Gear vendor's with 3:54 rear gears and th400?

[chewychevy67]

I am tossing around the thought of adding a gear vendor's Overdrive in my 67 build. I had a 700r4 in my last truck and more important than any fuel I might have saved I sure loved how quiet it was. The drivetrain is all stock 327 turbo 400 with a Dana rear with 3:54 rear gears. 700r4 is absolutely not an option on this build. I know this set up would be better with 3:73 gears but I have my diff all done and buttoned up with new parts and really don't want to change guts. Any input from others who may have done or have this set up or is knowledgeable about this kind of stuff would be great. Just don't want my truck to be sluggish because I added this with the lower gears. Thanks in advance, Rod.

[davischevy]

I have been thinking GV myself, but, I have to ask, why is the 700R4 out of the question?

[chewychevy67]

Because my tranny is already built and I have my stock 67 4jet carb and It would be a pain to get the tv cable correct on it. Plus I want to keep the kick down switch on the carb to look correct.

[kwmech]

22 percent overdrive will take you down to a 2.7 final drive. Kind of a tall ratio for a small block

[davischevy]

Gotcha.

I'm still in to see if anybody has input on the GV's.

[chewychevy67]

Here is what I got from their site. So a 2.7 final drive is too low As with 3:73 it's 2.9?

[jocko]

I am strongly leaning toward a GV behind my K20 for similar reasons - would prefer to keep the motor and t-case in the stock location, but the tradeoff is more $. GV behind an NP205 is around $3K, whereas a stout 700R4 could be a little less. Unless, of course, I forget and leave it engaged when in 4WD, then it just got a LOT more expensive . Anyway, it's personal preference.

My gut reaction was same as kwmech, i.e. 3.54 might lug the motor if in O/D below 55 mph or so. It's easier to see the impact by looking at cruising rpm rather than final drive ratio. Here's a comparison with a 30" tire of your current configuration, adding a GV, and a GV with 3.73s. ~100 rpm less at 55 mph (i.e. the 3.54 with GV vs 3.73 with GV comparison) might not sound like much, but when it's ~100 rpm less from 1790 rpm, you start to get in that gray area where you might lug the engine at lower highway speeds.

To be honest, a 3.54 is a pretty user friendly highway gear - a GV price is a fairly high one to pay when you're not already revving to the moon at 65 mph anyway. But I do understand - I want one pretty bad too (but I have 4.10s )

Also, to your comment about being sluggish in lower gears - it won't have any effect. 1st, 2nd, 3rd final drives all remain the same and you simply add a 4th o/d gear - unless you use it as a gear splitter to insert the .78 after each speed (i.e. operate as a 6 speed) - but even that doesn't affect your 'from a dead stop' performance, 1st is still 2.48 x 3.54 for a final drive of 8.78.

[special-K]

That will be a nice combination. My project has a 4spd manual and 3.42:1. 3.42s are the perfect in between ratio. I want Gear Vendors but will first put it together w/o and it won't be awful on the hiway. For straight drive it will cruise second to the 3.08s/better than 3.73s, but not hurt your low end power. Add overdrive and it's not too tall like 3.08s. Most Tahoes out there have 3.42s with O/D and they can cruise and haul. On a 3/4 or 1t with big tires I'd say no.

I have only had a Gear Vendors unit on a, '84 K30 6.2 (w/Banks Sidewinder)/TH400/4.10s/35" tires and I loved it. I wanted to pull it out but someone came along wanting the truck before I had it for sale and my new truck was coming with a 5spd manual anyway. I wish I had kept it for the old trucks.

[chewychevy67]

Yeah I figured that would be a problem with those gears. My tires are 29" tall so that's pretty much right on. I was Leaning to just purchasing it and installing and see where it goes but Maby the 3:54 gears will still be comfortable (quiet) enough for me.

[Don Quixote]

I've been doing a cost analysis for a GV. I want one badly, mainly so I'd have a gear between 3rd and 4th as well as overdrive. I pull a lot with my little 292 and 3.73 but I just don't want to part with it. With a GV I may even be able to step down to 4.11 and get some of my low end back but at $2K even for a used one, I'll just have to keep it at 60mph and the world can go around.

[kwmech]

Originally Posted by jocko

whereas a stout 700R4 could be a little less. .....

No such thing in my experience, not in a truck anyways

[Bad70sbchevy]

Originally Posted by kwmech

No such thing in my experience, not in a truck anyways

Not even with this guy? Claims up to 725hp rating.

http://www.tciauto.com/tc/streetfigh...ock-chevyhtml/

[jocko]

Originally Posted by kwmech

No such thing in my experience, not in a truck anyways

I'm not trackin... Most rebuilt/up-phased 700s I've seen are in the $2000-2500 range, to include K-case versions. Not talking Billy Bob's trans shop, places with at least some track record like TCI, Bowtie Overdrives, etc.
https://www.bowtieoverdrives.com/cat...SUBCAT&CATID=B

[emfh76]

The Gear vendors unit is a gear splitter so you will have a 6 speed instead of a 3 speed. You can also remove the gear vendors unit if you ever decide to sell the truck and put it behind any th350 or th400 for future projects. I spent almost 3000 having a 2004r built with all the good parts to handle the power. I will never do that again, i could have bought a gear venders and had it for life. I have had to put new clutches in the 2004r in 7 years so its not bad but the gear venders can handle a lot of power without the need to replace wear parts.

[kwmech]

Originally Posted by Bad70sbchevy

Not even with this guy? Claims up to 725hp rating.

http://www.tciauto.com/tc/streetfigh...ock-chevyhtml/

Sure, you can build them up to hold say 5-6 hundred horse power, but for how long? My experience has been with a 'built' unit life expectancy is about 50-60 thousand miles then back out of the truck to freshen up. 4l80 with a big block or any type of towing for reliability and endurance. Or old school with a 400 and a Gear Vendor.......which is what I put in my latest project and hopefully my last

[special-K]

Lot's more issues with overdrive transmissions. You can keep your old strong and reliable straight drive transmission and gain overdrive as well as gear splits with no sacrifice what so ever.

[jjzepplin]

What are you guys doing to these 700rs? I abuse the crud out of mine and it is almost 17 years since I built it. Even totalled the Blazer and stuck it in the pickup. Still killin it after all these years behind a 406...

[Alex V.]

29" tires with 3.73's and no OD isn't too bad (2,600-2,700) - since you're sticking with the 3.54's I really don't think the GV is going to be of any benefit. With a diesel, 383 stroker, or something like that it might be alright, but your drivetrain as-is with 3.54's will have the engine right in its sweet spot. I'd cruise that truck all day at 65-70.

4.10's with the 29's and a Turbo 400 + GV would be fun.

[davischevy]

I will speak like a politician on this one. I will take both sides.

I have replaced the 700R in every vehicle I have owned except one. Most I bought new. I replaced a 4L60E in my wife's suv at 60,000 miles.

In my mind the 700R is the bottom of the food chain in stock form.

We have two local guys that can build 700R's to last. WE have three behind 383 strokers and 3 behind big blocks.

My Longhorn only has about 30,000 on the 700R, but has done it's share of work. I spent as much on the build and installation as a GV would have cost. Why didn't I do GV? I didn't think of it. If the 700R gives up, I will put the fresh 400T back in and go GV.

In a car with under 500 HP I will do the 700R again and again, but in trucks from now on I will do GV. Mostly because I like to split shift.

[jeffahart]

I've been keeping my eye out for one for a couple years now. I just don't see the effort to put in a modern 5 speed. Even if you bought a new GV, I feel like you could recoup at least half the price back later on. Keep the original drive shaft, and pull the GV before you sell the truck and put it on ebay. You can get a lot of your cost back. Or keep it for another vehicle. My truck just runs too damned good with the mostly original equipment. I changed out the axles for the D60 and Corp14 with 4.56. Other than the low gears I love the setup 465 and 205, you can just flat forget about them! Trouble free! And, I really liked the 4.10s with 33s. But I'm to cheep and lazy to change gears. Plus for the price and effort... might as well GV!

GV, not a need to have, but a nice to have! I could go 35s and do a bit better. Or I could just wind it out for a few years, throw a rod and replace the pack for way less than a GV anyway! Plus I know what to expect with a new motor! GV is good on paper for me, because I've never actually owned one... so there's that!

[aerotest]

1700rpm at 55mph isn’t lugging the engine. Just make sure you have load based advance (vacuum) on your distributor and you will be GTG. My stock Tahoe runs 1250 rpm at 55 with 3.73 gears.

[Dynospeed]

I just put a 3.42 behind my ls 6.2 with 4l80, it’s supercharged but cruising I’m not in boost at all. If anything I would go with a 3.23. You can always not engugae the GV until 70-75 if you motor bogs down. I vote a GV unit.

[RPOZ11]

I'm my old 73, I had a mild low compression 454, T400, & 3:21 gears.
The way that combo ran, I felt adding a GV wasn't necessary as most of my power worked between 1500-4000 rpms.
I could do 90 mph no problem but felt adding the GV may lug the motor.

I will be using a 14 Bolt with 3:42 gears and add the GV in my Longhorn along with a T400 and a mild 496 with 10:1 compression.

With this combo, I feel that I will rely more on the torque side to move the weight of this.

[bbrriiaann1973]

I have a 70 c10 with a 383/700R4 3.73 lock rite posi and it's to sluggish While in overdrive. Liked the way it perfomed with the TH350.

[chewychevy67]

I'm wondering if I could get them to program the computer to get the Overdrive to shift in at 52-55 mph instead of 47 mph. Would that help this setup? It would keep the rpms higher into the shift. I could easily change the rear to 3.73 but my diff has new gears in it now and it's nice and clean. If I'm changing Maby 4.10 gears could be a possability if they will fit in the same case but that I'm not sure of.