ok this is kind of a newb question that i should know the answer to but dont so here it goes. i know what a lock up switch is but how does it work does it allow the trans to shift normally ie. up and down gears while always locked? or does it lock the converter so the trans is locked and cant down shift????? someone please explain it to me thanks. also what are the pros and cons of having one thanks

 

A lock up switch will let the trans shift locked up 2-3 and 3-4. A stock VB won't shift from 1-2 locked, I wouldn't recommend shifting from 2nd to 3rd locked.. 3rd to 4th probably OK. You can manual downshift the trans in lock up otherwise if you leave it in drive you'll stall the truck when coming to a stop, probably not the best thing to do on a stock trans.

 

I know a lockup switch is also beneficial when going down steep grades; allows you to lockup in 2nd and 3rd.

I found that when pulling up steep grades in 3rd and 4th I was fine, but when I had to go down to 2nd the tranny temp climbed rapidly. Same going down hills in 2nd. Would a lockup switch help me in this regard, by locking up 2nd gear and keeping so much heat from building up?

 

Sure, anytime you're in lockup will prevent heat buildup. I would manual select 2nd gear before hitting the lock up switch.

 

Mike is right on the money. That's one of the main reasons why I installed one in mine. I have a modified valvebody from Dave Goerend and mine will lock the converter in all gears. I've never been brave enough to use it for locked shifts as the tranny still has stock shafts in it, plus I see no reason in doing so.

I have found it very bennificial when towing the 5er in the mountains and it also helps when making runs on the dyno.

*Just remember if you do install a lock-up switch,,,,,,, it raises the risk of operator error by not using it properly. (NOT a pretty sight or sound if you forget to turn the switch off when coming to a stop! ,,,,,,, Don't ask me how I know,,,,)

 

How do you know Dennis? Sorry, couldn't help myself...

The shaking and the black smoke coming out the tailpipe will remind you pretty quickly to turn the switch off.

 

Ill be installing a Goerend VB modified to lock the converter in all forward gears soon in mine. The problem with the stock VB, is that the converter wont lock if you hold it in manual 2nd gear which means it will want to shift to 3rd. If you use them right they are awesome though . Of course i dont know if I use it "right" or not. I run locked 2-3 and 3-4 shifts at the strip with stock shafts, and plenty of beating on the street too Im sure its only a matter fo time. I just have to fight the urge to lock it in 1st and let it shift now when I get this VB in. I will use it when hauling hay and stuff in the summer though. Idling around in 4 low gets my tranny hot. If I can lock it, and idle around in 1st, it should stay much cooler.

Eric

 

The factory v/b up until 2002 has to be modified to allow 2nd gear lockup even with the lockup controller. 03+ with the 48RE will have 2nd gear capability, but you need to force lockup.

 

Not sure what your saying Pat?

Maybe it's something DTT does (I doubt it) but my 02 tranny locks in second. I came down off Pikes Peak in second at about 8500 lbs, and could have made it all the way with no brakes... if not for traffic!

RJ

 

Modified VB's will lock in 2nd...but factory ones won't.

Which reminds me, I need to call DTT and get a VB coming for mine
Chris

 

If I'm at a dead stop and flip my lockup switch, as soon as the tranny shifts into 2nd gear it locks up and will stay locked through OD.

Chris, I've already got one and hopefully in the next couple of weeks I should have the tranny.