The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Doing the T5 Transmission swap, a few questions

brap999 · 03-29-2011, 03:12 AM

After hours of searching and researching on other sites about T5's, I was able to answer one of my own questions. It is possible to convert the electronic speedometer output on the T5 to a mechanical gear driven type. I'll list it here in the hopes it helps someone else out in the future looking for this same info.

Basically you need to find a GM T5 Speedometer housing, which doing a quick search I found for sale on a few websites as well as Ebay. You will also need to get a Driven Gear for a GM T5 and a Drive Gear for a GM T5. The Driven Gear is apparently the hard part to find, as it seems not many places have them. Actually I wasn't able to find any. There are Ford T5 Driven Gears for sale, but I'm not sure these will work.

Fortunately, there is another solution. You can use the Speedometer housing for a Chevy TH350 auto transmission, and a Driven gear for the Chevy TH350, with the Drive gear for the GM T5.

Note that only the Chevy TH350 transmission parts will work, I saw this noted at the site I purchased my parts from. So don't go looking for TH350 parts from the Buick/Olds/Pontiac/Cadillac TH350

Next you will need to determine what size driven gear, and drive gear you will need. To determine this you need to know your rear end gear ratio, and your tire size.

Once you have these values, use the calculator found here: http://www.5speedtransmissions.com/calculators.html

It will tell you which size Driven Gear you will need. Here is a hint, it appears you will most likely use a 7 tooth GM T5 Drive gear, the only other option is a GM T5 9 tooth drive gear, but it seems it's not as commonly used.

I purchased the TH350 Speedometer housing, TH350 Driven Gear, and the T5 Drive Gear from this site: http://www.transmissioncenter.net/sp...n_______va.htm

A lot of the information I learned from another site and they also discuss how to install the parts, here: http://www.thirdgen.org/techboard/tr...ve-driven.html

Keep in mind, when they are discussing what size driven gear to use, they are using the rear gear and tire sizes on their Camaros & Firebirds, so make sure you use the information from the calculator linked above as it will give you the proper values for your truck setup.

03-29-2011, 03:12 AM	#4
brap999 Registered User Join Date: Mar 2011 Location: Springfield, VA Posts: 223	Re: Doing the T5 Transmission swap, a few questions After hours of searching and researching on other sites about T5's, I was able to answer one of my own questions. It is possible to convert the electronic speedometer output on the T5 to a mechanical gear driven type. I'll list it here in the hopes it helps someone else out in the future looking for this same info. Basically you need to find a GM T5 Speedometer housing, which doing a quick search I found for sale on a few websites as well as Ebay. You will also need to get a Driven Gear for a GM T5 and a Drive Gear for a GM T5. The Driven Gear is apparently the hard part to find, as it seems not many places have them. Actually I wasn't able to find any. There are Ford T5 Driven Gears for sale, but I'm not sure these will work. Fortunately, there is another solution. You can use the Speedometer housing for a Chevy TH350 auto transmission, and a Driven gear for the Chevy TH350, with the Drive gear for the GM T5. Note that only the Chevy TH350 transmission parts will work, I saw this noted at the site I purchased my parts from. So don't go looking for TH350 parts from the Buick/Olds/Pontiac/Cadillac TH350 Next you will need to determine what size driven gear, and drive gear you will need. To determine this you need to know your rear end gear ratio, and your tire size. Once you have these values, use the calculator found here: http://www.5speedtransmissions.com/calculators.html It will tell you which size Driven Gear you will need. Here is a hint, it appears you will most likely use a 7 tooth GM T5 Drive gear, the only other option is a GM T5 9 tooth drive gear, but it seems it's not as commonly used. I purchased the TH350 Speedometer housing, TH350 Driven Gear, and the T5 Drive Gear from this site: http://www.transmissioncenter.net/sp...n_______va.htm A lot of the information I learned from another site and they also discuss how to install the parts, here: http://www.thirdgen.org/techboard/tr...ve-driven.html Keep in mind, when they are discussing what size driven gear to use, they are using the rear gear and tire sizes on their Camaros & Firebirds, so make sure you use the information from the calculator linked above as it will give you the proper values for your truck setup. Last edited by brap999; 03-29-2011 at 03:21 AM.