Auto transmission slow acceleration and low top speed

[mgbman]

Hi from England.

I have a 1980 T25 Vanagon Devon pop top with CU engine, twin pdsit carbs and 010 Auto transmission.

I got the van as a project to restore during Covid and there were a lot of issues to fix.

Today, I would like help and advice about the auto transmission which is not working at all well.

The ATF was dark brown and smelling of GL5 axle oil and I drained the ATF and refilled a few times to get it back to red, I am using Dexron 2. I dropped the pan and changed the filter, which was clean and no metal on the screen.

Driving the van is no fun. The acceleration from stop is very slow and it does not change up or down correctly and kickdown not working ever. The maximum speed with pedal fully down is 35mph and less up hill. Selecting manual 1 or 2 makes no difference, it still struggles even with the pedal fully down and carbs fully open. The engine revs happily to maximum revs but not when put in Drive. The compressions are all around 150psi.

The van has done 105,000 miles and transmission looks original and its covered in oil and leaking fluid.

So where do I go from here?[/b]

[Wildthings]

What does the fluid in your final drive look like? Sounds like you may have had mixing of the ATF and the gear lube, if so you need to pull the tranny and replace all of the various seals that separate the two fluids, this job is not hard but care must be used to make sure the proper adjustment for the ring and pinion is not lost. The one small seal on the pinion shaft needs to be removed with great care as well as there is a little check valve hidden below it that is easily damaged.

The shifting of the 010 is very dependent on the throttle rod between the transmission and the carbs being the correct length. A 1/16" or 1mm difference in length is huge.

[MarkWard]

How does it roll in neutral when you and a friend push it? If the brakes were dragging it could cause problems similar to what you describe. If the trans were slipping, the symptom would be high revs with little acceleration. You are describing low power and poor acceleration.
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[mgbman]

One of the front callipers was stuck on, so replaced both sides. Now both wheels spin freely.

Rear brakes replaced and one side did get hot to start with, readjusted and now both wheels spin freely.

When I got the van, the accelerator pedal was cable tied and very slack cable and the carb butterflies were not opening much, replaced the pedal and tightened the cable to give minimal slack.

With pedal up, the auto lever arm rests at the bottom position, full pedal down to the floor moves the lever arm to fully up and the carb butterflies fully open.

The rod to the carbs is tight with little slack and setting the idle speed below 1400rpm is difficult. Any lower then the engine stalls when Drive selected.

Any advice please on how to correctly adjust the accelerator cable, arm position and carbs rod with spring adjuster?

As suggested, I also suspect mixing of the ATF and axle oil, I will check the axle oil level and condition.

[MarkWard]

We didn’t get carbs in the US, but you should look at how the factory connected the automatic to the fuel injection throttle body. Then look at how it’s adjusted. You need a way so you can have the butterflies full open before the automatic relay lever hits its stop. Vw used a spring loaded rod between the auto and the throttle body to accomplish this. The relay lever on the side of the automatic controls shift points and kick down. You’ll need to mimic that setup.

If you open the differential fill plug and fluid spills out, that indicates the unit is mixing fluids.
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[mgbman]

That's great, thank you.

I am new to the auto transmission as the first Vanagon and late Bay were manual transmission, where the pedal and cable to the carbs was simple and easy to adjust.

The accelerator cable to relay lever and carbs rod with its spring setup is not easy to understand and adjust so I am learning.

As I understand it, accelerator cable adjustment is at the pedal pivot and I could increase the cable tension so that the relay lever is off the bottom stop and then adjust the spring thingy at the carbs to ensure carbs open fully and the relay lever is below the stop.

So the carbs are fully open about 3/4 pedal and pedal fully to the floor should engage kickdown.

Does that make sense?

I will undo the 17mm final drive plug and inspect the diff oil and change the ATF again to try to get it looking red and clear.

[wesitarz]

They run like shit if the kickdown is not adjusted properly.

[mgbman]

I have no kickdown at all.

[Wildthings]

The arm on the transmission helps determine when shifts occur, the further forward it is the later the shifts occur. In adjusting the length of the rod between the transmission and the carbs you are looking get enough revs out of the engine to get good power but not have the tranny remain in the lower gears longer then necessary. If the engine doesn't respond to the throttle as it should it can be hard to get the rod adjusted satisfactorily.

FWIW my dad had a mid 80's Chevrolet with a V6 and an automatic that didn't seem to be working well at all. I took it in to the dealer and the shop foreman chastised me for not maintaining the engine correctly telling me I needed to add FI cleaner to the fuel from time to time. I thought he was nuts as the engine seems to be running fine and couldn't see how adding fuel injection cleaner to the fuel was going to fix a tranny problem, but I headed to a FLAPS and bought some fuel injection cleaner and within a mile of driving after adding it to the gas the transmission was shifting just fine. I really couldn't detect much difference in how the engine ran, but the transmission apparently could.

[mgbman]

The brakes sticking would not have helped, all fixed now. The engine had low compression on cylinder 1 due to hydraulic tappet not adjusted correctly. Fixed that and all compressions are good at 145 to 150psi.

Mechanical fuel pump was not delivering enough as the rod was worn down, fitted a new one and fuel delivery now ok.

Accelerator cable was very slack and did not move the relay lever much even at full pedal and carb butterflies never opened much. Most of the pedal was taking up the cable slack.

The ignition timing is spot on and all plugs are good and firing as they should in the right order.

The ATF is contaminated so the auto transmission will need repair or rebuild soon.

Just need to get the accelerator cable and relay lever position and rod adjusted so I can drive it and enjoy it.

[?Waldo?]

Isn't the CU engine the 1.6L air-cooled (basically a bug engine)? I can't imagine how ungodly slow that would be hooked to an automatic even functioning properly. Probably slower than a 1.6 diesel with a manual trans. Even still a top speed of 35 on flat ground sounds wrong.

[brickster]

[Wildthings]

The Vanagon Type 4 engine had a CV code, at least in the US. Pictures of you engine would help in identifying it.

[mgbman]

Very helpful suggestions thank you. I have the Bentley manual but the cable and rod adjustment procedure is not easy to get my head around.

You are lucky in the USA as you have many Vanagons and Bays with auto transmissions so more shops and more parts.

In England, things are different, very few autos and few shops to rebuild them.

So thank you for all your input and help.

The van restoration has been challenging and wish I had sorted the mechanicals first and then do metal and paint and interior. Lesson learned.

I saw a few clips on Youtube for the 010 tranny rebuild so I am learning.

When I drained the ATF for the first time, it was cloudy and very dirty so the governor and other internals may well be clogged with fine debris.

VW Heritage here sells the seal for the governor cover so I will look at doing that.

It is frustrating as the engine is a good one and sounds and revs sweet.

I found a few vacuum leaks and sorted those but have not removed the carbs and cleaned them, they would have some fine rust from the tank.

[mgbman]

Reverse works fine so assume atf pressure is good.

Van accelerates well from stop and shifts up but maybe too early. Going up hill it struggles and shifts down late.

maximum speed on the level is about 35mph and uphill can be as low as 5mph.

Selecting 2 or 1 going up hill makes no difference.

Going up hill is very slow and feels as if its in too high a gear so engine lugs and full pedal does not improve it. Engine runs slow even though pedal fully down.

Its the 2l CU engine and more than adequate for the van, the previous van had plenty of power and would accelerate and cruise nicely with the manual transmission/clutch setup.

This van feels as if the auto tranny or torque converter are wasting the power.

Bentley mentions a stall speed test. Is that worth doing and what would it tell me?

Removing the governor and cleaning it is suggested, but how do I remove it, is it straightforward to do.

[Wildthings]

For a couple of decades all VW boxer torque converters were physically interchangeable, but performance wise were very different. If you take a torque converter from an early aircooled car and install it in a heavy Vanagon the performance is going to be very poor. VW even recommends replacing the factory TCs used in the air cooled vanagons with the ones that came in the later watercooled Vanagons. Pretty much when a 2.1L WBXer engine is running at wide open throttle the engine speed is never below 3000 rpms, whereas the earliest TCs would at lower speeds hold the rpms down to 2000 rpms greatly limiting the power available at the wheels. Someone may have swapped to a longer set of gears as well, again limiting the power available at the wheels.

I think you want a TC with an "X" or and "H" stamped on one of the mounting lugs. Don't know how to determine which set of final drive gears you have without doing a tear down.

[mgbman]

That's very interesting to learn thank you. I must get underneath and check the TC code.

Somebody suggested doing a stall test and its mentioned in the Bentley.

How is this done and could I do it myself.

[brickster]

[mgbman]

Thank you for the advice, will do. Yes I can see the governor cap with spring clip. Its leaking a little, I assume its the cap O ring seal.