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Discussion Starter · #1 ·
I know this topic has been covered in various threads but I couldn't find my exact set of circumstances. Here's the deal: 95 w/ 5.0, 174K. Was running like a dream until yesterday when it started shifting hard, mainly on the first upshift from stop and a bit on the next one. Doesn't seem to shake or shudder like a bad torque converter. Doesn't leak any tranny fluid, color looks good.

I don't know the complete history on vehicle as I bought two years ago w/ 165K (so it's not driven much) but the tranny looks original. I pulled the codes, it has a 452, vehicle speed sensor signal fault, which I assume is related to the fact that the speedometer starts fluctuating at about 60 mph (a common malady related to a sensitive POSM as I understand).

The only other thing I can say is that (and I'm almost certain it wasn't doing this when I first drove it as I was replacing a thermostat and listened to the engine a few times previous to the hard shifting) it makes some kind of buzzing/whirring noise somewhere around the top rear of the engine and seems like it might be idling kind of high, sort of like a vacuum leak but it's not idling rough.

Anyway, I know that's a mouthful but hoping someone has some insight to point me in the right direction, even if it's to the nearest tranny shop!

Thanks,
Biederboat
 

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The noise could very well be a vacuum leak, but I doubt thats causing the tranny issue. Most likely the the ABS sensor in the rear end.
 

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Discussion Starter · #3 ·
Most likely the the ABS sensor in the rear end.
Just so I understand, the sensor ring in the rear axle housing, does it control ABS functions, speed, cruise control and shift points? It's always (since I owned it), had the erratic speedometer needle (but it used to shift smooth). How exactly would I go about determining this is the culprit? And if it is, are there some threads dealing with how to fix it?
Thanks, Biederboat
 

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First thing you can do is pull it out and take a look at it. If you've got some slime on there, there's a chance the metallic filings in it are toying with the VSS signal. Second thing you can do is take a look at the tone ring in the rear and see if there's any damage to the teeth on it all the way around. If there's severe enough damage, it's gonna need to be replaced.

Replacing the ABS sensor after you've cleaned it is the next step.
 

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i think a vacuum leak could cause it to shift rough(probably needs to be a big leak tho), the computer looks at the map sensor to figure out load i believe. i think its a good idea to fix the vacuum leak before doing much else, and if you have a code for your vss, test it, it could be causeing this issue as well. use carb spray or break clean to find the leak and fix it, use your manual to test the vss, or maybe its written up on here.
 

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Discussion Starter · #7 ·
Okay, I think this is starting to make sense, shaking speedo, 452 code, and now I remember previous owner had some rear axle work done. So here's the big question. I think I can take this through the inspection process but, assuming the tone ring is bad, does it need to go to a rear axle shop? Sounds like the ring gear needs to come out?

Thanks,
Biederboat
 

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Bronco Info: SAS on hold What does SAS stand for?
Solid Axle Swap.

I'm ever so slowly progressing on my bling bling dana60, and my bling sterling 10.25... so slowly that I'm practically losing progress on it. I sold my 39.5 IROKs because I don't want them sitting so long without being rolled on to keep them from drying out. :banghead



Yes, the ring gear, carrier and all that sheet has to come out and off the carrier to remove the tone ring.

You could do it yourself, just as long as you don't lose any shims or anything, you won't have a problem putting it back together.
 

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Is it happening when you come to a stop too? My 96 EB Bronco shifts fine from a stop but shifts HARD when I come to a complete stop, like at a light or stop-tional sign.
 

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Is it happening when you come to a stop too? My 96 EB Bronco shifts fine from a stop but shifts HARD when I come to a complete stop, like at a light or stop-tional sign.
Pull codes.
 

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I had codes pulled on mine - only shifts hard when i come to a stop. Nothing showed up.... could I have a vacuum leak?
Okay, what codes came from the EEC? You ALWAYS get a code.

If someone pulled codes and got no codes at all, they did the test wrong, or there's something else fud up.
 

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Ok, here I go using the "L" word again but...Mine did that in Limp Mode (hard shift 1st-2nd)... when I had a bad TPS (Throttle Position Sensor), but I know there are other codes that could put a vehicle in limp mode. The very second I swapped my TPS out, the hard shift went away. Of course, it came back when the wire on the new TPS wasn't seated correctly (defective new part), then on the 2nd one it went away for good. I think if the computer gets bad data (anything outside of the normal paramters)from a sensor, or certain sensors... it could cause the limp mode. At least, that was my interpretation when I had my issue. Here's some info on it that I found useful

http://web.archive.org/web/20040205144343/http://www.autotransinc.com/limp.htm
 

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Discussion Starter · #15 ·
Well, problem solved, sort of, I'm going to repost on a related issue but the tranny is fine. Closest explanation I have is that I had to clean the VSS and reset the codes, that made it shift normal. Took it to a shop for check-up, very normal wear in the bottom of the pan. Whew!!!!!

Biederboat
 
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