Early 80e question
Thread Starter
Joined: Oct 2011
Posts: 175
Likes: 21
From: Eastern PA --> Southwest VA
Early 80e question Currently building a 92 80e for a friend and I haven't messed with early cases at all. It has a failed aluminum piston in the direct and I know these are a weak point. Can I simply install the 97+ bonded pistons without issue?
Dumb question, but if the aluminum pistons are a failure point, does that also apply to the early TH400 aluminum direct pistons? I ask because many of the high HP aftermarket 4L80E builds that I see have that piston in them with the TH400 spring retainer and high rate springs and the work surface of the piston is machined to accept a 6 friction / 6 steel setup.
the early 80e piston and the th400 "dual rim" piston are two different animals. the th400 dual rim is waaay stiffer and has many radial stiffeners running from the piston cavity to the edge.
I have successfully used the early 80e aluminum (and the single rim th400) pistons in the direct drum at ~ 750 whp applications but you need to set them up carefully. I use a .100" kolene right on top of the 80e cast piston to add rigidity to the stack ( normal steels the rest of the way, no waves) and keep the stack tight. .045 dry.
This allows me to keep costs down on a unit that doesn't need billet hard parts, and lets lots of guys just have fun and do burnouts. I have yet to try one with a full sonnax LB1 kit or fixed line pressure. Usually I do the CK spring or just the sonnax boost valve with the stock spring in that configuration.
if its gonna need to hold big power in 3rd gear with sticky tires and you need that line pressure up fairly high to do so, yes the dual rim th400 piston is the piston to use. that or a billet unit. especially in a transbrake application when you need high rate springs to release the brake quickly
I have successfully used the early 80e aluminum (and the single rim th400) pistons in the direct drum at ~ 750 whp applications but you need to set them up carefully. I use a .100" kolene right on top of the 80e cast piston to add rigidity to the stack ( normal steels the rest of the way, no waves) and keep the stack tight. .045 dry.
This allows me to keep costs down on a unit that doesn't need billet hard parts, and lets lots of guys just have fun and do burnouts. I have yet to try one with a full sonnax LB1 kit or fixed line pressure. Usually I do the CK spring or just the sonnax boost valve with the stock spring in that configuration.
if its gonna need to hold big power in 3rd gear with sticky tires and you need that line pressure up fairly high to do so, yes the dual rim th400 piston is the piston to use. that or a billet unit. especially in a transbrake application when you need high rate springs to release the brake quickly
the early 80e piston and the th400 "dual rim" piston are two different animals. the th400 dual rim is waaay stiffer and has many radial stiffeners running from the piston cavity to the edge.
I have successfully used the early 80e aluminum (and the single rim th400) pistons in the direct drum at ~ 750 whp applications but you need to set them up carefully. I use a .100" kolene right on top of the 80e cast piston to add rigidity to the stack ( normal steels the rest of the way, no waves) and keep the stack tight. .045 dry.
This allows me to keep costs down on a unit that doesn't need billet hard parts, and lets lots of guys just have fun and do burnouts. I have yet to try one with a full sonnax LB1 kit or fixed line pressure. Usually I do the CK spring or just the sonnax boost valve with the stock spring in that configuration.
if its gonna need to hold big power in 3rd gear with sticky tires and you need that line pressure up fairly high to do so, yes the dual rim th400 piston is the piston to use. that or a billet unit. especially in a transbrake application when you need high rate springs to release the brake quickly
I have successfully used the early 80e aluminum (and the single rim th400) pistons in the direct drum at ~ 750 whp applications but you need to set them up carefully. I use a .100" kolene right on top of the 80e cast piston to add rigidity to the stack ( normal steels the rest of the way, no waves) and keep the stack tight. .045 dry.
This allows me to keep costs down on a unit that doesn't need billet hard parts, and lets lots of guys just have fun and do burnouts. I have yet to try one with a full sonnax LB1 kit or fixed line pressure. Usually I do the CK spring or just the sonnax boost valve with the stock spring in that configuration.
if its gonna need to hold big power in 3rd gear with sticky tires and you need that line pressure up fairly high to do so, yes the dual rim th400 piston is the piston to use. that or a billet unit. especially in a transbrake application when you need high rate springs to release the brake quickly
Last edited by 5.7stroker; Dec 29, 2020 at 04:42 PM.
TECH Junkie
Joined: Dec 2012
Posts: 3,615
Likes: 1,327
From: Iowa
The single work surface 80e aluminum pistons are prone to cracking.
I never use them. Ever.
If it has one, it gets thrown out and replaced with either a molded piston for lower power builds, or the TH400 dual work surface piston for higher power builds.
They work for plenty of guys...lots have used them and continue to use the with good luck...so don't think this is me saying nobody should EVER use one...but for me, the cost of a new piston vs the cost of a come back...I just can't justify using the junky 80e piston.
I never use them. Ever.
If it has one, it gets thrown out and replaced with either a molded piston for lower power builds, or the TH400 dual work surface piston for higher power builds.
They work for plenty of guys...lots have used them and continue to use the with good luck...so don't think this is me saying nobody should EVER use one...but for me, the cost of a new piston vs the cost of a come back...I just can't justify using the junky 80e piston.
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Thread Starter
Joined: Oct 2011
Posts: 175
Likes: 21
From: Eastern PA --> Southwest VA
When using molded pistons in an early case can I use the original spring cages and conical plates, or do I need to use the newer cages and wavy plates? I'm going through the forward now and, using the conical plate, I'm only seeing about 30 thousands clutch clearance. I don't think the conical and wavy plates are interchangeable are they?
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Verdad Gallardo i have used the spring cages interchangeably
i use a th400 style thick wavy in the forward if you are bumping line pressure. shoot for .040-.050 dry
i delete the cone plate, cushion plate or wavy in the direct. I like a .100 thick kolene up against the piston and build my stack from there. again looking for .040-.050 dry
i use a th400 style thick wavy in the forward if you are bumping line pressure. shoot for .040-.050 dry
i delete the cone plate, cushion plate or wavy in the direct. I like a .100 thick kolene up against the piston and build my stack from there. again looking for .040-.050 dry
TECH Junkie
Joined: Jun 2008
Posts: 3,202
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From: Nitro Alley
Generally the clutch pack cushion plates (Bellville or waved) in the 4L80E are inferior to the THM400.
The 4L80E plates are thinner, have a lower quality heat treatment, do not cushion the clutch apply as well, and fracture more easily.
Get some for a THM400.
The 4L80E plates are thinner, have a lower quality heat treatment, do not cushion the clutch apply as well, and fracture more easily.
Get some for a THM400.
TECH Junkie
Joined: Dec 2012
Posts: 3,615
Likes: 1,327
From: Iowa
The forward will be fine with anything from .015 to .065 clearance. I shoot for the lower end of that range
the direct you want .010 per clutch as a decent rule of thumb.
No Kolene
with a molded piston in the 80e direct drum, 9/10 times you can run 6 each .077 steels and .080 clutch and your clearance will be spot on
the direct you want .010 per clutch as a decent rule of thumb.
No Kolene
with a molded piston in the 80e direct drum, 9/10 times you can run 6 each .077 steels and .080 clutch and your clearance will be spot on
