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Gear Vendors

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Rambler Mexicano View Drop Down
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    Posted: Sep/11/2018 at 3:54pm
I have a 1981 VAM Rally GT (Spirit GT) with a Hurst-linked TREMEC 176-F four-speed manual transmission with a 1.00:1 fourth gear ratio plus a SPICER model 44 rear axle with a 3.31:1 rear gear ratio (DANA 44 if I'm not wrong, please correct me).

This is the factory specification for the Mexican-made car.

In the United States as far as I know the only AMC models to incorporate the TREMEC 176-F model transmission were the Jeep CJ-7 and the Scrambler (probably the Jeep CJ-5 too) except that these models did not have Hurst linkage.

Last time I took my car to the highway I got a 6.5 kilometers per liter mileage (around 15.3 miles per gallon) at an average speed of 90 kilomters an hour (56 miles per hour) at 2,200-2,500 revolutions per minute.

My engine is not economical, it's performance oriented. It's currently a 140 net HP 282 six cylinder with headers, dual exhausts, flat pistons, Holley 2300 with number 54 jets and number 85 power valve, 2.02 inch intake valve, 1.68 exhaust valve diameter, Chevrolet AC Delco High Energy Ignition (HEI) electronic distributor and an AC Delco 70 amp alternator.

In the following months I will be changing the stock VAM 266 degree camshaft in favor of VAM's performance 302 degree camshaft, which requires that I change the carburtor jets from number 54 to 60. Finally, I already had my engine head ported and reduced in height for higher compression.

This will drop the fuel economy even further.

I am seriouly considering to add an aftermarket Gear Vendors external overdrive unit.

The problem is what Overdrive MODEL can I use with my specifications (TREMEC 176-F transmission, 1.00:1 foruth gear and model 44 axle with 3.31:1 rear gears. Which is the best for my case?

The Gear Vendors site sucks and dosn't help in terms of determining an actual overdrive model that could help me based on my car's specs. There's not there for AMC, just brand-X.

My goal is to be able to drive my car with a better mileage on highway AND at higher speeds with lower RPMs. I am talking about doing about 120 kilometers per hour (75 miles an hour) at around 2,500 RPMs instead of my present 90.

VAM cars had a lower rear gear ratio used as standard issue depending on the model, a 3.07:1 one. I already have experience with such gears and it doesn't improve much to what I'm looking for in terms of speed plus RPM range plus improved gas mileage.

VAM cars with the 3.07:1 gears and stock regular production 282 sixes (129-132 net hp) get an average mileage of between 8 and 9 kilometers per liter (18.8 and 21.2 miles per gallon). The best highway mileage I've ever heard of a stock 282 VAM car with 3.07:1 gears is a 1981 VAM American ECD (Concord DL four-door sedan) is 10.5 kilometers per liter (24.7 miles per gallon).

A friend of mine with a 1973 Rambler American Rally (Hornet X) with a stock 282 six and 3.31:1 rear gears got the original 150-T Hurst-linked three-speed manual transmission changed in favor of a Ford Mustang/Thunderbird four-speed manual with a built-in overdrive fourth gear and the highway milage he got after that went from 8 kilometers per liter to 12 km/L (28.2 MPG).

This is probably what I would expect to achieve with my car. Sure my engine is not stock but my body is a lot lighter and the exhausts are shorter.

For these reasons changing the rear gear setup is out of the question, and also since I don't want to lose stand-still acceleration and torque going uphill. And also probably towing capacity in the future.

If 3.07:1 is not enough for my speed/mileage goals I am calculating that a ratio of between 2.77:1 and 2.69:1 would do it. This would mean around a 0.8:1 overdrive gear ratio.

People have told me to remove the original transmission in favor a Mustang T5 or Jeep AX5/AX-15 unit.

This is something else I am not doing in my car. I would loose the original Muscle Car-like Hurst linkage, I would have to open another hole in the transmission tunnel to accomodate the different shifter position, I would have to push back the transmission crossmember among other adaptations.

Between the price of the transmission plus all of the modifications to accomodate it will probably cost the same as a second hand overdrive in good shape. The over drive means a minor modification compared the whole original transmission. In both cases I would have to cut shorter and rebalance the driveshaft. I am keeping my car more original and reversible in terms of modifications this way.

What do you think? PROs and CONs.

Thanks in advance for any advice you can provide.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Sep/11/2018 at 4:17pm
Well last time I checked a Gear Vendors was quite a bit more money then the WC T5 install.
The tunnel hole change is not off by much for a T5, and the Hurst shifter vs a T5, personal choice I guess.
For the Gear Vendors unit you are likely going to have to widen the tunnel a little on the Spirit, maybe someone else can advise on this. I believe the Spirit tunnel is even narrower then a 68-70 AMX and those just barely fit a GV unit.
If you build for performance, changing cruising RPM by 300 to 400 is not going to gain a lot of MPG.
If you build for cruising, then you start getting MPG.
Don't think you can have both, and my personal driving view - 5 speed is much more fun then the 4 speed was.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/11/2018 at 4:39pm
The GV unit is around 0.70 OD. If you were talking about a longer wheelbase car a divorced unit would work. It keeps the output shaft of the stock trans and just has a coupling on the end. The driveshaft has to be shortened and a support made for the OD unit though. You would have to e-mail or call GV. The unit is over $1500 USD though. You'd be better off to change to a five speed manual trans.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote scott Quote  Post ReplyReply Direct Link To This Post Posted: Sep/11/2018 at 5:08pm
Go with the T5, you'll love it. I put a T5 in my 70 Rebel, it is the best modification I have ever made to a car. They make Hurst shifters for the T5, so you can still have a Hurst shifter.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 12:22pm
I will contact GV via email later this day. As for the 1500 dollar price tag, I really just plan to buy a second hand / preowned unit. The price is a lot more accessible via ebay, although I might have to put on some cash to fix it if it doesn't work.

I do plan on buying a T5 five speed, but that would be for any three-speed VAM car I might have in the future, such as the 1969-1974 Rally models, the 1976-1980 Gremlin Xs (79-80 Spirit sedan) and 1977-1983 American two door sedans (Hornets and Concords two-doors). I didn't know there were Hursts for the T5, that's good news for me.

At least this four-speed car, I plan the keep the original four unless there is no other way.

Thanks everyone for your responses.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 12:31pm
Originally posted by Rambler Mexicano Rambler Mexicano wrote:

I will contact GV via email later this day. As for the 1500 dollar price tag, I really just plan to buy a second hand / preowned unit. The price is a lot more accessible via ebay, although I might have to put on some cash to fix it if it doesn't work.

I do plan on buying a T5 five speed, but that would be for any three-speed VAM car I might have in the future, such as the 1969-1974 Rally models, the 1976-1980 Gremlin Xs (79-80 Spirit sedan) and 1977-1983 American two door sedans (Hornets and Concords two-doors). I didn't know there were Hursts for the T5, that's good news for me.

At least this four-speed car, I plan the keep the original four unless there is no other way.

Thanks everyone for your responses.


You can find many 4x4, dually or extended club cab or big towing trucks with gear vendor units. So I would imagine finding a wrecked truck with a big V8 or Diesel, will have one.

Just need to order an adapter kit for the unit. At one time getting an adapter was a mater of parts ordering.

If you do find one, make sure you get the complete wiring harness and computer control, if it has one... They are optional upgrades on older units.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 2:57pm
You know there were some overdrive versions of the Ford 4speed Toploaders, right?

They reversed 3rd and 4th gear with the linkage, and installed an overdrive gear in place of 3rd.

4th remained 1:1,
so the shifter would shift 1-2-4-OD3.

Most Ford guys don't like the OD Toploaders (so they're cheap)
and I believe you can tell the difference due to the extra bump out in the case for the taller 3rd gear.

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was Green/green now T/A red w/blk leather

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 2:59pm

I don't know if these are the same style as your Tremec, or if you could make the Hurst linkage work (maybe have to flip over one lever),
but if it works this mught be the cheapest solution:

https://www.jalopyjournal.com/forum/threads/toploader-imposters.284415/




Gear Ratios

Truck
1st Gear3.25:1
2nd Gear1.92:1
3rd Gear1.00:1
4th Gear0.78:1
Reverse3.25:1
Car
1st Gear3.29:1
2nd Gear1.84:1
3rd Gear1.00:1
4th Gear0.81:1
Reverse3.25:1


Edited by jpnjim - Sep/12/2018 at 3:05pm
71 Javelin AMX P-code Go pac 360/4spd/3.91's
was Green/green now T/A red w/blk leather

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Rambler Mexicano View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2018 at 1:19am
Gear Vendor's reply:

Unfortunately we do not have a kit that fits this transmission .

Thanks
Michael@Gear Vendors
1-800-999-9555 ex 123

Unfortunately, I won't be able to get an external overdrive unit for my car from GV unless I fully make an adaptation.

After this I talked to my regular mechanic about this and we are considering using any used external overdrive unit we can find that is in good shape and working. Since he's pretty good with performance and other modifications, he will be able to do it as soon as we find a unit and check on the prices. We will be using a different driveshaft for this, my original will be removed and kept intact because this will be a reversible modification in case of any circumstance.

The unit will most probably come from a bus or semi truck.


Originally posted by jpnjim jpnjim wrote:


I don't know if these are the same style as your Tremec, or if you could make the Hurst linkage work (maybe have to flip over one lever),
but if it works this mught be the cheapest solution:

https://www.jalopyjournal.com/forum/threads/toploader-imposters.284415/




Gear Ratios

Truck
1st Gear3.25:1
2nd Gear1.92:1
3rd Gear1.00:1
4th Gear0.78:1
Reverse3.25:1
Car
1st Gear3.29:1
2nd Gear1.84:1
3rd Gear1.00:1
4th Gear0.81:1
Reverse3.25:1


Actually, none of those two sets of ratios coincide with the ones in my TREMEC 176-F. The ones in my car are:

3.52:1 First
2.27:1 Second
1.46:1 Third
1.00:1 Fourth
3.52:1 Reverse

Thanks for the links, I had heard about those transmissions before, but I really have no clue if they were used in Mexico and in which vehicles. I have asked to the people I know that are into cars and so far the search has come up empty. I could by one from the US, the problem would be the delivery plus the price of it.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/14/2018 at 12:17pm
Another problem you will have with an external overdrive (called a "divorced" OD) will be the length of the driveshaft after the OD unit is installed. You have a short wheelbase. Taking another 18" or so out of the driveshaft will leave you with a very short driveshaft. You would be far better off to find a five speed manual transmission for the car. T5s from late 80s Mustangs with 5.0L will fit.

Gear Vendors shows a pic of a divorced unit on this page, so they must still make one.
It's in the upper right. Ask about that, including length.
Frank Swygert
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