Vetteran'81

I am preparing to reinstall a Bosch Relay Kit from BTO on my 700R4. When I purchased this car the PO had installed a toggle switch which was used to manually lockup.

Why would that be an advantage on a souped up vette?

The Bowtie Overdrives rep seemed confused, and said that the override was normally used on trucks. He recommended that I just reinstalled the relay without the toggle. (Actually, without the manual lock power at all) Just using the +12V keyed on only wire.

Thoughts?

bobs77vet

i have a 700r4 and reason why you have a toggle lock up switch is to defeat the lock up system.....why would you want to defeat the lock up system......at 60mph or above you dont want to, at 50 mph you dont want to.....at 45 mph you are still ok......at 40 mph or below at light throttle pressure you are locked up.....low rpm.....and have not induced a forced down shift.....give the car light gas and it will stay locked up and you are turning 1000 rpm....... now if you punch it it will force a down shift so by using the toggle switch you can have the car use 4th gear and then lock it up manually when you are cruising

heres another scenario a windy back road that goes between 40-45 mph you can get lock up and then lugging as you go in between the speeds.....so using the toggle switch you go into 4th but never get the lugging, keep the switch wired in you will use it.


what is your rear end ratio? if its 3.07 : 1 you will definitely need the switch.

...Roger...

There are times you want manual control of the lockup.

7T1vette

It is an added 'feature' to be able to prevent converter lockup when you choose not to have it. If the computer programming logic for turning the LU on & off were written better, you wouldn't need a "defeat" switch. But, when you are on country roads going 45 mph and up and down small hills, the LU feature wants to constantly shift on and off and becomes a nuisance. That's when you would like to have a "defeat" switch on the system. Another instance [as mentioned above] is when you want to "use the engine". You don't need the lockup clutch coming on during a 'power' run.

Vetteran'81

Thanks folks.

I reinstalled the relay, and will probably reconnect the toggle in the future, once I actually get a feel for what LU is. With automatic LU enabled, I took it for a drive and couldn't really feel a difference. Your descriptions are helpful, but I guess it's something I'll have to experience to understand. It may not even be working, for all I know.

7T1vette

If your tachometer is still working, you can easily check out the function of the tranny lockup clutch. Just find an open stretch of [suburban] road with a few hills/inclines on it. Get to normal driving speed and keep speed constant. Read tach to see what rpm you are going at that speed. Now, when you encounter an upslope, watch to see if the rpm's increase as the lockup clutch is dropped [automatically]. If you have cruise control, it makes this test even easier. Just set the cruise at normal speed and then check tach on level ground and as car starts up an incline.

If you do not get a noticible raise in rpm (on the tach...maybe not by the 'seat of your pants' feel), your LU clutch may not be working. All the lockup clutch does is mechanically connect the two halves of the torque converter (pump & turbine) so that there is no power loss due to converter 'slop'. The valve body hydraulic circuits 'decide' when to engage and when to drop LU.

Vetteran'81

Thanks 7T1. I'll try that out whenever I get a chance to drive upstate and find a hill. Not too many of those around the Carolina Low Country where I'm at. Might be a good excuse for a cruise.

gkull

the answer is simple The TC lockup clutch plates are small in surface sq. inches and they have a torque and HP maximum power holding ability just like the guy with a manual tranny and a clutch/pressure plate.

So the Bowtie Overdrives rep seemed confused What is hard to understand? I found that as my power went up that just flooring the car while in lockup would instantly smoke the lockup function. So I bought $1100 dollar multi clutch lockup 9.5 inch racing converter and right on the tag it said: use manual lockup because damage can occur if shifted while in lockup.

That was a good converter that lasted for 4 years or so. But it also met it's match when I floored my Vette at 150 mph in lockup and the big 427 small block ate it up. I gave up and went to manual tranny which can withstand 1000 hp on a regular basis. so my little motor will never hurt it.

c69vete

You should not need GOOD excuse for a cruise in a C3, only an excuse!!!

Vogie

So far the discussion has been primarily about acceleration. If you manually lock it, don't forget to unlock it before you stop.

redwingvette

I found that the trans does not unlock as you slow down so if you are cruising down the highway at say 70mph and come to an off ramp you need to slow down to say 30mph, if you try to speed back up slowly the trans will not downshift and that can cause the engine to ping or chug. Neither is good. I first installed the toggle switch, which allowed me to unlock the convector. This worked well as long as you had a hand free to hit the switch. The other thing you could do is to manually downshift the trans yourself. I later went a different route; I removed the toggle switch and installed a B&M trans controller. The controller does not allow the converter to lock unless you are traveling more then 45mph and unlocks it if you slow down below that speed. It also is adjustable so you set the speed you want depending on your cars setup. It was a little pricey but it made the trans completely hands free.

bobs77vet

you described the problem perfectly and i think that the B&M trans controller is the best set up of all of them out there, and it was not available when i put in the 700r4. so like all the guys before me we adapted our installs.....or as one guy said i keep it in 3rd around town and shift into OD when i hit the highway.