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Originally Posted by NetuSER
Besides lifting the truck will this help in the payload value? I carry 100 gals of water in my DC and wanted to know if this will help the sag. If it will I'm in...  |
There are four structural components that limit the load you can put in your truck: (1) frame, (2) suspension, (3) axle, and (4) tires. The rear axle is really the weakest of these four...it has a Gross Axle Weight Rating (GAWR) of only 3760 lbs in
all Tundra models including the DC. An
empty DC puts about 2700 lbs on the rear; one with a full tank of gas and some people/cargo in the cab will have nearly 3000 lbs on the rear axle. Add 100 gallons (800 lbs) of water and you're right at or slightly above the rear axle's GAWR.
The Toyota engineers designed the rear suspension so that it's just about down on the bump stops when you reach rear GAWR. Yes, you could get the truck off the bump stops with an AAL (or air suspension, overload springs, etc.) but you've still got that light duty axle...which people have snapped with too big a load.
And, if you lift the rear of the truck, you'll partially close the Brake Proportioning Valve which means your not-much-more-than-adequate front brakes will be doing most of the stopping...and that in turn means very rapid front brake pad wear and a very high likelihood you'll overheat the front brakes, which in turn means that front brake shudder and vibration are in your future.
Finally, the rear frame isn't all that strong either...I've seen pictures of a Tundra with a cracked frame on both sides of the truck that was caused by carrying too-heavy a cabover camper in the bed. The guy who had that truck tried to solve his overload problem by using overload springs/AALs and didn't realize that the suspension wasn't the only weak component.
Quite frankly you'd be much better off with Timbrens...they're not much more than really big air-bladder type bump stops...so they won't do much for the rear sag (honestly, you don't want to get rid of that because of the brake issue)....but they will keep the frame and axle somewhat better separated on rough roads.
The bottom line is the rear suspension, rear axle, and rear frame are about equally matched in strength. If you increase the strength of the rear suspension in an attempt to increase your payload, you're just making the expensive components like the axle or frame the place where a failure is going to happen.