Towing Newbie - questions

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JSpotMD

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Hi all, I have a 1995 K2500 Suburban with a 7.4L (TBI) and 4L80e. Currently on 315/75/r16 and 3.73 ratio 3 inch body lift, stock suspension.

Empty, it's a great highway cruiser. I've got minimal experience towing and I'm not sure if I've got problems with my setup.

Motor threw a piston through the oil pan before I bought it. Has a new GM Goodwrench L19 rotating assemby and I put in a "new" GM Goodwrench 4L80e in when the original tranny was malfunctioning (truck had 260k miles on drivetrain). I put in an Autometer transmission gauge in the pressure test port. Still on the 36k mile warranty on both.

We've acquired a travel trailer and I'm looking for advice. Trailer is a Jayco 29MEC, empty weight is 6100lbs and it's rated for total weight 7200lbs. It's hitched with a Husky 4-way weight distribution/sway control. I've taken it out twice now, once with a 1/2 load of water (300lbs). Truck is rated for 8000lbs with the stock axle ratio (10 000lbs with 4.10s).

I've been reading that people with 3/4 ton trucks don't "feel" the trailers behind them which I don't find to be the case. Trailer is stable, no sway but I can definitely feel it back there moving around. Is that normal? Getting up to speed at full throttle takes forever... Am I hurting my truck going WOT for so long? Cruises OK at 60mph towing but the transmission is not consistently locking the TC. Have not had it go to 1st gear or below 50mph on long grades (7% max) but I'm at WOT in 2nd gear all the way up. Again, I read people towing at 70+mph no problems in OD with the 4L80e... Bullshit?

Transmission has the HD cooler and stays at 150F-180F with the TC locked, 230 max unlocked with a headwind in 3rd, foot 3/4 of the way down. Do I have an issue there?

I'm thinking a re-gear to 4.10 would be the next step (need a new carrier for 4.56+) vs adding more power to the 454. I'm planning headers and full exhaust (stock stuff is getting really rusty). Should I stick to shorties or try to find long tubes that fit the K2500 chassis? I don't want to get into the motor until the warranty is up but then I was thinking an Edelbrock top end kit and maybe a Weiand 177 blower with a holley FI kit. I'm a surgeon so money isn't really an issue but I don't want to waste it and I love this truck so buying a different tow vehicle isn't my first choice. I've wanted one of these since I was 16 and my wife bought it for me.

Thoughts/Advice/Tips appreciated.
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Tavi

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First, those that say they "forget the trailer is behind them" are A. Full of crap or B. Inattentive driver. I've towed a 2k lbs trailer with a 30k lbs long truck, and could still feel it back there.

As far as your power issue, it is all in your gearing. Loaded to 17k lbs I was able to tow a 1-2% grade in OD lockup. That was with 225/75r16 and 4.10s. I had more gear and less tire. I think you will be much happier with the 4.56s.

By the way, nice rig. Might want to pull up on your WD. Your front end is pretty high. It will effect braking.
 

shovelbill

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your gearing and tire choice is poor combo for the job.....i'd get a second set of stock size tires load rated for towing, an "E" rated tire. if you are going to keep those 35's then 4.56 is a must to have reasonable gearing, which is the same as 3.73 and 31" tire.....and that's still not ideal for that 'aerodynamic' combo, but better.

if money wasn't a "biggie" for me and that was my rig, i'd gear to 4.56 and keep a set of "towing" 33's around considering your body lift v. aesthetics......and don't forget you raised your center of gravity on the truck too......i'd install a rear sway bar and maybe a deep trans pan for extra capacity......4.88/35=4.56/33=4.10/31.....those make for good towing choices and a much easier job of work for your 'burb.....remember, the larger the tire the more rolling resistance your brakes have to overcome, i'd do 33" at most.

make sure you have a good tow controller and your braking system is in the absolute best state of repair.......remember, you tongue weight should be 10%-15% of the loaded trailer weight, that's a given......if the burb still squats put in a good set of air bags to level it off.....as Tavi stated before, that sagging stance absolutely affects steering and braking.

when towing.....overkill is your friend, "adequate" is dangerous at best.....a good cross wind can fu@k you bad, you're pulling a giant sail down the road.

that's my $.03
 
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kwslvdo96

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your gearing and tire choice is poor combo for the job.....i'd get a second set of stock size tires load rated for towing, an "E" rated tire. if you are going to keep those 35's then 4.56 is a must to have reasonable gearing, which is the same as 3.73 and 31" tire.....and that's still not ideal for that 'aerodynamic' combo, but better.

if money wasn't a "biggie" for me and that was my rig, i'd gear to 4.56 and keep a set of "towing" 33's around considering your body lift v. aesthetics......and don't forget you raised your center of gravity on the truck too......i'd install a rear sway bar and maybe a deep trans pan for extra capacity......4.88/35=4.56/33=4.10/31.....those make for good towing choices and a much easier job of work for your 'burb.....remember, the larger the tire the more rolling resistance your brakes have to overcome, i'd do 33" at most.

make sure you have a good tow controller and your braking system is in the absolute best state of repair.......remember, you tongue weight should be 10%-15% of the loaded trailer weight, that's a given......if the burb still squats put in a good set of air bags to level it off.....as Tavi stated before, that sagging stance absolutely affects steering and braking.

when towing.....overkill is your friend, "adequate" is dangerous at best.....a good cross wind can fu@k you bad, you're pulling a giant sail down the road.

that's my $.03
Ya I agree with shovelbill on this one your tires are to big for gearing and pulling that big of trailer 4.56s would help out ton. Or just pull that sucker down into 3rd gear and let it rev at 65mph with your gearing and bigger tires should only put you at like 2600 rpm which is nothing I tow my camper in 3rd gear at 65 with stock tire size im at 2800 rpm and my truck id 5.7 vortec half ton.
 

JSpotMD

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Can't fix the aerodynamics of a brick towing a brick. Not wanting to go any faster than 65.

Thank you all very much for the advice. Just to clarify - the truck isn't squatting much, it looks worse since the front stance is so much wider and I have no "real" front bumper.

Knowing my gearing is suboptimal I've only been towing in 3rd and it maintains 62mph fine on anything but the hills @ 2500rpm with the TC locked, 2800rpm unlocked up slight grades. I just go WOT in 2nd at 4000rpm to go up the hills with just a little speed lost.

I like the idea of going to 33s since I was planning to trim my front fenders to clear the current tires better. Any recommendations for a good tire for most terrain and towing? I can always throw the BFGs on in the winter when she runs empty.

I won't ever be towing more than 8000lbs with it so would 4.10s still be too little gear? I'm concerned that since the truck runs unloaded 75% of the year it will be a pain for highway cruising with 4.56 gears. Cruising speed on the highway I am usually on is 120kmh/h (75mph).

Brakes are good and recently replaced, I also run a Tekonsha P3 TBC and the front suspension/steering is all new.

I'll put high capacity transmission and engine oil pans on my to do list. The oil cooler is not in use, when GM put the new short block in they bypassed it, the line runs right back into the block. Should I be planning to install an oil cooler?

What's the consensus on headers for a TBI 7.4? In the motorhome world it seems everyone is going long tube...

Thanks again for the advice!
 

BoxerPitMix

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Hmm I don't really have any experience with big block performance, so I can't be much help there. It sounds like others have pretty much covered the other things.

Good call on the P3, I like those controllers. Anything Tekonsha is the way to go. I also really like that White Hawk you have! Did you get the "Theater Seating" in the slide out across from the entertainment center? I always liked the nice open floor plan on those.
 

andy396

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I won't ever be towing more than 8000lbs with it so would 4.10s still be too little gear? I'm concerned that since the truck runs unloaded 75% of the year it will be a pain for highway cruising with 4.56 gears. Cruising speed on the highway I am usually on is 120kmh/h (75mph).

If you want to build the ultimate GMT400 towing truck, put 4.56 gears in and combine that with a gear vendors overdrive unit. It will give you the best of both worlds.


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Biggershaft96

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If you plan to ditch the 35s and go to 33s while towing i would say 4.10s would do the job, but i would do 4.56s if it were mine just for those up hill on ramps and the higher gear you go, the less the rest of the drivetrain will strain. The only drawback is fuel, but i dont imagine the milage is very great with the trailer hooked up in the first place lol. I think youll notice a world of difference with 4.56s, a rear swaybar, and a deep (preferably finned aluminum) trans pan.
If your looking for tires to tow with firestone transforce ATs all the way. Theyre made for hauling/towing and pretty much last pretty much forever. They just dont do so well off road.
 

JSpotMD

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Good call on the P3, I like those controllers. Anything Tekonsha is the way to go. I also really like that White Hawk you have! Did you get the "Theater Seating" in the slide out across from the entertainment center? I always liked the nice open floor plan on those.

We did, it's great! Have a Nintendo NES Classic hooked up to the TV as well :banana-mario: We only have one kid camping with us so no need for a bunk model and the two recliners work as beds in a pinch.
 
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