Spliting the big end

[Richard WMember]

The poor old CRF did the big end bearing last weekend. The guys at Mud’nTar say they can send it away and get it pressed.
How hard can this be?
I’ve got a 30 ton jack in the shed but would have to make a frame to press it.
One side of the crank has a sleeve bearing, does this have to be taken off first?

[Mick DMember]

So that was the big bang she let rip with on Saturday?? Lucky she blew up where it did mate. I would suggest that you contact Watt and Parsons Engineering in Port. 6581 2203

They are in Arcacia Avenue.

I just gave them a call and they said they can do it. (the chicky babe on reception said they could anyhow).

[ScottMember]

If you have never rebuilt a crank before I wouldn’t be attempting it.

A quick rundown of how I was taught It has been a while so hopefully I get the steps right
Put it up between centres and see how much run out it has on the bearing surfaces. (This gives you something to work to after you press it back together)
Scribe a line with a rule mark a straight line across the crank webs. (You use this when pressing back together)
You really need a workshop press.
A special jig that supports the crank whilst pressing the pin out.
Press apart
Install new rod and bearing
Align previous scribed marks and press back togther.
Put up between centres and check run out on bearings.
Use a soft hammer and a big block of timber to belt in alignment (Trueing the crank)
Re check between centres
Keep on going until you get in back to what it was before pressing apart or better

[Mick DMember]

Get it wrong and she will vibrate herself to bits!!

[malleeMember]

Mate!!
This is a don’t F##k with me type of job. I am in the motor game and do all my own work except
for a few things and this is on of them. It you get it wrong you will have to pull it all apart again.

Save yourself the time and probbley in the long run the Money and get a machine shop to do it.

Just my 2bobs

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what the heck– do it:evil:

Mallee

[ianMember]

mallee wrote:

Mate!!
This is a don’t F##k with me type of job. I am in the motor game and do all my own work except
for a few things and this is on of them. It you get it wrong you will have to pull it all apart again.

Save yourself the time and probbley in the long run the Money and get a machine shop to do it.

Just my 2bobs

---

what the heck– do it:evil:

Mallee

I split my 510 husky for a bigend rebuild and saved myself $800 to $1000 on labour the onlything i got someone to do is press the crank and align and put the new bigend in which cost a $100 and it was spot on i put it back together and it fired first kick and was sweet, so i dont know your mechanical background ( im a truckdriver and have just learnt things along the way but have a pretty good success rate:blink: ) so unless your really sure id give that part to someone else sure it might cost some, but your still in front with doing everything else your self and as mallee said you wont know until your got it all back together and then ….. your got to pull it completely to bits again to fix it

[DeanMember]

micknmeld wrote:

So that was the big bang she let rip with on Saturday?? Lucky she blew up where it did mate. I would suggest that you contact Watt and Parsons Engineering in Port. 6581 2203

They are in Arcacia Avenue.

I just gave them a call and they said they can do it. (the chicky babe on reception said they could anyhow).

Yep those guys did the crank on my Old RMX im rebuilding only cost $80 concur with what the rest say and get a shop to do it.

Ollie

[Richard WMember]

badbowie wrote:

If you have never rebuilt a crank before I wouldn’t be attempting it.

A quick rundown of how I was taught It has been a while so hopefully I get the steps right
Put it up between centres and see how much run out it has on the bearing surfaces. (This gives you something to work to after you press it back together)
Scribe a line with a rule mark a straight line across the crank webs. (You use this when pressing back together)
You really need a workshop press.
A special jig that supports the crank whilst pressing the pin out.
Press apart
Install new rod and bearing
Align previous scribed marks and press back togther.
Put up between centres and check run out on bearings.
Use a soft hammer and a big block of timber to belt in alignment (Trueing the crank)
Re check between centres
Keep on going until you get in back to what it was before pressing apart or better

Is it standard to replace the conrod? the idea of splitting it myself was to check the condition of the conrod and save $$

[ianMember]

i can only say about the husky, but the bigend kit came with the new conrod as well

[GregMember]

Dickie wrote:

]

Is it standard to replace the conrod? the idea of splitting it myself was to check the condition of the conrod and save $$

If it did a big end like I thought I read the rod will be unserviceable ( read rooted ) besides I can’t ever remember buying a big end on it’s own

TB

[stephen nagleMember]

hot rod sell cranks for $390 rrp why would u bother rebuilding it for that price serco in qld sell them

[Richard WMember]

cycle tune wrote:

hot rod sell cranks for $390 rrp why would u bother rebuilding it for that price serco in qld sell them

Well, $390 = 2/3 of a cow off to market, didn’t want to have to sell too many.

[Richard WMember]

No luck, didn’t even move.

[malleeMember]

Mate,
Look at It, Spent half a day making the jib/priss, working in a durty area, one bit of st#t in the new bearing and it will be RS in one ride, you won’t have enough hands to hold, align it and press
it all togeather.:unsure:
Most have said about $100- $150 to get it pressed- money well spent!!

Mallee

[ScottMember]

From the photo it looks like you are trying to push the pin right through the two crank webs and the big end bearing.

Try holding it behind the crank web that way you are only pushing the pin out of one web.

You need to get it right if your not pressing dead staright the pin can pick up on the way out, basically destroying the web.

[Author]

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