bikecarbfred
|
| posted on 22/10/17 at 03:12 PM |
|
|
conrod alignment on crankshaft
I've heard of complaints in regards to bottom end fail due to cheap arp bolts. However the main rebuttal to this is inproper engine build and I
can see why as I am carrying out my first build.
I can see a problem where conrods are not aligned in their correct/central place on the crank
I can see where journal bearings do not accurately align with their opposite counterpart due to fraction of movement in the main bearing caps whilst
installing.
Bearings in the conrod do not have a locating groove there fore could slightly slide a fraction when installing.
The problem with these bearings are this problem is hard to spot as the crank is surrounding this region.
I also have a question.
1) When securing the conrod to the crankshaft how do you know you have it dead on centre where it should be.
Is it wise to hand tight the conrods and then turn the engine over twice for the rod to force it's way to it's central place and then
torque the bolts up to the required specification?
|
|
|
|
|
daviep
|
| posted on 22/10/17 at 07:46 PM |
|
|
What engine are you working on?
Traditionally caps are dowelled to ensure correct alignment, more modern engines may use "fracture split" conrods which are not dowelled
as the fractured faces fit together perfectly ensuring precise alignment.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
|
|
|
bikecarbfred
|
| posted on 22/10/17 at 08:47 PM |
|
|
that's a very aggressive profile pic you have on there.
the engine is afh 1.4 16v
|
|
|
britishtrident
|
| posted on 22/10/17 at 09:10 PM |
|
|
Life is too short stop looking for problems that don't exist if big end bolts fail it is due to over revving or a seized bearing or over
tightening or leaving them slack.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
snapper
|
| posted on 23/10/17 at 05:45 AM |
|
|
When tightening rod caps a feeler gauge either side will help (but not completely) prevent the rod twisting as you apply the final torque to the
bolts.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
perksy
|
| posted on 23/10/17 at 01:31 PM |
|
|
Don't forget to build it up with Plastigauge to check clearances
DTI the crank to check end float
If somethings not right when building it all up it should be pretty obvious to be fair
Especially when turning it over by hand
Also if using ARP bolts double check to see if the cap need chamfering to suit the radius under the ARP bold head, Some do some don't
Use the ARP lube and follow the instructions to the letter...
[Edited on 23/10/17 by perksy]
|
|
|
FuryRebuild
|
| posted on 23/10/17 at 04:47 PM |
|
|
can I just raise a point of order m'lud. ARP are a brand of bolts, and are exceedingly good. There are lots of knock-off sat around there on
auction sites, etc. and I only buy them from a supplier I can trust. If they're cheap, it's for a reason.
britishtrident is right - and also maybe counterfeit bolts that aren't up to scratch.
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
|
|
|
bikecarbfred
|
| posted on 23/10/17 at 07:44 PM |
|
|
quote:
Originally posted by perksy
Don't forget to build it up with Plastigauge to check clearances
DTI the crank to check end float
[Edited on 23/10/17 by perksy]
When you say Dial gauge the end of the crank. Do you mean to check the end play. How much movement left to right there is?
|
|
|
mark chandler
|
| posted on 23/10/17 at 08:37 PM |
|
|
Cheap and ARP do not belong in the same sentence! The forces trying the split big ends apart are, phenomenal on the overrun at high RPM cheap bolts
may fail.
|
|
|
snapper
|
| posted on 23/10/17 at 09:51 PM |
|
|
quote:
Originally posted by FuryRebuild
can I just raise a point of order m'lud. ARP are a brand of bolts, and are exceedingly good. There are lots of knock-off sat around there on
auction sites, etc. and I only buy them from a supplier I can trust. If they're cheap, it's for a reason.
britishtrident is right - and also maybe counterfeit bolts that aren't up to scratch.
Depending on application some ARP products need shortening to fit, mainly in blind hikes
Just saying
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
Hornet
|
| posted on 24/10/17 at 09:36 PM |
|
|
Big ends can move side to side on crankshaft by clearances set by manufacturer. You do not need to worry about it. just fit them with plastigauge and
if happy with results fit ARP bolts to correct torque with supplied arp lube.
|
|
|
perksy
|
| posted on 25/10/17 at 03:46 PM |
|
|
quote:
Originally posted by bikecarbfred
quote:
Originally posted by perksy
Don't forget to build it up with Plastigauge to check clearances
DTI the crank to check end float
[Edited on 23/10/17 by perksy]
When you say Dial gauge the end of the crank. Do you mean to check the end play. How much movement left to right there is?
You set the DTI up on one of the crank webs and then check the endfloat (backwards & forwards) If its out you'll be changing the thrust
washers
Follow the Haynes manual or similar and all should be revealed
Use a good quality torque wrench and set of feelers
Measure everything if you have the right equipment
Use plenty of assembly lube or similar
Personally I like cleaning all the threads out of the assembled parts and all the oilways in the engine etc
I like packing the oil pump with Vaseline  
Most important is you take your time and everything is spotlessly clean
|
|
|
