We've got an 1975 Argosy 26 footer. The 454 turns about 3000 RPM at 60 MPH with the gearing (TH400 trans) it's got ... I hate to turn an older engine any faster than that. We've been thinking about an overdrive ... cheapest = about $1600 at US Gear. I can get a rebuilt TH 700-R4 (basicly a heavy duty TH400 with a 30% overdrive) for much less.
Has anyone out there in the listening audience tried this ??
Originally posted by Hayseed We've got an 1975 Argosy 26 footer. The 454 turns about 3000 RPM at 60 MPH with the gearing (TH400 trans) it's got ... I hate to turn an older engine any faster than that. We've been thinking about an overdrive ... cheapest = about $1600 at US Gear. I can get a rebuilt TH 700-R4 (basicly a heavy duty TH400 with a 30% overdrive) for much less.
Has anyone out there in the listening audience tried this ??
700 R4 is not stronger then a TH400. 700r4 is the sandard tranny in half ton trucks such as the S10 and the 1/2 ton fulsize truck. That tranny was NEVER put behind a 454 from GM. It couldn't handle the torque. That's why the 1 ton trucks and the 454's were still running the TH400 as late as 1990.
The tranny that replaced the TH400 as the heavy duty unit i in 91 is the 4L80e. It's about $2500 from GM. It's a computer controlled tranny and you would also need a $500 or stand alone controler modual.
What you might do is look for a totaled 91 or newer truck with a 454 and salvage both the engine and the transmission with the FI and all it's gear. Good chance you could get a low mile set up for around $3k maybe less. Ideal would be a 91 Burb or crew cab. That was a hold over year on the body and GM basicly made a retrofit harness. The FI Harness was stand alone and a very easy swap.
You could proably sell your current 454 for around $1k if your able to sit on it for a while.
If you can do the motor swap then that would be the way to go and should improve MPG a good bit.
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1959 22' Caravanner
1988 R20 454 Suburban.
Atlanta, GA
US Gear and Gear Vendors are very good solutions to just your problem. Engines run at high rpm not only wear faster, the extra heat generated is hard on all the engine components.
Gear Vendors is probably more convenient in use, but some believe the US Gear unit to be stronger. I really don't know about that.
I agree that the 700r4 was not ever put behind a big block from the factory. That being said ,I know of a lot of 700's that are abused on the drag strips and streets with alot more h.p. than the stock 454 ever produced! It it a very popular trans and there are bunches of mods that cam make them live and live long under extreame conditions.
I.M.H.O.I believe that a 700 will live in a M.H. if driven as a it should be (and even adused a little) with just a few mods . You will however have to modify your front drive shaft as it is approx. 1" too long.
Also the rear mount is is approx. 5" farther foreward on the 700r4.
Also the converter lock up will have to be activated by a vacuum switch or manual sw. as most later veh. it is activated by a computer.
and you will have to add a kick down /t.v. cable to the carb as the 400 uses a electric sw. and a vacuum modulator to control shifts.
YES, it is do able just how much do you like to tinker is the question. I would try it but I am a "tinkerer"
Im working on this mod. on a 89 sub. 2 wheel drive 454 Making it a 4 wheel drive with the 700r4 with a Dana 60 in the front and a 14bolt in the aft. and 2in. lift with 3/4ton springs. Real Trucks Are Not Found They Are Made!!!!!!!!!!!!!
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Never has so few. Done so much, With so little, That now we can do anything, With absolutly NOTHING!!!! AIR# 300
Originally posted by DaPlumber Im working on this mod. on a 89 sub. 2 wheel drive 454 Making it a 4 wheel drive with the 700r4 with a Dana 60 in the front and a 14bolt in the aft. and 2in. lift with 3/4ton springs. Real Trucks Are Not Found They Are Made!!!!!!!!!!!!!
There is another company that sells "Quadzilla" performance manual 4L80E tansmissions. Not sure if that's what your looking for, here's the link, check it out.
Sounds like the trans swap will yield an inferior setup in terms of reliablity/durability. Of course there are other candidates that may work better. I have done powertrain swaps before and they are always more complicated and costly than originally thought. The gear splitters such as US gear, work and work great. They are basically bolt-in with the only major issue being the shortened driveline ( will cost to cut down old DL and the shortened DL could cause vibration). I have been researching gear splitter conversions for use on my rig, and have heard mostly good things about them. They seem to be durable, reliable and deliver the performance advertised. The only drawbacks are as you mentioned, cost and is your existing trans up to the task? It would be a bummer to spend all that $ and then have the old trans puke! If you do go with a under/overdrive setup, I like the Gear Vender unit, seems to have an edge in reliability, more people saying good things about this unit.
"Sounds like the trans swap will yield an inferior setup in terms of reliablity/durability." Not!!!!!!!! Dont read between the lines. I have run this setup for 8 year in an older Sub. That now has 241,593 miles on it...... Pulling around a 45 foot off shore power boat... On a good day I can get 13.2 mpg one time on flat land with a tail wind I got 14 There is nothing INFERIOR about the 700R4!!!!!!!!!!!!!!!!!! But you need to under stand how lock up works.... Do you want full lock up in 4th or do you want to put it on a switch?????? You need a fleet overhaul kit a modified 4th gear valve, and a small torque converter this is ware most will go wrong and go with something bigger then you need. Oh ya you need a bigger pan two extra quarts, and I like a remote-mount filter and temp gauge, but I love to watch gauges!!!!!!!!!!!
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Never has so few. Done so much, With so little, That now we can do anything, With absolutly NOTHING!!!! AIR# 300
If the 700R4 is designed for a light duty 1/2 ton trucks is it a good idea to use it in a vehicle that is pushing 12,000lbs everyday of its life? I'd think if you are going to the effort to do a trans. swap you would want to go go stronger not weaker. It sounds like the 4L80E is the way to go but then again that sounds like big $'s and lots of tweaking to make it work. I just helped a friend swap the AX15 trans in his Jeep Wrangler for a NV4500 out of a Full size Chev truck. No if's and's or but's, the NV4500 is a Much stronger unit. This was supposed to be a "cheap & easy" swap. Many hassles and nearly $2.5K later he has his new trans. The under/overdrive gear splitters just seem like a better solution. You will end up with 7-10% more torque and gain about 15-20% on your milage. At any given speed you will be pulling about 20% lower RPM's and have much more power for the hills/towing. You will have in effect, six speeds fwd and a whole lot more control, Plus much easier installation. Read the posts here on this and other Motor Home forums about Gear Vendors. Generally happy campers and exceeded expectations. The down side, Big Bucks, about $2500-2600, Whatever you end up doing, do it right. People tow 25ft boats with their minivans. I've seen those same minivans on the side of the road, smoke billowing out from the undercarriage. Breaking down in the middle of nowhere because of a pieced together trans would be a major bummer.
Ok,
you all have read my previous post.
now if yall promise to put your chainsaws away, I will go out on a limb
I think myself and da plumber also other "gear heads" probably enjoy our time UNDER our coaches as much as we do in the living comp.
looking back at the origional question, I think I.M.H.O. that it would be easier, less of a hassle, and possibly less expensive for Hayseed to go with a o/d .
I.E. gear vendors, U.S. Gear, they are good units
with no drawbacks.BUTas previously mentioned his trans should be in good shape as it would be discourageing to have it installed only to later have to rebuild the 400, altho the 400 is bullit proof and is less expensive to o'haul , like anything else,they do wear out. A trans cooler is a must for ANY trans that is doing H.D. work.
Yikes, here comes Paul and BABE, the blue ox!
I'm otta here
Don't underestimate the versitility of more gears. I ran a Gear Vendor under drive in an Airex 36' motor home with a 454 chevy for many years and was very happy. I am convinced it improved the reliability and it sure did make the rig nicer to drive. The ability to select an appropriate gear allowed me to climb hills much better. I didn't get passed often.
I finally got my new GearVenders overdrive installed ... did it my self ... installation was a snap !! Had a local welding shop shorten the front drive shaft.
It dropped the RPMs at 60MPH from 3000 down to about 2300. UNBELIEVABLE difference in the drivability !! It is REAL comfortable (with itself) at 65 MPH. It's real odd to leave the OD out until about 55 MPH ... about that speed it starts to 'labor' real hard ... hit the OD button and it wants to fly !!
One problem I need help with ... small vibration under load (no ... not universals ... they're new). I think it's because the two pieces of the driveshaft are not aligned properly.
I lost the alignment reference between the front and back halves of the two piece driveshaft when I took it off. Can someone out there crawl under their P30 and see what the proper alignment should be ?? I think mine (see the picture links below) is it 90 degrees out.
Obviously pictures would be great, if anyone could eMail some.
If the shaft has been shortened then I would say it needs to be balanced by a shop that does that. It should not cost much, but it makes a diffrence on a long shaft like we have.
This should be done if the shaft has been dissassembled and not reassembled in the same position, or U-joints have been replaced. The new U-joints will be cast slightly diffrent than the originals and can affect the driveshaft balance.
Did you replace the carrier bearing too? If not it could need it from being messed with.
That vibration over time can do some damage.
On the other side of the coin I am happy to hear it went in well and works so well. Gives me something to think about adding to make my new engine last a long long time.
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Brett G
WBCCI #5501 AIR # 49
"Stop worrying about the potholes in the road and celebrate the journey." -- Fitzhugh Mullan
Wise men talk because they have someting to say; fools, because they have to say something. -- Plato
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OHHHHHHHH YAAAAAAAA!!!!!!!!!
Not!!!!!!!! Dont read between the lines. I have run this setup for 8 year in an older Sub. That now has 241,593 miles on it...... Pulling around a 45 foot off shore power boat... On a good day I can get 13.2 mpg one time on flat land with a tail wind I got 14
overdrive
Overdrive (ie; US Gear) VS trans upgrade ...
Linear Mode
