I'm looking for some input, on a couple of things about a 80E and RPM shifts.
First, I'm curious about the factory drum in these and how much RPM these are safe to spin/shift at?
I have heard a few different things on this.
My other question is on the speedo sensor. Recently upped the shift rpm and it wiped out the speedo sensor. I know these are pretty close in tolerance and I imagine the extra rpm either lost a little fluid film on the bushing or maybe it just lost tolerance. Curious if anyone else has this issue?
First time I've had this happen on a 80E, but I definitely wiped out a few sensors in 60's in the past.

 

IMO the direct drum needs to change much above 7000 rpm to aluminum ,
If all the bushing are snug and on particular all in the rear planets , case, tail . You could not see an issue with the sensors being killed.

 

I agree with Frank.
However there are three options as far as I am concerned.

I need to remember/ determine the manufacturers of these drums, and would need to know what type of valve-body is being used.

Stock valve-body: go with a 36-Element iron drum (some use stock dimension Intermediate Frictions, some use Ford C6 Frictions) and you keep the Overrun Band for manual 2nd-Gear.

Aftermarket/ modified valve-body that does not retain the overrun band for second gear: go with a 34-Element half aluminum and half steel drum. it is an aluminum drum with a steel center to spline to the Sun Gear Shaft and for the Teflon sealing rings.

The third and most expensive option would be the above drum but with a 36-Element Sprag instead of 34.

-Chello III

 

I appreciate your response. I wasn't sure about the drum needing changed, but I had kinda heard that.
This particular transmission, I didn't build, so I don't know for sure if the bushings were changed or not when it was gone through, but I don't think it's coincidence that I had just changed the shift rpm up to 7200 on this particular car, and now, it's shifting a little weird like it tagged the sensor. Pull it out this week, I'm expecting to see a little love mark.

 

continuing the discussion, are there any downsides to using an aluminum direct drum? i have read somewhere about loosing 2nd gear engine braking, but that's not a huge deal for most of us.

can a 4L80e with aluminum drum still be a streetable transmission that lasts for 30-50k miles, or is it kind of a track only deal at that point?

 

I see no downside and while not suggested I have even seen units with them that retained the functional 2nd brake band that had been running long term and only really noted some . wear at the drum where the band grabbed. The particular unit had around 30k on it since the build . The wear was not severe and not the reason I was in it .
i certainly would not suggest it if you were actually planning to use manual 2nd for braking to any extent.

 

thanks for the reply, that's great because that's exactly what i need, a 4l80e that can shift 1-2 at 7500 rpms but will survive on the street for awhile.

 

is there a preferred vendor for the aluminum drums? what would be the pros/cons of the different offerings?

just from a basic search i've found coan, CK, suncoast? and looks like maybe jake's has one although it wasnt clear to me if they are making it in house or buying one

 

FTI is a sponsor here https://ftiperformance.com/products/...ent-sprag.html

 

A stock 4L80E drum is generally safe for shifts up to around 6200-6500 RPM. Beyond that, you risk pump cavitation and wiping out the speedo sensor from the increased shaft speed and loss of fluid film exactly what you described. It's a known weak point when pushing RPM.

For higher RPM, you need a built transmission with a billet drum and better pump to prevent fluid starvation. The sensor failure is a classic sign you're exceeding the stock fluiding limits.

 

Question why use aluminum? It is such a soft less strong material than steel is, or is it a weight issue for the higher speed? Just curious.

 

It is a Mass/ Inertia problem...
You could think of it as a Centrifugal problem, where a given Mass must be accelerated and decelerated without loss of control/ or coming apart.

The lower the Mass/ resulting forces, the less work required to keep said given control.


@truckdoug has been working on some R&D for his own really killer set-up for a High RPM 4L80E project!
Check out his YouTube Videos!!!

 

thanks for the lead on truckdoug, do you know what his youtube handle is? i wasnt able to find it

 

The 4L80e Guy

 

thanks. holy crap, i was not expecting to watch mads mikkelsen building transmissions today but here we go

@truckdoug do you have any suggestions for which videos to watch regarding high RPM and 4L80e specifically?

i did find this one about the 36 element sprag, was very informative -

 

There are definitely negatives to using an Aluminum Direct Drum.


First the wear and tear on them is terrible.
The splines where the Drum engages the Sun-Gear Shaft strip-out...
The Bore that is a sealing surface for the Teflon Sealing Rings on the Center Support get grooves and stop sealing...
The Lugs inside the Drum where the Steel Plates of the Clutch Stack are start to both groove and round-over/ strip-out...
And if you have an Intermediate Overrun Band, the Band surface of the Drum wears away!

All that Debris goes into the Fluid!
And if you have a high-flow Filter for a Trans-Brake... none of that debris gets caught by the Filter!

Some of this can be minimized with a Hard Anodized half Steel, half Aluminum Drum.

The all Aluminum and Non-Anodized are the WORST!

 

do you have a recommendation for a drum that you prefer?

also, how do you feel about the billet steel drums with 36 element sprag for high RPM shifts ( say, 7500 rpm )

Thanks

 

BTE sells a half aluminum/ half steel Direct Drum that works well.

Yes, a billet steel drums with 36 element sprag can work in that application as long as power is not super high.
There are also billet steel drums that have been lightened and work great!