# Gear Vendors Overdrive



## gtoearl (Dec 21, 2009)

I've posted this request before with no response. I'll give it another try. I have been unhappy with my turbo 400 in my 66 GTO. That is to say, the transmission performs well with one needed feature. I really want and need an overdrive that is to say a fourth gear. Now I know some of you will say why don't you just put in an overdrive transmission, I believe 2004R is the one for the Pontiac. I thought about that and the cost of having one built for me and installed at the transmission shop is somewhere around $4000 . I cannot do the install myself from my home. I've also considered purchasing 2004R transmission from bowtie overdrive in Southern California. The cost is reasonable at around $2400. But again I have no way to install it and transmission shops i've talk to shy away from installing other companies products. So, I have decided and then going forward and purchased the gear vendors overdrive. $2800 ..... I believe the instructions are clear and I can install this at my home with little difficulty. So my question is : Has anyone installed gear vendors in your GTO and are you happy with the performance? Thanks in advance for any response to this post.


----------



## PontiacJim (Dec 29, 2012)

I honestly can't recall anyone on the forums going to or using a Gear Venders OD. Most will go with the later automatic trans with the OD.

Doing a little fact checking, seems the automatic OD can run near $4-$4,500 - Ouch! the 2004r seems to be the easiest swap, but not necessarily the best when it comes to handling big torque and sticky tires. The other trans types seem to require more mods and electronic controllers to work. Sounds like too much work and rigging to me.

The TH400 is one of the most rugged of them all, so the Gear Venders OD seems to be the better value overall. Read all the installation info and it seems fairly straight forward. Got to have the driveshaft shortened and you have to change fluids every 5,000 miles. 

If you do it, post your progress with some pics and then give us your opinion on it all. :thumbsup:


----------



## gtoearl (Dec 21, 2009)

Thanks very much for responding to my post. Yes, I've done a little fact checking myself and as you stated the cost of an overdrive transmission whether it's the 700 or the 200 is more than I want to spend. I understand there's other issues with the kickdown adjustments and or install. Anyway I've begun the process of putting it in my GTO. I've taken the driveshaft off and I've taken the tail housing off the turbo 400. One thing that those of you that are considering this may look out for, there's no gasket for the New tail shaft housing but your vendors. They have engineered an O ring seal for that purpose. So far, it's been somewhat of a struggle for me to knock out or in large , if you will, the tunnel for the gear vendors to properly fit the A body. Here is a video of what I've accomplished so far. It's a video I made for my friend Bob.


----------



## gtoearl (Dec 21, 2009)

Sorry can't seem to post a video on this thing. I'll keep trying. If not I'll take some stills tomorrow and post them.


----------



## PontiacJim (Dec 29, 2012)

gtoearl said:


> Sorry can't seem to post a video on this thing. I'll keep trying. If not I'll take some stills tomorrow and post them.


Pics will work. More research seems to indicate that you may have to dimple the floor slightly for those two top bolts/ears. 

No bad comments or reviews on the unit and some guys have them behind big cube/high HP engines with no problems at all. Looks like a good investment and better choice over a modified OD automatic.


----------



## dd68gto (Nov 14, 2012)

I have a 68 that I'm working out some bugs in now. It has the 2.93 gears so the gear vending unit with maybe 3.55 would really wake this up and still be fun on highway. Please take a ton of pictures and post us as you go. I will be most likely doing the same on my 68. Doug


----------



## gtoearl (Dec 21, 2009)

*update*

Thanks so much again for the comments. I have gotten a little further in the install. I think I'm almost there as far as the "massaging" of the tunnel. Here is a few pictures. I do have a short video but unable to upload to this site. I also ran across an article on the subject. Got it from the PY Online Pontiac blog.

Must download photos to your computer to view....Must be too large of a photo to view from the site directly. Sorry.


----------



## PontiacJim (Dec 29, 2012)

Pictures that are too large, ie pixel settings, won't upload. I have one of those free picture resizer programs to reduce the size of the photo so I can post them here. That may be what is happening with your photos. 

Looking good so far and seems fairly simple and forward with the install. :thumbsup:


----------



## gtoearl (Dec 21, 2009)

*Getting closer*

Well after a few sessions of modifying the tunnel area the gear vendors overdrive portion has been installed. I will start on the electrical portion in a day or so. I do have a few questions for those of you out there that are reading this blog. I plan to change The fluid in the Turbo 400 transmission. Also will be installing a fresh transmission pan gasket and filter. My question is: I believe I need Denton III fluid.. i've looked around and Dexron three specifically is not out there..... there's other types of fluid that say replace Decron three... synthetics and mixtures that say replace the dexron III... any ideas on transmission fluid in general?


----------



## PontiacJim (Dec 29, 2012)

You want to be careful as to what fluid you select. No expert, but do the research. It is my understanding that some of the "modern" fluids can be too slick for the later tranmissions unless recommended by your builder. Many use the Ford Type F fluid instead of the Dextron which I was always told was a thicker/heavier fluid. 

The power steering on my '97 Toyota required the Dextron. It had a good leak in one of the hoses. I used the Type F because it was thicker. It slowed down the leak and I didn't have to fill as often. If I used Dextron, I had to keep and eye on the fill level and add more often. Ran it that way for 3-4 years until the leak got to the point I had to install a new hose.

You might want to use an aftermarket fluid like B & M. Yes, it'll cost more, but it is good. I used it in one of my GTO's with TH-400 when I was a kid. Most would recommend this if you asked around, so I used it myself. No problems and it held up to my lead foot. https://www.summitracing.com/parts/bmm-80259


----------



## gtoearl (Dec 21, 2009)

Here is some pics of the install. Sorry it took so long , I put it in a couple months ago.


----------



## dd68gto (Nov 14, 2012)

gtoearl said:


> Here is some pics of the install. Sorry it took so long , I put it in a couple months ago.


As I have said earlier I'm thing about the same path as you in my 68. Have you had it out on road yet ? How do you like it ? Also , what I have read it gives you a low and high in all three gears , really making it a six speed auto ? I guess the most important is driveabilty and RPM range on highway . If you got any video please send to my email I pm you. Thanks Doug


----------



## 1968gto421 (Mar 28, 2014)

Thanks for the pics and for the Gear Vendors article. Also, did you ever decide on a fluid for your TH400 oil and filter change? Like Pontiac-Jim, I have heard that synthetics will tend to leak unless you do ALL new seals and gaskets (ouch).


----------

