story, its fixed.

It doesn't matter that items are made for a specific engine you still need to blueprint and double check the items that are going together.
Click to expand...
Agree in principle but not in practice. The fact is when getting the engine balanced, the rods were the only parts the engineer could not make perfect as one was 9g lighter than the next lightest. This guy is the god of engine machining in the NW of UK so his skills are not in doubt. Maybe PAR did a bad batch for the GtiR...it happens, when you're on the end of it though its frustrating and whatever the reason it was "inconsistent" engineering being polite.

These too don't have the oil hole from the big end, you will find that most forged conrods won't have them either.
Click to expand...
I'm aware of this, mine and the engine builder's question was about the oil channels in the small end bush. If Nissan puts them in, why do PAR take them out. Are they needed, if not why not? This is still a genuine question.

Also i VERY much doubt the noise you are getting is from side movement on the rods, especially at the tolerances you mention. I have ground loads of crankshafts and the tolerance on the side cut is huge
Click to expand...
I have to side with Jobi on this one. I double checked what he said and when you compare it to what Nissan says, the fact is the "gap" is out of tolerance. After discussing why it might matter with the engine builder, his general thinking was if the gap is too large, oil can escape too quickly from the bearings causing problems. The 0.05 might be the straw that breaks the camels back. Notice I use the word gap and not rod. I'm hoping to measure all the rods thickness and if they are inconsistent this would support what Jobi is saying. If they are the same then no blame could be put on PAR for this one.

I disagree with everything you have stated and feel it is very selfish stating PAR problems on an open forum.
Click to expand...
Isn't this the point of the forum :wink: I'm happy to discuss openly and unemotionally the problems so they don't escalate for me and Jobi can get some closure on what has happened to him.

PAR could hold you liable for everything you have said.
Click to expand...
They could, but I would hope they would try to find out if there is a genuine problem here rather than calling for the lawyers.

Any support anyone can give is appreciated.

Cheers,
Jim.[/quote]
 
G

GINGA

Active Member
It doesn't matter who built and put the engine together, the fact of the matter is that the engine was NOT blueprinted during the assembly stage. Yes, blueprinting does take more time but it will find any small defects early on which could then be addressed.
Click to expand...
If that be the case then the rods should have been thrown in the bin from new as they were out of tolerence and you can't make them bigger :wink:
From what you've just said the rods were no good from the start and machined to small so not allowing for any blue printing to be done :(
The other option is to replace the crank (If it was worn past tolerance) which seems a bit silly for the sake of possibly wrongly machined rods and when the standard rods would fit and work perfectly ok

It just seems to me that every time theres a problem with a Par product its always the assemblers fault for not doing to right :roll: surely there can't be that many people getting it that wrong :?: and nothing to do with Par's machining tolerences :roll: I mean 9g difference between the lightest and heavest rod is a hell of alot for something that should be spot on from the moment they leave the factory :wink:
Maybe Par need to rethink there fitting instructions if there are any supplied :?: as I know some people didn't receive any or maybe send them out as unfinished goods as thats what it sounds like :(
 
O

Odin

Guest
I will be takeing my par rods to the machine shop next week so they can have a look at them and tell me what they think :roll: ......

As Paul has stated you can't make them bigger :evil: so I hope mine are ok, As far as weight's go mine are pretty good I think 3 are the same weight at 680 gram's and the other is 675gram's so I'll have to take 5 gram's off the other 3.... And the shaft size is 22mm on them all at the piston pin hole is that good or bad :?: :? .


Mine have oil hole's in the piston pin end too


rob
 
A

ard1ey

Guest
How do you mean can't make them bigger? If its the small end bush or big end diameters then they can be honed to the right size, at work the rods we make have a tolerance of ±0.004mm on the small end, don't know the Nissan spec offhand.
If its the centre distance you're on about then bang on, you can't change that (unless you fancy using the rod in a tug-of-war :D )

Ian
 
A

ard1ey

Guest
Yeah, I was being a dumbass - I read the bit about the rod width and then forgot it straight away. IMO the small end bush diameter, I can understand PAR's point of view - they don't know what pistons you are using and piston pins vary in diameter. All other dimensions (i.e. length, thickness, allowable bend & twist and big end dia) are pretty much set in stone if they are made for a standard crank and should be within limits if PAR are as good as they say.
 
G

GINGA

Active Member
ard1ey said:
How do you mean can't make them bigger? If its the small end bush or big end diameters then they can be honed to the right size, at work the rods we make have a tolerance of ±0.004mm on the small end, don't know the Nissan spec offhand.
If its the centre distance you're on about then bang on, you can't change that (unless you fancy using the rod in a tug-of-war :D )

Ian
Click to expand...
Talking about the gap between the side of the rod and the side of the crank which is effected by the width of the rod and the crank as Jobi stated that this gap was out of tolerence then it would appear that either the rod or crank are to thin and as neither of these parts can be made larger the only answer is replacement it could be that the crank has excess wear but if it didn't have a knock before with standard rods then can't really see it being than, also you would have thought that if the rods were designed to be blueprinted then they would have had excess metal on them to allow for them to be machined down to get to the stated correct running clearance.
Might be a good idea to measure the width of the standard rod against the width of the Par rod and compare as theres always the possibilty that whoever machined the crank has fucked up before going to far into saying the Par product is definantly the problem :oops:
 
campbellju

campbellju

Moderators
Staff member
vpulsar said:
Mine have oil hole's in the piston pin end too
Click to expand...
Its the small channels in the small end bush itself I'm on about. When you compare them to a standard rod its stands out a mile and makes you wonder why? Was it just Nissan being super careful about getting oil in. Do all the Nissan tolerances assume the channels are there. Will it work without it or starve the pin of oil.

Can anyone comment?
 
O

Odin

Guest
I was talking to Paul about this and we think that the hole's in the Par rod will catch oil that is squirted at the underside of the piston's by the oil squirter's so lubing the pin :wink: .


rob
 
campbellju

campbellju

Moderators
Staff member
That's the same concencus of opinon we've come up with too. The fact that Jobi's con-rods didn't seize and just knocked is good evidence its enough too :shock:

I still feel like I'm crossing my fingers a bit on this one.
 
W

Websnowbo

New Member
The rods dont touch the crank, so why would their width make a noise? The bearing determine where the big end sits on the crank, which is why the cranks have a radius on the journal. In theory the rod could be much thinner than the bearing, but over time the bearing would wear badly on the edges and cause problems.

The rods should weigh similar sizes, but you dont measure rods on their own when balancing an engine you weigh them with the pistons fitted, i agree you would have thought being aftermarket rods they would be nearly the same weight, but anything up to 10g's aint that much really, measure your pistons too Rob as they will vary and you will be able to mix and match the heavier pistons with the lighter rods etc etc
 
campbellju

campbellju

Moderators
Staff member
websnowbo, you're correct about the balancing, like I said I went to the "God" of engine machining in the NW. He balanced all the individual parts first before balancing them together. He didn't want to take too much off the roads in case he reduced their integrity. In the end we had one rod that was 4g out that we balanced accordingly with a piston. As a package its fine but I'm dealing with perfectionists here.

The rods dont touch the crank, so why would their width make a noise? The bearing determine where the big end sits on the crank, which is why the cranks have a radius on the journal. In theory the rod could be much thinner than the bearing, but over time the bearing would wear badly on the edges and cause problems.
Click to expand...
Its a very good point but what's your understanding for Nissan specifying a "Side clearance limit" of 0.5mm for the rod then and why would exceeding this cause problems?
 
W

Websnowbo

New Member
mmmmm..........well i would like to look at a manual. But does it give a maximum and minimum clearance?

If not then 0.5mm will be the minimum clearance to allow for expansion. Thats a fair old clearence though, 0.5mm.

A maximum clearence will be based on too much metal being removed from the crank during a re-grind i imagine.

All these clearences are based on movement of the shells on the big end though, not the Rods. The redius' on the crank determine how much movement the Rods have.

Oh and a crank must always be ground with exactly the same radius too.
 
W

Websnowbo

New Member
Again, I think this is based on the crank, not the rods. As I mentioned previously the clearance between the Rods and the crank is dependent on the journal width and radius’ of the crank. I admit if the Par rods are undersize it makes it hard to measure the clearance.

But this could be resolved by fitting the new shells onto you existing rods to check (I realise you shouldn’t really have to do this)

I think this is going to come down to common sense, basing it upon the fact that as long as your crank is standard and has been measured correctly i.e not worn, then you shouldn’t really need to check these clearance’s.

You can tell if there is something wrong if you fit the shells into the rods and they petrude past the side of the Rod by a significant amount (Highly unlikely).

Going back to the reason for this post initially, Jobi was claiming that the knocking noise he had heard was down to the clearance between the Rods and the crank. I believe the knocking noise came from the small end bush’s, as he had used sand paper to increase the size of the bushes they would be full of high and low spots and once the engine was running, the high spots wore quickly resulting in too much play.

Also, you've got to be careful as in an extreme case the pin could end up sitting at an angle and wearing the piston and rings unevenly (In an extreme case)
 
O

Odin

Guest
Unlucky for me all my piston's weigh the same, So it does make you wonder if CP can make me some forged piston's for $299 and even after
I have had them swain and teflon coated they all weigh the same 8) why
is it Par can not do the same after all they are charging me nearly £800 :roll: :?: ..........


rob :?
 
You must log in or register to reply here.
Top