98 SHO possible speed sensor/transmission issue

[Blackdr16]

Little issue that bugs me and hopefully has been caught in time to prevent damage if I'm on the right track. I've owned this SHO for about a month or two, out about 1500 miles on it so far. Question being, when i first take off gently and it goes to shift from 1-2 there's about a 25% chance it will shift harsh. Sometimes its flawless without any issue but when its harsh you can feel the car ****. Its nothing insane like slamming into gear but definitely harsher than normal, almost like full line pressure in the trans when its shifts at redline. I should probably note here that when I am stepping on it the shifts are very clean and precise, no slippage or harshness. I have changed my filter and fluid recently. probably could stand to do it again soon being that the old fluid was most likely original. (141,000 miles) No chunks or anything abnormal in the pan when I dropped it. So here is the other factor I'll throw in before suspecting the trans to be going out. Sometimes when I'm driving and i go to hit the brake, the ABS will kick in the anti lock when I'm nowhere near locking the brakes up. No ABS light on, no codes in regards to trans or speed sensors. (Only code is air pump one) These things in itself make me suspect a wheel speed sensor but not sure if that's where the trans gets its speed input. (I did some forum searches and found some info but nothing definite) The speedometer seems to be working flawlessly, not jumping around and is within 1 or 2 mph vs my GPS.

The last factor I'll throw in here is the variable speed assist on the steering has been in full hard mode 2 times in the last day or so when I start the car. Within a minute or two of driving it will go back to full assist at low speeds, but definitely harder to turn wheel when in parking lot as the issue is happening. Does this also function from the same set of speed sensors? If this really is a speed sensor issue, where would you start to find the faulty one? Sorry for the long post, lots of details and I haven't given up hope yet that my tranny is still good, just getting bad info on when and how hard to shift at lower speed.

 

[99sho-time]

The v8sho gets its speed through the ABS module so i hear. I have the same exact symptoms regarding shifting and abs kicking in when slowing down it's an annoying strange feeling because it feels like the tranny has a mind of its own. My abs light goes on and off stays flickers but my ABS code was left rear low voltage.
Ive also heard that having an abs wheel sensor that's going out will effect the car without a abs light.

actually my part should come in tomorrow hopefully it fits ill report back if it cleared up the shifting issues.

In the meantime clean the main abs connector and electo grease it try inspecting all four abs wheel speed sensors and their wire harness also the exciter rings. to remove them youl most defiantly have to break them so make sure you have the corrrect part first.

 

[rubydist]

I expect that your random shifting ******* first easy upshift is unrelated to your possible ABS sensor issue.

There are two possible issues with the trans - the EPS solenoid is bad or sick, and the seals on the 2nd gear clutch pack are worn so they slide too easy.

Based on the apparent randomness, I suspect the EPS in your case. My trans guy says that the EPS in these trannys is suspect, and it is the first thing to replace. iirc, you can pull the pan off the left side of the trans (not easy but is possible) and replace the EPS w/o having to pull the trans or tear it apart. If that is correct, I would suggest you do that straight away.

If the seals are worn so the 2nd gear clutch engages too easily/quickly, it should do that repeatedly under similar conditions - in other words it should do it consistently at part throttle shift. If that is your problem, you will have to rebuild the trans to fix it, so live with it until you can't stand it any longer.

 

[Blackdr16]

Thanks guys, 99sho-time let me know what the results are on yours. Rubydist, I suspect your right with the EPS solenoid, as much as I dread pulling that side cover I should at least rule it out. Can anyone confirm this is the correct part number for the EPS? (STANDARD MOTOR PRODUCTS TCS66) The issue doesn't always happen but I can say it does it almost always when the car is cold. (Within first 10 min of driving then clears up and shifts normally at part throttle). This makes me suspect your right on with the solenoid either weak or gummed up. Has anyone ever had any luck running Lucas or something to clean up malfunctioning solenoids if gunk is the case? (Yes, im thinking how to possibly not have to pull that cover even tho I know its much worse to pull the trans after its ruined)

EDIT: I had wrong part number initially, but corrected it. Hopefully this is the right one.

 

[99sho-time]

Ruby can you confirm that ABS issue may cause shifting problems?

 

[99sho-time]

well I got the old one out but the bolt holes dont line up so I have it zip tied for now the tranny seemed to act better for the first day but I dunno. inconclusive atm.

 

[Blackdr16]

New EPS ordered, not driving car currently until installed. Ill post update on how its working once part is installed.

 

[Blackdr16]

EPS replaced. Didnt know car could shift so smoothly, 1-2 shifts are perfect now as well as all the other shift points are extremely smooth. Thanks Rubydist!!