I am thinking of getting new 2-4 servos for my transmission. My current trans has the following:
1. A valve body reprogramming kit (custom from the builder)
2. Raybestoes Z-PAK with 13 clutches
3. Raybestoes high temp energy clutches throughout the rest of the unit, along with all new steels, bushings, and rings.
4. A .500 boost valve
5. 4140 hardened pump rings
6. Teflon Pump bushing
7. 10 vane pump rotor
8. 29 element sprag
9. Sonnax Wide Open Throttle Valve
10. Sonnax Sunshell
11. Hardened input shaft and drum.
12. Kevlar band
13. Corvette servo
14. blocked off 1,2,3,4 accumulators

This unit was bought from a nonsponsor so I won't mention the name, so far it has been great. seems like the 2-3 shift could be a little tighter though and every once in a while I think it slips between shifts. My friends think its in my head and shifts great but I think I need new stuff and trans parts need love too! What does everyone think about getting rid of the corvette servo and replacing it with a fairbanks/sonnax combo? From what I understand the corvette servo is standard on a F-body anyways.

 

The Fairbanks servo might help your 2-3 problem...but...I'm sorry to discourage you, but the rest of that build sheet leaves ALOT to be desired. There are a few things that scream out "potential failure area".

I thought everyone knew about the teflon pump bushing problems with walking out.

Nobody uses a Kevlar band anymore. The material is too hard, and prone to premature failure.

Why did they re-use a Corvette servo? The Sonnax 4th and Fairbanks 2nd servo come standard in our $1000 "Race", and $1400 "Pro Race" rebuild.

The Sonnax wide open throttle valve is for a 700R4, not a 4L60E.

Did your builder re-install the 3-4 "Load Release Springs"? If so, you'll always have 3-4 clutch issues.

Did your builder address the fact that a 4L60E is designed to start dropping pressure at 5000 RPM's, in stock form?

Sonnax doesn't make a sun shell. We use "The Beast" in everything...Even our "Stock" builds.

Is that Sprag a Borg Warner Sprag?

Now...About that hardened input drum. If this drum is sleeved, they've created a larger problem than they were trying to fix. The aluminum forward piston is a weaker area than the drum splines. You can't even use the much more superior steel piston set with a sleeved drum. They actually made your transmission WEAKER!

Frank
CPT

*EDIT* Wait a second. I just found your other reply to the "Goodfellas" thread. In that thread, you were bragging about how good your transmission works???? It looks like they have alot to learn.

 

I was not bragging about how good it works, although it does work pretty well. It's not one of yours so feel free to tell me how bad I f*cked up by not getting one of yours. Oh wait I think you just did that. At least in your rant you did accidently answer my original question. I would ask you why you recommend the fairbanks 2 and the sonnax 4 rather than both fairbanks servos but I don't know if I can take the criticism.

 

jmho
If the 2nd gear accumulator has been completly locked up and your running a kevlar band. I wouldnt put the fairbanks/superior servo in. Its gonna be a really harsh shift possibly ripping out the lugs on the band or breaking other hardparts.

But again this is just my opinion, i prefer a positive shift not a shift that brakes the tires loose completly(at 30 % throttle).

 

The criticism wasn't aimed at you. I'm sure you didn't know you were buying an inferior product. I was merely pointing out that you may be looking at other areas for the root of your problem, and that you may see failures in other places. You're the one that posted their mods list, so I told you what I've experienced as being FACTS about some of these parts. Sorry I had to be the one to break the news to you, but I call them as I see them. I'm not going to try to "sugar coat" anything.
You guys still don't get it. It's not stricktly about me wanting all your work. It's equally about me not liking to see other members spend money on inferior stuff. If my machinist tells me he's seen 12 out of 15 sets of a certain brand valve spring fail, and warns me not to buy them, I'd look into another brand. wouldn't you? I'd respect his word, because he deals with it on a daily basis. If 12 of those sets failed, it wouldn't be THEORY, it would be FACT. Keep in mind, I only state facts.
Another scenario. Let's say you bought a new, high dollar starter for your car, and it didn't work. You take it to a local place and they disassemble it and find a bunch of junk parts in it. The next day, your buddy calls you and tells you he's thinking about buying that same brand starter. Wouldn't you feel obligated to tell him?
I've been doing this for 18 years. If there's a part for a transmission, I've probably tried it somewhere along the line. I know what works, and what doesn't.

To answer your question, The Fairbanks 4th servo doesn't have as much apply area as the Sonnax servo does. The Sonnax does give you a better 3-4 shift, also.

Frank
CPT

 

Your correct, I did not know I was buying an inferior product until I already bolted in the car. But I am stuck with it and now I want to try and make it better. I called the place today and talked to the builder a bit and he wants to send me new solenoids. I also requested the actual parts listing from my transmission which I will post when I get it. I know your product is superior, I don't need to be told that, I need to know what I can do with what I have to improve it.

 

I've been using the Fairbanks/Sonnax combo for a very long time. Is your 2nd accumulator is blocked, you may end up with a pretty harsh 1-2 shift with the Fairbanks 2nd servo. That'll also depend on what other mods are done to the trans. We use the wide red lined Alto 2-4 bands in our "Race" and "Pro Race" units. This band coupled with that servo combination has completely eliminated any band failures. We have these things that are 3-4 years old, and the bands still look like brand new. The other problem with billet servos is, they will break the band anchor out of some bands. The Alto band has a reinforced anchor.
Unfortunately, many of the things that are needed to make these things live in a racing application are internal modifications. If you can get a detailed build sheet, find out if they reinstall the 3-4 "load release springs". Using these in high RPM applications will always result in 3-4 clutch failure. Find out of they use the Sonnax high RPM pump slide spring. These help keep pressure up above 5000 RPM's.
The Z-Pak is a good set of clutches, as are the high energy in the rest of the unit.
As what sprag is in it. The single cage sprags (SKF) are very well known for failing in high HP/hard launching vehicles. Cross your fingers, and hope yours is a Borg-Warner.
I'm a little lost as to why the builder thinks you're having a shift solenoid issue. I can't see them causing a 2-3 shift problem. Both solenoids go off for 3rd.
If you get a detailed build sheet, let me know what you've got, and we'll see what we can do to make it better.

Frank
CPT

 

I have an ATSG manual (automatic transmission service group) for the 4l60e and there is a note on page 62 that says; atsg recommends that you remove and discard the 3-4 load release spring assemblies shown above, all models, for a much improved 2-3 shift!

 

And then in the update manual it says to reinstall them......
Im not going against what cpt does they build amazing units. From what i have seen it is a personal preferance from builder to builder wether to leave them or not.

 

Remember...the ATSG manual is instructing you to rebuild these for stock vehicles. We've proven that reinstalling these springs in race units will ALWAYS result in 3-4 failure. We researched this extensively around 12 years ago, and proved this fact. I definitely wouldn't call it personal preferance...LOL I'd just ask how long you want the clutches to last and how good you want the 2-3 shift.

Frank
CPT