TRNW-2: AX4S, o-ring the o-drive servo pin

Fri May 23 11:35:25 PDT 2025

I did not see anywhere where anyone asked why do you need the oring? If it is no 4th gear, we would put a pressure tap in the cover and test to see if there is any pressure there (which would also tell if pressure was low like a pressure leak). If it is shift quality, I think looking at the valve body would be where to start, then you can air check the servo circuit. I have never had to put orings on any AXODE or AX4N so am curious as to the why.

Sincerely,

Glenn Pattison
B&M Transmission and Car Care
Kamloops, BC Canada
http://bmtrans.ca<http://bmtrans.ca>

Common sense is like deodorant, those who need it most tend to use it least!
________________________________
From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of Lee Hughes via trnw2 <trnw2 at trnw.net>
Sent: Friday, May 23, 2025 10:17:13 AM
To: Technical Discussion Forum; Wayne; Fred Whitaker
Subject: Re: TRNW-2: AX4S, o-ring the o-drive servo pin

Thanks Wayne and Pat , Thanks for the offer Pat but I just rebuilt this thing and was trying to avoid pulling it. I called my self really checking that pin bore during rebuild they must not allow much wear I did not see much at all as far as pin wobble in the hole or deformity and air checked good, I thought ! it has been several months. It originally had stripped torque convertor splines.If I put o-rings on pin should I barely feel a bump when rubbing fingers across it. If the spring will return it , is that ok and not to tight? Once I cut the grooves I will try O-ring vs. teflon seal scarf cut. If I use teflon seal is it the same rule should barely feel a bump? Sorry but I have never done this kind of modification before! Lee
On 05/23/2025 12:25 PM EDT Lee Hughes via trnw2 <trnw2 at trnw.net> wrote:

Thanks Wayne, Fred and Pat,
can you look at this photo and tell me exactly where I need to cut the groove?
On 05/23/2025 10:06 AM EDT Wayne via trnw2 <trnw2 at trnw.net> wrote:

Lee, I’d mimic the servo of sonnax’s 4r70 for the width and depth, and use that o ring. There are several width inserts, to cut grooves, and it’s quite easy to do. Do you need a pic of the holding tool and insert? (Only applicable if you’ve got a lathe).
Sent from my iPhone

On May 23, 2025, at 6:52 AM, Fred Whitaker via trnw2 <trnw2 at trnw.net> wrote:

  I used to do this with a hacksaw as Pat said. I did it before we all had battery drills,and servobores.com.  Chuck the piston pin in a drill and put the drill in a vice and lock the trigger on (you now have a lathe,and something to steady your hands on).  You should be able to see on the pin where it has been riding on the case. Cut a groove just above the feed hole.  I used to use one of  those white 700 servo pin rings. (You will have to cut it to size) Cut the groove just deep enough to barely bury the ring.

________________________________
From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of Lee Hughes via trnw2 <trnw2 at trnw.net>
Sent: Thursday, May 22, 2025 8:55 PM
To: Wayne <wagarrick at yahoo.com>; Technical Discussion Forum <trnw2 at trnw.net>; pat schulte <zzyzxpat at gmail.com>
Subject: Re: TRNW-2: AX4S, o-ring the o-drive servo pin

Thanks Wayne, never done this before so trying to be cautious. where exactly on the pin does the groove cut go and how do you know how deep a groove cut needed? parts for these are getting scarce! thanks For any advice Lee
On 05/22/2025 9:00 PM EDT Wayne via trnw2 <trnw2 at trnw.net> wrote:

It’d be easy to do with a lathe and groove cutting insert.
Sent from my iPhone

On May 22, 2025, at 4:03 PM, pat schulte via trnw2 <trnw2 at trnw.net> wrote:

I have cut oring grooves in pins before with a hacksaw blade or cutoff wheel.

On Thu, May 22, 2025 at 12:57 PM Lee Hughes via trnw2 <trnw2 at trnw.net<mailto:trnw2 at trnw.net>> wrote:
Date: Thu May 22 12:56:45 PDT 2025
Subject: AX4S, o-ring the o-drive servo pin

Hello Everyone , I would like to add an o-ring to the 0-drive. servo pin. I looked everywhere for chuck stansy # to get in touch with him as he said he has done this several times any way has anyone else ever done this modification that I could ask a few questions to. The trans is in the car and I would like to avoid pulling it. Thanks have a nice day! Lee

Lee Hughes
Hughes Precision Automotive
Martinsville, Virginia USA
TRNW Member Since: 9/14/2007

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Pat Schulte
AAMCO Transmissions
Temecula, Ca.
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