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Anybody know anyone who has done a Gear Vendors overdrive unit behind a Turbo 400 into a Quadratrac? These are very interesting units that effectively give you 6 speeds from a t400.
I know they make the driveline a foot longer, and the gas tank on a 79 would need to be modified.
Just curious if it's been done and what the results were?
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet.
I did a lot of looking into the GV. I put one in my 73 Mustang behind a C6 tranny. I love it!
The Jeep is a different story. GV doesn't make a unit that works with our transfer case. Typically with the 4wd option the unit is mounted after the transfer case and will only function in 2wd. The controller has a 4wd lockout mode, this is done electronically. You could probably wire it into the 4wd indicator light.
For about the same amount of money you could swap the transfer case with an Atlas 4 speed. This is the route I took with my Jeep instead of a GV or fitting in a GM or other 4 speed OD tranny. I run 4.54 gears with 37" tires. It drives fine on road and doesn't over rev on the highway.
The transfer case I bought has these ratios: 1:1, 2:1, 2.72:1 and 5.44:1. This gives me the low gearing if I need it on the trail. There are several options for the main case with the secondary gear set always being 2.71:1. Here's the info from their site:
Atlas 4 Speed Ratios
1.0:1 / 2.72:1 / 1.50:1 / 4.08:1
1.0:1 / 2.72:1 / 2.00:1 / 5.44:1
1.0:1 / 2.72:1 / 3.00:1 / 8.16:1
1.0:1 / 2.72:1 / 3.80:1 / 10.34:1
The 1.5:1 ratio was not available when I bought mine. If I was to do it again I would have to give it some consideration. Although I find the 2.0:1 to be perfect for light wheeling and blasting down sandy washes.
I bought mine used and saved a bunch.
Last edited by will e on Sun Sep 23, 2018 3:30 pm, edited 1 time in total.
That's good info will e. I'm looking for a reduction under 1:1 for a final drive ratio. I dont know that the Atlas will give me that?
fulsizjeep ... Yes, very familiar. It's on there with bubble gum, rainbows and unicorn feathers ... right? lol
Last edited by Fast79Chief on Mon Sep 24, 2018 6:07 am, edited 1 time in total.
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet.
That's good info will e. I'm looking for a reduction under 1:1 for a final drive ratio. I dont know that the Atlas will give me that?
fulsizjeep ... Yes, very familiar. It's on there with bubble gum, rainbows and unicorn feathers ... right? lol
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet.
The Atlas won't help in normal driving. You leave it in 1:1. The advantage of the Atlas is I am able to run taller gears without sacrificing crawl speeds. At 65mph I am pushing about 2800 RPM.
But on the trail a typical Jeep transfer case with a 2.61 gear (Np208) would provide a final drive ratio of 29.16 in first gear. This is okay most of the time but when you really have to crawl it's doesn't have enough reduction. With the 4 speed TC my final drive ratio is 60 which great for getting up the harder stuff but way too low for shelf road, washes and normal wheeling.
Have you considered transmission swaps? If you swapped in a 4 speed transmission you will typically get the advantage of a lower 1st gear too. The GM TH700R4, for example, has a first gear of 3.06 compared to the TH400 first gear of 2.48.
grimmjeeper.com has a great web site calculator for comparing options.
Yeah will, I am looking at that too. I did a 700R4 swap in my 1972 K20 pickup years ago and love it. With 33" tall tires and 4.10 gears I'm turning 1800 rpms at 60 mph. NP205 transfer case in there. Bowtie Overdrives built me a nice Level II trans.
I'm just exploring ways to maybe keep the T400 and get overdrive for highway. Maybe there is a solution for the old brute (T400), maybe not.
Thanks.
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet.
It's going to be pretty pricey and difficult (if at all possible) to get OD with the TH400/QT combo. If you were running a different t-case, you'd have a lot more options. You're probably way better off swapping transmissions. The 700R4 is definitely a good option, as is the AW4. The AW4 is going to be a lot easier to bolt in, but needs the electronics piece sorted.
aa
1983 J-10 - 4.6L(MPFI)/CS130D/Hydroboost/NV3550/D300/44/44/3.54/Disc-Disc/32s/42 gallon 'burb tank
Only two transmissions can work with the BW Quadratrac. The TH400 with the OEM adapter and tail shaft is one. You can swap between any TH400 though the clocking on the rear of the transmission is slightly different between AMC cases and non-AMC cases.
The only other alternative is the 700R4. Advance Adapters sells an adapter that lets you bolt together the case and the transmission with the right shaft to drive it. I don't remember off hand if it's a replacement tail shaft or if it slips over the standard 4x4 tail shaft of the 700R4 to extend it.
Anything else would have to be 100% custom to make work.
derf wrote:Oh, and will e, you forgot one combo for the 4 speed Atlas:
1.0:1 / 2.72:1 / 4.30:1 / 11.70:1
I grabbed the info from their site. They still mention the 4.3 and 5.0 for the two speeds but specifically list the 4 options I copy/pasted above for the 4 speed.
derf wrote:Oh, and will e, you forgot one combo for the 4 speed Atlas:
1.0:1 / 2.72:1 / 4.30:1 / 11.70:1
I grabbed the info from their site. They still mention the 4.3 and 5.0 for the two speeds but specifically list the 4 options I copy/pasted above for the 4 speed.
It's possible they have discontinued the 4.3 with the 4 speed but it's what I'm running in my JK.
That's a lot of reduction! And what's the first gear in your JK? Crawl city! Next time you have it up in Ouray I would love to ride in it when in Low Low.
will e wrote:That's a lot of reduction! And what's the first gear in your JK? Crawl city! Next time you have it up in Ouray I would love to ride in it when in Low Low.
4.46:1 first gear. 4.56 axle gears. Total combined low-low-first gear is just a hair shy of 238:1.
will e wrote:That's a lot of reduction! And what's the first gear in your JK? Crawl city! Next time you have it up in Ouray I would love to ride in it when in Low Low.
4.46:1 first gear. 4.56 axle gears. Total combined low-low-first gear is just a hair shy of 238:1.
That's insane! Mine is 60 and I think that is low.
You need to update your calculator to add the 1.5 Atlas option...
Hey derf and will e ... lets get back to the O.P. topic. lol
Ways to get Overdrive from a TH400 and a Quadratrac.
1979 Cherokee Chief S, V8, MSD Pro Billet Distributor with New Factory Ignition Box (are these 2 even supposed to work together?), HEI Wires, Edelbrock 1406, Edelbrock Performer manifold, 3.54 gears, Tru-Trac Locker in the rear, Turbo 400, New Quadratrac, Dual gas tanks, new 32 x 11.50's, Big 9000 winch, Homemade 2.5" full length exhaust, Custom Headlight Harness, Custom front bumper working, Custom Rear Swing-out Bumper, Class V receiver hitch ... and a lot of work to do yet.
Fast79Chief wrote:Hey derf and will e ... lets get back to the O.P. topic. lol
Ways to get Overdrive from a TH400 and a Quadratrac.
There used to be an OD kit for the QT by MileMarker, don't know if that's still available or not. That's pretty much going to be your only real option while keeping the TH400 and QT.
aa
1983 J-10 - 4.6L(MPFI)/CS130D/Hydroboost/NV3550/D300/44/44/3.54/Disc-Disc/32s/42 gallon 'burb tank