Attention: TDR Forum Junkies I recently had a Gear Vendor Overdrive unit and PacBrake XBR installed on my 2005 G56 6sp 4wd dually by Camping World in Wilsonville, Oregon. I bought the GV unit mainly to lower the RPM's when driving faster than 60mph. My buddy with an 04. 5 dually 4wd NV5600 had one installed and loves it.
My experience so far is one of disappointment.
1. The gear ratio of the GV unit is such that it doesn't work well unless I'm going 70mph, which I can't do legally anywhere in Oregon. At 65mph the tach is reading just above 1,500 rpm but the truck feels like its lugging even when empty. At 70mph and above the GV unit works very well.
2. The gear ratio of the GV and the closeness of the G56 gears also doesn't give the 1/2 speed ability that other transmission's would benefit from. 2nd overdrive is nearly identical to 3rd gear, 3rd overdrive is nearly identical to 4th gear and so on... ... Strangely 5th overdrive is a bit higher than 6th gear... ... I didn't buy the GV unit to give me the additional 1/2 speeds in the lower gears so this is only mildly disappointing..... However if you are a G56 owner considering the GV unit for added 1/2 gears while towing you will be very disappointed.
3. There is a just a hint of a shudder when starting out either in 1st or 2nd... ... More pronounced when towing... ... They have to shorten the drive shafts when they install the GV unit and I think this is what causes the shudder... ... Not a huge issue (yet) and my buddy with the 04. 5 did tell me about this prior to me purchasing mine.
4. The dash switch / overdrive indicator lamp rattles which is a nuisance only... ... I had them mount the dash switch in the small compartment behind the gear shift on the lower center dash which is a great place to install it.
5. I do have a serious problem which is a binding that occurs after starting the truck and then backing up... ... Less frequently the binding occurs going forward also after start up... ... I've had the truck back to Camping World twice now (1. 5 hours each way) to solve the problem... ... They haven't fixed it yet but have isolated it to the 4wd lock out safety feature that the GV controller has..... The GV unit is installed after the transfer case... ... So you cannot have the GV unit in overdrive and go into 4wd or try to go into overdrive if you are also in 4wd... ... Not that anyone would need to... ... The safety lockout in the GV controller will deactivate the overdrive unit if the transfer case is put into 4wd... ... My truck has the electronic shift transfer case which apparently goes through a diagnostic test upon start up... ... The GV controller is also going through a diagnostic test upon start up which lasts for 7 seconds..... If I wait 7 seconds before I drive no problem... ... . If I get in start up and go before the 7 seconds the binding will occur... ... Now you might say just to wait the 7 seconds... ... Hey we wait for the glow plug light to go out on the dash before we crank the engine, what's another 7 seconds to wait before you drive... ... If I were the only one to ever drive the truck I might accept that... ... However if anyone else drives the truck and takes off before the 7 seconds is up, I can imagine that they might just give it a bit more throttle instead of stopping like I do when the binding occurs... ... That would mean a very expensive fix to the drive train for sure..... I've spoke to Gear Vendor and they think it is an install issue... ... I'm going to be taking the truck back next week to Camping World and hopefully this will be fixed.
6. There is a small price to pay in fuel consumption when driving any gear..... The GV unit even in direct drive is still turning gears which eats up fuel.
7. You have to think about what you're doing when you use the GV unit..... You begin to feel more like an engineer on an old locomotive when using it... ... Proper engagement of the overdrive requires a half depress on the clutch while flipping the toggle switch on the gear shift... ... Proper disengagement is to put the transmission in neutral and fully depress the clutch to take stress out of the drive train... ... I'm told other people just flip the switch in and out of overdrive without depressing the clutch... ... I personally don't like wear and tear problems so I don't subscribe to the latter.
The GV unit shifts smoothly into overdrive, but it shifts with a very pronounced thump (which you hear and feel) when going out of overdrive.
If I had it to do over again I wouldn't buy it..... The cost was $3,500 installed and I can't benefit from it most of the time.
If I drove 70mph or more most of the time I would consider it.
Other posts I've read state that GV is best for automatics and that the US Gear over/under is best for manual transmissions.
The G56 6sp and 3:73 rear end are a good combination for most of my driving..... I drive about 50% city and 50% highway... ... The gears seem to be well suited to the power band of the Cummins with the exception of needing a 7th gear for driving over 60mph... ... I tow large boats and small trailers mostly and I like the low gear for starting off..... 99% of the time I start in first out of habit, but I really don't mind having to shift..... I've read from some that they don't like the close ratio between 1st and 2nd gear, but I do like it... ... Less wear and tear on the machinery in my opinion.
Hopefully this will help someone else make a better buying decision than I made... ... . There are many that love the GV unit and swear by them including my buddy that has the 04. 5 NV5600 6sp.
The PacBrake XBR is great..... Not a bit of a problem with it.
I'll post again next week after my visit to Camping World.
My experience so far is one of disappointment.
1. The gear ratio of the GV unit is such that it doesn't work well unless I'm going 70mph, which I can't do legally anywhere in Oregon. At 65mph the tach is reading just above 1,500 rpm but the truck feels like its lugging even when empty. At 70mph and above the GV unit works very well.
2. The gear ratio of the GV and the closeness of the G56 gears also doesn't give the 1/2 speed ability that other transmission's would benefit from. 2nd overdrive is nearly identical to 3rd gear, 3rd overdrive is nearly identical to 4th gear and so on... ... Strangely 5th overdrive is a bit higher than 6th gear... ... I didn't buy the GV unit to give me the additional 1/2 speeds in the lower gears so this is only mildly disappointing..... However if you are a G56 owner considering the GV unit for added 1/2 gears while towing you will be very disappointed.
3. There is a just a hint of a shudder when starting out either in 1st or 2nd... ... More pronounced when towing... ... They have to shorten the drive shafts when they install the GV unit and I think this is what causes the shudder... ... Not a huge issue (yet) and my buddy with the 04. 5 did tell me about this prior to me purchasing mine.
4. The dash switch / overdrive indicator lamp rattles which is a nuisance only... ... I had them mount the dash switch in the small compartment behind the gear shift on the lower center dash which is a great place to install it.
5. I do have a serious problem which is a binding that occurs after starting the truck and then backing up... ... Less frequently the binding occurs going forward also after start up... ... I've had the truck back to Camping World twice now (1. 5 hours each way) to solve the problem... ... They haven't fixed it yet but have isolated it to the 4wd lock out safety feature that the GV controller has..... The GV unit is installed after the transfer case... ... So you cannot have the GV unit in overdrive and go into 4wd or try to go into overdrive if you are also in 4wd... ... Not that anyone would need to... ... The safety lockout in the GV controller will deactivate the overdrive unit if the transfer case is put into 4wd... ... My truck has the electronic shift transfer case which apparently goes through a diagnostic test upon start up... ... The GV controller is also going through a diagnostic test upon start up which lasts for 7 seconds..... If I wait 7 seconds before I drive no problem... ... . If I get in start up and go before the 7 seconds the binding will occur... ... Now you might say just to wait the 7 seconds... ... Hey we wait for the glow plug light to go out on the dash before we crank the engine, what's another 7 seconds to wait before you drive... ... If I were the only one to ever drive the truck I might accept that... ... However if anyone else drives the truck and takes off before the 7 seconds is up, I can imagine that they might just give it a bit more throttle instead of stopping like I do when the binding occurs... ... That would mean a very expensive fix to the drive train for sure..... I've spoke to Gear Vendor and they think it is an install issue... ... I'm going to be taking the truck back next week to Camping World and hopefully this will be fixed.
6. There is a small price to pay in fuel consumption when driving any gear..... The GV unit even in direct drive is still turning gears which eats up fuel.
7. You have to think about what you're doing when you use the GV unit..... You begin to feel more like an engineer on an old locomotive when using it... ... Proper engagement of the overdrive requires a half depress on the clutch while flipping the toggle switch on the gear shift... ... Proper disengagement is to put the transmission in neutral and fully depress the clutch to take stress out of the drive train... ... I'm told other people just flip the switch in and out of overdrive without depressing the clutch... ... I personally don't like wear and tear problems so I don't subscribe to the latter.
The GV unit shifts smoothly into overdrive, but it shifts with a very pronounced thump (which you hear and feel) when going out of overdrive.
If I had it to do over again I wouldn't buy it..... The cost was $3,500 installed and I can't benefit from it most of the time.
If I drove 70mph or more most of the time I would consider it.
Other posts I've read state that GV is best for automatics and that the US Gear over/under is best for manual transmissions.
The G56 6sp and 3:73 rear end are a good combination for most of my driving..... I drive about 50% city and 50% highway... ... The gears seem to be well suited to the power band of the Cummins with the exception of needing a 7th gear for driving over 60mph... ... I tow large boats and small trailers mostly and I like the low gear for starting off..... 99% of the time I start in first out of habit, but I really don't mind having to shift..... I've read from some that they don't like the close ratio between 1st and 2nd gear, but I do like it... ... Less wear and tear on the machinery in my opinion.
Hopefully this will help someone else make a better buying decision than I made... ... . There are many that love the GV unit and swear by them including my buddy that has the 04. 5 NV5600 6sp.
The PacBrake XBR is great..... Not a bit of a problem with it.
I'll post again next week after my visit to Camping World.
