Having 2-3 shift overlap - Thinking of switching from 4.2 apply lever to 3.8 - Any Other Thoughts?

[MobileCustoms]

Hi guys,
I'm in the middle of lots of maintenance items on my Barracuda, one of which is addressing the 2-3 shift overlap clunk. We built this tranny (727) several years ago (2015) and it's still running strong but has the nasty 2-3 overlap clunk only when under very light throttle conditions.

It's currently got a 4.2 lever in it with I believe to be 12 springs, but possibly 15. I can't remember and my old photos don't show what we loaded for springs.
It's also got a reverse manual valve body with billet servos, heavy duty bolt-in sprag, etc.
I've been reading through the threads quite a bit and it seems like swapping a 3.8 into it might be good idea. I should probably also check the adjustment on the band today. From what I've read, that should be around 1.75 turns out for the 4.2 and 2 turns for the 3.8, correct?
Also, I have a 4400 stall and mainly street driven.
Thanks!
-Doug

 

[71Demon528]

Hi guys,
I'm in the middle of lots of maintenance items on my Barracuda, one of which is addressing the 2-3 shift overlap clunk. e built this tranny (727) several years ago (2015) and it's still running strong but has the nasty 2-3 overlap clunk only when under very light throttle conditions.

It's currently got a 4.2 lever in it with I believe to be 12 springs, but possibly 15. I can't remember and my old photos don't show what we loaded for springs.
It's also got a reverse manual valve body with billet servos, heavy duty bolt-in sprag, etc.
I've been reading through the threads quite a bit and it seems like swapping a 3.8 into it might be good idea. I should probably also check the adjustment on the band today. From what I've read, that should be around 1.75 turns out for the 4.2 and 2 turns for the 3.8, correct?
Also, I have a 4400 stall
Thanks!
-Doug

View attachment 1716247846

I have gone 2 or 2 1/4 turns out for 4.2 lever after torquing to 72inch pounds. I have also gone 2 turns always for a 3.8. Is the second gear servo a dual spring setup (Early year model). What ATF are you running? If it’s Type F, it has no friction modifiers in it, so it engages the clutches very very quickly, which can sometimes add to that 2-3 overlap at light throttle conditions.

With the transmission you have, 15 springs in high gear drum, dual spring second gear servo, and 4.2 lever is how I would set it up if it were mine or a customers. Being that it is out of the car, I’d verify the springs in high gear drum, and if the second gear servo is single or dual spring. I had a 3.8 in mine for years with a big piston High gear drum 18 springs installed. When driving around the pits warming my car up on a fast idle I would still feel the 2-3 overlap pretty good. As soon as the trans saw a little bit of temp (125 degrees and higher), the 2-3 overlap would be smoother and not as noticeable. Going down the track wide open throttle I would never feel it, it just shifts quick, precise, and no issues. Best thing I can say I would do at light throttle conditions, when you go to shift into 3rd, back off the throttle and let car coast for a second then put it in 3rd. That is what my good friend does with his to avoid that harsh overlap feeling at light throttle. I hope this helps!

RJ

 

[MobileCustoms]

Thanks. I’m running type F but would have to open it up further to verify the other things unless I can find some old photos. I planned to put the same fluid back in that I drained out. Not sure if switching fluids would be safe at this point?
Actually, the 2-3 overlap is the worst if I'm coasting and shift to 3rd. This is a street driven car, mainly.

 

[71Demon528]

Thanks. I’m running type F but would have to open it up further to verify the other things unless I can find some old photos. I planned to put the same fluid back in that I drained out. Not sure if switching fluids would be safe at this point?
Actually, the 2-3 overlap is the worst if I'm coasting and shift to 3rd. This is a street driven car, mainly.

I’m definitely a fan of Type F no doubt. But in a street car Dex/Merc is way to go in my opinion. It’s not an issue if you switched to Dex/Merc right now. It may not make a HUGE difference with what your experiencing but it’s not going to hurt. I didn’t realize it was mainly a street car. I would put a Dacron filter in as well.

I guess I explained it poorly, basically pull foot back off throttle and bump into 3rd real quick, kind of simultaneously. I can understand a true coast you would feel the overlap more. If you don’t pull front pump and drum out, I’d at least verify the second gear servo has dual springs, and if it doesn’t, I would certainly make that change. That will help the overlap because it will allow the band to release quicker.

 

[MobileCustoms]

I’m definitely a fan of Type F no doubt. But in a street car Dex/Merc is way to go in my opinion. It’s not an issue if you switched to Dex/Merc right now. It may not make a HUGE difference with what your experiencing but it’s not going to hurt. I didn’t realize it was mainly a street car. I would put a Dacron filter in as well.

I guess I explained it poorly, basically pull foot back off throttle and bump into 3rd real quick, kind of simultaneously. I can understand a true coast you would feel the overlap more. If you don’t pull front pump and drum out, I’d at least verify the second gear servo has dual springs, and if it doesn’t, I would certainly make that change. That will help the overlap because it will allow the band to release quicker.

I pulled the servo and it has just one big spring as shown. The second photo shows the only other spare springs I have on hand. Either one of them fits inside the main large spring. Should I consider adding one of these to it?

Also, I checked the kickdown band adjustment which was set at 1.5 turns out from snug. I adjusted it to 2 1/4 turns out and made a note label for future reference as shown in the 3rd photo. I do also have a 3.8 lever on order, to have in hand if needed.
I've seen so many different views on what's best. Anyone else got any input to add? @fishy68
Thanks.
-Doug

 

[71Demon528]

I pulled the servo and it has just one big spring as shown. The second photo shows the only other spare springs I have on hand. Either one of them fits inside the main large spring. Should I consider adding one of these to it?

Also, I checked the kickdown band adjustment which was set at 1.5 turns out from snug. I adjusted it to 2 1/4 turns out and made a note label for future reference as shown in the 3rd photo. I do also have a 3.8 lever on order, to have in hand if needed.
I've seen so many different views on what's best. Anyone else got any input to add? @fishy68
Thanks.
-Doug

View attachment 1716248094
View attachment 1716248095
View attachment 1716248096

I would not put one of those other big springs inside the original one. That can create a bind when it’s applied, then not want to fully release, and smoke the band. I don’t run the red sonnax servo but I know it’s not designed to function that way with the two big springs. And if I’m wrong, and it is designed to function that way, it’s news to me. The dual spring servo has a 3/8” rod, with a small inner spring, and large outer spring. I would get a new servo from A&A if it were mine to help the 2-3 overlap. Or just run it the way you have it and call it day lol. The 2-3 overlap will always be there, but minimizing it is the goal.

 

[MobileCustoms]

I would not put one of those other big springs inside the original one. That can create a bind when it’s applied, then not want to fully release, and smoke the band. I don’t run the red sonnax servo but I know it’s not designed to function that way with the two big springs. And if I’m wrong, and it is designed to function that way, it’s news to me. The dual spring servo has a 3/8” rod, with a small inner spring, and large outer spring. I would get a new servo from A&A if it were mine to help the 2-3 overlap. Or just run it the way you have it and call it day lol. The 2-3 overlap will always be there, but minimizing it is the goal.

I appreciate the advice. Do you think switching to a 3.8 lever would help with the overlap at all, especially if my front clutch has 12 springs rather than 15?

 

[71Demon528]

I appreciate the advice. Do you think switching to a 3.8 lever would help with the overlap at all, especially if my front clutch has 12 springs rather than 15?

Happy to help! Yes it should help some especially with the potential of 12 springs in the front clutch. Part of why you’re feeling the 2-3 overlap more is because you have a reverse manual valve body, which typically carries higher line pressure than a stock valve body. Although a stock valve body will technically have more 2-3 overlap than a reverse manual, a stock valve body is used to a front clutch with 3-4 frictions and ton of clearance with different friction material. Reverse manual is best way to go, but when you combine all the little details such as valve body, shift lever ratio, servo style, front clutch spring count, front clutch clearance, firm shifting ATF, all those little things add up to a 2-3 overlap that your going to feel pretty good at low speeds.

 

[MobileCustoms]

Happy to help! Yes it should help some especially with the potential of 12 springs in the front clutch. Part of why you’re feeling the 2-3 overlap more is because you have a reverse manual valve body, which typically carries higher line pressure than a stock valve body. Although a stock valve body will technically have more 2-3 overlap than a reverse manual, a stock valve body is used to a front clutch with 3-4 frictions and ton of clearance with different friction material. Reverse manual is best way to go, but when you combine all the little details such as valve body, shift lever ratio, servo style, front clutch spring count, front clutch clearance, firm shifting ATF, all those little things add up to a 2-3 overlap that your going to feel pretty good at low speeds.

Cool, Thanks again for all your info. I'll switch to the 3.8 and replace the screen filter with a dacron. It'll probably be at least 2-3 weeks before I have everything back together. I'm hoping to drive it to Mopars In The Park, Minnesota.
I have my work cut out!

 

[71Demon528]

Cool, Thanks again for all your info. I'll switch to the 3.8 and replace the screen filter with a dacron. It'll probably be at least 2-3 weeks before I have everything back together. I'm hoping to drive it to Mopars In The Park, Minnesota.
I have my work cut out!

View attachment 1716248140
View attachment 1716248141

LOL! You sure do! Happy to help, or try to at least haha.

Best of luck getting it all done and I hope to hear some good news when you get back about the overlap.

 

[oldkimmer]

Does that rmvb have low band apply? What are the clearances in both drums? How many clutches in each drum?

 

[MobileCustoms]

Does that rmvb have low band apply? What are the clearances in both drums? How many clutches in each drum?

No low band apply. It's been a long time since it was built so my memory is vague. I don't know the clearance #s but I believe it has 5 red clutches. These days, I take much more detailed photos and notes of everything I do to the car. I should have done better on tranny build day.
Haven't had a chance to take it to the track yet but if that happens, I'll do my burnout in 2nd gear.

 

[oldkimmer]

Well then u shouldn’t have bind up. In order for that to happen the front band comes on b4 the rear band fully releases. I would put 2 springs into the front servo. So then I suspect u don’t have enough clearance/springs in the front drum. U need bare minimum .020 thou clearance per clutch plate. Even as much as .025 wouldn’t hurt. So with 5 fingers u need at least .100 tho clearance. What was done to the accumulator if anything? Switching levers may help a bit. U may have to loosen it more than recommended. The reason for less gap for the higher ratio levers is that they have to travel farther to clamp the band on. They also have more holding power. Hope this helps. Kim

 

[71Demon528]

Well then u shouldn’t have bind up. In order for that to happen the front band comes on b4 the rear band fully releases. I would put 2 springs into the front servo. So then I suspect u don’t have enough clearance/springs in the front drum. U need bare minimum .020 thou clearance per clutch plate. Even as much as .025 wouldn’t hurt. So with 5 fingers u need at least .100 tho clearance. What was done to the accumulator if anything? Switching levers may help a bit. U may have to loosen it more than recommended. The reason for less gap for the higher ratio levers is that they have to travel farther to clamp the band on. They also have more holding power. Hope this helps. Kim

Kim, I think you’re talking more about the 1-2 overlap. The OP is talking strictly 2-3 overlap. The LBA valve body can create a little bit of 1-2 overlap, which is where the dual spring servo, and second gear lever ratio can help take care some 1-2 overlap. But the LBA valve body has no bearing on 2-3. The low band is already fully released by the time the transmission is shifted from 2nd to 3rd. The 2-3 overlap is solely the release of second gear band while the high gear clutch is being applied. Not telling you anything you don’t know. But I think there’s some confusion. That’s where we both agree with the dual spring servo, less ratio lever, and high gear clutch clearance, with spring count, all matter for that 2-3 overlap.

 

[oldkimmer]

Kim, I think you’re talking more about the 1-2 overlap. The OP is talking strictly 2-3 overlap. The LBA valve body can create a little bit of 1-2 overlap, which is where the dual spring servo, and second gear lever ratio can help take care some 1-2 overlap. But the LBA valve body has no bearing on 2-3. The low band is already fully released by the time the transmission is shifted from 2nd to 3rd. The 2-3 overlap is solely the release of second gear band while the high gear clutch is being applied. Not telling you anything you don’t know. But I think there’s some confusion. That’s where we both agree with the dual spring servo, less ratio lever, and high gear clutch clearance, with spring count, all matter for that 2-3 overlap.

Ya, I don’t know what I was thinking. Thanks for the correction

 

[MobileCustoms]

Is there a center spring that I could order or pick up to add to my current billet servo? I hate to buy a whole new kit if I could avoid it. Maybe someone has an extra? Maybe I'll talk to the locan transmission guy. Just asking. I want to get it back together asap.
Thanks again, guys.
-Doug

 

[71Demon528]

Is there a center spring that I could order or pick up to add to my current billet servo? I hate to buy a whole new kit if I could avoid it. Maybe someone has an extra? Maybe I'll talk to the locan transmission guy. Just asking. I want to get it back together asap.
Thanks again, guys.
-Doug

A stock one will work fine if your local guy has one.

You can’t buy just the inner spring to my knowledge because the rod diameter is smaller on the dual spring compared to the single spring.

 

[oldkimmer]

What was done to the accumulator? Spring top or bottom or no spring at all? U possibly could get a restrictor plug for high gear like what Trans Go has in their kits. Tranny shop should have a spare as the 904 usually doesn’t need it. Kim

 

[MobileCustoms]

What was done to the accumulator? Spring top or bottom or no spring at all? U possibly could get a restrictor plug for high gear like what Trans Go has in their kits. Tranny shop should have a spare as the 904 usually doesn’t need it. Kim

Sorry, I forgot to mention that before. No spring , I believe if memory serves me correct. I'm heading out this afternoon, my band has a show tonight, but will continue to follow-up as quick as possible. Thanks again.

 

[oldkimmer]

I would put a spring between the servo and the case. Kim

 

[Duster346]

This is one of my favorite torqueflite topics. As we all know the 727 historically can get stuck in two gears at once on the 2-3 shift and cause a bind or overlap.

We go to great lengths on our transmission builds to achieve a clean, quick and firm (not harsh) 2-3 shift. There are a lot of variables involved and we really need to know more details, such as valve body manufacturer and build date, a line pressure reading, etc. Servo design and spring rate, type and quantity of 3rd gear return springs, lever ratio, clutch pack clearance and valve body design all play a part in how the transmission will operate.

So we need to ask ourselves, what causes a bind, or overlap opposed to shift flare?
A bind or overlap on the 2-3 shift is caused by the high gear clutch applying before the 2nd gear band is fully released. Of course, the opposite of that would be a flare on the 2-3 shift which is caused by the 2nd gear band releasing before the high gear clutch is fully applied.

So, with an overlap condition decreasing the number of high gear return springs will make the overlap more amplified as you are now speeding up 3rd gear clutch apply. The more springs installed, the slower the clutch will apply. The idea with all 15 springs, in a high pressure manual valve body or trans brake application is to delay the 3rd gear clutch from coming on slightly, as to not have the bind or overlap. Also, in a trans brake application they are used to get the high gear clutch off quicker upon trans brake release.

A numerically higher lever ratio will apply the 2nd gear band quicker (1-2 shift), but it will take longer for it to come off, or release the band (2-3 shift). So, to answer your question, yes going to a 3.8 lever "may" help your 2-3 overlap condition.

We typically use a stiffer 2nd gear servo spring to get the band off quicker to prevent 2-3 shift overlap. I'd agree with RJ in ditching the (red) sonnax servo in favor of something better, with a stiffer spring.

With a high quality high pressure reverse manual valve body you typically:
- Block the accumulator piston
- Use 15 return springs in the 3rd gear clutch
- Use a modified or billet 2nd gear servo with a stiffer spring
- Use a billet low/reverse piston with a stiffer spring and thicker billet retainer (the factory stamped retainer can and will blow out of the case and the OEM piston can break and/or flip in the bore).

Hope this helps...

 

[MobileCustoms]

I would put a spring between the servo and the case.

This is one of my favorite torqueflite topics. As we all know the 727 historically can get stuck in two gears at once on the 2-3 shift and cause a bind or overlap.

We go to great lengths on our transmission builds to achieve a clean, quick and firm (not harsh) 2-3 shift. There are a lot of variables involved and we really need to know more details, such as valve body manufacturer and build date, a line pressure reading, etc. Servo design and spring rate, type and quantity of 3rd gear return springs, lever ratio, clutch pack clearance and valve body design all play a part in how the transmission will operate.

So we need to ask ourselves, what causes a bind, or overlap opposed to shift flare?
A bind or overlap on the 2-3 shift is caused by the high gear clutch applying before the 2nd gear band is fully released. Of course, the opposite of that would be a flare on the 2-3 shift which is caused by the 2nd gear band releasing before the high gear clutch is fully applied.

So, with an overlap condition decreasing the number of high gear return springs will make the overlap more amplified as you are now speeding up 3rd gear clutch apply. The more springs installed, the slower the clutch will apply. The idea with all 15 springs, in a high pressure manual valve body or trans brake application is to delay the 3rd gear clutch from coming on slightly, as to not have the bind or overlap. Also, in a trans brake application they are used to get the high gear clutch off quicker upon trans brake release.

A numerically higher lever ratio will apply the 2nd gear band quicker (1-2 shift), but it will take longer for it to come off, or release the band (2-3 shift). So, to answer your question, yes going to a 3.8 lever "may" help your 2-3 overlap condition.

We typically use a stiffer 2nd gear servo spring to get the band off quicker to prevent 2-3 shift overlap. I'd agree with RJ in ditching the (red) sonnax servo in favor of something better, with a stiffer spring.

With a high quality high pressure reverse manual valve body you typically:
- Block the accumulator piston
- Use 15 return springs in the 3rd gear clutch
- Use a modified or billet 2nd gear servo with a stiffer spring
- Use a billet low/reverse piston with a stiffer spring and thicker billet retainer (the factory stamped retainer can and will blow out of the case and the OEM piston can break and/or flip in the bore).

Hope this helps...

Thanks for taking your time to help explain how and why some of these work together. I pulled the accumulator to verify and there are no springs and has the blocker rod. I'm not 100% positive, but I think I remember adding the additional springs to the front clutch pack for 15 total. I'd rather not open up that area up at this time if I can avoid it.
Is there a particular 2nd gear servo I should get?
Here's two options I was able to find.

 

[71Demon528]

Thanks for taking your time to help explain how and why some of these work together. I pulled the accumulator to verify and there are no springs and has the blocker rod. I'm not 100% positive, but I think I remember adding the additional springs to the front clutch pack for 15 total. I'd rather not open up that area up at this time if I can avoid it.
Is there a particular 2nd gear servo I should get?
Here's two options I was able to find.

View attachment 1716249029


View attachment 1716249032

Part number 22905EBADR is the one from A&A that you want. It’s $145 compared to $165 from Cope. The only difference between the part number I supplied and the one you have pictured from A&A’s site is the one I supplied has dual rings over a single ring. This is for better sealing when this servo is applied. Chris Andrew’s should also have the A&A servo in stock.

 

[MobileCustoms]

Part number 22905EBADR is the one from A&A that you want. It’s $145 compared to $165 from Cope. The only difference between the part number I supplied and the one you have pictured from A&A’s site is the one I supplied has dual rings over a single ring. This is for better sealing when this servo is applied. Chris Andrew’s should also have the A&A servo in stock.

Thanks so much! I just ordered it.

 

[71Demon528]

Thanks so much! I just ordered it.

No problem! Happy to help