Info on 2 Speed Rear for C30 ??

[CCCC]

If you can answer any of these inquiries, it would be very helpful.

In 1971-72 (or before?) did Chev or GM supply a 2 speed rear in the C 30? If so, who made it and how was the shifting activated (solenoid, vacuum, strictly mechanical, etc)?

If the 2 speed rear was not a factory item, was another manufacturer (Eaton, Rockwell, Spicer, etc) making them for after-delivery installation in the C 30? If so, how was the shifting activated?

Replies to the above and any other info on this topic would be appreciated.
Thanks, CCCC

[special-K]

As ar as I know GM never did this in 1t trucks.I know that Internationals from the same era until the end sometimes had them.I always assumed everything had Dana70s back then,but it may have been Spicer,Eaton,Clark,Rockwell.I never found out anything about them.

[Elephanthead]

Well what is the easiest way to either add overdrive or a 2 speed rear to a manual transmission C30, 50mph is not safe anymore on the highway.

[special-K]

The 2spd rearsgive a reduction and normal 1:1 final drive.

[watahyahknow]

it isn't a two speed rearaxle but it does the same thing : http://www.usgear.com/v2od.htm

[haysonj]

The best way is to add a Gear Vendors OD if you can afford it http://www.drivetrain.com/overdrive.html

[Tx Firefighter]

Originally Posted by special-K

The 2spd rearsgive a reduction and normal 1:1 final drive.

Yep, a 2 speed rear gives you what you have now and even lower, not higher. It's a common misconception.

[Helidoc]

Years ago my family had a C30 not sure of the year but had the 327 4sp with a "Brownie" 2speed. I think there called Brown-lipe aux gearbox. Hope this will jog a memory or 2 of the "brownie". Our 2 speed was a red push-pull knob on the stick may have been vac. operated.

[Bus Ted Knuckle]

No two speed rear in a 1 ton, and like the other guys said, the other speed is not an overdrive! I have a eaton vacuum shift two speed in my wrecker, high is slow and low is slower. BUT it will climb a tree.

[CCCC]

Thanks to all for the comments and info so far. Because the C30 splits to a lower ratio the fellow may just think it is a two speed rear but has not looked closely enough to see what is going on. It very well may be an Eaton or Brown-Lipe unit behind the transmission. But, still waiting for someone to tell me that Chev/GM did put a 2 speed rear in some.

I have a Brown-Lipe here that soon will go into a C30 and I beleive that, depending on which way it is installed (which end forward) it will either raise or lower the final ratio That unit has a pull-push cable for shifting. Does anyone have experience with thes Brown-Lipe unit and will it perform as stated above, depending on end-for-end installation?
Thanks again.

[Bus Ted Knuckle]

Originally Posted by CCCC

Does anyone have experience with thes Brown-Lipe unit and will it perform as stated above, depending on end-for-end installation?
Thanks again.

Keep the cable lubed or it will freeze up!!!!

They are great units, you should get good service from it.

[Elephanthead]

For the price of that overdrive I would just buy a new truck, or new tranny. It defiantly would work though. I need bigger tires.

[Longhorn Man]

you should be able to do 50... you should be able to do 100.
No stock GM installed overdrive or splitter or 2 speed rear.

[chevy29267truck]

i do know the trucks in the 50s and befor that had 2 speed rearends

[special-K]

Just Medium Duty GM trucks had 2-spd rears.10 thru 30 = light duty.

The auxilary gears are a much better way to go than an o/d tranmission,IMO.The term "Brownie gears" was dubbed when guys started installing a second transmission behind the other to gain multiple ratios with o/d and underdrive.A manual transmission with an auxilary o/d is the best way to get o/d for toughness and reliability.
*Overdrive transmissions are way less durable than non-overdrives.
*Overdrive transmissions cost more.Non-o/d are cheap to replace,if the need arrises.
*Towing kills o/d transmissions
*Auxilary gear boxes are virtually bulletproof
*You can split gears with an auxilary box

Auxilary gear boxes can be installed later and removed when vehicle is sold.I`m building a little shortbed with an M22 4spd and 3.42 rear.I figure this is as tall as I`d like,to maintain some grunt while still rolling down the hiway pretty well.If and when money allows I will be installing a Gear Vendors unit.I will have two solid gear boxes.With o/d the 3.42s will only get better on the hiway and that`s as tall as I`d want.If I never get the o/d I will still have a more modern ratio.I wouldn`t have this flexibility if I went with an o/d trans.I`d have to build for o/d and be committed or use 3.08 with no o/d and lose my bottom end.

[haysonj]

Originally Posted by Elephanthead

For the price of that overdrive I would just buy a new truck, or new tranny. It defiantly would work though. I need bigger tires.

I have 4.09 gears with 35 inch tires behind a GV OD. this truck will tow my boat up hills at 55 all day plus it cruises at around 1900 rpm. Disconnect the boat and it will snap your neck between every gear. set it on auto and it shifts like a six speed. Like I said earlier if you can afford it IMO there isn't a better setup. Its way stronger than a OD trans.

[4x4longbed]

As mentioned a Gear vendors Overdrive is probably the best way to go, however....I worked for Eaton Corporation for 15 years and several C-30 trucks were fitted with Eaton 2 speed rears, which are electric shifting by the way. The Allentown Region for the truck division did the conversions, the Region Service Manager at that time behind these was a man named Tom Hoy, I know he is retired, I can probably track him down. What I remember is Tom used a Eaton 2 speed center then "re-tubed" it with the correct tubes and wheel end equipment. Now here is what most missed there were a varity of ratio's available one low and one high, I do not remember all of the combinations but the are listed somewere I am sure. It would be a neat conversion, if you want somwthing different. In the late 80's he was getting 25 plus mpg from a dually.

Good luck!

[Longhorn Man]

you are talking conversion, and not assembly line work... there is no RPO (regular production option) for a 2 speed rear in the light duty trucks 67 - 72.

[4x4longbed]

Yes, Exactly I am talking conversion. In his original question he asked about conversions. If I did not make that clear, I apologize.

[special-K]

I`d like any info possible on these.It`s like hunting Snipes or the Doh-doh Bird.I`ve heard of them but never see them.I am sure about one in a 1t IH wrecker around 1978 I checked out.

[4x4longbed]

He is what I have learned so far.......this is from the retired head of Eaton field Service...he is getting me more information..... I will post as soon as I recieve......It is interesting to know the truck still exists around Allentown Pa

You recall correctly. We used a cast 15 series housing center section out of Eaton Argentina. They made an axle that looked like a large Dana 70 series that had pressed in axle tubes and a cast center section. We used Dana 70 series housing tubes that were bushed to fit the Eaton cast center section. The axle shafts were Dana 70s that mated to Eaton 15 series side gears that we had splined by Detroit Automotive.[Ie] Dana 70 series splines in Eaton 15201 side gears. We used a std 15201 head assembly with a 4.56 gear set and an OD Clark transmission. The truck still exists in the Allentown area as we sold it to one of Tom’s race car buddies. I have a set of side gears with the Dana splines that you can have. We would need to get O’Boyle to use his clout to get a housing center from Argentine. I will send you Tom Hoys e-mail. Roger

[special-K]

That is great!Thanks alot.That`s so cool to learn stuf like this.

[4x4longbed]

Thanks...most would be suprised to learn the "special projects" that went on at the OEM's and OES (original equipment suppliers). The biggest thing to remember is the were truck guys with resources!

As I get more information I will continue to post here.

[special-K]

Yeah,they had the ability to think it and make it.Back then they really began expanding what light trucks could be used for.I`m sure there were many a pipe dream experimented with.