C4 issues

[jeffncs]

Researching this before I pull it apart…

Specs:
70 bronco, c4 that was supposedly running fine by PO with unknown mileage, tired 302, 32s, 3.50 gears

Symptoms:
Trans won’t consistently go into any drive gear (fwd or rev)
When it does, it seemed to shift as expected.
Last test drive, it went into gear but I had to give it a lot of fuel to limp home. Felt like the trans was slipping really bad. Once home I tried again, and the trans seemed to shift into gear again and work as expected (didn’t leave garage - just shifted gears and felt the trans engage).

I initially overfilled the trans at install which has since been corrected.

My planned next steps:
Recheck the fluid level after warm while running in P
Install new modulator
Measure vacuum pill at the modulator

Am I wasting my time? I have 3 more used trans in storage and know they’re supposed to be good...which was the same with this one.

Should I pull it for rebuild? Can I rebuild it myself (very mechanically inclined but never messed with auto)? Should I just trailer it to the trans shop and “pay the man”?

This truck will be driven by my wife and I dont want her stranded with a trans issue if I can help it…

 

[jeffncs]

ATF smells burnt which isn’t a good thing for autos…..

 

[Broncobowsher]

Shift as expected tells me the modulator is working correctly.
Sounds like the trans is ready for a rebuild. Burnt fluid and all the symptoms of burned up clutches and failed seals.

 

[nvrstuk]

Sorry to say but it's time to jack it up and R & R the trans especially since it's for the better half.

 

[jeffncs]

Thanks guys. That’s what I was expecting but not what I was hoping!

Debating taking this on myself. Should I take it to the shop or try doing it myself?

 

[Bajabrewer]

I did mine myself with the Badshoe video http://www.badshoeproductions.com/c4.html I would tell you to take your time & enjoy learning a new skill even if it's the only Transmission you ever rebuild.

 

[Broncobowsher]

C4 is a pretty simple transmission. Good choice to learn on. It is what we had at school for a transmission to learn on.

 

[nvrstuk]

There are so many good videos now as a resource compared to yrs ago. I say go for it.

Caveat is this: make sure you use a video that others have recommended as a friend of mine was watching a 400turbo video and caught a mistake that would have been costly. If you didn't know what he did wrong then you would have been in for high dollar rebuild.

Course we've all seen vid's where the guy checks crank brg clearance by trying to wiggle the crank. Star of the video said if you can't wiggle it then your brgs are fine.

There's guys on here that could rebuild them with their eyes closed so if you have questions ask away (not me).

Have fun.

 

[jeffncs]

Thanks to all. I’ll talk to the trans shop just to get an idea of pricing but I’ll likely tackle it myself. I appreciate the support and confidence-inspiring words!

 

[Torkman66]

The bad shoe video is outstanding. I had never built one and used his video. Had a couple questions and he responded with answers via email immediately. Highly recommended.

 

[skrit]

Thanks to all. I’ll talk to the trans shop just to get an idea of pricing but I’ll likely tackle it myself. I appreciate the support and confidence-inspiring words!

@jeffncs - if you have the time and patience and a some mechanical ability and tools, rebuilding the C4 should not be that difficult with proper step by step Youtube guidance.

That C4 I sold you a few weeks ago was running fine when I removed it. Reminder it has been sitting for 10 years inside my garage but the pan was not removed nor the fluids drained. I replaced a modulator at some point and changed the fluid when I had my truck running- that was it. I probably only put 500 miles on it before tearing my truck down to the frame but have no idea how many were put on before I purchased my rig. I hope it works for you.

I completely rebuilt the 4r70W I have. The hardest part was pressing off/on some bearings on shafts (without a press which I ended up buying), learning about acceptable part wear, fighting loads of snap rings and trying to put on lip seals without tearing them for the third time. I hope I didn't screw it up - time will tell once I get beyond the rolling chassis stage.

Here is my post on it:

https://classicbroncos.com/forums/threads/build-thread-1974-horse-with-no-name.322617/post-3538611

 

[73azbronco]

I did mine myself with the Badshoe video http://www.badshoeproductions.com/c4.html I would tell you to take your time & enjoy learning a new skill even if it's the only Transmission you ever rebuild.

So did I, turned out great. It would have been cheaper to let shop down street do it with 3 year warranty

 

[Bajabrewer]

So did I, turned out great. It would have been cheaper to let shop down street do it with 3 year warranty

I'm sure I saved money doing it myself based on the quotes I got from a couple local shops. Now after driving it for 2 Summers I want a 4R70w - I'll rebuild that if it needs it when the time comes.

 

[dmoses42]

Does anyone have any comments on the Transmission Bench videos for the 4R70W? I watched them during the COVID lockdown, and they look pretty straight forward, but I've never rebuilt a transmission before. Are they thorough enough? Any incorrect info?

 

[jeffncs]

So did I, turned out great. It would have been cheaper to let shop down street do it with 3 year warranty

Making sure I understand your comments….

The rebuild following the video was successful. BUT you’d have sent it to the shop instead? Why? (if you don’t mind me asking)

 

[jeffncs]

Any suggestions for C4 part vendors? Looking for a basic/stock rebuild. Nothing crazy but I’m willing to upgrade anything that should be improved while retaining the stock feel.

 

[jeffncs]

Any suggestions for C4 part vendors? Looking for a basic/stock rebuild. Nothing crazy but I’m willing to upgrade anything that should be improved while retaining the stock feel.

With this said - I’m going to throw the @skrit c4 into my truck. I may build the next truck’s c4.

 

[FordBronc]

Pull it and do it yourself, seems easy enough according to everyone else. Badshoe makes it look easy also. Then if it does work you saved some money and learned a valuable lesson. But if it does not work...at least you only have yourself to blame. Or your beer drinking buddies that helped.

Then if you then pull it again and take it to the "man". 1st question for the man would be what kind of warranty (if any) comes with a trans HE rebuilds, but the customer installs. That part might be the fly in the axle grease. I would like to know what he says.

 

[jeffncs]

Pull it and do it yourself, seems easy enough according to everyone else. Badshoe makes it look easy also. Then if it does work you saved some money and learned a valuable lesson. But if it does not work...at least you only have yourself to blame. Or your beer drinking buddies that helped.

Then if you then pull it again and take it to the "man". 1st question for the man would be what kind of warranty (if any) comes with a trans HE rebuilds, but the customer installs. That part might be the fly in the axle grease. I would like to know what he says.

Long while back I spoke with a shop about this same trans - he wanted $2500 for the bench build (“that torque converter is hard to get and expensive!”). Kicker - no warranty if I install it.

 

[FordBronc]

Yes that is generally the deal, if they install you get a warranty, if you install NO warranty. Interesting to hear that about the torque convertor and glad that I have a couple of spare C4's (w/torque converter) in my parts shed.