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88 S4 Auto Transmission wont downshift into 3rd

 
Old 10-03-2017, 11:01 AM
  #1  
Mrmerlin
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Default 88 S4 Auto Transmission wont downshift into 3rd

Been searching and not finding any answers to this issue.

My 1988 S4 Auto transmission has been working great for the last 120K miles ,
while on the fun run this past frenzy,

I noticed that the trans would not downshift into 3rd when the selector was moved from D to 3,
the engine just stays at idle,

If I select 3 while coasting at 80 MPH and gas it the trans will shift to 3rd but its slow,
once in 3rd, if I put it into D then it will shift into 4th

If i start in 2 it starts off in first then can be shifted to second by doing the 2 3 2 .
Once in second I can go into 3rd by placing the shifter into 3
this all seems normal to me.
Any advice or suggestions would be appreciated.
Thanks.

NOTE the trans had the new (at the time 2005) updated vacuum modulator installed, all external seals replaced and front pump radial seal and O ring replaced and fluid and filter changed 30K miles ago.
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Old 10-03-2017, 12:07 PM
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Bertrand Daoust
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Hi Stan,

Your 2-3-2 sequence is good.

Does it shift soon (low RPM) or at the right moment in 2 to 3 and 3 to 4?

If it shifts to soon, the cable at the quadrant is too slack.

Migth worth also lookin looking at the cable adjustment at the transmission.

Fluid level is good?
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Old 10-03-2017, 12:42 PM
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dr bob
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Hi Stan --

My casual first steps when looking at odd AT shifting includes looking at fluid level, and replacing the fluid. With 30k on the fluid, you are a little past due for new fluid anyway at least according to my conservative 20-25k max change interval. The fluid swap is cheap and easy in the giant scheme, and offers an opportunity to clear out anything that might be gumming or sticking the works.

As always, start with the easy stuff, and remember that it was working fine a thousand miles ago so don't go futzing with major adjustments right away trying to mask a symptom.

Considering that the symptom started during a usually-spirited Frenzy fun drive, I'll suggest that there was ample opportunity to relocate some small bit or wear particles. Maybe the fluid swap will relocate that to your drain pan. If you find on inspection that the fluid level is a bit low, a bit of Trans-X or your favorite AT treatment for a few miles will often help too.
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Old 10-03-2017, 12:52 PM
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soontobered84
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Stan,

So, if I understand correctly what you posted, instead of shifting out of D and into 3, your transmission just shifts out of D but doesn't shift back into another gear?
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Old 10-03-2017, 01:50 PM
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the transmission will not down shift into 3rd when the selector is put into 3 from being in D at say 80MPH

For example, lets say i am going down a hill, the trans is in D and want to slow down without touching the brakes , click it back to 3rd nothing happens, the car keeps coasting in D
If I give it a lil bit of gas the trans seems to shift into 3rd but it takes a while.
It will upshift into 3rd from being put into 3rd from being in 2nd .
My only issue now is that I can`t get it to downshift into 3rd,
it will downshift into 2nd when placed at 2

Otherwise all the cables appear to be working fine , the fluid level is good,
the car was running fine during the fun run then the issue started with the downshift.

I am wondering is is worth swapping out any shifting springs,
or inspecting any springs in the valve body while I change out the fluid.
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Old 10-03-2017, 02:13 PM
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The problem is located in either one of two places.

Either you have a bad seal in or on the shaft to the K1 clutch pack. Or you have a problem in your valve body.
The hard-driving it may have seen at the frenzy is unlikely to have caused anything to do with this.

If it were my car I would rebuild that valve body and install a few springs out of the valve body spring kit and see if that rectifies the problem. If it does not, then pull the transmission and rebuild it. If you are going in that far do not just replace the couple seals that may be shot. Replace them ALL!

If the car shifts normally into third from second with the shifter left in 3, yet only has a problem with the downshift, then the problem is in the valve body. If it is tardy going into 3rd even from 2nd, then it is a 50/50 chance of being either the clutch packs or valve body. Either way though, if it is slipping at all going into 3rd DO NOT CONTINUE TO DRIVE IT. The steel plates in the clutch packs are very expensive to be buying new.

Also, I recommend LubeGard ATF for the transmission. It is really good stuff that the transmissions work really well with.
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Old 10-03-2017, 06:07 PM
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I will defer to Colin's expertise and knowledge in the above post.

But I would say that if you are draining the pan and replacing the filter, the replacement K-1 spring assembly is only like $15. And as you are well aware, it would be a great time to replace it.

In addition, it would be a perfect time to replace the B2 valve solenoid, but I'm not sure that it would have anything to do with your particular symptoms and it is much pricier. But again, it would be a perfect time to replace it if you are so inclined.

Good Luck.
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Old 10-03-2017, 07:28 PM
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Colin thanks for the info,
John C thankyou as well

this is a true statement for me.........If the car shifts normally into third from second with the shifter left in 3, yet only has a problem with the downshift, then the problem is in the valve body.

The trans shifts fine going into third from second with the shifter placed in 3. no delay .
the only issue is the trans not downshifting back to third from D when placed back into 3.

Colin, Any chance you have a diagram and directions with pictures on what springs need to be replaced and what spring package you suggest


I have been using Valvoline Max life ATF synthetic .
are you suggesting adding one bottle of this Lubeguard fluid?
any particular item number here?
Thanks for your assistance

Last edited by Mrmerlin; 10-03-2017 at 11:51 PM.
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Old 10-03-2017, 07:58 PM
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Originally Posted by Mrmerlin View Post
Colin thanks for the info,

this is a true statement for me.........If the car shifts normally into third from second with the shifter left in 3, yet only has a problem with the downshift, then the problem is in the valve body.

The trans shifts fine going into third from second with the shifter placed in 3. no delay .
the only issue is the trans not downshifting back to third from D when placed back into 3.

Colin, Any chance you have a diagram and directions with pictures on what springs need to be replaced and what spring package you suggest


I have been using Valvoline Max life ATF synthetic .
are you suggesting adding one bottle of this Lubeguard fluid?
any particular item number here?
Thanks for your assistance
Pictures of serial #
Attached Images   
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Old 10-04-2017, 01:31 AM
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x98boardwell
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Question for the experts, is there a diagram which shows which cable controls what gear, I know the quadrant by the the throttle body has a few but my car is also shifting early. Downshifts are fine unlike Mrmerlin which makes me think it isn't internal and maybe just cable related. Thanks for any help, great info in this thread!!
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Old 10-04-2017, 08:11 AM
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Bertrand Daoust
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Originally Posted by x98boardwell View Post
Question for the experts, is there a diagram which shows which cable controls what gear, I know the quadrant by the the throttle body has a few but my car is also shifting early. Downshifts are fine unlike Mrmerlin which makes me think it isn't internal and maybe just cable related. Thanks for any help, great info in this thread!!
This is for the S4 and later cars.
What is called the bowden cable is the one to play with.

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Old 10-04-2017, 12:49 PM
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Originally Posted by x98boardwell View Post
Question for the experts, is there a diagram which shows which cable controls what gear, I know the quadrant by the the throttle body has a few but my car is also shifting early. Downshifts are fine unlike Mrmerlin which makes me think it isn't internal and maybe just cable related. Thanks for any help, great info in this thread!!
When I removed and replaced my trans with another one, I just removed the quadrant from the intake manifold, and put it back by the firewall. I never disconnected the cables. So no changes.

I slid the trans off the torque tube, disconnected everything from the trans, and did the swap in reverse order.

All the shifting is controlled inside the trans, except the kickdown for passing. That's controlled by the Bowden Cable I believe.

Vacuum modulator, and valve body, controls the shifting. At least that's my thinking.

Greg Brown, is the expert! I'd ask Greg.
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Old 10-04-2017, 01:31 PM
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Thanks guys, very helpful! The trans was rebuilt when the PO had it but it has only driven 3,000 miles in 9 years before I purchased it so I'm guessing just needs adjustment on the cable as mentioned. Appreciate all the help!
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Old 10-04-2017, 06:07 PM
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One additional thing, when I go to full throttle in first gear it shifts past redline and then all other shift too early. Is that still bowden cable?
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Old 10-04-2017, 06:47 PM
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Not to be rude, but maybe you should start your own thread.
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