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1. Am I correct in that TH400 pistons in the forward and the direct with the higher work surface area are the good ones to use in 4L80E performance applications with a D3 brake? These are part number U34965 (with checkball)?
2. The work surface of the pistons needs to be machined for proper clearance within the 4L80E forward and direct drums correct?
3. Do you guys take a depth measurement of the drum to determine how much to machine off the piston work surface or do you just typically put the piston in a lathe and machine the face flat?
4. The machined TH400 direct and forward pistons should not be used with a direct/forward dished cushion .054", but rather a direct/forward steel wave (12 Lugs .060") part number 34127, correct?
5. TH400 spring retainers in the forward and direct are much better than the flimsy 4L80E retainers and should be used instead?
6. That being said, where can I source some high rate springs for the forward and the direct? Are these the ones being used: https://www.sonnax.com/parts/1913-he...-return-spring
7. What is the difference between "high rate springs" and the springs that are used in the TH400?
This is an electronically shifted 4L80E with jakes D3+ brake in a street car that will be turned up to about 1200 rwhp at the track and about 650 on the street
My forward clutches in this 2005 4L80E core are smoked and my forward drum shows signs of the input shaft eating in to the sealing ring lands. My plan is to buy a sleeve, machine the drum, and press the sleeve in rather than buy a whole new drum. https://sales.omegamachine.com/Produ...ductCode=33353
At least the captured bearing in the OD is still good.
Should I replace this direct clutch pressure plate:
Last edited by 5.7stroker; Nov 21, 2020 at 10:44 AM.
heads up be sure and use some green loctite 640 with the sleeve. it wont seal with just an interference fit. you'll also need to hone it afterwards depending on what your press fit was like.
heads up be sure and use some green loctite 640 with the sleeve. it wont seal with just an interference fit. you'll also need to hone it afterwards depending on what your press fit was like.
Good info here! I'll explain what needs to be done to my machinist.
I hope you are buddies with your machinist and he will do this for ya for a beer or some wings or something
Because for the cost of a good used fwd drum...vs the cost of the sleeve and machine time...Id bet the good used drum will be the friendlier option
I was wondering about that. The thing is that I have several things that need machining in addition to that:
-clearance the TH400 direct and forward pistons
-Machining a bearing pocket on the center support so that it fits a late TH350 rear pump thrust bearing and washer
-Machining the case to fit the reid bellhousing adapter
-Drill press to put 2 more locating holes on top of the output carrier so that I can use a brass 4 tang output thrust washer instead of the plastic one.
I was wondering about that. The thing is that I have several things that need machining in addition to that:
-clearance the TH400 direct and forward pistons You can use a molded 4l80e direct piston, 6 .080 frictions, and 6 .077 steels and this usually stacks up almost perfectly and puts clearance right in the sweet spot. You may have to mix in 1 or rarely 2 .060 steels to get you where you need.
-Machining a bearing pocket on the center support so that it fits a late TH350 rear pump thrust bearing and washer This is a nice touch, but many many high hp builds don't even do this. It does work well to center the drum if you're able to tighten up the endplay enough, but having the stock thrust setup where the direct drum passes thrust through the sun gear tube works well as long as the center support bushing is good
-Machining the case to fit the reid bellhousing adapter You need a mill and rotary indexer to machine the pump properly for the adapter
-Drill press to put 2 more locating holes on top of the output carrier so that I can use a brass 4 tang output thrust washer instead of the plastic one. Throw away the plastic and don't use a brass. If you'll be getting everything machined, just get the reaction carrier (where the band rides) machined for a th350 bearing. 2.90 OD and about .070 deep
- Pressing in the bushing on the center support If you know anybody with a harbor freight 20 ton press you're in business. Just line the holes up properly and you can handle this. Be sure to not leave a ridge on the edge you press from.
Left a couple notes in your post above.
Also, better machine the FWD hub if you're doing everything else.
Left a couple notes in your post above.
Also, better machine the FWD hub if you're doing everything else.
Thanks again for your comments! I was planning on getting the billet rollerized forward hub. I'm wondering if it's cheaper to just buy the adapter and pump already machined. I'm not to far from extreme automatics (40 min), so maybe they can cut the case for me since they do it all the time. I believe jake only charges $100 to cut the case, but then I have to ship the case out to him.
Lonnie at extreme is a good guy.
Him or jake...either can take care of ya
I think jakes sells a kit with the machined pump, bellhousing, and adapter if you need to source that still
Lonnie at extreme is a good guy.
Him or jake...either can take care of ya
I think jakes sells a kit with the machined pump, bellhousing, and adapter if you need to source that still
Excellent! I’ll be ordering that kit from Jakes today!
5. TH400 spring retainers in the forward and direct are much better than the flimsy 4L80E retainers and should be used instead?
6. That being said, where can I source some high rate springs for the forward and the direct? Are these the ones being used: https://www.sonnax.com/parts/1913-he...-return-spring
7. What is the difference between "high rate springs" and the springs that are used in the TH400?
High rate springs are thicker/stronger. Said to stop direct drum apply when you dont want it applying among other things.
From what Ive read, some people use the powerglide reverse springs for the forward drum, they are said to be somewhere in between stock springs and some high rate springs out there.
Then stronger high rate springs for the direct drum. FTI has some, but these could be the powerglide ones? I have a set of those coming, and also bought a set of high rate from a local trans builder who recommends them for the direct drum (and he sells weaker springs for the forward drum) I will compare his springs with the FTI ones (which I suspect are the glide ones because of 17 in the kit).
High rate springs are thicker/stronger. Said to stop direct drum apply when you dont want it applying among other things.
From what Ive read, some people use the powerglide reverse springs for the forward drum, they are said to be somewhere in between stock springs and some high rate springs out there.
Then stronger high rate springs for the direct drum. FTI has some, but these could be the powerglide ones? I have a set of those coming, and also bought a set of high rate from a local trans builder who recommends them for the direct drum (and he sells weaker springs for the forward drum) I will compare his springs with the FTI ones (which I suspect are the glide ones because of 17 in the kit).
The forward drum is on all the time vs the direct drum so that is the reason for some builders using different springs.
So you are saying "high rate" springs are not the same spring rate as TH400 springs found in the direct clutch of a TH400 that uses an aluminum piston?
The forward clutch is stable in every forward gear, so I'm not sure if a TH400 aluminum piston is even needed there.
Yes, these "high-rate" springs should be used for the direct clutch when "dual;-feeding"... and in the forward clutch for a trans-brake.
Use no waved steel plates in forward or direct in this situation.
Yes, but these "high-rate" direct springs are the same springs that are in the direct piston in early model TH400? That's what I'm wondering.
Since I'm running a transbrake should I use a TH400 direct/forward aluminum piston (machined for proper clearance) from an early TH400 in the forward as well?
Last edited by 5.7stroker; Nov 23, 2020 at 01:15 PM.
So you are saying "high rate" springs are not the same spring rate as TH400 springs found in the direct clutch of a TH400 that uses an aluminum piston?
The forward clutch is stable in every forward gear, so I'm not sure if a TH400 aluminum piston is even needed there.
Not the same springs, they are stronger again, and its recommended to replace the stock TH400 springs with the higher rate in performance builds.
I do like aluminum pistons (I have bent/deformed a steel one in the direct) ... whether its needed in the forward and intermediate is debatable, depends on the application, but I have read quite a few trans guys say they dont like the steel pistons anywhere.
It's the early TH400's that have aluminum pistons that have visually have double the surface area at the piston to first steel area correct? These are the ones to use in a 4L80E core for the forward and direct since dual feed mod and transbrake shifting at 6700 rpm? From what I understand, some have a check ball in the piston and some don't, but as long as I get the one with the checkball in the piston, then it doesn't matter if the drum has a checkball or not, correct?
It's the early TH400's that have aluminum pistons that have visually have double the surface area at the piston to first steel area correct? These are the ones to use in a 4L80E core for the forward and direct since dual feed mod and transbrake shifting at 6700 rpm? From what I understand, some have a check ball in the piston and some don't, but as long as I get the one with the checkball in the piston, then it doesn't matter if the drum has a checkball or not, correct?
if you have an 80e 34 element direct drum, it very very very likely has a check ball. I cant remember seeing one that didn't.
I've got a jakes D3 36 super drum on order and they don't know just yet if it will have one or not. My forward drum has the check ball. It's OK for both a piston to have a checkball and the drum to have a checkball, correct?
TH400 vs 4L80E piston, retainer and springs 
