3-4 shift flare ONLY when cold

[berge]

92 Legend. a/t has 3-4 shift flare on cold starts(flares about 500RPM). After less than 5 minutes of driving, flare on 3-4 shift is gone.
A/T works fine in all other aspects. Fluid is clean (honda atf, change every 10K) and car has 90K on it. I auto-rx'd last summer. problem started last week.

time for synthetic fluid or start looking for another transmission?

thanks

 

[TheLoneRanger]

Berge, flaring shifts are usually caused by low line pressure in these new solenoid activated transmissions. The low pressure can be caused by several things; loose valve body bolts, blown v.b. gasket, clogged solenoid screen, or a defective solenoid.

It's possible that the AutoRX broke loose some debris that partially clogged a solenoid screen....? (Just guessing since I'm not that familiar with the Accura trans.)

Best thing would be to drop the pan and look around for loose v.b. bolts, and clogged solenoid screens. At that mileage, you don't need a new trans unless there's metal found in the pan (although trans shops tend to want to rebuild them).

 

[berge]

thank you.

 

[punisher]

Excessive apply piston clearance will also cause cold shift flares. As the steels and clutches wear the clearance between the apply piston and the clutches increases, needing a greater volume of fluid to apply the pack. Cold fluid= more viscosity= greater resistance to flow= longer apply time= shift flare. Once the fluid warms up a bit and flow increases the flare alleviates.

A good trans shop will have pressure guages to hook up and make short work of a diag. Good luck with it.

 

[berge]

quote:

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Originally posted by punisher:

A good trans shop will have pressure guages to hook up and make short work of a diag. Good luck with it.

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I've already been to a couple of transmission shops, local and national chains. When I ask for line pressure tests, which I am willing to pay for, I get the 'homer simpson' look.
Know of any shops in toronto?

 

[ryansride2017]

I also have a shift flare between 2nd and 3rd gear except it only happens when the vehicle is well warmed-up. The vehicle is a 2003 Nissan Sentra with 61K miles. What causes that? It's been doing this for the last 15K miles and it doesn't seem to be getting much worse, but it's a nuisance. I'm thinking of putting Red Line Transmission fluid in it to try to reduce it as much as possible. I'll try to baby it since a new transmission (or rebuild) is rather pricey. Any ideas?

 

[TheLoneRanger]

These shift flares were never a problem until the electronically shifted transmissions came on the scene. The cause is low line pressure, but I think the solenoids get clogged or worn, which causes the low pressure. This seems to be a very common problem on several different makes of vehicles....?

My Explorer has what's called an EPC solenoid (Electronic Pressure Control), which has a very fine screen attached. The screen tends to clog up and cause flaring shifts, at least from what I've read.

The cure is to drop the pan and clean/replace the solenoid(s) that are faulty. On most vehicles, this can be done with the transmission in place.

 

[berge]

thanks all for the info.
I think I'm going to auto-rx the transmission again as I can't seem to find anybody in toronto who can do any sort of diagnostics on import transmissions other than 'let's see if there are any codes'.

 

[daves66nova]

i have the same problem. i have a 96 saturn sc2. i had the trans rebuilt,and i believe it started right after that. or maybe after 10,000 miles. it surges after the 2-3 shift for about 5 minutes when cold. after that, it runs fine. would auto-rx help?

 

[berge]

success.

I auto rx'd the transmission.
did a t-tec like it was recommended. (with honda atf)
nothing changed.

drove like that for a while, enormously ****** off.

I then did a 4X drain/fill with honda atf.
nothing changed.

got even more ****** off and did nothing about it for a while again.

then I got 14L of Mobil 1 ATF.
did one drain. (drain 3.3L-total capacity 9.6L)

next morning, flare was ALMOST all gone.

drained again that day.

next morning, flare totally gone.

yes, the shifts are a bit firmer than with the honda atf, but not uncomfortably so. my wife, for example, did not notice a difference.

thanks all for the advice.

 

[TheLoneRanger]

Berge, congrats on the fix, and thanks for posting back your results. Sounds like the Mobil 1 ATF did the trick.

I just ordered a kit for mine, that's supposed to boost the EPC pressure (per a Ford TSB). After installation, I plan to add a bottle of LubeGard, and keep my fingers crossed.....

 

[berge]

quote:

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Originally posted by TheLoneRanger:
Berge, congrats on the fix, and thanks for posting back your results. Sounds like the Mobil 1 ATF did the trick.

I just ordered a kit for mine, that's supposed to boost the EPC pressure (per a Ford TSB). After installation, I plan to add a bottle of LubeGard, and keep my fingers crossed.....

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I thought about adding the lubeguard black, but, honestly, I am very satisfied with the shifting as is. It is nice and crisp. Was too mushy with the honda atf or with dino dex III with lubeguard.

good luck to you.