I have kind of an odd question regarding 700R4 vehicle speed sensors. If you look at this handy chart it gives you all the part numbers for VSS' and the different drive gears and driven gears that are available:
http://www.corvetteforum.net/c4/vett...Gearshtm.shtml

Notice in '91 the part numbers for the VSS change which I know means the VSS changed in design somewhat. Now my question, will the older style VSS, specifically #25007308 fit in my 91. The reason I'm doing this is I'm in the process of switching from a 3.07 rear to a 3.33 and it looks like if I use this VSS and the lt blue driven gear I can get away without changing the tailshaft drive gear.

I already have the new VSS and I tell by looking at it that it is definitly different than the one currently in my car. I haven't got a chance to get under the car yet so I was wondering if anyone knows if the two styles are interchangeble. Thanks in advance for any help and sorry if this sounds a bit confusing :crazy:

 

I see what you're talking about. Is 1991 the first year that you have to reprogram the the ECM for the gear ratios? My parts book only goes to 1990. I'm trying to remember my previous advice. Didn't you say you had changed from 2.59s to 3.07s? Didn't I say that you could save changing the drive gear by using 3.31 speedo gears? I think I gave you the part numbers for that swap. I also think, I ended up telling you that for a 3.07 to 3.31 change over, you would retain the 3.07 VSS. If that is what I told you, I gave you the pre-1991 VSS part number. BUT, the situation remains the same. IF you have speedo gears for the 3.07s in there, all you have to change is the driven gear. Help me remember. Good luck, and...

RACE ON!!!

 

My car originally did originally have 2.59s. Last year I swapped in a Dana 36 with 3.07s. At that time I changed the VSS and driven gear to correct the speedo (I used the part numbers listed for 1991). Last season my rear went which is why I bought the Dana 44, but also at some point the rod on my VSS snapped (leaving me in need of a rear as well as a VSS). So now I have a new Dana 44 rear on the way, but I don't have a functional VSS. This was the point I contacted you and asked for advice. I ordered the light blue driven gear and the aforementioned VSS. I did this because the 91 chart indicated that a switch to 3.33s would necessitate a change of the driven gear so I figured I would need the VSS that corresponded with the lt blue gear. It wasn't until I received the VSS that I realized that it was a different style than the one in my car. It may still work, but I was hoping someone would know if the two styles are, in fact, interchangeble. Darn, now my head is spinning :crazy:

Do you think the VSS I had in there before with the 3.07s (part #10456091) would work with the light blue gear? BTW, thanks for all the guidance you've given me. :cheers:

Also, I believe it was 93 when GM changed to a system that required the chip to be reprogrammed for a gear swap, so mine is still the "older" style.

 

Who's on first??? No, I think I've got it. The part number I gave you for the VSS, was for a pre-1991. I have no clue as to the the differences in the 1991-up and the the earlier, VSSs. The VSS on these cars only positions the DRIVEN gear in the correct alignment with the drive gear. You had to change the VSS when you went from 2.59 to 3.07 speedo gears because of the larger driven gear. The 3.07 and the 3.31 uses the same VSS. If the early VSS works, great, but I would be prepared with the proper, 10456091 VSS for your 1991, in case it doesn't. I THINK, at the end of the origional conversation, I said you had no need to change the VSS. That is still the case. I hope I haven't screwed YOU up too much. Good luck, and...

RACE ON!!!

 

I think the best thing for me to do is send the VSS back and get the proper '91 model. It'll save me some bucks, too because for whatever reason the pre 91 VSS' cost about $75 where the 91s cost about $25 :crazy:

Anyway, thanks for taking the time to help me out with this :cheers:

 

That is what you really need, anyhow.

RACE ON!!!

 

Right back at ya :cheers: