Jump to content
SAU Community

RB26 crank modification

ylwgtr2

By ylwgtr2,
in Victoria

 Share

Recommended Posts

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

well i have pulled down an RB26 for rebuild and found a knackered crankshaft........new cranks are priced quite resonable so i bought 2 new cranks one for the engine and one for myself....heres the mods that i did on one of them today.......first we set up one end in a 4 jaw chuck,and we put a bearing on the other end and clamp that in a steady rest .....we check its true by placing a dial indicator on the main journal surface and spin the crank in the late....we then adjust it until its true..... then we start machining our first crankweb counterweight,we take it from as close to the rod end journal as we can get it right to the main journal at around a 50 degree angle(i cant remember exactly what the angle was)the working back toward the front end of the crank(you will notice only every second web is getting done,this is because every first web needs to be cut back to the opposite end of the crank,we do this by reversing the crank in the lathe)i managed to get all of the

second webs done today....i will have the first webs done tomorrow then start balancing it...heres the pics

Link to comment
https://www.sau.com.au/forums/topic/51675-rb26-crank-modification/
Share on other sites
inark Grand Master

inark

Posted
Posted

... i have no idea what ur doing... or what it does... but it looks damn impressive :P any pages u can refer me too so i know exactly what this does? or wanna give dummies like me a run down on what this does overall in the way of performance???

Laurence Mentor

Laurence

Posted
Posted

If you make things that spin around lighter, they can spin faster, or more easily, unless you made them too light because then they break. Also if the spinny thing has to sploosh through oil it is easier if there is a nice edge on it.

I think ylwgtr2 should probably post a pic of the bucket of metal filings that must have come off those cranks to give people a better idea.

Snowman Grand Master

Snowman

Posted
Posted
... i have no idea what ur doing... or what it does... but it looks damn impressive :P any pages u can refer me too so i know exactly what this does? or wanna give dummies like me a run down on what this does overall in the way of performance???

I have this problem just about every time I speak to troy! LOL

He's always doing something that is way beyond my comprehension - I just have to nod and presume what he's doing is a good thing!

inark Grand Master

inark

Posted
Posted
I have this problem just about every time I speak to troy! LOL

He's always doing something that is way beyond my comprehension - I just have to nod and presume what he's doing is a good thing!

its amazing how a lot of people seem to get this issue when troy speaks :P

troy... from now on i reckon u need to dumb it down a little for us.

ylwgtr2 Grand Master

ylwgtr2

Posted
  • Author
Posted
... i have no idea what ur doing... or what it does... but it looks damn impressive :P any pages u can refer me too so i know exactly what this does? or wanna give dummies like me a run down on what this does overall in the way of performance???

ok......gojira is pretty much on the money....."rotating mass" is the word for today.....Ever fitted a lightned flywheel?(andrew? ;))Its the same deal with cranks,pistons,rods and any thing thats rotating or reciprocating...the lighter it is the easier it will move and the less force it will take....therefore more response however there are trade offs.....example you will find that an engine that is made for smooth power will have heavier crank assembley(balancer and flywheel included)For take off heavy crank assemblys are good eg an idle no accelerator take off is easy......but try doing is with a light set up and you will most likely stall....This is because of the "stored energy" in the heavy setup is greater for obvious reasons....ITS HEAVIER!So in laymans terms it takes more grunt to drive a heavier flywheel/crank assembly but our aim is not to sit at constant speed...its to get it to the point of where everything happens in a hurry!Hope that makes some sense.....Oh and messing with the crank doesnt really cause them to break......its poor balance that usually does that...if you have a look at my doctored pic you will see the red line....thats the part that takes the stress i have only just taken the cast marks out of that.....the real weight has been taken off the crank webs on the opposite side.....just spinning the crank up it seems so much more "right"......you can see the crank doing "its thing" in the last pic

ylwgtr2 Grand Master

ylwgtr2

Posted
  • Author
Posted

oh and in the 3rd pic the left hand side of the conrod journal has been "done" and the right hand hasnt been done yet so you can see there is no material taken off the the "Power transfer section"of the crank

ylwgtr2 Grand Master

ylwgtr2

Posted
  • Author
Posted
This is a great thread! keep up the good work :P

Im glad your enjoying it!.......In regards to gojira's "oil splooshing"comment this engine will also wear a "crank scraper plate"Which runs a tight clearance between it and the crank edge....this removes any oil from the crank to stop it flinging all around the show inside the engine block....more on this later

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Unpeeling the Orange

      By MBS206 · Posted

      I'm normally copping my own abuse from neglecting my daily drivers. "Those suspension bushes will last a bit more", "Don't worry about the oil leak, just keep topping it up". The project cars I'm always doing things slowly on them as I'm wanting them to be done better, and neater, and nicer. Luckily I don't have to deal with 18 year old Matt's "Learning to wire" stuff in the project cars. And there's only one piece of wiring I'm displeased about in the Landcruiser, and it's about to be cut out... However, the box loads of parts that have been going through this place lately for the Landcruiser... Brake pads Brake Rotors Full handbrake overhaul Wheel Bearings Seals Swivel hubs Steering Boxes Half the suspension joints Shocks Air bags (Ones to go in the rear springs for towing) Water pump Timing kit Lower timing case Harmonic Balancer Radiator Lots of other little seals and shits Gas struts for the bonnet New power window switches And god knows what else I've forgotten... Ha ha ha I have my fingers crossed the pinion seals don't start leaking on the diffs, that the transfer case doesn't leak, and the gearbox input shaft doesn't leak, nor the rear main seal. As they're about the only seals I haven't replaced in the driveline! I'm seriously eyeing off buying new caliper rebuild kits front and rear brake calipers... I'll probably recheck all the valve clearances soon too, and hopefully, it should be all good and sweet to haul some long distance trips again!
    • GTSBoy
      Unpeeling the Orange

      By GTSBoy · Posted

      Every time I pull my 3x gauges out of the console and see the crack-addict way that I did the wiring, and I just can't bring myself to tear it all apart and "make it nice", because it is currently working. In fact, the last time I was in there I probably made it worse.
    • Kinkstaah
      Unpeeling the Orange

      By Kinkstaah · Posted

      The best part is when you own the car long enough that you look back and find your OWN ham fisted amateur shit!
    • MBS206
      Unpeeling the Orange

      By MBS206 · Posted

      The annoying part about neglect, is when you start to replace one thing, and find ten more broken things. Ham fisted monkey repairs you normally only find out about when trying to do something unrelated! Ha ha   Neglect you can kind of anticipate the huge costs to fix it all. Ham fistedness is normally a shock the first time your work on a new old car, as everything "looked" good before.
    • MBS206
      What brakes on R34 GTT(Europe)

      By MBS206 · Posted

      For DBA, check out their guide table here. https://dba.com.au/wp-content/uploads/2023/01/Direct_Replacement-Guide-2021.2.pdf   Additionally they have some other guides and info on how to make sure you choose the right pad.
×
×
  • Create New...