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Discussion Starter #1
I'm thinking of installing a gear vendors unit and putting in a 3rd member to go from 2.79 to 3.55. My questions are:

How much do I have to shorten the drive shaft?

Would I be happier with 3.25s?
 

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Do you have a link? I didn't know you had to shorten your drive shaft. That's a first I've heard.
 

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I would line up a driveshaft repair/fabrication business, then install the Gear Vendor unit and give them the dimension between the tailshaft yoke and the differential yoke. They will know how much to shorten your shaft.

I like the GearVendor unit. A whole lot easier than doing an AOD swap. I would probably go with the 3:55's if you install the O/D.
 

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Discussion Starter #4
Thanks Andrewmp6,

I'm not a manual type of guy. I understand I'm adding 2 more gears but the way I see it, you can leave it on auto and is like is not even there, because it puts the overdrive at the end. Now if you want to show your friends then you can **** all the gears yourself. I went through a lot of ideas (AOD, 4R70W) and got some input from PAULS, seen plenty of input from forum members (Starfury also comes to mind). But I'm going with gear vendors, as a matter of fact I might be calling Nick today.

Yes, you're right in the driveshaft. I open a thread hoping to get a reply from somebody who has done it, to give me an idea on how long does the drive shaft have to be. I understand the unit adds 13" and common sense would say subtract but I guess if push comes to shove I'll just take the one I have to get cut. Instead of ordering an aluminum from Mustang Plus.

The engine kit and the rear gear is what I still debating. The edelbrock kit I think is making the most sense, although I waiting from a response from comp cams. I'm going to call them this afternoon to get their input because I want to get their input and put something together. I hope is better and maybe cheaper.

Now the rear end, I've looked at the calculators and I think what's going to make the difference is, what the engine setup works best with, for street performance(Any chance I get driving).

Sorry guys I have another thread going (NEED HELP DECIDING WHICH SETUP FOR MY 67 MUSTANG)

Yes I was hoping to avoid cutting my shaft and just buy another one. I don't think I can order it and get within 7 days, but that may be the case. There is a place near by that could do the job from what I was told.
 

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I did almost the exact same rear end swap, 2.79 to 3.50. I put in an AOD, with the 2.79 gear it was great for highway cruising, but not great off the line as you can imagine. About a year ago I changed from the 2.79 8 inch to a 3.50 9 inch. It totally changed the car. It is more fun to drive and feels loads more powerful.
The Gear Vendors deal, will be interested to hear how it works out.
 

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the more gears you have in the transmission, especially if you have overdrive, the bigger (numerically) gears you can put in

i went with 3.25s because i'm keeping my c4 which only has 3 gears. if i got an AOD, i'd get 3.55s because it can handle doing 70-80 on the highway without passing 4k rpms

not sure about the GearVendors unit.. actually never heard of it lol
 

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My Dad has a GearVendors/C4 combo in his 1950 Ford Shoebox. The actual unit is great when it works. The problem he has is with the controller. The brain has been replaced twice, and the installation was actually inspected by GearVendors many years ago, so it had their approval.

The problem is that it won't shift into overdrive with any regularity. It seems to have a mind of its own. We've checked grounds, connections, double checked installation methods........Dad has just decided to let it do its own thing. When it wants to shift, it shifts.

GearVendors may have improved/fixed the control box during the time since his was purchased, I don't know. Considering the cost of the unit, it may be wiser to sell your C4 and go with an AOD which will give you all of the functionality of the GV/C4 combo without the Frankenstein complications.
 

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The GV unit is the bomb! You get great reduction. You don't have to stop at 3:55. As far as the drive shaft goes, it is always best practice to get the unit installed then take the proper measurement. The other plus, in some cases, you can leave the tranny in place and simply remove the tail shaft.
Happy Motoring!
 

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I kept telling him get a aod,I have a gear vendors on my truck just to make it easier on fuel its a diesel.One of my friends had one on his cummins he tows with everyday burn up in 9 months.They told him it was because you have to shift it in neutral down hill with a big load.
 

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Discussion Starter #10
I will be updating by the end of august on the setup.

I'm going with the edelbrock kit, gear vendors, 3.25 3rd, Holley avenger tbi and Hedman headers with magnaflow kit.

Let me know if I'm forgetting something.
 

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I will be updating by the end of august on the setup.

I'm going with the edelbrock kit, gear vendors, 3.25 3rd, Holley avenger tbi and Hedman headers with magnaflow kit.

Let me know if I'm forgetting something.
Hi,
Why not a 3.55 rear? Are you getting a "deal" on the 3.25?
You certainly won't be hurting with any excessive RPMs. Not to mention, you'll add more performance together with your other add-ons. Just curious?
 

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Discussion Starter #12
No I think 3.25 will give me enough performance for know, I will probably do more distance travel like this. If it's not the case, I'll bump up in the future to the 3.55s.
 

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i know this is an old thread but if anyone with one of these units could help me out I would really appreciate it.

I have been thinking about one of these for my c4 but the one thing I seem to be confused on is the operation of the unit.


my big question and concern is if i have one installed and decided to go racing.. i see it has a manual feature? so would I be able to go business as usual and line up brake up on the converter launch and just bang 1st,2nd,3rd as always like its not there and still perform the same. or do i have to be hitting buttons in between the whole time like 1st,1st-over,2nd,2nd-over etc.. as i am reading all i can find on the unit it sounds more like the latter. which would lose my interest lol.

thanks alot!
 

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HI,
When I contemplated a G/V unit I received lot of support from their tech folks. I should think you would too. Especially, as to how strong their warranty might be. I would be "up front" with them on your usage.
Good Luck with your project.
 
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