Gear Vendors Overdrive

[NevadaGeo]

Originally Posted by jdalrymple

HA. We are having trouble deciding which to take.

I do believe my playa tuxedo would be particularly svelte attire exiting the 350 LE. With stainless martini stemware, of course.

The purchase was not really my idea. I blame Cindy. She says it spoke to her.

But, on the other hand, it seems that everyone has more than one Airstream anymore.


The American Aluminum Dream, right?


Regards,

JD

We'll have to have Zep draw in a MotorHome subdivision in our camp plan this year. Ron has had that solenoid problem, some interesting stories there for him and Bam to tell. Yes, you two do make the epitome of fine elegance on playa for Burn night.

[Lance M]

Originally Posted by Colin H

You wouldn't have to pay the core charge if you supply the core though right? Your costs may be lower than a new tranny, which may only require gaskets etc. One of my former employees was a certified mechanic who grew up in his fathers transmission shop. He told me that heat was the big enemy of automatic transmissions, so if you have a great remote oil cooler & the fluid has not turned black, you may be in good shape with some minor seals & gaskets.

Several years ago I did the numbers for my Suburban set up & figured that with its current gearing, the engine was running at about 2600 rpm at 65 mph & would reduce to around 1800 if I installed the Gear Vendors & 3.73 gears. That's right in the sweet spot for the 6.2 diesel with the Banks Turbo. I'm really curious now to install it all...............when I "have time" My 59 Ambassador is lighter than yours & it punches a smaller hole in the wind, so I'm hoping that it'll work out well.
If you do decide to go with a "new" 700-R4, you might want to look into some of those specialty transmission shops that advertise in the numerous Street Rod mags. They've likely figured out all of the "tweaks" to make it right.
Colin

JD I hope you don't mind a little "extra" information-

I went to the local hot rod transmission shop to inquire about a new 700-R4. Something similar to this. I was told they could build a 700-R4 for towing with all the wide bands, etc and install it for around $1,800. That is IF you have a 700-R4 already. It will cost an additional $500-$750 for a custom driveshaft, move crossmember, mount TV cable and an updated flywheel. So about $2,500 or so. That is all parts and labor. I thought that sounds a little bit too much for me for right now.
I called Gear Vendors to inquire (again) about an exchange. I was told that my old Laycock J type overdrive (Made in England) was obsolete and they recommend I upgrade to the newest P type unit. That would be $1,300 and the new electronics would be $400 and since the P Type and J Type are not the same length, I would have to get the drive shaft shortened, so that would be another $500. Total for the upgrade $2,200 for parts only. I don't know how much labor a shop would charge for this work.
I told the guy on the phone at Gear Vendors that that was a little too much for me, so he said they could, if I begged and promised not to tow in OD, rebuild my old J Type for around $1,000. I would have to get a special return authorization. I would take it off, ship it to them, they would rebuild it and return it. While that was going on I could have the TH 350 rebuilt/refreshed with an aluminum pan with a temp bung and have things better than when it was new in 1970.
Then I read some things on the internet forums about rebuilding an old GKN Laycock Type J OD. It is all an interesting story. GKN (the same company that owned Henschen Axles we all know so well) also owned Laycock Engineering LTD. There are other places to get your Laycock J Type OD units rebuilt.
This one, Maximum Overdrive, was mentioned a few times on some truck forums. From what I read, the prices from this vendor are a good bit lower than Gear Vendors. I'll give them a try.

[jdalrymple]

Thanks for all the information.

I really don't want to get into a tranny swap.

I can install overdrive myself.

But, moving cross members, changing parking brakes, shift linkages, cooler lines, flywheels, torque converters, etc, etc, is a lot of work.

It might be a the edge of my skills, and is certainly past my time budgets right now.

As far as a 454 lasting 100k at high RPMs, maybe. But remember most all cars of that era lasted only 100k.

I understand there have been many improvements in engines that have increase lifespan.

But, I firmly believe that the slower RPMs of today's drivetrains have made a substantial improvement in durability as well.

My mind is not made up, I guess I just need to decide if 55-60 mph is fast enough.

Certainly, the cost of the GV product is at a premium, but a lot can be said for a complete, bolt on kit that has a warranty.

Sometimes the dollar amounts can end up being the same, we just spend the money at different rates. All at once, or buying another part to correct an unforeseen problem that has to be completed to make the money we have already spent not seem wasted.

Which, in the big picture, may be what I am doing, seeing as the beast is sitting in my yard.



Regards,

JD

[J. Morgan]

The biggest advance for engine longevity was the elimination of carburetors in the incorporation of EFI.

With EFI there is much less "fuel washing" of cylinder walls caused by poor atomization of fuel and excessively rich conditions that are common in carb engines, especially in warm up and "sticky chokes".

Low tension piston rings also add a lot to longevity.

Having run these 454s in commercial service, lots of them, the biggest enemy to these is crossfiring through old plug wires, destroying pistons. The old HEI ignitions made a lot of current, cross firing was easy.

Dropping engine speeds will have an effect on engine wear, just not nearly as much as common perception would impress.

If the advice of someone who has done a LOT of swaps from stock, (if not ever a gear vendors unit) as far as the gear vendors unit goes regarding installation, it is my opinion that when all is said and done a 700R4 swap would be an easier, less complicated, and cheaper instal.

How many miles on the stock trany? What if you instal the gear vendors unit and then the trany goes out?

Sorry, I don't mean to be pushy, but think it through, don't get stuck in "gadgetits", this can be an expensive condition.

[DKB_SATX]

Remember you'll also need to have your driveshaft shortened with the GV installation.

[jdalrymple]

J Morgan:

I agree with your comments about the EFI as the single biggest improvement in longevity of gasoline internal combustion engines.


I don't have a need to run out and buy something, I am simply investigating ways to add some useful life to a 23 year old motorhome, with only 23k original miles.

There are many folks that say the 700R4 has absolutely no business in an application such as this, so your suggestion creates as many questions as answers.

Growing up on a ranch with farm machinery, I have seen many "simple" upgrades and swaps turn into complete disasters.

Regards,


JD

[J. Morgan]

Lol, in reality there aren't many simple swaps. Usually one change causes the need to make two or three other changes ...

Also take note, if in the next 20 years the motor home gets driven as much as it was in the prior 20 years, is a 20% increase in engine longevity worth the price of either upgrade?

Where might you better spend the 3k that either swap is going to cost?

Of note also, when I tow my 31' trailer, I get better fuel economy locked out of overdrive in my tow vehicle.

[DKB_SATX]

For a transmission swap into that heavy beast, I think you'd want something like a 4L80E instead of a tow-prepped 700R4. I'm sure someone's done it (on another old truck if not an Airstream moho). I don't know if its electronics are self-contained or if it needs input from an engine-control module to work right.

A bone-stock 4L80E should be able to handle a 454, and an hd-prepped rebuild should last for decades of trips to Burning Man as long as the transmission cooler is decent.

[Waipio Rim]

There are at least a couple of threads here about swaps like this, search for threads by choctawmel and bkahler. After reading them, I decided to live with my stock tranny and just drive slow. Replacing the carb with a tbi setup sounds like as good a step toward better mileage, and might actually be within my skill set.

[Ice Berg]

Thinking about doing a trans change out to one with and overdrive . My mechanic was saying an early 90's trans has a manual overdrive and would a simple change . But the cost and time . . . what I am going to get one of those light up signs that says " bite me " and put in back window for those getting all clogged by yours truly

[andyleonard]

You must have just missed the 4L80E. My 92 300 came with one.

[crazeevw]

Raveson did the TBI swap last summer, just before he took off for a 4 month cross-country trip. He spoke to me about what an amazing difference it was having the TBI on the 454. Of course, he towed a Jeep Wrangler the entire trip, mpg surely increased, but can't remember by how much. I've priced the TBI, and thinking that at some point before I retire, it will be a definite upgrade.
Good Luck, Derek

[tevake]

Hi Derek and others here. I took over from Raveson as caretaker of his 345 about three months and three thousand miles ago. While I don't have experience with these motorhomes with the stock engine set up, I can say that the engine with the TBI is easy starting and smooth running with it. Also Richard said the power doesn't fall off as the altitude climbs. It does struggle a little in climbing but is dragging a lot of weight up them mountains. As for MPG, I've been getting around 7.5. Up a bit from the 6.5 that Richard experienced in his trip towing the Jeep. I think the real advantage is the clean running , ability to self adjust to altitude, and engine longevity.

Back to the OP's question about the overdrive. The real noticeable advantage for me is the more relaxed feel of the coach at speed. The overdrive seems to add about 10 MPH in top gear at a given RPM. While this may not make a big difference on lesser roads where the average speeds are lower. While driving on interstates with average traffic speeds of 70/75mph, being able to cruise at 65/68 mph. Vs 55/58 mph makes better miles per day and a much more comfortable driving experience in relation to the other traffic.

[SebasSF]

I have read through everything I can find on Gear Vendors and trans swaps, and my conclusion is that the GV is the best solution. With my 91 there is a way to swap the ECU and wiring harness to use a 4L80E, but that sounds like a pain, and my trans was rebuilt 4k miles ago. I can install the GV myself and I get overdrive on the highway and second with OD for those long hills that kill me at the moment. The TH475 that our RVs came with is one of the most durable transmissions ever made. I have been looking on eBay and CL for months and have not found one for sale, but I'm really just waiting till I have cash for a new one and find a good price.
I was down in San Diego the other day, and dropped by the GV headquarters...nice folks, gave me a tour, and explained some of the issues they had in the past, and how they are all fixed for years now. I'm sold.

[thebullet]

Smartstream - I have an Isuzu Powered 345. I struggle with the same RPM issue at highway speeds. Do you know the part number and gear ratios of the Gear Vendor unit you purchased? I would like to look at one of those units for my rig. Thanks, Tim

[Smartstream]

Originally Posted by thebullet

Smartstream - I have an Isuzu Powered 345. I struggle with the same RPM issue at highway speeds. Do you know the part number and gear ratios of the Gear Vendor unit you purchased? I would like to look at one of those units for my rig. Thanks, Tim

Hi Tim, all Gearvendors are .78 to 1 ratio. They only sell one unit. The difference in application is the front housing. On the TH400 you remove the tail shaft housing, bolt on the Gearvendors adapter and bolt on the Gearvendor OD unit. Normally you have the driveshaft shortened so everything fits. On the TH400 in the Airstream the rear housing of the Gearvendor also is changed to accept the driveshaft mounted parking brake. If you acquire a used Gearvendor unit they will sell you the adapter to mount to whatever trans you have. For the rear housing for the parking brake they want you to send your unit to them because you have to dismantle the unit to change the rear housing. If you have one of their units and want to change from one car or truck to another they are very helpful. Last I heard I don't believe they have an adapter for an Allison trans if that is what you have.


I hope that answers your question. If not let me know and I'll do my best to help.

[chriscraw]

very interesting stuff as I've just driven my newly acquired 1991 350LE from Seattle to Austin, Texas (see link 350LE Seattle to Austin in the on the road forum). I too am concerned when running at between 2700 and 3000 rpm in top gear, my over the ground speed on straight roads, 45mph up the hills, was around 60 mph which was and is way to slow for modern highway cruising. So, do I shell out $3300 plus labor for a Gear Vendors overdrive unit or put this money towards an engine overhaul (out to 496 cid) which would include a new head, roller cams, hydraulic lifters, fuel injection, multi-spark ignition, high volume coolant and oil pumps, maybe Banks etc. etc.
This would produce a high performance engine, smoother revving to sustain 4500 rpm highway cruising in top gear with the existing 4.56 rear end gearing ???

[cwf]

"More POWER!"... well, I would consider the O.D.... revving even a well built motor, under load, will have it's downside. Having the OD means you CAN shift into it if NEEDED... so, you will have 'granny gear' when slow work needed.... and can drop the R's when underway..

[streamquest]

Back in the day I had a Corvette with a big block that would rev well over six or seven thousand rpm, and it was basically the same motor that we have in these coaches. The biggest difference is that it was pushing 10-12-14 thousand fewer pounds, using a radiator of about the same size to cool it, and dealing with a dramatically smaller frontal area that had to be pushed through the wind. At highway speed it ran at 170-180 degrees doing 2700-3300 rpm.

The Cummins in my 325 with Gear Vendors runs at 190 degrees at 60 mph, but quickly heads up over 200 degrees when pushed harder.

The temperature of the 460 Ford motor in my recently acquired 370 also rises similarly when pushed above 65 mph, and I have never driven it in weather above 80 degrees. I'd love to put an overdrive into it as well, but I really wonder how much difference it would make with coolant temperature. Theoretically, while an overdrive does lower your rpm's at a given speed, it is also working your engine against a less advantageous final drive ratio.

Just as a point of interest, I think I once read that 90% of the energy used to push a bicycle above say 30 or 40 mph, is required to overcome wind resistance. So given the frontal area of our motorhomes; at highway speed on flat ground, that motor thinks it's pushing uphill.

So since we can't make these things any smaller, lighter, or more aerodynamic, I guess my thinking is that engine temperature might best be managed through enhanced cooling (and I doubt that turning the AC off, and the heater on, will be of much help).

Has anyone experimented with any supplemental cooling? Perhaps in place of the front air dam, whether it be water or oil? Just curious.

[Smartstream]

Originally Posted by chriscraw

very interesting stuff as I've just driven my newly acquired 1991 350LE from Seattle to Austin, Texas (see link 350LE Seattle to Austin in the on the road forum). I too am concerned when running at between 2700 and 3000 rpm in top gear, my over the ground speed on straight roads, 45mph up the hills, was around 60 mph which was and is way to slow for modern highway cruising. So, do I shell out $3300 plus labor for a Gear Vendors overdrive unit or put this money towards an engine overhaul (out to 496 cid) which would include a new head, roller cams, hydraulic lifters, fuel injection, multi-spark ignition, high volume coolant and oil pumps, maybe Banks etc. etc.
This would produce a high performance engine, smoother revving to sustain 4500 rpm highway cruising in top gear with the existing 4.56 rear end gearing ???

Remember what you are driving. Somebody put an aluminum can on a truck chassis designed back in the 70's. The brakes and suspension aren't like your modern car or pick up. Also you are driving a "recreational" vehicle. Slow down and enjoy the ride. Let the guys in a hurry go around. As said above the big power modified engines don't do well for the long haul.