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When rolling is wrong... Line locks

scottystills

scottystills

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So after tearing some suspension off the frame, I finally finished mending the frame and restructuring the xmember with a lot of reinforcement. Rolled it out of the garage onto the drive to bleed the steering (also fixed the cracked frame and put in the ORD frame repair). Long story short, hopped out of the truck, in gear with the engine off - no parking/ebrake - and it rolled very very slowly down the grade of the drive.

Thoughts on the likely culprit? In my mind it's either a wildly slipping clutch (felt fine on my test ride) or a devastating loss in compression. Both obviously mean I'm not wheeling this weekend, but also need quite a bit of investigating so figured I'd get the CK5 team's opinion before I start tearing into it.
 
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transfer case engaged..?:whistle:
 
If it drives okay, I'd rule out a compression problem. Transfer case in neutral or clutch engagement would be my bet.
 
Yeah I wouldn't over think it. I never understood why people park in low gears. Wouldn't you think 4th gear would put more resistance against the motor instead of giving the weight mechanical advantage over the engine with a low gear ratio?

Or am I thinking about that backwards?
 
Ya other way around. If you think about it, in a low gear the engine needs to turn say 5 times to turn the wheels once (just an example don't check my math!). In a high gear the engine needs to turn once to turn the wheels once (again, example).

Going the other direction, in high for the wheels to turn once the crank would be turning at the same speed against the compression of the engine. In a low gear the engine would have to turn at a much higher speed against the compression in order to turn the wheels once.

Ah well eff it. No sense ripping everything apart if there's nothing major wrong. I've already got to do the output seals on the tcase and tranny this weekend, and do some work on the fuel system (seems I have a backflow problem somewhere). Why create more work.

I'm going to order some line locks for the brakes and not worry about compression or clutch until there's a noticeable issue.
 
Backwards...

The lowest gear will hold it back more and prevent it from rolling ,than a higher gear will..think about it--why is a pinion mounted disc brake so much more effective than regular disc or drums on the wheels?..
Because the gearing in the diff forces the pinion to spin several more times per revolution of the wheels,which makes it that much more "powerful"..same principle applies to the gearing in the transmission...this is why a tiny disc brake on a winch can hold back the rated capacity of the winch,its mounted after the gearing,which multiplies the braking effect..

I'd put a SM465 in "granny low" or reverse to take full advantage of compression braking...however,even an engine with good compression will still fail to hold the vehicle,if the incline is steep enough,especially if the valves let compression "bleed off" a bit...
 
I always try low first, but if it's not lined up I get lazy and just throw it in first. Which is 95% of the time. Usually no problems.

Had the same thought about the valves, especially since the "paper towel incident"
 
If you put it in granny low AND low range,it'll be that much harder for it to roll...I once lived on a steep hill that had a 45 degree incline,I had to use low range when I parked my 72 K5 there and always remember to turn the wheels towards the curb,if I wanted my truck to be where I parked it the night before,when my E-brake wasn't useable!.
..one night I parked it and put it in "first" (not granny low),and it rolled "gently" into the car parked in front of me during the night--no damage done,but my upstairs neighbor,he was pissed,woke me up at 4 am to tell me "You HIT my car you bastid",and I had to go move it so he could go to work!..:doah:...
 
HA! Yep we've all had a few mishaps along those lines I think!

This is why I'm shopping for line locks today. I'd really like to get the electric type, but is there such a thing as normally closed line locks? ie that will stay engaged with the ignition turned off? I like the electric ones so I don't have to run lines into the cab, but then they don't do me much good for parking...

Edit: Actually found these guys for hydraulic trailer brakes.

http://www.bobstrailers.com/150_Brake%20Controls.pdf

Top of page 7. Think they would work if i were able to get the adapter fittings? They're lock outs so the brakes don't get engaged, not sure if they'd be able to hold pressure if they were engaged with the pedal depressed. But I assume if they can block braking pressure on one side of the line, they'd be able to hold it from the other side.
 
I dont have much experience with line locks,other than one a ramp truck we had at the junkyard had on it--it couldn't be trusted to hold the brakes applied for a long duration,it was probably well worn though,we sometimes had it "release" enough while loading a vehicle on the ramp to cause some butt clenching moments...the one we had,you had to step on the brakes,then flip a lever to "lock" them on,I think it was manual,not electrically controlled..

Anything electrical is prone to failure--those solenoids you linked too ,do they "hold" when they are energized,or when they shut off?...if they hold when "on",you'll be draining the battery ovenight,and they might heat up and fail--if they hold with no voltage,if they lost power while driving,that would be very inconvenient..:eek1:...

I dont think I'd trust a line-loc to hold the brakes on overnight--more like a few minutes...but I'm no expert on them,others here might know more about them..
 
diesel4me said:
if they hold with no voltage,if they lost power while driving,that would be very inconvenient..:eek1:....
Click to expand...

That's actually an excellent point I hadn't considered. The normally closed ones would hold with no voltage, great for parking overnight, but disaster if they lost power while driving you're right. I guess one could put in a 12V ATV battery or the like with an override switch in case of an emergency.

The normally open ones would just act normal and lock when energized. Either the other SKU on that list or something like these launch controls

http://www.summitracing.com/dom/parts/bmm-46075/overview/

The reason I'm looking at electric is just for ease of plumbing. Running some wires is no issue, but to use a mechanical valve like these

http://www.summitracing.com/dom/parts/aaf-all48010/overview/

would mean cutting either some hard lines or maybe just some braided lines into the outputs of the proportioning valve into the cab. Granted I could probably mount them on the floor maybe behind the shifter to make it easier, but still a PITA.

I'm really not too concerned about it for parking; leaving in gear really isn't too much of an issue as long as I'm making gear selection properly. I have found having no ebrake while winching can be pretty damn annoying. Also not willing to spend $500+ to replace rear calipers to get a cable brake. Buying two of these for $50 each and maybe $30-40 in random stuff to lock front and rear up is pretty tempting though!
 
I used to have an electric line lock, worked great. Accidentally left it on for at least several days a bunch of times (maybe a week) and was still holding strong. Not a good long term parking brake, but worked well short term.

Now I'm using a ball valve like the one posted above, they're more expensive to plumb in but I like it a lot better. We have these on several rigs at ORD and they get used (misused) as long term parking brakes all the time and I've never seen one fail. I wouldn't trust it with important things downhill long term, but they're cheaper than mechanical parking brakes, work WAY better (they can make 100% of your normal braking force) and they don't have a battery to draw down.

Honestly, I'd trust the ball valve more than I'd trust a factory mechanical e-brake, I've had those pop loose on several vehicles. Again, not for weeks/months, but they work really well.

Of course, they aren't emergency brakes and don't pass inspection if they require that. But they are excellent (especially short term) parking brakes.
 
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Fortunately inspection is well in the past, and around here you don't get another one unless something goes HORRIBLY wrong and the police force it on you.

Any preference between Allstar, Keyser, or AFCO?

Edit: Nm, ordered the Allpro one, just because it looks like it has a better handle and it'll mount through the floor onto the tunnel by the shifters. Fingers crossed.
 
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