Gear Vendors Overdrive
Thread Starter
Intermediate
Joined: Feb 2012
Posts: 30
Likes: 0
From: Waterloo Illinois
Gear Vendors Overdrive
Has anyone ever installed or know of someone who has installed a Gear Vendors overdrive unit in a C3 Corvette? I am having difficulty trying to fit this unit into my 79.
Thanks for your time.
Thanks for your time.
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
If you don't mind an honest opinion the overdrive unit from Gear Vendors in a car like a C3 would be a waste. There are a lot of OD automatic transmissions available. The TH200 bolts right in. The TH350C and the TH700 are also great options not to mention the 4L60 / 80 transmissions. For any purpose there is an OD transmission you can swap in place of your stock unit. The reason I say this is because the GV OD unit is long and heavy. It'll add a lot of weight to your car and instead of just adding a 4th gear and lockup you're adding a ratio to every gear. In essence you are making a 7 speed automatic transmission. While that sounds good, possibly too complicated. You have to manually switch ratios every time you're in a gear if you want to utilize the ratio change and if you're using it as an OD you're wasting that unit on every gear but 3rd. My advice, get a 4 speed automatic with a lockup converter. Less money, roughly same size and weight and much simpler to install. I also for forgot to mention the drive shaft tunnel in a C3 is very tight around the drive shaft. You would certainly have to modify the tunnel in order for the GV OD unit to fit.
Race Director
Joined: Jan 2007
Posts: 14,928
Likes: 3,334
From: NYC NY
I have NO personal experience but I'll share what I have seen and heard. The G/V unit is indestructable..........but it's heavy and very hard to package.
I think you have read the same thing in the previous post also.
I think you have read the same thing in the previous post also.
Thread Starter
Intermediate
Joined: Feb 2012
Posts: 30
Likes: 0
From: Waterloo Illinois
Thanks
If you don't mind an honest opinion the overdrive unit from Gear Vendors in a car like a C3 would be a waste. There are a lot of OD automatic transmissions available. The TH200 bolts right in. The TH350C and the TH700 are also great options not to mention the 4L60 / 80 transmissions. For any purpose there is an OD transmission you can swap in place of your stock unit. The reason I say this is because the GV OD unit is long and heavy. It'll add a lot of weight to your car and instead of just adding a 4th gear and lockup you're adding a ratio to every gear. In essence you are making a 7 speed automatic transmission. While that sounds good, possibly too complicated. You have to manually switch ratios every time you're in a gear if you want to utilize the ratio change and if you're using it as an OD you're wasting that unit on every gear but 3rd. My advice, get a 4 speed automatic with a lockup converter. Less money, roughly same size and weight and much simpler to install. I also for forgot to mention the drive shaft tunnel in a C3 is very tight around the drive shaft. You would certainly have to modify the tunnel in order for the GV OD unit to fit.
Thanks for your response.
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
What 4 speed automatic and lockup trans package would you recommend? I am running a 383 stroker with 475 hp and a reinforced TH350. Would this new 4 speed bolt right up without any modifications, ie. Cross member, cooling lines, drive shaft length?
Thanks for your response.
Thanks for your response.
For a bolt in option the TH200R4 is the best choice. You can re-use everything that is already on your car and the gear ratios closely resemble that of the TH350 so 1 - 3 will be almost the same. Then added 4th and OD. I recommend one from a top rebuilder maybe like Bowtie Overdrives. They sell several high HP applications. They will provide all the installation assistance you need and can set you up with a transmission and converter that best suits your needs.
Drifting
Joined: Feb 2008
Posts: 1,560
Likes: 4
From: Arlington texas
What 4 speed automatic and lockup trans package would you recommend? I am running a 383 stroker with 475 hp and a reinforced TH350. Would this new 4 speed bolt right up without any modifications, ie. Cross member, cooling lines, drive shaft length?
Thanks for your response.
Thanks for your response.
The 200r4 is as close to a drop in as you could probably get. Problem is, they are hard to find. I have been looking for one at a reasonable price knowing that it will have to be rebuilt to be able to hold up. There is the 700r4 which is not quite a drop in unit and is easier to find.
Bowtie overdrives is one company that sells both units as well as anything that you are going to need to complete the swap on your car. They have different versions to handle different HP ratings.
Have you contacted Gear venders to make sure that you have the correct part to fit your car?
Le Mans Master
Joined: Oct 2010
Posts: 6,930
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
if i remember correctly gear vendors is an updated version of the hone overdrive unit Joel Rosen put in his motion performance corvettes years ago. the g.v unit is an anvil you really have to abuse it to hurt it. a200 overdrive is going to be expensive to handle 475 h.p. i have been thinking of that unit myself.
Race Director
Joined: Apr 2007
Posts: 14,062
Likes: 602
From: Henderson Nv-Rohnert Park/Sonoma C o. ca/born in NY Rockaway Beach.
I am about to do the same exchange myself to and OD from a th350.. I am going to a 2004r from bowtie..... I called and talked to rich and he set me up with a package with everythign ill need for the swap....for around 2k you can have a nice stage 2 set up and an easy swap...
this comes with trans.TC, lock up system,tv set up . the works..
remember if you use bow tie to make sure and read warranty ... you have to call in with pressure #ers...
this comes with trans.TC, lock up system,tv set up . the works..
remember if you use bow tie to make sure and read warranty ... you have to call in with pressure #ers...
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Racer
Joined: Oct 2004
Posts: 379
Likes: 0
From: Thief River Falls Minnesota
I in fact do have experience with doing this.. Put one in behind a 700-r4 in a '76 vette. It requires you to ding the transmission tunnel (by ding I mean cut out and weld in a 1/2 box and beat the hell out of it with a 5lb hammer.
Race Director
Joined: Oct 2002
Posts: 12,065
Likes: 2
From: Smalltownville Michigan
Cruise-In 5, 6 & 10 Veteran
St. Jude Donor '09
i put a 700 in mine.. used the bowtie overdrives crossmember and had to have the right side exhaust bent around the pan.. other than that, it wasn't bad to install
oh yeah, you have to have your driveshaft shortened too... 3.875" if memory serves right
oh yeah, you have to have your driveshaft shortened too... 3.875" if memory serves right
1st Gear
Joined: Apr 2012
Posts: 1
Likes: 0
I looked at the GV for my 70' with TH400 and spoke to the company. There have been very few installed in automatic C3's acconding to GV. They told me I would need to cut the tunnel and the drive shaft would be almost on the end of being too short. I'm ok with mods and extra cost if it works well. Then I took a hard look at the gear ratios thru all the gears vs a 700R4. I went with the 700R4, the gearing is much better for accelleration in 1st and 2nd, and the over drive gear is much taller so cruising at 70mph is nice at around 2300prm with 3:70's in the rear. Another drawback with GV is you only use the unit for D.O. because the manual shifting is a hassle, shifting 1st in under,1st over, then shift back to under and trans to 2nd.... 2nd over
The 700R4 fits really nice, no cutting. It really gave my car a kick in the nads.
The 700R4 fits really nice, no cutting. It really gave my car a kick in the nads.
