Adjusting VSS for electronic spedometer
#1
Adjusting VSS for electronic spedometer
Yesterday someone offered to sell me a 3:27 posi disk from a firebird. According to RPO code in my car it has 2.73, and I'm assuming it hasn't been changed. I hadn't really looked into swapping a new diff or going to disks but it got me interested. It seems like the only problem I would run into is adjusting the speedometer to read correctly. (Although, if someone could tell me any other problems/disadvantages that would be great)
I've done some searching, and it looks like I can either change the gears in the VSS so match the new ratio, or I can get this electronic module that changes the signal. It looks like the module is about $150, but I though switching the gears would be cheaper and easier...I just can't find where to get them.
Anyone have any idea? Thanks!
I've done some searching, and it looks like I can either change the gears in the VSS so match the new ratio, or I can get this electronic module that changes the signal. It looks like the module is about $150, but I though switching the gears would be cheaper and easier...I just can't find where to get them.
Anyone have any idea? Thanks!
#2
Moderator
iTrader: (5)
Re: Adjusting VSS for electronic spedometer
You might pursue the link below for general info about the swap (combination valve, parking brake cables, speedo gears, etc.):
https://www.thirdgen.org/forums/tran...-10-bolts.html
You don't mention what type of trans you're running, but you might find what you're looking for from the following company:
http://www.transmissioncenter.net/sp...n_______va.htm
JamesC
https://www.thirdgen.org/forums/tran...-10-bolts.html
You don't mention what type of trans you're running, but you might find what you're looking for from the following company:
http://www.transmissioncenter.net/sp...n_______va.htm
JamesC
#3
Supreme Member
iTrader: (58)
Re: Adjusting VSS for electronic spedometer
Did you search at all? Because there are threads about changing from drum to disc on the brake board, and there are more then a few speedometer gear threads too.
You can get the gears from GM, or aftermarket suppliers like http://www.transmissioncenter.net/sp...0gear%20driven
3.27 is a Borg Warner ratio. Which would mean it's a 85-89 rear end. Which brings up the question of the 85-88 disc brakes. Long story short, unless that rear is out of an 89 with PBR discs, it's not worth the trouble to swap over. A short search will tell you why...
You can get the gears from GM, or aftermarket suppliers like http://www.transmissioncenter.net/sp...0gear%20driven
3.27 is a Borg Warner ratio. Which would mean it's a 85-89 rear end. Which brings up the question of the 85-88 disc brakes. Long story short, unless that rear is out of an 89 with PBR discs, it's not worth the trouble to swap over. A short search will tell you why...
#4
Re: Adjusting VSS for electronic spedometer
You might pursue the link below for general info about the swap (combination valve, parking brake cables, speedo gears, etc.):
https://www.thirdgen.org/forums/tran...-10-bolts.html
You don't mention what type of trans you're running, but you might find what you're looking for from the following company:
http://www.transmissioncenter.net/sp...n_______va.htm
JamesC
https://www.thirdgen.org/forums/tran...-10-bolts.html
You don't mention what type of trans you're running, but you might find what you're looking for from the following company:
http://www.transmissioncenter.net/sp...n_______va.htm
JamesC
As far as I know it has the stock trans for a 92 tbi.
Did you search at all? Because there are threads about changing from drum to disc on the brake board, and there are more then a few speedometer gear threads too.
You can get the gears from GM, or aftermarket suppliers like http://www.transmissioncenter.net/sp...0gear%20driven
3.27 is a Borg Warner ratio. Which would mean it's a 85-89 rear end. Which brings up the question of the 85-88 disc brakes. Long story short, unless that rear is out of an 89 with PBR discs, it's not worth the trouble to swap over. A short search will tell you why...
You can get the gears from GM, or aftermarket suppliers like http://www.transmissioncenter.net/sp...0gear%20driven
3.27 is a Borg Warner ratio. Which would mean it's a 85-89 rear end. Which brings up the question of the 85-88 disc brakes. Long story short, unless that rear is out of an 89 with PBR discs, it's not worth the trouble to swap over. A short search will tell you why...
Like I said above, I wasn't sure if the VSS gears were different between cable and electric vss, and didn't find anything specifically addressing that.
In the picture he sent it did look like the calipers were mounted on opposite sides, which, according to the link JamesC posted above, would mean that it would have the older style breaks. However, I wasn't really looking at it for the disk factor, I was more interested in posi. Are the 82-88 disks worse than my 92 drums?
Thanks for the help, like I said I did search a lot and found a lot of information it was really the specific question about the VSS that I couldn't find an answer to.
#5
Moderator
iTrader: (5)
Re: Adjusting VSS for electronic spedometer
https://www.thirdgen.org/forums/tran...ve-driven.html
Many members will maintain that drums are better--especially since the Delco-Moraines have a tainted reputation here on TGO. That said, with the recall kit in place and with the parking brake used with regularity, I personally never experienced any problems with them. Frankly, I upgraded to PBR's because I had the time and money. Glad that I did? Sure.
JamesC
#7
Supreme Member
iTrader: (58)
Re: Adjusting VSS for electronic spedometer
Stock drums are better then the Delco discs. Under ideal conditions the iron caliper discs work as well as properly functioning drums, but they aren't really an upgrade. It speaks volumes that GM went to PBR for a rear disc setup that actually works. The expense of changing the prop valve, and the E brake cables is reason enough not to swap to the old discs. IMHO.
Changing the speedometer gears is easy. The hardest part is determining which gear you actually need.
If, and that's a big IF, the limited slip in that Borg Warner rear still works, it'd probably be a worthwhile upgrade for the improved gearing and posi. BUT if you ever have to service that rear, parts are hard to come by and expensive.
Personally, I would have to think long and hard before spending the money to switch from a 10 bolt to a 9 bolt. Even if you get a really smokin' good deal on the used parts, the unexpected expenses are going to make it an expensive upgrade for the actual improvement. If it were a 10 bolt with good gears, a functioning limited slip, and PBR discs it's a much clearer upgrade. Depending on the situation, I'd consider upgrading the rear you have now, before swapping to a junkyard/used rear.
Changing the speedometer gears is easy. The hardest part is determining which gear you actually need.
If, and that's a big IF, the limited slip in that Borg Warner rear still works, it'd probably be a worthwhile upgrade for the improved gearing and posi. BUT if you ever have to service that rear, parts are hard to come by and expensive.
Personally, I would have to think long and hard before spending the money to switch from a 10 bolt to a 9 bolt. Even if you get a really smokin' good deal on the used parts, the unexpected expenses are going to make it an expensive upgrade for the actual improvement. If it were a 10 bolt with good gears, a functioning limited slip, and PBR discs it's a much clearer upgrade. Depending on the situation, I'd consider upgrading the rear you have now, before swapping to a junkyard/used rear.
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#9
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Re: Adjusting VSS for electronic spedometer
The last year for the BW rear was 1989, which was also the first year for PBR disc brakes. That rear might have just been removed from a 1990 Formula, but it didn't come in that car from the factory. That's an 85-88 rear axle.
#13
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Car: 1990 & 1991 Firebird Formula 350's
Engine: 350 ci
Transmission: T 5 & 700r4
Axle/Gears: 3:23 & 3:27
Re: Adjusting VSS for electronic spedometer
check out "Everything I know about 9-Bolt Rearends!" and then come see the 9 bolt on my '90 formula with 33K miles.
#14
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Re: Adjusting VSS for electronic spedometer
https://www.thirdgen.org/forums/hist...c-l98-g92.html
JamesC
#15
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Car: 1990 & 1991 Firebird Formula 350's
Engine: 350 ci
Transmission: T 5 & 700r4
Axle/Gears: 3:23 & 3:27
Re: Adjusting VSS for electronic spedometer
I'd suggest that the rear is an 89 'left over.' The following thread might prove to be interesting reading.
https://www.thirdgen.org/forums/hist...c-l98-g92.html
JamesC
https://www.thirdgen.org/forums/hist...c-l98-g92.html
JamesC
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