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Bearings and connecting rods.
hus22l - August 12th, 2015 at 03:24 PM

Hey all,

I have brand new AA I beam rods and silverline bearings. Crank is new and standard, vw journals mic out perfect... Problem is I have some sticky rods at the first "hang" in the crank. They all rotate, but it's certainly not free as a bird like it should be.

I didn't notice any burrs on the rods or bearings. Everything went together quite well though some bearings seem to want to walk off dead straight either on the rod or cap, (non tang end). So I have moved them into position as best I can to assemble them.

Anyone else have issues with this combo of parts? There are a few installing tricks I have read up on that I will try (it's early days in my grapple with this issue). Should I try different bearings? Mahle? "Klobberejeshmittt" ?

Hus


ragged - August 12th, 2015 at 05:51 PM

I'm assuming you have torqued the bolts? Dave


dangerous - August 12th, 2015 at 05:56 PM

This is a common problem.
The tangs on the bearings do not sit deep enough in the rod groove.

You also need to measure oil clearance.
Correct procedure is to measure the journal, and mounted and torqued bearing
to determine if the oil clearance is within specification.


bajachris88 - August 12th, 2015 at 05:58 PM

Not specific to your manufacturer of components, but I had similar issues.

some of the 'caps' on the rods were not providing correct alignment. in addition, clearances varied from loose to seized on crank when due to deviations in the OD with the rod itself (although the crank did have varying journal sizes too).

A few things to think about.

I just put it all in a box, took it to a machinest, and asked them to make it work. To which they did beautifully :tu:! Oh... and bearings, bearings themselves don't promise consistency with sizings either. Not rod, but my main bearings (which were vw genuine) varied in tolerance of size too. Crazy :sniffle:


hus22l - August 12th, 2015 at 06:54 PM

Thanks for the responses.

Yep, I have torqued the bolts a bit at a time up to 38ftp as per the sticker on the box, with the bearings in, onto the crank. Just to get the initial fitting checked.

I'll take them off tomorrow and see if there are any shiny spots on the bearings and then I'll have another look that they are set in the tangs correctly. Check oil clearances etc.

Fun fun fun
Cheers


psimitar - August 12th, 2015 at 11:01 PM

Hmm, my Gregory and Haynes manuals both say 24lbft for rod bolts so that may well contribute. Try and find what a Bently manual states to confirm.

I found it was making the new bearing shell sit down properly into the rod otherwise it seemed to bind when torqued up. Bit of gentle bending of the shell and making the tang sit snugly in the rod solved my tight spots.

Oh and did you say the crank had been mic'd to check for oval?


fish26 - August 13th, 2015 at 08:13 PM

Torque depends on the rod bolts used, Phil are they 3/8, triple check all measurements and clearances before final assy make sure you have a nice radius on the crank with good side clearance and as said above bearings perfectly seated.


baja_01 - August 14th, 2015 at 04:43 PM

Had new CB Unitech rods that needed to be honed to the right specs. Got this done at a local engine builder(V8s).


hus22l - August 14th, 2015 at 05:29 PM

Thanks for the post and message responses. Still fiddling with em, I'll let u all know when and how I resolve the issue. Slow going this building buzz eh. Hope to have it progressed and better assessed by the end of the weekend.


hus22l - September 1st, 2015 at 07:21 AM

Alright then, so there appears to have been a few contributors to the issue.

The edges of the rods had a couple of tiny burrs that I have nicked of with a touch of very fine sandpaper. There was one on the edge of the crank too. A more significant issue was the silverline big end rod bearings, they were random in size. I measured .058 in quite a few places, this appears to be the main issue. A couple were also not fitting perfect in the tang groove on the rod, I even tried opening up the tang gap with a teeny tiny file. Still they just didn't fit so well.

The rod ID was a little varied and out of round, but not too bad.

I got some Clevite bearings and they fit way better, thickest point was .055.

So looks like I'm off to find my next fitment issue. Hopefully there won't be one!!