Has anyone ever tried one of Gearvendors Underdrive units? If so what did you think.


CC

 

Just completed my install, and it works great! Because my '74 high-boy doesn't have an indicator light for the 4x4 being engaged, I wasn't able to cook up a safety disconnect even with GV's help. (GV goes behind transfer case, so you can't use OD in 4x4). But other than that, it was a fairly straight-forward bolt-in, in spite of a pretty sketchy installation manual.
It is a little "clangy" when it down-shifts, because it has to bring the separate x-fer case, center driveshaft, and tranny all up to speed, so that was a little alarming at first. But I'm already getting better at synchronizing everything so it's not nearly as prevalent. The best part is how quiet the cab seems running down the road, as the 4.10's really had the engine singing before at highway speed. Now the wife and I can even talk to each other, and now I can hear her squealing when I drive in my usual "spirited" style. Hmmm, wonder if that's going to create another problem?!? :-)
One suggestion: unless you have an "in" with somewhere to get a better price, join "Camping World President's Club" for $19.95 and you get 10% off on the GV unit, no small potatoes!
One big surprise came when I went to GM(ugh) to get the recommended synthetic lube for the overdrive, and found it sells for nearly $21 a quart! I griped to GV about that, and they said it was a Castrol product re-badged by GM, and they are trying to do something about getting a better source for it. I then contacted RedLine Oils and they indicate to use their MT-90, for less than half GM's price. The reason this got my attention is that GV recommends changing the oil every 10,000 miles or yearly, and the idea of going in to get raped by GM every year sticks in my craw big time!
Along this line, I just got my NP435 overhauled, and was unhappy with the synchros and shifting using the spec'd 50 wt motor oil. So replaced that with 90 wt gear oil, still not too great. I then replaced that with the RedLine MT-90, and what a difference! It is anything but cheap, but now it never grinds, shifts easy, and quieted the tranny. I wasn't expecting much in spite of all the propaganda on RedLines web-site, but for once found something that really does what it says it will!
Steve

 

I have had my GV in my '69 F250 for about a year now. I dito everything Steve said. My downshifts hard also, and it is behind a C6 auto. I have found that it shifts much smoother under a little throttle. That might not be possible with a manual tranny since GV recomends you press-in the clutch.

I looked into Mopar's GM equivalent of the oil and found it actually cost more than the GM. My GV took a little more than a quart, so there goes a $50 bill every 10,000 miles.

I gained about 1 MPG with it and my 410FE; however, I drive about 10 MPH faster now on the freeway as I no longer feel like I am over-revin' the engine. I suppose if I try to keep her back to 60 again, I may find an additional MPG.

The control box went out on me last week. I switched the togle over to "auto" one day and it never shifted after reaching 40 MPH. So then I switched it back to "manual" mode and it still never engaged. About then I started smelling a burnt-electrical odor. [Don't you hate it when you never know if it is you or the car in front of you?] The fuse was fine, so I wired the on/off switch directly to the GV, and now it works again. I guess I will find out about their return policy when I send back the defective control box.

Steve, please keep me updated on your research for alternative/less expensive oils as the 10,000 mile mark is just around the corner. Maybe we can split a case.

 

Kris(Like M.),
Just got back from my first road-trip with new 410 (actually 419) and GV Overdrive, and must say I'm still mightily impressed. I seem to have picked up 2-3 mpg, and with the new engine I still pull every grade in OD without ever slowing down! Like you, I find I tend to drive even faster now because it's so much quieter, so that probably isn't helping the mileage. I'm just sorry I didn't do this years ago, even tho the increased mileage will never remotely come close to defraying the GV cost.
I already bought a case of the RedLine MT-90 for a slight discount, and, as well as it worked in my tranny and transfer case, figure it's got to be the ticket for GV too!?! GV says you can still use a dino oil anyway, if you want to put up with even stiffer shifts, so I have no qualms about the synthetic MT-90.
Steve

 

I just got back from Mo-ark-ok-tx pulling a 14000lb 5th wheel with a F-550,auto. the gearvendor worked fine. I couldn't pull the mountains in overdrive but it keep me in the power range at all time.Jerry