Ahh man everytime this topic pops up I get super excited then I remember, oh yeah I have the oddball X frame in my 69 Riv and I don't have the room for the extra 14" GV unit
GV is the only way to go if you want overdrive, if there is a downside, it would be the lack of a lock up converter, other than that they are fantastic and as close to bullet proof as you can get. I would venture to say the turbo 400 would break before the GV. Running 3.42 rear gears and 295/50-15s @ 70 MPH it's turning about 2100. Bob H.
Great to see this discussion. The unit just came in the other day, this things looks nice, good instructions. Hope to put it in in a few weeks, I am going to have the guy who did the engine rebuild install it with a new steel shaft. If what I have been reading here, I cant wait. This car is going to come alive and be an all round pleasure to drive, and still be able to boil the tires off at will. Thank you all for the information. I found the pricing to be reasonable when comparing what the cost of a used tranny with rebuild would be ( never was an option to change out the T-400, I wanted this to remain stock). Now if I could just get the interior and top, this will be done.
I get excited about the GV too when I read about it. My gears and tires are exactly like yours and I'd love to be turning 2100 at 70 MPH.
That is the goal, to have the same car , as built, and just the right modern touch. This should make for one enjoyable ride.
I keep looking at Gear Venders too. You know they are tough when they survive Drag Week in cars year after year.
The one I put in a 90 ss pickup behind a 600+ hp 509 bbc has been flawless for a decade minus it has a minor fluid drip
Gear Vendor unit installed, They did do a slight mod to the floor. It will never be noticeable after the carpet and bench seat are installed. All I can say is wow. Hard to believe that I still have the 3.64 gear in the back. Car cruises nice on the hiway at 75mph. I will say, pricey, but worth it to keep the car stock.
4L80e and be done. The Th400 / GV combo versus 4L80e debate is always comical. For the riv, just use a mid-model 4L80e. A little know how and it can be done at a reasonable price.
What would folk's opinion be on being at 3010 RPM @ 70 without OD - still worth getting the GV unit? I have 3.73s but run a taller tire.
Only you can answer that question. The GV will drop your RPM approximately 600 RPM. I run a 28" tire with 3.73 gears. Without the GV, I am at 3000 RPM at 60 MPH, not 70 MPH. With the GV on, RPM at 60 MPH is 22-2300 RPM. 70 is closer to 2600 RPM. You say you are running a taller tire, how tall?
I agree. Back in 2006, the 4L80E wasn't an option for me. If I was doing it today, I'd go right for the 80E. The GV does the job for me now. The 6L80E would be an awesome swap. Probably too big though. Anybody ever attempt that? Gears are 4.02/2.36/1.53/1.15/.85/.67
29.9" - 315/60-15 • 3.73 • TH400 Your car with GV is 2600 @ 70, mine with just the TH400 would be 3013 @ 70. That's not much of a bump, but I'm fearing I'm just so used to OD that I would find it annoying. Other than cutting the bell for an Ultrabell, I have not had either the trans built nor a driveshaft made yet, so now's the point to 'change lanes' in the trans tunnel if I were to.
That doesn’t make sense to me. I have 3.73 with a taller tire, same as you. 2900 is 60 MPH. Are you sure of your tach, or do you have a loose converter? 336/28 X 3.73 X 70 = 3133 without converter slip. You should be turning around 3300 at 70 MPH with 3.73s unless your tires are 30".
You said on page 1 you had a 28" tire. I have a 30" tire. Car not built yet, so using an online RPM calculator. 3.73 • 30" • 1:1 @ 70 MPH came up as 3013 RPM. Using your formula above with a 30" tire, I got 2924 RPM @ 70, not 3300. Taller tire = less RPM at a given speed, right?
OK, 30" tire. Yes, 2924 RPM. Those formulas don't account for converter slip. That's an additional 150-200 RPM. So say~ 3100. So back to your question, is that too high for you?
When I can get back into my Sierra 10-spd (recovering from knee replacement), I'll take it up to 70, put it in 'manual mode', and downshift it to see what it feels/sounds like near 3K (if it'll let me). Larry - when you take your '70 out, are you commonly cruising at 70 / on the highway, or moreso on varied smaller roads/varied speeds? I don't even know if I would take my car on the highway much...
