Rockhounder
Explorer
Thanks for the referral, I will give them a call. I definitely think that there should be a good solution, just needed to hook up with the right guys who are gurus on this!
Really, really want to get rid of my 700R4 in 88 suburban and upgrade
- Thread starter Rockhounder
- Start date
Thanks for the referral, I will give them a call. I definitely think that there should be a good solution, just needed to hook up with the right guys who are gurus on this!
justcuz
Explorer
Talk to Dave, or his son and tell him what you are doing with the Suburban.
Show him what you have and see what he recommends.
I have 3.42's in my 2015 Suburban, but the 4-1 first gear of the 6 speed trans gives you a 13.68 gear reduction.
With your 3-1 first gear in the 700R4, you would have to have 4.56 gears to achieve the same reduction.
One other thing to consider with an automatic vs a manual transmission, torque multiplication from the converter at low speeds in lower gears is equivalent to or lower than most modern truck transmission low gears. A clutch that would handle that weight is not a cheap date either.
You can tow the Queen Mary with a Briggs and Stratton lawn mower engine, it's all about gears!
In all seriousness you may even want to consider some type of under drive for towing.
If any or all these modifications are cost prohibitive, you may need to either upgrade to a heavier duty Suburban, or buy a specialized medium duty tow vehicle. You would be surprised to find how cheap a crew cab International with a diesel and an Allison are these days.
Show him what you have and see what he recommends.
I have 3.42's in my 2015 Suburban, but the 4-1 first gear of the 6 speed trans gives you a 13.68 gear reduction.
With your 3-1 first gear in the 700R4, you would have to have 4.56 gears to achieve the same reduction.
One other thing to consider with an automatic vs a manual transmission, torque multiplication from the converter at low speeds in lower gears is equivalent to or lower than most modern truck transmission low gears. A clutch that would handle that weight is not a cheap date either.
You can tow the Queen Mary with a Briggs and Stratton lawn mower engine, it's all about gears!
In all seriousness you may even want to consider some type of under drive for towing.
If any or all these modifications are cost prohibitive, you may need to either upgrade to a heavier duty Suburban, or buy a specialized medium duty tow vehicle. You would be surprised to find how cheap a crew cab International with a diesel and an Allison are these days.
4x4x4doors
Explorer
I agree that you are likely overloading the tranny.
That being said, the 700R4 frequently got bad-mouthed for poor adjustment of the kickdown (tv) cable which also led to premature death of more than one. Check for proper adjustment may buy you some time.
That being said, the 700R4 frequently got bad-mouthed for poor adjustment of the kickdown (tv) cable which also led to premature death of more than one. Check for proper adjustment may buy you some time.
What's the engine?
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I'm with rayra, something is wrong, first guess would be the lockup in the converter, either it's failed or the controls have malfunctioned. It's not complicated and should be easy to diagnose.
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The 700R4 is a darn good tranny and should be able to handle anything any moderate engine puts out. It's not really the weight that matters but the torque the engine is putting out. You'll never burn up a 700R4 in good condition behind a stock 305 even towing 30K, you'll just go slower.
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Personally I'd invest in a 700R4 before a 4L80E(or E4OD), there's a lot to be said for the simplicity of an old school automatic. Even been considering adapting a 700R4 to my Ford.
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I'm with rayra, something is wrong, first guess would be the lockup in the converter, either it's failed or the controls have malfunctioned. It's not complicated and should be easy to diagnose.
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The 700R4 is a darn good tranny and should be able to handle anything any moderate engine puts out. It's not really the weight that matters but the torque the engine is putting out. You'll never burn up a 700R4 in good condition behind a stock 305 even towing 30K, you'll just go slower.
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Personally I'd invest in a 700R4 before a 4L80E(or E4OD), there's a lot to be said for the simplicity of an old school automatic. Even been considering adapting a 700R4 to my Ford.
D
Deleted member 9101
Guest
I think this would be our first choice, any leads to the kit manufacturers would be appreciated.
Look on Pirate4x4 they have a few discussions on the swap.
These guys sell some of the parts and have info on the 6 speed version, it appears to be a damn beast:
http://www.transmissioncenter.net/4L60E_to_4L80E_Swap.htm
http://www.transmissioncenter.net/PATC_Innovations,%20700R4%204L60E%204L80E%20AOD%2047RE%20Transmission.htm
we had this done the last two trannies.... so need to go heavier duty
Or change shops ;-). I have seen them in the past rated to take 500HP as well as under bog trucks on 44's... they can be made muuuch stronger.
what ratios do you suggest, where when we are not towing, but going on long trips we can get halfway decent mileage as well?
Well, the ratio is up to you and how much MPG you want to sacrifice. With that being said, a 1or 2mpg drop is fuel economy is vastly cheaper than rebuilding a tranny. 3.73 gears would probably even things out since you have taller tires, but 4.10's would help even more.
I can... usually in 2nd, going 25 mph. Towing the boat, our combined weight is in excess of 9,000 lbs
Yeah, that's pushing it for a 1500 of that vintage...lol. How about ditching some of the weight from the truck?
I will take pics of the underside and top rear of the bumper to show the airflow is actually unimpeded flow. The bumper actually was built and designed to slide onto the existing front bumper, then bolted onto bumper and frame. It is open on the underside[/QUOTE]
This is just me, but I would still knock some holes int he front of it just to aid in air flow. Since you are going beyond what the truck was designed to do, you need airflow that goes beyond what was designed.
Look on Pirate4x4 they have a few discussions on the swap.
These guys sell some of the parts and have info on the 6 speed version, it appears to be a damn beast:
http://www.transmissioncenter.net/4L60E_to_4L80E_Swap.htm
http://www.transmissioncenter.net/PATC_Innovations,%20700R4%204L60E%204L80E%20AOD%2047RE%20Transmission.htm
we had this done the last two trannies.... so need to go heavier duty
Or change shops ;-). I have seen them in the past rated to take 500HP as well as under bog trucks on 44's... they can be made muuuch stronger.
what ratios do you suggest, where when we are not towing, but going on long trips we can get halfway decent mileage as well?
Well, the ratio is up to you and how much MPG you want to sacrifice. With that being said, a 1or 2mpg drop is fuel economy is vastly cheaper than rebuilding a tranny. 3.73 gears would probably even things out since you have taller tires, but 4.10's would help even more.
I can... usually in 2nd, going 25 mph. Towing the boat, our combined weight is in excess of 9,000 lbs
Yeah, that's pushing it for a 1500 of that vintage...lol. How about ditching some of the weight from the truck?
I will take pics of the underside and top rear of the bumper to show the airflow is actually unimpeded flow. The bumper actually was built and designed to slide onto the existing front bumper, then bolted onto bumper and frame. It is open on the underside[/QUOTE]
This is just me, but I would still knock some holes int he front of it just to aid in air flow. Since you are going beyond what the truck was designed to do, you need airflow that goes beyond what was designed.
A good built tranny will hold just fine once you re-gear that beast. For just a little occasional towing the 3.73 will work. But you sound like a "not a reasonable towing" kinda guy, so get some 4.10 gears and be done with it. The tranny has OD to help minimize the rpm's when not towing.
Rockhounder
Explorer
Anyone know the cost to swap out the front and rear gears to a lower ratio? This might also help the torque load on the tranny
warrpath4x4
Adventurer
your better off finding a set of axles already geared to what you want, also at this time think about going 3/4 ton axles with a 14BFF (14 bolt full float).
D
Deleted member 9101
Guest
X2. See if you can find a CUCV and rob the axles and other heavy duty parts off of it. The M1008 trucks used open Dana 60 front axles, with the M1028 and M1031 variations often having a Trac-Lok limited slip. In the rear, the M1008s used the GM 10.5-inch (270 mm) 10.5" Corporate 14 Bolt Differential with No-Spin lockers (the commercial trade name for the Detroit Locker). Though the M1028A2 and A3 duallies have Dana 70 HD axles. The axle gear ratios were 4.56:1,
Buddha.
Finally in expo white.
http://www.grimmjeeper.com/gears.html
You can plug in your numbers here to see what a gear change would get you.
Looks like 33" tires and 4.56 gears is 2275rpm at 70mph in over drive.
You can plug in your numbers here to see what a gear change would get you.
Looks like 33" tires and 4.56 gears is 2275rpm at 70mph in over drive.
rayra
Expedition Leader
yeah definitely have to find a way to keep it in the zone, especially with those loads. Not gonna brute force it. Re-gearing sure seems like the right answer. But I don't really know much about it other than the generalities.
eta and getting down to such low speeds in the heavy tow is just helping kill it, insufficient airflow. Definitely add some fans mounted to the coolers, if you continue to tow as it is. That's a real easy and inexpensive thing to jury-rig
eta and getting down to such low speeds in the heavy tow is just helping kill it, insufficient airflow. Definitely add some fans mounted to the coolers, if you continue to tow as it is. That's a real easy and inexpensive thing to jury-rig
zoomad75
K5 Camper guy
3.42's and 33's would be worthless for towing regardless of the transmission. You don't have enough gear. The engine does not have enough torque to manage with that combo and it ends up working harder. It's exactly why you just throw it in 4lo out of instinct to get it the rest of the way up the hill. You just gave the engine a 2 to 1 (not sure which t-case you got) mechanical advantage over what you were at in high range. This is exactly why you need more gearing.
Best bet, quickest route for deeper gears would be to look for some 3/4 ton axles as a matched pair. The axles could be found under a truck or 3/4 ton suburban. You'll pay less than getting the 10 bolts regeared. That is as long as the 8 lug axles are in decent shape to start with. 4.10's with the 33's would be probably the best balance between torque and fuel economy. The engine can handle it. Remember they put the same engine in 3/4 ton burbs along with 3/4 ton and 1 ton trucks in the same years. Granted, you can't beat the torque advantage a big block would put out but it's not a requirement. Gear it right, follow others suggestions on one large trans cooler with a fan vs multiple that will probably restrict flow in the long run and starve the trans the fluid it needs.
The added bonus at least for the rear axle upgrade would be getting a 14b full floating axle over the 14b semi-floating axle. The word bulletproof would apply in your application. The 350 won't hurt it and no fear of a broken axle shaft causing a wheel to exit stage left or right at the worst possible time. The full floater would come with bigger brakes and have higher weight capacity than the 10 bolt you will need to pull out of it's way. Axles interchange from the start of the squarebody to the end (73-91 for the burbs, 73-87 for the trucks) which is the beauty of GM's design.
Best bet, quickest route for deeper gears would be to look for some 3/4 ton axles as a matched pair. The axles could be found under a truck or 3/4 ton suburban. You'll pay less than getting the 10 bolts regeared. That is as long as the 8 lug axles are in decent shape to start with. 4.10's with the 33's would be probably the best balance between torque and fuel economy. The engine can handle it. Remember they put the same engine in 3/4 ton burbs along with 3/4 ton and 1 ton trucks in the same years. Granted, you can't beat the torque advantage a big block would put out but it's not a requirement. Gear it right, follow others suggestions on one large trans cooler with a fan vs multiple that will probably restrict flow in the long run and starve the trans the fluid it needs.
The added bonus at least for the rear axle upgrade would be getting a 14b full floating axle over the 14b semi-floating axle. The word bulletproof would apply in your application. The 350 won't hurt it and no fear of a broken axle shaft causing a wheel to exit stage left or right at the worst possible time. The full floater would come with bigger brakes and have higher weight capacity than the 10 bolt you will need to pull out of it's way. Axles interchange from the start of the squarebody to the end (73-91 for the burbs, 73-87 for the trucks) which is the beauty of GM's design.