K3500 with nv4500 bucking when going into 1st gear

[GreenMonkey]

So I recently picked up a 1998 k3500 with 454 and nv4500. Been driving it and fixing things as I go. The other day i was leaving (cold start), and as I was letting the clutch out in 1st gear, it started bucking pretty bad and seemed like the rear wheels were locking up some too. I did manage to get it through the gears and drive it normally after that. Didn’t give me an issue anymore that trip. However, this scenario happened again yesterday and it seems like it’s a little worse this time. I’ve changed the fluid in the tranny, transfer case, and rear diff since I’ve owned it, and nothing looked bad when I drained them. Engine idles good and runs smooth. Clutch seems normal outside of these instances. Has anyone else ran into this problem? Thanks in advance for your help.

 

[Schurkey]

Wheels spinning on snow/ice/gravel?

Verify fuel pressure.

Connect a scan tool, assure no misfires recorded; check for "codes", and look at the data stream especially while the truck is "bucking".

A grabby clutch when cold is a sign of contaminated friction material. But about the only way to verify...is to remove the trans and inspect the clutch disc/flywheel/pressure plate.

 

[GreenMonkey]

Thanks for the reply Schurkey. Little update on the issue since I’ve been out looking at it today. Everything is operating as normal when in reverse. However the driver rear wheels (dually) are locked when in a forward gear. So I’m thinking there is a braking issue at hand. I’m about to pull off the rear wheels and drums and see what I can find. Will report back afterwards. Thanks

 

[GreenMonkey]

You must be registered for see images attach

You must be registered for see images attach

Here’s few pics I got once the drum was off. Nothing sticks out to me as bad, but I’ve only done drum brakes once before. Do you guys see anything that would cause a wheel to lock up. Thanks

 

[GoToGuy]

Did you try to simulate the condition with the wheels off the ground? Did the wheels turn when jacked it up? If they move at all it's not the brakes. Worn out clutch down to rivets or metal on metal is " grabby, jerky " when going from stop to start moving.

 

[Schurkey]

1. Does the park-brake work like it should? Grabs when engaged, releases fully? Park brake cables aren't seized or overly-stiff?

2. Are the contact pads on the backing plate worn by the edges of the shoes?

I'm not seeing anything obvious except that the park brake doesn't look like it's FULLY releasing.

 

[GreenMonkey]

When I got the truck, the parking brake didn’t function as it had so much slack and was also corroded. I removed the front cable and cut the driver cable just behind the backing plate until I could get the new ones installed. Been driving it with no issue after that until two days ago. The cable you’re seeing in the pic is severed just on the outside of the backing plate. Would an unconnected cable be able to hold parking brakes? Anyways, my new cables came in this past week, so I’m replacing those while I’m in there.

As far as the backing plate pads, there is some wear. I’ll attach a couple pics as I’m not sure if it’s normal or too much. Thanks for any guidance on this issue. I’m no mechanic, but doing my best to get this road worthy. Thanks.

 

[GreenMonkey]

I figure it wouldn’t hurt to get some new backing plates. But I’m unable to find any for sale. Where are y’all getting them, or is there a way to repair the existing ones?

 

[HotWheelsBurban]

I figure it wouldn’t hurt to get some new backing plates. But I’m unable to find any for sale. Where are y’all getting them, or is there a way to repair the existing ones?

Probably the wrecking yard is your best bet on backing plates. One of the bad things about owning and repairing the big trucks (8 lug 2500/3500s) is there weren't as many of them made as the half tons, so parts are more scarce to begin with. Then factor in that these were, and still are, work trucks and so got the snot run out of them on a regular basis. So a lot of the parts we now need are worn out, or close to it, and the supply of replacement parts has been depleted too....
My one ton is in very good shape, being a South Texas truck all its life and having low mileage. But I do see it as an investment and plan to upgrade a few things, and be sure it's properly maintained. We're having a rainy streak for the next several days, so an oil change is in the plans once it's dry again (I have to work on my trucks in the driveway).

 

[0xDEADBEEF]

Bucking in 1st gear is pretty normal for a manual transmission. Holding a constant speed at lower rpm in 1st and sometimes 2nd is going to buck some.

Does it go away if you just throttle through it? If so, I would say it's normal.