Trailering

[Stm3784]

Hey guys I got a 30 foot camper that 7700# light. Can I use my 78 k20 to pull when it's done? It won't be the prime mover for the trailer but if need be. 350cid SM465 NP205. I think 3.73 rear. The Silverado 1500 4.3 won't get out of its own way without pulling anything. Looking into a 2500 HD. That will be the prime mover, but would like to know if the 78 could do the job

[Irish_Alley]

as long as you can stop you shouldnt have a problem. do you know the gvwr of your truck?

[Stm3784]

Hey guys I got a 30 foot camper that 7700# light. Can I use my 78 k20 to pull when it's done? It won't be the prime mover for the trailer but if need be. 350cid SM465 NP205. I think 3.73 rear. The Silverado 1500 4.3 won't get out of its own way without pulling anything. Looking into a 2500 HD. That will be the prime mover, but would like to know if the 78 could do the job

[Stewart G Griffin]

i'm guessing yes, especially on mostly flat ground.

It should be able to pull 7700#'s............tongue weight 770 pounds.......hopefully your hitch is rated for that.   The rear axle, which is the aspect i'm most concerned about these days, should be able to handle 770 lbs tongue weight?  It's a 14 bolt?

[Stewart G Griffin]

Oops, double post.

[Stm3784]

Yes it's 14 bolt. As I said I believe it's a 3.73 rear. It's my project build/show truck however. I do want to be able to use it if needed. As far as GVWR I'm going with what the truck was rated in 1978.


2014 Silverado 1500 W/T
4.3 V6
Daily driver

1978 K20 Silverado package
5.7 V8
Money pit

[werewolfx13]

Use a *proportional* trailer brake controller, ensure your suspension height stays at a stable range ( install helpers if necessary), use a weight distributing hitch if at all possible, and assuming your brakes are of good quality semi-metallic or carbon-metallic, calipers working smoothly, rotors in good condition, all aspects of the rear brakes working correctly, wheel bearings nice and tight, hitch of the proper capacity and design, etc, it shouldn't complain much. My 76 k20 is a 6800 lb gvwr flavor with 4.1x gears, sm465, and np205 but has since been upgraded with rear disc brakes, hydraulic trailer brake controller, front PFC carbon metallic pads, Wagner rear semi metallic pads, new calipers all the way around, larger bore master cylinder, 4 row factory radiator from a 1980 c10 diesel, wix 51794 larger capacity oil filter, 1987 TBI swap, probably other stuff I'm leaving out. I wouldn't hesitate to drag 10-12k behind it if the hitch was up to the task. It seems to tow about as well as my 99 c3500hd does, but the 99 doesn't have trailer brakes, and in its utility body/former bucket truck dress, boxes partially full, bed empty, easily weighs double what my 76 does empty. The 99 runs a much higher gear, something in the low 3's, and its a 4l80e so its vortec 454 is MUCH happier at modern highway speeds than my 76 with a TBI 350 is.

Assuming the mechanical basics are up to task, truck and trailer brakes are good, keep your speed around 55-60 mph or less and drive happy.

[Stm3784]

Use a *proportional* trailer brake controller, ensure your suspension height stays at a stable range ( install helpers if necessary), use a weight distributing hitch if at all possible, and assuming your brakes are of good quality semi-metallic or carbon-metallic, calipers working smoothly, rotors in good condition, all aspects of the rear brakes working correctly, wheel bearings nice and tight, hitch of the proper capacity and design, etc, it shouldn't complain much. My 76 k20 is a 6800 lb gvwr flavor with 4.1x gears, sm465, and np205 but has since been upgraded with rear disc brakes, hydraulic trailer brake controller, front PFC carbon metallic pads, Wagner rear semi metallic pads, new calipers all the way around, larger bore master cylinder, 4 row factory radiator from a 1980 c10 diesel, wix 51794 larger capacity oil filter, 1987 TBI swap, probably other stuff I'm leaving out. I wouldn't hesitate to drag 10-12k behind it if the hitch was up to the task. It seems to tow about as well as my 99 c3500hd does, but the 99 doesn't have trailer brakes, and in its utility body/former bucket truck dress, boxes partially full, bed empty, easily weighs double what my 76 does empty. The 99 runs a much higher gear, something in the low 3's, and its a 4l80e so its vortec 454 is MUCH happier at modern highway speeds than my 76 with a TBI 350 is.

Assuming the mechanical basics are up to task, truck and trailer brakes are good, keep your speed around 55-60 mph or less and drive happy.

Ok thanks for the advice. Like I said. I would only use it if I absolutely have to. I was already planing on throwing an electric brake control in. A couple extra leafs if that would help and was kinda figuring on leaving the drums. The rear. What do you think?

[werewolfx13]

The drum brakes should be fine as long as they are working correctly and are properly adjusted. On your trailer brake controller, make sure you get a proportional controller, not a timed unit. Timed brake controllers are only marginally, if at all, better than NO trailer brakes at all. Look for a prodigy p2 or p3. Those are one of the more affordable, good quality brake controllers.

The difference between timed units and proportional units, is in how they apply the trailer brakes and to what extent they apply them.

Timed units use a time based sequence that is triggered by the brake lights. Once they receive a signal from the brake light circuit, they apply the brakes at a rate that is user adjusted, scaling from very slowly to the very quickly, how fast depends on the dial usually on the  side of the unit. They will never apply any more brakes than the adjustment dial on the front of the unit, which controls the voltage output from the controller. This is bad, because if you have to panic stop, the unit doesn't care, it applies the brakes as fast or slow as you have it set to, and only to the max level you have it set to. If you were to max the range out, then slightly tapping the brakes would cause them to jerk the trailer or lock up entirely, so you back the brake power down to a level that acceptable under normal stopping conditions...now you wont have full force trailer brakes if you have to suddenly stop.

Proportional units rely on some means of applying the brakes in a way that is relevant to how fast the vehicle is trying to stop. Older units, like my hydraulic controller, operate off of the rear brake line, tee'd in at the master cylinder and run into the cab. These are great, because they react based on how hard you press the brake pedal. Modern units act like a pendulum, and as the vehicle decelerates, it applies more trailer brakes. The harder the effect of deceleration, the harder it applies the brakes. In either case, this allows you to increase the maximum controller output voltage and still only have the brakes you NEED in normal stopping, but still have ALL the brakes you can get for a panic situation. The biggest downside in my eyes to a pendulum based unit, is if you drive a manual transmission and downshift to slow down a bit, or even an automatic and just snap off the throttle abruptly, it will detect that deceleration and start applying trailer brakes, and you might not want any trailer brakes applied on a slick road.
 There are a few very high end controllers for OBD2 vehicles that serve the same purpose as my hydraulic controller, without interfering with the brake hydraulics (and as such, the ABS).