I'm building my first '01 4l60e using the Blueplate Special clutches, and a host of other supporting mods. I'm finally to the point of reassembly, and have measured .030 clearance in the Reverse input drum...but am shooting for at least .050, as this is the recommended clearance for the Sonnax smart tech input drum using the same clutch material. I'm assuming that the clearance should be the same if not more like .060 for the Reverse pack, as it spends most of it's life freewheeling.

Thoughts?

 

First using Blue frictions for the reverse input drum is probably overkill. Also, there is little correlation between the clearance in the reverse drum with the clearance of the 3/4 clutch. Since you (probably) are not engaging Reverse at high throttle, the clearance is less critical and can be higher.

When Blue frictions are used in the 3/4 clutch my suggested clearance is .005 to .007 per friction (e.g. .050 total). At .007 per friction times the 4 frictions in the reverse drum, I would consider the minimal clearance to be .028. But I would also aim for a bit more.

Also, congrats on doing your own rebuild.

 

My clearance was initially like 0.070-0.075, which is technically within spec. But I swapped out the backing plate with the thicker one and got it down to about 0.050.

If you have a micrometer, you can measure your backing plate size. It's possible you have the thickest of the three sizes. Or you can take it to a shop and they can measure it, with you saying you need to buy a thinner one.

 

You can also substitute the bottom dished plate with a wavy steel and it should free up to within spec.

 

Thanks for the info and help ;-) Yeah, I had a bit of a brain fart regarding clearance....as far as I can tell, the minimum in the 3/4 works out to be .0055/plate, so I'm likely in the ballpark for the reverse input @ .030, but I'm thinking that .040-ish should be better, given the material. And yeah, I'm learning that the Blues are overkill for everything but the 3/4 pack, but I bought them all at the same time in a "package deal". We'll see how it all goes :-)

 

I measured the .030 with the .076 turbulator steels....looks like they are also available in .067, which should get me to .048 by swapping 2 of them. Any thoughts on using 2 different thickness steels in the pack?

 

I would keep the reverse input drum on the loose side to prevent clutch drag (that's why they made the turbulator steels). Also, if you are using the Transgo orifice cup plugs on the reverse piston and have tight clearance, you will definitely have drag issues.

 

I used two thicker steels in my 3-4 clutch pack and put them in the center of the pack. Works just fine.

 

I have been told by several builders not to use the Transgo reverse drum orifice cup plugs, at least not in newer ('96+) 4L60E. Perhaps they were a relic from the 700R4 and very early 4L60E days?

 

I'm not sure. When looking for replacements, they list as "93-up"...and this unit is a 2001...appeared to be bone stock on disassembly. So, you're thinking that I should just go with conventional steels? Also, do you think that .040-ish will still be too close for this setup?

 

Sorry for any confusion, I meant not to use the "Transgo orifice cup plugs" and was hoping for MPTrans' confirmation. Will update my previous thread to correct the confusion.

 

Use the "waved" steel to replace the Belville steel. This will stop the metal contamination from the Belville eating the drum. Set the clutch clearance to .040" - .070". Always use the Turbulator steels as they get rid of the excess drag. DO NOT install the orfice plugs from TransGo, as they will cause the piston to try to apply at hi-rpm (5,500 & up) from centrifuge which will burn the clutches and gradually you will lose reverse. Leave the aluminum piston alone. The reverse apply feed hole in the separator plate should be .104".

 

^^^ As always, thank you Dana. Especially for the very definitive answer.

 

MUCH appreciated Dana. I'll double-check the reverse apply feed....but I'm sure it's right, as you set it all up for me :-)