VW Golf Mk2 Owners Club

Big end bolts. 16v.

June 22, 2020, 05:37:23 PM

I am trying to find some replacement big end Connecting Rod bolts for my Mk 2 1987 16v Golf rebuild after £125k miles.
VW does not say they are single-shot, but opinions vary on whether I should replace them or not.
I think the correct  part number that I need is 048 105 425. I cannot find that in stock anywhere, but there are other similar-looking (I know!)  big end bolts available, including:
052 105 525 A, 056 105 525 B and 056 105 525 C - all of these are available.

Is it possible to use any other bolt as an alternative to mine like-for-like?
Can I have my connecting rods machined to take any of the other VW bolts?
Should I buy pattern parts? E.g. Febi Bilstein 02126
Or should I just bang the originals  back in and torque them up and see if they go cheesy - then decide!?? They tap out anyway if they break.

Views gratefully received.

Confused of Chichester

Re: Big end bolts. 16v.

Reply #1 – June 23, 2020, 08:21:56 AM

Hi Confused!

The general rule of thumb is if you put a stretch on a bolt after you have torqued it down, they should be one use as the extra 90 or 180 degrees stretches them.

I've had a big end bolt let go on me at 120, it wasn't fun and ended up costing nearly 2k.

If it were me rebuilding it (and I recently did this to the wifes VR), I'd stick a set of ARP bolts in, no worries then.

Re: Big end bolts. 16v.

Reply #2 – July 04, 2020, 06:16:31 PM

Hmm. Bit of a set back. I asked the engineering shop if I should bring them in or have a go, and they said have a go.  The bolts are a very tight fit and I had to wind them in using a nut and increasing numbers of washers, with brass ones at the bottom end to stop them damaging the con-rod.  Looks like they've come out at a slight angle, as I cant get the cap on.  Also, by eye it looks like the flat shell case may be distorted near the bolt exit, so I think I may have wrecked the con rod. Ah well, back to the engineers shop Monday!

Ah well. Crank went into the main bearings a treat, at least. Spinsnicely after torquing them up - and i didn't forget to put in the piston oil sprays first!