O.K., put a new solenoid in my '88 and now the O/D works, sort of....

no response in 2nd and 3rd, O/D will engage in 4th, but only under the lightest throttle, feels almost like it's slipping. Goes back to direct drive real easy. There was a ton of metal bits and crap when the pan was dropped. Valve body moving parts were stuck. All has been cleaned up and freed up. New filter and Dex III fluid.

How is this system supposed to work when all is proper? Was there some sort of up date that eliminated the cable? Mine seems to be missing....

With the 3.07 rear end, mybe I'll just drive this thing like a 4-speed and say the hell with it till spring.

Any thoughts on the Termec 5-speed?
Jeff :banghead:

 

I was interested until I got to this part:
You're living on borrowed time. It sounds like you're hydraulic paths are still crammed with scrap metal. If it can't maintain enough pressure, it will disengage the planetary, and rotate as one piece.

 

:iagree: Either that, or it is so far gone that it slips under the torque in all gears except under very little pressure.

I hate to say it, but Eckler's sells rebuilt units...

 

:iagree:
And if your cable is missing, you probably don't have a hole in the tranny for it either, in which case, a latter model OD.

 

Thanks guys, Think I'll park it for the winter and figure out what to do next....

Driven the car 10 miles since buying it.

:banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

Jeff

 

Unplug the overdrive relay and enjoy the car in the first 4 gears for now.

 

Quote:
Any thoughts on the Termec 5-speed?

If you're really looking to upgrade consider the Richmond six speed. They make it so it's about as direct a replacement as you can get. It bolts up to the stock bellhousing so you retain your clutch/master cylinder setup. Every so often they pop up on Ebay or on the C4 Parts For Sale here on the Forum.

My .02.

:seeya

 

:iagree: Not fun for long freeway trips, but it won't harm anything but your gas mileage.

 

Yep, heck I know 4th is good for like 150mph @ 6000. :D Seriously though just make sure you have reverse gear because it is common for reverse to go bye bye if you have trashed your OD unit. If you still have reverse then I'd unplug the relay and enjoy it for now.

 

Tell me, is your O/D light on the tach coming on when the O/D works? Also is the light on when the O/D isn,t working? Unlike the 84 to 86 4+3s 87 and 88 O/D lights are operated by the ECM through data sent to the LCD which means the only thing that can be determined by the light is weather the ECM is trying to operate the O/D unit. When I first read your post that first thing that came to mind is weather or not you have the correct ECM PROM, it almost sounds like it's trying to operate like a locking torque converter. But it could be the O/D clutches are slipping and are not holding in the lower gears. This would not be hard to find out but what you need to do is see if the O/D is working or trying to. Just drive the car with the car at operating temp it should shift into 2nd O/D when shifting from 1st with light throttle, the O/D light in the tach should come on and the O/D relay should energize sending power to the O/D unit. If the light comes on then then try using the shifter switch to turn it off and on and see if the RPMs change. If they do not turn the O/D light on and bring the RPMs and speed up and let off the gas, see hard hard the engine slows the car down(this is engine braking) if you get little or no engine braking then I suspect the O/D clutches are burned and needs to be rebuilt. But if there is engine braking then you may need to replace the relay because I suspect it my be intermitten or inop.(there still could be other reasons for this but this would be the next logical step.). Now if the O/D light does not light up when you shift from first to second then you will have to look at other things like incorrect ECM PROM of bad first gear switch.
But check it out and let us know.

David Fulcher

 

pay attention class, this guy can fix it. Hello David, I'm going to check your progress on the ZR 1.....this week....

 

Hold on a sec... On my '85, the overdrive light comes on when the ECM closes the relay. (At least I think so.) So, if conditions are met, (not in first gear, not above 110 mph, not above a certain throttle level), the ECM will activate the relay, sending 12V to the OD solenoid *assuming the pressure switch is closed).

So, how is this any different from 87-88? :lurk:

 

You are correct, the ecm does control the OD relay in the 84-85, not sure about the later models. There are some changes from year to year on the OD control. The way I see it on the 85, the manual control switch turns OD control or operation over to the ECM. The ECM/prom then has the mapping for throttle and veh speed built into it that you refer to.. however I believe there is a mechanical failure with the amount of debris in the pan?

 

Sounds like I have more investigating to do.
Thanks to all for the help

Jeff

:seeya

 

The difference between 84 - 86 and 87,88 is that you can't go by the O/D light to tell if the relay is sending power to the unit. 84 to 86 O/D light is turned on by the same relay as the unit that terminal on the relay has two wires one goes to the O/D unit the other to the O/D light, light comes on power is going to the Unit, this is not so with the 87,88 there the relay only powers the unit you could have a O/D light on on the tach but have a bad relay and no O/D operation or intermitten operation. That is why I go about tracing down problems two differentn way. I also like to pass on some of my reasoning so people are able to have some kind of idea why I look at what I do. But you are correct the ECM does control the same relay from 84 to 88 but the light is not.

David Fulcher