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Crank Collar Clearance Issue

urtwhistle

By urtwhistle,
in Engines & Forced Induction

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urtwhistle Proficient

urtwhistle

Posted
Posted

Hey guys,

I have done a bit of a search and can't find any thing that helps.

I have just had my rb30 crank machined and a crank collar put on. I just test fitted the oil pump gear on the collar and noticed there seems to be a lot more clearance than what I would have expected. I measured a total of 12 thou, Ie 6 though on each flat face. Firstly is that normal? that amount of slop I would have expected to negate the whole purpose of the collar.

Do people shim up there gears? I'm think about getting 2 small peices 4 thou shim and loctite 406'ing it to the crank collar just to tighten it up a little. I noticed tonight that the glue added about 1 thou. so In theory it would bring it down to about 2 thou.

What does every 1 else do?

Lastly when using a standard rb25 pump on a built rb30, do people put say a 2mm washer in the oil relief valve?

regards

Chris

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bubba Grand Master

bubba

Posted
Posted

Chris, that is why I'm a fan of welding the snout up and machining to suit the particular gears you are using. For me, 12thou is way too much slop!

As for the oil pump relief, I'm running a stock RB30E pump on my next engine and I shimmed the relief spring with an approx. 2mm washer.

urtwhistle Proficient

urtwhistle

Posted
  • Author
Posted

Hey Mr Bubs, In hind sight I think your onto something and I probably should have gone the welded route.

12 thou makes the oil pump gear rock back and forth like its on a rocking chair. I don't understand why there isn't alot more post's relating to this subject I mean its so damn obvious to me lol

r33_racer Grand Master

r33_racer

Posted
Posted

Yeh that point is a good one. However, What does the clearance become when the engine is running and everything has heated up and expanded?

Also another point is the crank doesnt run perfectly centred at xxxx rpm, there is always a certain amount of runout. Too tight on that clearance and it will be just as bad as not having a collar at all. How much runout there is i dont know, But there is no way the snout is always perfectly centred when your at 7000rpm bouncing off the limiter.

But 0.012" is alot, and no doubt it can probably be run abit tighter. But there is no way of knowing until someone who has run tighter can say its been fine and tells you what clearance they actually did run. Or you try it yourself and see what happens.

But I dont think 0.002" is enough. Hopefully someone else with more exp can shed some light here.

If I was going to machine a collar Id probably aim for about 0.006" overall, 0.003" per side. But thats just my own guess. Without knowing expansion and run out its hard to say.

MrStabby Grand Master

MrStabby

Posted
Posted

Yeh that point is a good one. However, What does the clearance become when the engine is running and everything has heated up and expanded?

If both pieces are made from the same metal (or if they have the same coefficient of thermal expansion), the clearance will not change if they stay at the same temperature.

t_revz Grand Master

t_revz

Posted
Posted

Chris, that is why I'm a fan of welding the snout up and machining to suit the particular gears you are using. For me, 12thou is way too much slop!

how hard did this hit the back pocket? significantly more than collar?

urtwhistle Proficient

urtwhistle

Posted
  • Author
Posted

Doesnt the aftermarket crank collars and a std r33/r34 crank measure up the same OD?

I think you might be right but I no longer have the neo Rb25 block to mic it up. I went with the 4thou shim and its still possible a bit tight. I'll have more of a look tonight now that the glue has dried and I can take the sharp edges off the shim.

bubba Grand Master

bubba

Posted
Posted

how hard did this hit the back pocket? significantly more than collar?

Not sure on cost as I haven't done mine yet as my forged build is on hold for a while, chuckie should know soon. We had it done to my mates 30 in his GTS4 and that thing cops an absolute beating, 8500rpm limiter launches and burnouts, still going strong.

Realistically, it should add much onto the cost of machining at all. Wouldn't take more than an hour to weld the snout up and if just fitting a collar the snout needs to be machined right down anyway.

On the topic of crank runout.... why would a splined setup ala JZ, not completely destroy itself?

sky30 Mentor

sky30

Posted
Posted

Not sure on cost as I haven't done mine yet as my forged build is on hold for a while, chuckie should know soon. We had it done to my mates 30 in his GTS4 and that thing cops an absolute beating, 8500rpm limiter launches and burnouts, still going strong.

Realistically, it should add much onto the cost of machining at all. Wouldn't take more than an hour to weld the snout up and if just fitting a collar the snout needs to be machined right down anyway.

On the topic of crank runout.... why would a splined setup ala JZ, not completely destroy itself?

is you mates motor rb26 or rb30?

r33_racer Grand Master

r33_racer

Posted
Posted

Not sure on cost as I haven't done mine yet as my forged build is on hold for a while, chuckie should know soon. We had it done to my mates 30 in his GTS4 and that thing cops an absolute beating, 8500rpm limiter launches and burnouts, still going strong.

Realistically, it should add much onto the cost of machining at all. Wouldn't take more than an hour to weld the snout up and if just fitting a collar the snout needs to be machined right down anyway.

On the topic of crank runout.... why would a splined setup ala JZ, not completely destroy itself?

Whats the 2J setup look like exactly? How many splines and do you know what sort of clearance it runs? No doubt its better then our nissan design. Seems toyota also improves on everything nissan didnt :( Splined from the get go sounds alot better.

Im guessing it probably has ample clearance as well, or maybe their cranks are made of better material and dont flex/runout as much?

bubba Grand Master

bubba

Posted
Posted

is you mates motor rb26 or rb30?

25t/30

We had it done to my mates 30

:thumbsup:

Whats the 2J setup look like exactly? How many splines and do you know what sort of clearance it runs? No doubt its better then our nissan design. Seems toyota also improves on everything nissan didnt :( Splined from the get go sounds alot better.

Im guessing it probably has ample clearance as well, or maybe their cranks are made of better material and dont flex/runout as much?

It looks pretty much like an axle end where it goes into the diff.. as for clearance, I have no idea. Shanef was working on a splined setup for RB's but got ripped off by his machinist or something :/

2JZ-GE oil pump..

oilpump.jpg

urtwhistle Proficient

urtwhistle

Posted
  • Author
Posted

Hey so it turns out that 4tho shim is still too tight and I can't get the oil pump gear on. which is a pain when I know that if the gear is in position I can push 2x 6 tho feeler gauges under it.

Also Loctite 406 is not a valid option as it is extremely hard to get it to key on and stop the shim from peeling off. Thats If you are quick enough to actualy get the glue on without gluing the shim to your hand first.

My boss suggested using Loctite 680 high strength retaining compound. So I'll let you know I go with that experiment.

At the rate I'm going this motor is going to take about 2 years to get running. Almost give you a run for your money ay Bubba????

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