'85 Bronco II Shudder at 45 mph

[ford4wd08]

Hey guys, have a weird problem I'm trying to diagnose.

My B2 has a weird shudder it has developed.

It only happens when I come to a slight incline at 45 mph and at a certain throttle position. If I give it more gas and up the rpms it seems to go away. If I let off the throttle completely and let it coast, it goes away.

It happens at 45 mph and will stay until around 50ish unless I give it more gas.

This is when I am in OD on the trans selector, but it is in 3rd gear.

Any thoughts? 2.8 carb with duraspark distributor and HEI.

The rig seems to be running great otherwise. I don't believe it is tire or wheel bearing related, and my driveshaft is brand new.

Could it be leaning out or something? It has been doing it consistently and I have done some carb adjustments (went from #48 -> #49 jets) and I got the timing set correctly after setting the lash on the valves. All of that had no effect on the shudder.

Only other thought I have is a torque converter shudder, but it is brand new in my recent rebuild adventure.

Any thoughts?

@19Walt93 @RonD @Uncle Gump

 

[black_demon69]

sounds like drive shaft related possible bad u joints

 

[Uncle Gump]

So it doesn't do it if you're on flat ground at the same speed/throttle position?

Does the TCC locks up normal outside of your described scenario?

Sounds to me like a perfect storm where the TCC doesn't know if it should lock or not. Light accelerator under load (slight incline).

 

[ford4wd08]

So it doesn't do it if you're on flat ground at the same speed/throttle position?

Does the TCC locks up normal outside of your described scenario?

Sounds to me like a perfect storm where the TCC doesn't know if it should lock or not. Light accelerator under load (slight incline).

TCC lock is controlled by me now with a switch, since it does not have a computer.

Now that you say that, I noticed it isn't working at the moment.....

But I have not been locking or unlocking the converter since I got OD back.

I did order some Lubeguard to try and see if that will help....

I'm starting to think it is TC shudder, I'll try locking the TC when it starts shudder next time with the switch and see what happens.

 

[19Walt93]

More info would be helpful:
What year is it
What transmission is it, it sounds like an A4LD
What RPM does the shudder happen and do you hear it as well as feel it
If the shudder starts and you let off on the throttle does it change
If you put it under load on flat ground does it shudder

 

[ford4wd08]

More info would be helpful:
What year is it
What transmission is it, it sounds like an A4LD
What RPM does the shudder happen and do you hear it as well as feel it
If the shudder starts and you let off on the throttle does it change
If you put it under load on flat ground does it shudder

It is an '85 A4LD 2 wire (only solenoid is for the TC lock).

No idea on RPM, I don't have a tach.

I don't believe I can hear the shudder, just feel it.

If I let off the throttle, it stops immediately.

I don't believe it does it on flat ground.

 

[97RangerXLT]

turn the o/d off and see if it still does it.

for the basics, check the tranny fluid and make sure that it is not low.

AJ

 

[ford4wd08]

I think I've confirmed it is TC shutter. Bump it down to Drive and it goes away and doesn't change gear.

Maybe the lubeguard will help. I'll check fluid level tonight and see if I need to add any.

 

[19Walt93]

Have you tried it with the convertor locked in 3rd gear? A scored servo piston bore can cause a shudder if my memory serves.

 

[ford4wd08]

Have you tried it with the convertor locked in 3rd gear? A scored servo piston bore can cause a shudder if my memory serves.

When I flip the switch on the servo, nothing happens. Maybe it is dead? I know it is not closed because it doesn't bog down when down shifting. So it must not be locked.

Also it is getting voltage. I confirmed that.

 

[19Walt93]

There's a kit to repair the servo bore but it's done as part of an overhaul and not for the inexperienced. I wish you luck.

 

[ford4wd08]

Bringing this back from the dead.

Still driving the B2 daily.

Still have a shudder at 45 on a incline. It seems to have gotten a little better, but still shudders.

I did some more reading on the manual and it appears the A4LD will hydraulically lock the TCC and the solenoid is more for fine tuning that timing. (see picture)

I dropped the pan over the weekend and installed a new one with a drain plug (no more ATF baths!). During this time, tested the solenoid by seeing if could here a click when I flipped the switch, it appeared to be making noise, so I left it be. It still doesn't appear to do anything while I am driving when I switch it on and off.

I did notice I no longer have a kick down. I believe that is because the core trans they use is from an '87 and my kickdown rod was from the '85 and not compatible. It kicks down from OD fine now because of the governor and I don't seem myself ever needing to really kickdown from 3rd to 2nd for the way I drive.

I'm wondering if installing a spring for anti shudder for the A4LD from Sonnax would be a solution....

Sonnax Ford A4LD Anti Shudder Spring Automatic Transmission

Check out the deal on Sonnax Ford A4LD Anti Shudder Spring Automatic Transmission at Oregon Performance Transmission

www.oregonperformancetransmission.com

Otherwise Bronco is running great and shifts great!

This frankenbronco carb and HEI setup has been a learning curve, it has been fun getting a late 70's carb to work on my mid 80's bronco. The accelerator circuit was different in the 70's and only had a check ball (or at least mine did) and a different screw that would not allow a weight to fit. I retrofitted my 2150A check ball, weight, and screw and the accelerating response is much better, I believe I was getting air in the system without the weight present.

 

[ford4wd08]

So... a few more updates....

I decided to buy and install the Transgo Jr. A4LD kit. Man, what a great kit and support!

I installed it over the weekend. I don't know why I let the valve body scare me, it was not that bad of a job. The instructions on the internet and Transgo's included instructions are great.

I am still having a small issue about the TCC, but have spoken to Transgo and they have given great support and recommend I upgrade to the newer 2 hole solenoid for the TCC lock up.

I did some googling and found a NOS two hole solenoid on Ebay for $40, seemed like a decent price so I ordered it.

It will be here in couple of days and I'm going to replace the modulator with a wheel for fine adjustment vs the screw type.

Unfortunately I have to drop the valve body again, but it is not that bad of a job. Was able to make myself a clean work area and follow the directions from Transgo.

 

[ford4wd08]

So update time...

My NOS 2 hole solenoid came from eBay.

I dropped the valve body yesterday morning and replaced my old one and it is fixed!

Now when I flip my switch my TCC locks and RPM's drop like they are supposed to.

So the biggest lesson I learned from this is that the pressure can leak past the solenoid even if it is on or off. Basically it was a mechanical issue with my solenoid and that was causing the shudder.

My original thoughts where if the solenoid was unhooked I had eliminated it from troubleshooting, but that is not necessarily true.

Trans does great with the Transgo kit in it too. I highly recommend it if nothing but for the directions and exploded valve body diagram alone.

 

[RobbieD]

I'm glad to hear of the progress that you've made with this truck. As much work as you've put into it, I hope that it's smooth sailing from here. B2's are fun to drive.