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Discussion Starter · #1 ·
So I had a VSS fault on my 95 (code 452). I pull the sensor, had some shavings on it (pretty minor), reset codes, seems to be okay. However, I still have speedometer bounce at 60+ mph. There is one tooth on the tone ring in the diff. that has a clear "chip" on the crown. Most of the tooth is still there. My question is, what is likely causing the bounce? It is:

1. The sensor going bad? Seems like I would have other issues like faulty ABS.
2. The bad tooth? Any way to repair a chipped crown w/o taking the whole diff apart?
3. Bad PSOM? I know there's a TSB out on this, what's my option here? Do I pretty much have to buy a new one? How do I know if I buy one from a wrecking yard if it's a "newer" less sensitive type (as I understand from the TSB).

I want to fix the bounce but don't want to start throwing money at the problem, bottom line, is there any way to tell FOR SURE what's causing the problem before I start with the cheapest solution and work my way up.

Thanks,
Biederboat
 

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My guess for the high speed flutter would be the chipped tooth on the ring. I wonder if you could have a welder put a little bead on it, and file it to a nicer, more defined point to solve the problem, rather then tearing it down and putting a new tone ring on.
 

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Discussion Starter · #3 ·
I wonder if you could have a welder put a little bead on it, and file it to a nicer, more defined point to solve the problem, rather then tearing it down and putting a new tone ring on.
That was one of my thoughts, anyone have an answer?

Biederboat
 

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I know some of the late models have a speed sensor in the rear diff and in the transfer case. A buddy of mine had to replace both in his 93 to solve a speedo bouncing problem. I don't remember at what speeds his bounced though.
 

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I know some of the late models have a speed sensor in the rear diff and in the transfer case. A buddy of mine had to replace both in his 93 to solve a speedo bouncing problem. I don't remember at what speeds his bounced though.
Your buddy didn't have a speed sensor in his 93's transfer case, just his rear axle.

91- the VSS is in the TC and ABS is in the rear axle, and 92+ both the VSS and ABS are in the rear axle.
 

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Actually yes his did. I helped him do it. His was also a former sheriff's vehicle with a police interceptor package. It had quite a few goodies that your average bronco didn't have. Sorry, forgot about that. Yes parts get replaced unnecessarily, we were told one goes haywire more frequently that the other, so we replaced it. Didn't fix it, so we replaced the other and then it was fixed.
 

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Actually yes his did. I helped him do it. His was also a former sheriff's vehicle with a police interceptor package. It had quite a few goodies that your average bronco didn't have. Sorry, forgot about that. Yes parts get replaced unnecessarily, we were told one goes haywire more frequently that the other, so we replaced it. Didn't fix it, so we replaced the other and then it was fixed.
Ford never offered a 'police interceptor' package on a Bronco.

And, even if you had swapped a 91- transfer case on the truck, the truck still didn't even have the provision for a VSS hookup at the transfer case...

Aaaaaaand, even if it did, which it didn't, because there was no reason for it to exist there... it wouldn't do anything. The EEC uses information given to it from the PSOM, which was fed by the ABS sensor, after it goes through the ABS module.

Parts don't get replaced unnecessarily if you test them first.
 

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Okay, but doesn't the rear diff have to be bascially completely diassembled to replace it? Is that significant $$?

Biederboat
On an 8.8, it's not that difficult.

The most difficult part of it is pulling the axles out, which you have to take the c-clips out. Sometimes takes two people, one person pushing in on the axle shaft so you can get ahold of the c-clip, and after that, it slides right out.

Throw the tone ring in the oven for a short period to get it hot if it doesn't slip right on by itself, and then bolt everything back together, torquing the bearing caps properly... I think it's 55-60ft lbs, but it's been over a year since I did the outer bearings.
 

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It's an easy press-fit, even when cold. Why risk burning your fingers? :shrug
Dunno. The mechanic that helped me with my detroit install said that you had to heat the tone ring to get it on the carrier. Though he didn't specify if that was something with the detroit, just said that it needed to be done. He used a big toaster oven in his shop to do it... not super heated, just warm-hot, and it dropped right on.

May not have needed to do it at all, he didn't even try it at first, just went over and threw it in the oven as we were in the middle of unpacking the detroit and cleaning up the ring gear.
 
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