I have a 70 727 that has a modified auto valve body. It has the TF2 kit, and much heavier shift springs than stock to delay, and to even out the WOT rpms at the shift points to get them closer to the same rpm.

At the lightest acceleration from a stop, the 1-2 shift is quiet (no problem), but the 2-3 shift has a loud THUNK noise. Under medium to heavy accel, the 2-3 shift is quiet.

Is there anything that I can do to soften the low speed 2-3 shift noise?
Do I need to look at an aftermarket valve body to clean this up?

I am driving the car a lot more and I just want to get away from the hard 2-3 noise during in town driving.

Thanks
Dave

Search is your friend, this has been covered a number of times here. You may get various opinions on how to address it, but I always reduce the high speed clutch pack orifice like the shift kits do. What you are feeling is the overlap of 2nd band and the high clutch pack. So slowing the timing of the clutch pack engagement is the easiest thing to do after the tranny is in the car. May take a couple of whacks at it to get the balance between a clunk at slow speeds vs flair-up at RPM, but you can get it.

Thanks Dave. I'll start searching.

As already pointed out it is the valve body not releasing the front band before applying pressure to the front clutches that causes the problem your having, good luck on this

try backing off the throttle pressure adjustment. I have a TF2 in one of my cars and hate it. I think the throttle pressure spring is too heavy for normal driving and leads to too much 2-3 overlap. I tried reducing the orifice size as mentioned but it didn't make any difference. I much prefer the older TF1 type kit.

Thanks guys!

My throttle pressure linkage is maxed out at WOT (at carb linkage) to keep my shift rpms at 5800rpms with a 5600rpm govener. What if I swap in my 5800rpm governor and then turn down the throttle pressure linkage?

If not, then I may email Cope to see if one of his valve bodies may fix this issue.

Thanks again!

How small did you go with the restrictor? I personally have never seen an instance where you couldn't get the hole small enough to get the job done. In fact, it is easy to go too small and introduce a flair.

Back in the day, a 2-3 flair on higher mileage 727s was common due to clutch wear which caused extra clutch pack clearance which took longer to fill thereby slowing the high clutch application. Either way, controlling the filling of the clutch pack changes the timing of the clutch pack application.

And why not put a stock throttle pressure spring back in? Or as you suggested, maybe just back down the one you have in there now? There is a lot of adjustment in either spring. As you probably know, lowering the line pressure lowers the holding pressure to the clutch packs. IMHO, there are better ways to address the 2-3 overlap.

Although changing the valve body could impact your 2-3 shift, it is not likely to dial it in. And it may cause a 1-2 and 2-3 shift split which can be much more difficult to dial in.

If everything else works like you want, keep on track and only change what needs changed. Control the high speed clutch application by controlling it's rate of fill. It's cheap, easy and effective.

""If everything else works like you want, keep on track and only change what needs changed. Control the high speed clutch application by controlling it's rate of fill. It's cheap, easy and effective.""

Everything else does work the way I like it, so I would like to give this a try. In the attached photo, the High Speed Clutch description may be called something else. Can you confirm which orifice needs the modification?

Thank you!

Dave

This is a picture of my transmission case during the rebuild a few years back for reference.

Thanks

My search so far shows tapping the Front Clutch orifice, then drilling out a plug starting around the .140” range. So I have a few blank plugs, a 1/8”-27 tap, and a few drills (.136”, .1405”, .1406”, and a .144”) for testing.

But before I start, I want to confirm that this is the direction I need to go.

Review: The “clunk” noise on the low speed 2-3 shift (driving around town) is the only issue. Medium to hard accel it shifts good.

Thank you guys!
Dave

A lot of folks consider the orifice restrictor a Band-Aid but if it works so what? Cheapest and easiest way to mitigate overlap.

I would start out small (.080") and go bigger if you experience flare.

Thank you John!

The TF2 comes with an orifice plug. Was it installed?

I used the same size hole the comes in the transgo shift kit welch plugs. I thought it was 9/64" but could be wrong. I firmly believe the heavy throttle pressure spring is the culprit. I know backing the throttle pressure adjustment makes a very noticeable difference in harshness and it's the only way to prevent runaway shift points. i'm using the stock 4600rpm governor too. trans was built by A&A.

What is the proper way, and what are the most expensive and most complicated ways?

The "proper way" is to fine-tune the components when building the trans. (easier said than done)

The "most expensive" way is to start shotgunning suspected parts.

The "most complicated" way is to swap in a TH400.

The plug that comes with the kits is way too big, something like .130 or .140 if I remember right. Like John said, you need something well under .100.

And you don't have to drill, tap, and buy expensive brass for this. A box of Dorman part number 555-115 3/8" core plugs will do. Just drill the port so that it fits snug. Even if it's not real tight, it can't go anywhere. Start in the .080 to .090 range. If the hole is too large and still slaps, run a screw into it and pull it with a claw hammer. If it is too small and flairs, you can pull it and replace it, or you can put some grease on the end of the next size drill bit to catch chips, drill it, and then flush it with some brake clean to catch any missed chips. (if you don't like that last part, just ignore it. I know it's not a good idea, but I have done it a bunch of times, so...) And you can leave the valve body hanging by the park rod if you want.

One more hint, jack the car up higher on the driver's side so that the fluid runs away from you as work from that side.

Once you get close, .002 or .003 will make a big difference. And with the temp swings of the fluid, you may not be able to get it perfect for every occasion. You may have to settle for a little slap at very low throttle or a little flair at WOT. Pick your preference.

It was a long time ago when I put the TF2 in, so I don't recall if I put the plug in at that time. The picture above is of the trans a few years ago when it was getting rebuilt and it does not look like there is a plug in it now.

I will start pulling the valve body tonight. I have several drill bits under .100" for my carb tuning .

Thanks everyone and I will check back when I test it out.

Dave

I got the VB removed and tapped the hole for my 1/8" plug. Then I used a .086" drilled hole in my first plug for my first test.

Before I put the VB back in, I have a quick question about the Pressure Regulator Adjustment per the TF2 instructions. Per the picture, the instructions say to adjust the plate until it touches the retainer bracket. I set mine (several years ago) so that there is a 5/32" [.156"] gap to bring up the pressure to achieve 57/5800rpm shift points with my A&A 5600 governor. Can I leave this setting alone even though it is higher than the instructions? The TF1 instructions say to make a gap which ends up around 3/16" [.187"].

I would like to keep it setup just as it is since all my shifts are where I want them (except for the current low speed 2-3 issue) unless it is going to hurt something.

Thanks!
Dave