bad rod bearings

[dan2288]

Ok, so im gonna change the rod bearings this weekend. My dad said if it was the rod bearings then maybe the crank is damaged and would have to be machined. Would i be ik with just putting in the new rod bearings? I read that you can go over the crank journals with really fine sand paper. Maybe ill do that?

 

[Backinajiffy12]

It depends on how bad your journals are. but why are you replacing them?

 

[BoredDSM]

You should not go over the crank journals with sand paper. Doing so can cause uneven wear on the journals and will make you spin bearings more often. Depending on how deep the grooves on the journal are, you might have to get it micro polished or worst have it turned.

If you do get it turned you have to use over-sized bearings, and it is suggested you get it re nitride coated but is not necessary.

 

[Jeff99GS]

If you just try to put in new rod bearings with a scored crank you will need new bearings every 3 days hahaha.

At least have the crank Micro polished and checked with a mic. If you're going to try sand paper then use like 400-800 wet/ dry sand paper. I have seen a friend do this after a spun bearing....it lasted about 2 months. He polished the crank real good with 800 wet sand. It still spun the new bearing within 2 months.

Just pull out the engine and rebuild it.

If the rod bearing went bad than the mains aren't far behind.

 

[FLASH1970]

Pull the engine and rebuild it.

 

[dan2288]

It depends on how bad your journals are. but why are you replacing them?

Well im getting knock and it sounds like rod bearings are bad

 

[joe sobo]

if you try to just put bearings , you are wasting time and money. the odds of it lasting more than 2 hrs of driving are slim to none

 

[Backinajiffy12]

yeah i would just rebuilt the whole motor. As joe sobo said its just a waist of time and money to replace just the journals.

 

[shredwin]

My friend had a guy do his motor cause he had a spun rod bearing. The guy put a brand new OEM crank, new bearings but the dumbass used the same rod where the bearing had spun.. well he didnt even drive it for 20 miles and got a spun bearing again on the same exact spot just because he didnt change that rod, the rod was scared up really bad ..


I dont think it would be a good idea to use sand paper, or to use the same rod unless you want another spun bearing.

 

[dragonforce]

cutting corners will get you in trouble. Do it right the first time. get a reground crank or a new crank.