I have the Turbo Action 17680 FMVB w/o LBA. The 1-2 shift is fine; the 2-3 shift is fine flat-out at high RPM, but feels like it wants to break the driveshaft at part-throttle lower RPM shift points.

What I've read tells me I should install a front clutch orifice restrictor, but the sizes I've seen recommended have ranged from .150" to .090". I'd have to go dig up the notes from Jim Hanrahan on how many springs were used with the front-clutch piston, if that's a determining factor.

Can I get some feedback on what size restrictors people have used (or at least tried), and what the results were for that size? I don't quite understand what the "tuning" implication is on this orifice size (not very knowledgeable about auto trans stuff), so examples could help me with selecting an starting restriction size.

Thanks - Brad

One other semi-related question...

Turbo Action has replaced my model of valve body with a new "Xtreme Action" series 17880XA. From what I recall, I paid around $200 for the 17680 about 10 years ago. The new one is almost $400, yet I don't understand what about the description justifies the significant price increase (even taking into account the 10 years between price comparisons).

The features listed for the new vb are:

•Race Only (No Trans Brake) >> SAME AS BEFORE

•No Low Band Apply >> SAME AS BEFORE

•Engine Braking 2- & 3-gear only >> SAME AS BEFORE

•P-R-N-3-2-1 Pattern >> SAME AS BEFORE

The 17880XA has a safe clean neutral and no need to use a button to backup. Provides full manual control only. No automatic features. Maintains stock shift pattern. No Band applied in Low Gear. Allows full engine braking in Second and Third gear only. This valve body is great for Drag Racing. Eliminates use of passing gear linkage. >> WHAT HERE JUSTIFIES THE BIG PRICE INCREASE?

WHAT'S A CLEAN NEUTRAL DO FOR A STOCK SHIFT PATTERN, AND I DON'T NEED A "BUTTON" TO BACK UP NOW, EITHER.

trans brake needs button to back up . clean neutral would be reverse pattern
Brad I have a griner rmvb . it was always quite harsh shifting at lower rpm/speed . Almost like someone ran into you , higher rpm smooth as shift .
I just thought that was an end result

Tex

I understand the Griner VB are the best ever made. If you can find one, get it.

The clunk at slow speeds is a result of the high clutch pack grabbing before the 2nd gear band completely releases. So, for a brief second both 2nd and high are engaged which kinda stops everything's forward motion and takes the play out of the drive line which produces a clunk. In more extreme cases, it can actually feel like you tapped the brakes.

It comes down to a matter of timing between the 2nd gear band and the high speed clutch pack. And there are several ways to change that timing. The only way that I have been able to consistently deal with it is by putting a restriction in the high speed clutch port. Which slows the flow down so that it delays the engagement of the high speed clutch pack until the 2nd gear band fully releases while having no other impact.

I use Dorman 3/8" expansion plugs (like mini freeze plugs) part number 555-115. They usually press right into the high speed passage but occasionally the opening will need a light touch-up with a drill bit first.

Most of the time, the ones I have done want an opening somewhere around .090". It varies a little bit from tranny to tranny so I start a little smaller and test it. Then open the hole up a tiny bit at a time until I'm happy. And there is usually very little difference in the size that has no 2-3 overlap but has a flair up vs very little overlap and no flair up. Often, to get rid of all the flair at WOT, there ends up being a tiny bit of slap at slow speeds.

So, for a track car, I set them up with no flair since the low speed clunk isn't as big a deal. While a street car, I may leave a small WOT flair so that there is no around town clunk. That being the preference of the owner.

I usually just swing the valve body out of the way without removing it completely. And I put some grease on the drill bit when I re-drill the plug. The grease catches most (if not all) the tiny metal pieces.

Open up the hole a tiny bit at a time and after a few times, you will have the best balance between the clunk and the flair.

IHTH

that hole can also be tapped to 1/8 x 27 NPT as it is usually slightly larger than the .332 hole required for the tap. tap the hole just deep enough so a hex head pipe plug fits below the surface where the valve body mates. you can then have a selection of pipe plugs with various size holes to tailor the shift to your liking. and no worries you get all the chips from drilling the cup plug.

While i havent played with restrictions
He 4.2 lever seemed to help
I also pay attention to my foot and try to hold the pedal down a "touch" longer so that the 2-3 shift on the street is clunk free.

At WOT at the track it does like stated above, shifts fine in all gears

I wouldnt be against trying the restriction to experiment

1. Bump

2. Somebody... please give me a good compromise restrictor size to use when I pull the valve body off in the immediate future.

As much as I like testing different things, this really isn't something I want to have to go back & forth multiple times given the PITA factor.

If I need to provide more info than what's listed already, let me know. Thanks - Brad

I used to use .125 with 6 springs and .090 clutch clearance, 4 front clutch, worked ok but always worried about that flair up as it wore. It is something you will need to play with to get right with your trans.

I'll have to dig up the build sheet that Jim Hanrahan gave me when we went through the trans years ago. I don't recall much about how he set it up w/ the rebuild that also included upgrading a number of parts.

To be blunt, I lived with it when it kicked like a mule at lower RPM... but I didn't like it. If I can start with a commonly used restrictor size that reduces that kick to a "reasonable" level w/o slowing down the 2-3 shift noticeably at high RPM, I'm not going back into it.

For some things I have the patience to keep changing and testing; draining ATF and pulling the valve body multiple times isn't one of 'em.

FWIW, the orifice restrictor in the Transgo kit is .140" (#28 drill).

Brad, the restrictor size needed will depend on a number of factors unique to your tranny. And it will depend on which way you prefer to lean with a one time shot.

It looks like the range used here so far is somewhere between .090 and .125. Are you more concerned with the overlap or are you more concerned with a WOT flair? Pick your preference and go that direction.

Frankly, you are in a better position than anyone to pick a compromise size within the range noted here.

Good luck.

Typically if running the driveline on jackstands at slow speed, there will be a "grab" or hesitation at the 2-3 shift if the shift is right at high speed. If not, it will flare. Bringing it all to a stop for an instant is too much overlap. Never used a restriction. Instead, I always used spring loads in the high drum and 2nd servo to get the balance I wanted. Spring pressures control how quickly or slowly things happen.

Run 15 springs in the front clutch. .015" per friction. Inner an outer springs in the KD servo. 3.8 lever and you probably will not need a restriction. If you set it up to flare sooner or later it'll take out the high gear clutch.
Doug

This is the better way to go for street driving, more front clutch springs, put an extra rear servo spring in front servo, and play with clutch clearance. I never liked the restrictors, used it until trans was pulled to change or inspect front clutch. You are always on the hairedge of flareup if you try to eliminate the overlap.

Problem with building a trans with "perfect overlap" (some overlap is required to prevent flareup) is that the setup changes with time. Disc wear, sealing ring wear all change the timing and the removable orifice is a quick/easy to change the timing.

If you watch - and listen - to video of AH cars on YouTube, you may notice a touch of flare on the shift to high gear in many of them. They are concerned with minimum ET and maintenance every few runs is not an issue for most.

FWIW, I pulled out the build sheet from Jim Hanrahan. This isn't everything on it, but covers most of the details people commented on above. FYI, I'm an auto trans idiot.

- switched to TCS steel front drum
- 12 springs in high-gear clutch
- front clutch clearance .092"
- 5-plate high-gear clutch pack w/ waffle-pattern Alto(?) red plates
- switched to stronger front strut
- switched from 3.8 to 4.2 lever and added 2nd servo spring (leftover OEM outer spring)
- switched to billet low/reverse servo piston w/ spring that came with my old JW valve body
- solid low/reverse clutch pack (Alto red)
- 4-pinion planetaries front & rear
- replaced worn-out red-type rear band with "OK condition" used OEM band Jim supplied because we didn't have another replacement on hand
- replaced red flex-type front band with new red solid
- switched to bolt-in sprag
- removed restrictor plug from previous Trans-Go TF-2 kit

At this point I'm thinking I put a .150" restrictor in it and go from there. I'm more concerned w/ WOT flare-up than low-speed "comfort", but the way it "bangs" now at lower RPM doesn't make me happy.

The setup I've listed above has over 300 passes with no detectable friction material wear. Been inspected twice during that time. All clutch components and bands have been reused. 900+hp @ 3340-3450lbs.
Doug

I believe .150 will bang pretty good, too.

hi

just for info if you use a throttle psi linkage / cable set up with your manual vb you can have soft low sped shifts AND firm wot shifts for street driving . done it many times .

my personal car i us fully auto shifts , select drive and stab go pedal on 2nd yelloooooow !

And your sprag loves you for it.