question Zetor UR1 - conrod bushing to tight

Hi hoping someone could help with a problem rebuilding engine on a Zator 5011 Z5001 3cylinder engine problem i have is new bushings in conrod when fitted are compressed to tight for gudgeon pin to fit correctly have been told i have to drill oil hole in bush when fitted and then bush must be reamed to fit gudgeon pin doesn't sound right to me but would be grateful for your opinion

Yes they will need reaming out. Had the same issue when I was rebuilding a crystal engine.

@lou0151
Congratulations...

New bushings in the connecting rods not only need to be reamed to fit (with a reamer), but the connecting rod also needs to be angled afterward, a job for a specialist.
And then you should always weigh the connecting rod and piston BEFORE installation and, if necessary, compensate for any weight differences at the specified points on the connecting rod and piston.

Another point is, it would be nice if you, as a new member, briefly introduced yourself and your tractor before asking the first question.

Stephenmenhen10111 said:

Yes they will need reaming out. Had the same issue when I was rebuilding a crystal engine.

Click to expand...

thanks for the confirmation suppose now i will have to find a machine shop before i can go any further

Joachim said:

@lou0151
Congratulations...

New bushings in the connecting rods not only need to be reamed to fit (with a reamer), but the connecting rod also needs to be angled afterward, a job for a specialist.
And then you should always weigh the connecting rod and piston BEFORE installation and, if necessary, compensate for any weight differences at the specified points on the connecting rod and piston.

Another point is, it would be nice if you, as a new member, briefly introduced yourself and your tractor before asking the first question.

Click to expand...

hi many thanks for the additional information a bit more of a proses then i expected

I can only report from a German perspective – here, straightening the connecting rod is already more expensive than a new one – so it's hardly been an issue so far. Finding a suitable reamer isn't the issue, but straightening the connecting rod is something for professionals.

The problem is that the new bushing is usually not 100% square after reaming. To correct this, the connecting rod is usually clamped and "bent." While this is relatively easy on a moped or car, it's a real job with the significantly larger tractor connecting rods, or you need special machines for it.

Weighing the connecting rod is important to ensure the engine doesn't run unnecessarily unbalanced. Zetor has guidelines within which the weight differences are acceptable. The connecting rod must be weighed once at the connecting rod end and once at the connecting rod bearing end.

All of this is done to ensure an engine that runs as long as possible and can also handle high speeds without damage.