I think I got screwed, please help me out!

[Benzo]

Make sure the fluid is not peptobismal colored! If it is, the radiator coolent is leaking into the trans cooler in the radiator. This causes all kinds of weird shifting and other problems.

 

[Outshine2]

Alright... checked and the kickdown lever was in the up position where it should be. I traced the vacum line from the tranny to the engine and it was ok. Though, some of the caps on the vacum "tree" on the maifold were worn through and surely not capping much. Could this be causing a loss of vacum and causing the problems? I'm gonna run and see if I can find some more caps just to replace em anyways...

 

[Jeepster]

Rusty, do you know the proper way to adjust the modulator w/adjusting screw? Mine shifts hard. I'm thinking its got a shift kit but I'm not sure.

 

[Benzo]

Jeepster, <br>Sorry I am not rusty, but if you adjust the modulator out, it will lower your shift points and they shouldn't be as hard.

 

[Rustytruck]

If I remember right you screw it in to soften the shift. its been a long time since I've screwed with it so try it will be obvious. Also the truck comes with a modulator that is non adjustable ford unit with an orange/red stripe on it and a change to a yellow stripe will shorten the shift. The down shift lever must be tied up or it will move on its own causing erratic shifts. On a stock set-up the rod goes to the carb and is hooked to a lever on the carb with a spring attached. Take off the down shift rod and you have no spring and if you move the lever below you will feel a spring tension but it isn't enough tension. Internal tranny problems will normally show up as slipping when cold in the morning. Unless you hear bad noises or fluid dumps at your feet. The C-4 is a tough little unit if you have real problems take it to a good little shop and not a chain. The Bronco transmission is different than a car C-4 and you want a Bronco tranny back and not a recased car unit. If you have a stock Bronco Modulator with 2 ports and none of the smog stuff is there make sure you dont have full manifold vacuum to the smaller port. You want full vacuum to the larger port only the other port go's to a vacuum can as part of the smog hook-up or if you dont use this stuff then put a cap on the smaller port.

 

[Outshine2]

Rusty (or anyone!): I got the tranny to now shift fine between 1-2 and back 2-1... but it will not shift into 3rd no matter how far I wrap the engine up... would adjusting the screw in the modulator (I checked and it does have the screw) affect the shift point for going into 3rd, or does adjusting the modulator just affect the crispness of the shift? Thanks again to everyone, im feeling better about this, slowly ;D

 

[thesnake]

All I can offer is to try what has been suggested. It sounds like you still came out okay on this. Good Luck.<br><br>snake

 

[Hnrys69]

Did you ever trace your vacum?? Sounds like vacum to me. At least thats what mine did when it was having probs going to 3rd.

 

[Guest]

A vacuun leak in my intake manifold caused the exact same problem in my truck. I'd have have to agree with everyone else who say it sounds like a vacuum leak. The kickdown can def. cause problems, there really is no such thing as a "passing gear" the kickdown increases line pressure making the trans shift to a lower gear. It is not intened to be an on off kind of operation. On all the c4s I've had it is connected by a rod, this rod moves when the throttle moves increaseing line pressure at the point of enough pressure it will make the trans shift. You can drive a c4 without it personally I would not recommend it, an AOD trans work similar, but driveing it without the throttle control valve cable (same operation as the kickdown rod) can be deadly to the trans. As for the deal you got on your Bronco, at my body shop we charge atleast $2000 for a paint job as long as its no color change. I'd say you got a good deal.<br>Don't won't to step on any toes, but Weber makes Edelbrock carbs. The name is cast into the carb body, it is in my anyway. <br>Keep the faith.<br>

 

[GRIZZLY]

If the truck hadn't been used in a while, the vacuum hoses may have deteriorated to the point where when you put some run time on it it popped a hole in one somewhere.

 

[Jeepster]

The modulator takes the engine vacuum signal and uses it to control the shift characteristics, so if vacuum is low (because the engine is out of tune or because there's a vacuum leak), the transmission will behave as if the car is being accelerated and "stiffens" the shifts. With the engine idling, disconnect the vacuum hose and feel the hose end for a strong vacuum (at least 13 in. if you want to check with a gauge). Also test for a leaking diaphragm by inserting a cotton swab into the neck. If there is any transmission oil on the swab, the diaphragm is leaking. Replace the diaphragm unit. <br>

 

[74bronc]

[quote author=Outshine2 link=board=5;threadid=9416;start=45#67720 date=1032835342]<br>Rusty (or anyone!): I got the tranny to now shift fine between 1-2 and back 2-1... but it will not shift into 3rd no matter how far I wrap the engine up... would adjusting the screw in the modulator (I checked and it does have the screw) affect the shift point for going into 3rd, or does adjusting the modulator just affect the crispness of the shift? Thanks again to everyone, im feeling better about this, slowly ;D<br>[/quote]<br><br>I am assuming you have reverse on your C-4? I am just trying to eliminate possibilities. I think it is going to come down to a vacuum problem or modulator problem. I have the adjustable modulator in mine and it is killer.

 

[Outshine2]

Yeah, reverse works just fine. I did a check yesterday and alot of those rubber caps on the carb and vaccum tree had deteriorated so I replaced those. I traced the line from the manifold to the tranny and it looked fine. I'll have to pull it while the engine is running and feel for vaccum.

 

[Outshine2]

Ok, i pulled the hose with the engine running and felt alot of vaccum. Checked both the inside of that hose and the inside of the modulator and there is no fluid in there. I'm not too sure how to check for a vaccum leak except maybe get some carb cleaner and spray it around the base of the carb and manifold with the engine running? Also, when the engine is cold the tranny will not shift out of first at all... till it's run for 3-4 mins then it will start shifting on it's own...

 

[SpaceRanger]

Your starting problem definetly sounds like the automatic choke. I also have a 75 Bronco 302 with electric/automatic choke and C4 transmission. First I would check that when the engine is cold the butterfly on the carb is also closed. If it is, start it and let it warm up. It should open all the way up when warm. If it doesn’t, which often causes the problem your describing, your mixture becomes to rich essentially flooding the engine. If it’s not opening all the way shut it off and loosen the three screws and turn the black cover clockwise and counter clockwise to see if the butterfly moves. If it’s not, then internally it is not connected properly or in some cases I have seen them completely rusted out inside. If it does move, you may just need to adjust the butterfly to open or check to make sure that wire feed is also suppling current.<br><br>Hope this helps.

 

[Jeepster]

if you want to buy a tool...get a vacumm pump

its very handy with things of this nature. you can check lines for leaks, the modulator to see if it holds vacumm. lots of other things. suspect the modulator...its the cheapest and ez fix right now, if not you might have dirt or something in the pan.

 

[Rustytruck]

I still think it is a modulator issue When the modulator goes out the system reverts to govener control and it just wont shift untill the system builds full pressure at high RPM when and if it does shift it will scare the crap out of you. You need the vacuum off Idle too, not just at Idle only. The modulator moves a rod and then a shuttle rod in the valve body that may be stuck in the casting. I would put a vacuum guage on the system and see if you get good high steady vacuum at Idle if not something is leaking vacuum or the carb and or timing is way off and will have to be dealt with first. Get the engine running right before sinking any money in the tranny those problems can easily be causing your tranny problem. If you have an EGR valve make sure it isnt stuck open.

 

[JTCamp]

Sorry to chime in on this one, but Rustytruck I've got a question. My 302/C4 has 2 vacuum lines hooked up to the manifold with a t-connection. They both run to the modulator, small and large ports get vacuum from the same place. Shifts really rough, also my modulator has a red stripe with a screw on the body of the modulator. What does all this mean? I thought the screw adjusted it, but now I'm not so sure...and the vacuum lines, whoa. <br><br>John

 

[Hnrys69]

You can use a propane torch to test for vacume leak, dont light it and turn it on real low.... Listen for rev changes as you move it around the lines and fittings..

 

[TahoeBRONCO]

all this help is pretty cool huh!<br>like to see it (bronco brotherhood)<br>Hope your chillin <br>I still think you got a much better deal than I did,and others I know.<br>I never decided to have an EB for a primary vehichle.<br>GoodLuck<br>TB