Hey guys! just finnished installing a th350 in my kids 87 firebird. This car had no engine or trans when we got it, but it was a 2.8 auto car, now has a 350/th350. Anyhow, went to hook up the speedometer cable and couldn't find it!! Crawled under the dash and looked right at the back of the speedo and NO cable. So I am assuming that it is an electric speedo. We also have an 85 firebird parts car. This one HAS a speedo cable!!! Sooooo.... I am hoping that I can swap gauges and run the cable from the 85 in the 87. Will this work. I would find out for myself but we just got a foot of snow dumped on us and the parts car is outside. Thanks for any advise!!!!

 

Um, get a VSS for a T5 and call it a day... Assuming you left the rearend alone, you will need a 19 tooth speedo gear for the VSS. If there is a 7 tooth on the output shaft of the trans already, that is.

 

Ummm..... Not quite sure if you are understanding whay i am getting at. The speedometer in my car is elctronicly driven, meaning the speedometer needs a sensor on the tranny, which the TH350 does not have. It has the old school cable driven sender in the tail housing. I DO have an older, 1985 firebird with a cable driven speedometer. I am wondering if the speedometer out of the older parts car can go inplace of the electronic speedometer in the 87 we are working on. Then I could just run the cable to the trans and be done with it. Like I said I would rip the parts car apart right now, but it is snowing as we speek on top of the 12" we got a few days ago. Damn snow!!!!

 

Um, let's say I understand perfectly. Your TH350 uses the same speedo parts as a T-5. All you need is a pre-90 VSS and call it a day, provided that you already have the right speedo gears. You don't need to mess with installing a speedo cable and rewiring and replacing the instrument cluster.

 

Does a T-5 use the plastic speedo drive gear on the output shaft like a th350? Or do I need to remove the tail housing on the 350 to install a T-5 toothed reluctor wheel?

 

The T-5 uses either a 7-tooth purple or 9-tooth red plastic gear on the output shaft to drive the VSS/speedo cable gear. If you currently have the RED one, you will need to hunt for a drive gear as the purple ones are hard to find, and you will need a 19-tooth driven gear on the VSS if you didn't swap out the factory 3.42 rear axle. The VSS uses a gear that has a D-shaped hole. Some cable adapters use the same gear on a metal shaft that drives the cable, some use a plastic gear with molded speedo cable shaft in one piece. Make sure you get the right gears.