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Jun Crank Collar

Swiper the Fox
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B0oStEr Mentor

B0oStEr

Posted
Posted

I didn't use a jun collar.

I took my r32 gtr crank to an engineering workshop and got them to machine the nose down and heat shrink a 4140 moly sleeve onto it.

They then machined it to r33 gtr specs.

They charged me $169 all up for everything but prices elsewhere could vary.

They can get most of the measurements they need from the r32 crank before they machine it down.

You just need to tell them how long to machine the flats.

If you go for a jun collar they still have to machine the crank and heat shrink it on.

Swiper the Fox Grand Master

Swiper the Fox

Posted
  • Author
Posted
I didn't use a jun collar.

I took my r32 gtr crank to an engineering workshop and got them to machine the nose down and heat shrink a 4140 moly sleeve onto it.

They then machined it to r33 gtr specs.

They charged me $169 all up for everything but prices elsewhere could vary.

They can get most of the measurements they need from the r32 crank before they machine it down.

You just need to tell them how long to machine the flats.

got the collar with the pump...good price too...thanks CRD

so ill fit it...looks like the nose of the crank is machined and the collar is pressed on.

it comes with two grub screws so they will hold it in place.

Mik Experienced

Mik

Posted
Posted
I build my own engines.

thanks Nik (amaru)

I take it the grub screws are inserted 90deg from the drive faces (flats)?

The grub screws are just an extra precaution. You need to machine the crank to the right clearance (negative) for an interference fit.

Bob Lee at Action cranks has fitted squillions of them for a lot of engine builders.

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

when we do our we oil bath the collar also so its a little tighter on the tolerance (heat bath etc), but yeah as mentioned, machine the old drive off the crank, tolerance fit the new one, and drill grub screws on the flats of the drive ensuring they are bellow deck height, lock tite them in and your away.

r33_racer Grand Master

r33_racer

Posted
Posted
when we do our we oil bath the collar also so its a little tighter on the tolerance (heat bath etc), but yeah as mentioned, machine the old drive off the crank, tolerance fit the new one, and drill grub screws on the flats of the drive ensuring they are bellow deck height, lock tite them in and your away.

Bingo, exactly what we did with our rb30det in the racecar. Except it was an rb30 crank obviously. Has worked with no dramas so far. I must say the drive section of the collar is massive in comparison to the std drive on the crank, well once again for rb30 crank lol. Bigger is better in these circumstances strangely enough.

Sydneykid Grand Master

Sydneykid

Posted
Posted (edited)

It's a 2 thou interference fit. Then put the crank in the fridge and the collar in the oven and press it on. Temperatures normalise and it ain't going anywhere. Grub screws are just a precaution.

>_< cheers :wave:

Edited by Sydneykid
Swiper the Fox Grand Master

Swiper the Fox

Posted
  • Author
Posted
It's a 2 thou interference fit. Then put the crank in the fridge and the collar in the oven and press it on. Temperatures normalise and it ain't going anywhere. Grub screws are just a precaution.

>_< cheers :wave:

some say to put the screws in on the flats...and others say 90deg from the flat face. Will a rebalance be needed??

Sydneykid Grand Master

Sydneykid

Posted
Posted
some say to put the screws in on the flats...and others say 90deg from the flat face. Will a rebalance be needed??

We put them on the flats, I am not sure that it matters. They are also loctited in of course.

The diameter and weight of the flange is not really enough to put the crank out of balance.

That said, I always check the balance of RB cranks every time I disassemble an engine. It’s cheap insurance.

>_< cheers :wave:

Swiper the Fox Grand Master

Swiper the Fox

Posted
  • Author
Posted
We put them on the flats, I am not sure that it matters. They are also loctited in of course.

The diameter and weight of the flange is not really enough to put the crank out of balance.

That said, I always check the balance of RB cranks every time I disassemble an engine. It’s cheap insurance.

:wave: cheers :wave:

Yeah...same...will balance after collar fitted

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

FOr the 30 mins it takes to check the balance we always do it!! I have never put the screws on the round side always on the flats, dont think it matters as mentioned there a precautionary measure.

We dont need a freezer in canberra just leave them outside in the morning in winter in canberra and bingo you have a crank thats -4 in temp!!!hahaha

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