Gear Vendors Overdrive

[sgms18]

My m1028 has a SM465/np205 & I've been wanting to do a NV4500 swap for the 5th gear because 3k at 60mph sucks bad. Then I started looking at putting a Gear Vendors OD on the set-up I already have. The only way I'd go nv4500 is if I can find an early one because I'm not willing to loose my granny gear. So if you look at the ratios from both transmissions they are very similar the NV just has 5th gear. The splits are pretty bad in either. As is if I'm going up a decent hill I wind 2nd till it sounds like it's going to blow up & it still falls on it's face when I hit 3rd. The NV4500 looks a little better on paper but not much at all & I doubt there's any real world difference. I had seen the bolt on OD units in the past & thought it was just OD. I didn't realize you could split gears throughout the range basically turning my 4 speed into an 8 speed. That definitely seems like way to go to me. Question is durability/reliability. They are expensive but if it's a quality unit that I can expect long service life from I don't mind spending the money. Anyone have real life experience with the Gear Vendors units? I don't beat the hell out of my truck like I use to 20yr ago but I still get a wild hair to hit the rut roads every now & then. Can they stand up to off road use & towing? I don't tow crazy loads but 20ish ft boats & campers pretty regularly. Can they be rebuilt? Let me hear it, good, bad & ugly. Are they worth the investment?

 

[sgms18]

Sm465

 

[sgms18]

Nv4500

 

[sgms18]

Sm465 w/Gear Vendors OD

 

[nyoffroad]

Never had a Gear Vender OD but I do know they can only be used in 2 wheel drive because they mount after the TC.
Any older truck junk yards down around you? If so look around in the old 1 and 2 ton trucks for a cast iron overdrive unit that mounts in FRONT of the SM465. It moves the tranny back 8" and you need to bend the shifter a bit to clear the seat but well worth the effort. The name escapes me for now but IIRC they were made in Tx and easily rebuilt using almost all SM465 parts and gives you I believe .85 overdrive in any and all gears. It also doesn't hang down low like a GV overdrive.

 

[sgms18]

10-4. To clarify I had no intention of trying to use the OD unit while in 4wd. I'm not sure why you would even want to. I was just wondering if all that extra meat behind the T-case would weaken the driveline.

 

[MarcusOReallyus]

I've never had one, but I've read a few threads on here over the years. It's been discussed a lot. A search should turn them up. Lots of good info.

Might have to search in the CUCV Modifications forum, but I'd bet some are in this forum, too.

 

[MrMikey4026]

I had an underdrive behind a 460 with a C6. Towing a trailer that weighed about $16,000 lb. In the western part of the United States there are some very steep passes. I never had any trouble with it. Never broke anything and it worked great.

 

[Skinny]

This is the exact reason I didn't go with an NV4500 when I did my overdrive swap. I didn't want to have the wide ratio spread with the gutless engine.

I am not a big fan of the gear vendors overdrive for a lot of reasons. Mostly because it isn't a deep enough overdrive that you need with the 6.2 considering how much it costs. I think there are better options for the money.

I mean I have less in my 8.1 4L80 Burb swap. So that's one...

Are you dead set of a manual?

I was more interested in swapping a close ratio 5 or 6 speed from a half ton but didn't want to downgrade in strength for that swap. Nothing exists in the 1 ton world in manual with the ratios that work well with tha turd unfortunately. Well IMO anyway. Hence why I went 4L80 in my M1031. But I always wonder if the NV4500 would have been better.

 

[sgms18]

I would like to stay manual but I'm not dead set on it. I played with a couple rpm calculators & at 60mph there's only about 80 rpm difference between the .75 4L80 & the .78 SM465/GV. Going by the ratios the 700r4 looks good but that seems like introducing a weak link to me. I'm sure there's transmissions I haven't considered. I've been looking at the numbers on the 465/gv, 4500, tr4050(probably too much $$) 700r4 & 4L80. Any other good options?

 

[chevymike]

I have been happy with my GV unit. I found one on FB Marketplace and by the time I was done, I was in about $1000 less than new. Running it behind the TH400/NP208. Gave me about 10 mph more at the same RPM than without. Best thing is the gear splitting. Had a few hills where splitting between 2nd and 3rd (ie 2.5) works great. Keeps me from high revs from 2nd but not bogged down in 3rd.

 

[sgms18]

I have been happy with my GV unit. I found one on FB Marketplace and by the time I was done, I was in about $1000 less than new. Running it behind the TH400/NP208. Gave me about 10 mph more at the same RPM than without. Best thing is the gear splitting. Had a few hills where splitting between 2nd and 3rd (ie 2.5) works great. Keeps me from high revs from 2nd but not bogged down in 3rd.

How long have you been running your GV unit? Approximate milage?

 

[MarcusOReallyus]

Going by the ratios the 700r4 looks good but that seems like introducing a weak link to me.

The 700r4 will handle a lot more than the 6.2 can throw at it.

 

[chevymike]

How long have you been running your GV unit? Approximate milage?

Sadly not many miles, a few hundred at this point but I do know a few people who have had 10's of thousands of miles on theirs without issues. Biggest thing is changing the fluid every 5000 miles.

 

[sgms18]

The 700r4 will handle a lot more than the 6.2 can throw at it.

Well, maybe so but not for long. It's been my experience that with any hard use they need rebuilt every few years. I drove a 87 1/2 ton 4x4 on 38s for 10yr & had to rebuild the 700 in that truck twice. My current daily driver is a 89 c1500. I've had if for 7yr now & I'm on trans number 3. I know the TBI 350s make about 50hp more than the 6.2 but that dosen't seem like a big difference to me. I like the 700r4 alot they just don't seem to hold up for long.

 

[79Vette]

Advance Adapters manufactures an aluminum case 2 speed transmission (.73 OD and 1:1) that mounts in front of the SM465. I run one in my m1009 and it works well. You can split all gears in 4wd, 2wd, low or high and it is very useful off road to keep the diesel in it's power band. With 3.73 gears and 33s I run 80mph at 2200rpm in overdrive.

They are out of stock currently, but you should give them a call or send an email and let them know you're interested. Ask for Mike Partridge. I've been trying to get another one for my C30 work truck, and they indicated they would do another production run if there was interest.

 

[sgms18]

Hmm....that sounds interesting. I had no idea such a thing existed. I'm definitely going to check that out. Thanks!

 

[Curtisje]

I put 10 or 20 thousand miles on a GVOD. It was on my M1008 when I bought it. I had to manually shift it because it wouldn't down shift appropriately and it would "shudder" awfully bad if I didn't. It now sits on a shelf in my garage and I won't be installing it on anything again but perhaps someone will need it for parts one day.

That being said I could move down the road in SoCal traffic at 75-80 mph no problem. I made many trips from Twentynine Palms to either Camp Pendleton or San Diego.

It was a decent unit other than it had an issue from the previous owner. Also, GV won't sell you parts. They only sell whole unuts.

I wouldn't buy one today. Too many 4 speed (or more) options out there. But thats just my opinion. Good luck.

 

[sgms18]

Also, GV won't sell you parts. They only sell whole unuts.

Well that seems kinda shady. I don't know if I could buy a $3000 anything that the manufacturer won't supply parts/support for. Everything wears out or breaks eventually.

 

[sgms18]

Well, I emailed Advanced Adaptors and this was their response


Unfortunately, we do not have any plans to bring it back, and we do not have any inventory left to make any units.

Thanks
Orren Euler
Technical Sales


That sucks. After reading up on em a little bit the Ranger units seem like the way to go. It's starting to look like my dream of putting an awesome gear splitter on my sm465 is going up in smoke.