Dakota differential in B4B - emergency brake & fluid drive

[Bobacuda]

I swapped the entire diff in my B4B (fluid drive) with one out of a 1990 Dakota to have available, less expensive parts, a wider range of gears, and rear wheel emergency brakes rather than the band around the drum on the end of the transmission.  BTW, I salute those of you that can make the original band-on-the-end-of-the drum e-brakes work without fear of failure, but I have never been able to keep them working longer than a few months at best.  I live in an area full of hills and I am tired of always looking for something solid to park against, or bringing wheel-blocks around and hoping I get them set before the truck rolls off.

 

So, I obtained an 8.25 diff from a 1990 Dakota, 2 wheel drive, V6.  It has the 9" drum brakes.  I moved the mounting brackets, rebuilt the brakes, rerouted my e-brake cable from the cab (my truck has the handle under the dash, not a lever through the floor), and custom made a few brackets to hold the cables.  Once I got it all hooked up, I pulled the e-brake handle, and it moved about an inch - just enough to snug the cable.  I cannot pull it far enough to set the brake shoes in the Dakota diff. 

 

I know the cable from the handle is free and not binding and that all of the hardware (including the e-brake cables from the drum brakes) are new.  However, the pull required is impossible for my original e-brake handle at this time.  It is even hard to pull the e-brake lines to each rear wheel by hand.

 

If my truck were not a fluid drive, I would just put the old e-brake back on and accept that I could never trust it to hold my truck on a grade, especially with a load.  I still have my original e-brake, I can pull out my shop manual and put it back on, and it will fail again.  I would rather have  fairly modern, functioning e-brake.

 

Has anyone else swapped out the diff in a fluid drive truck and run into this problem?  If so, how did you solve it?  Looking for real world experience and advice.

 

Thanks in advance.

Edited January 26, 2015 by Bobacuda

[Plymouthy Adams]

I have done three such swap and did not have issue with the hand pull being unable to set the brake by hand.  What kind of  cross over did you use and what style terminator did you use for the brake cable coming out of the rear brake housing? 

 

As a PS edit here, have you verified that the cables are not pinched anywhere along the way...it is not uncommon for the original cable to get messed up and did you verify the action of the  cables in their housing on the Dakota donor....rule these out first I would think..

 

on my setup I made my crossover out of captured cable with roller bearing bracket and roller/guide..they are built that even if cable is completely slack they will never bind anywhere within the roller assembly/bracket.  My center pull also connects to the original front cable at the transmission by the construction of a special fabricated mount. 

Edited January 26, 2015 by Plymouthy Adams

[Dodgeb4ya]

Not sure why you could not get your'e brake band to work.

There are thousands of chryslers and desotos...all with the fluid coupling and must have a good working E-brake band.

My cars all do. The brake bands work very well.

The brake band system only requires a straight shot pull handle. The leverage is built into the brake band pivots.

 

The rear axle style e-brake system has the leverage built into the e-brake pedal assembly or the backing plates or a leverage transfer bar just rear of the transmission.

 

Regardless now you will have to figure out a hand or pedal E-Brake with the proper leverage ratio so you can hopefully park safely and not against a curb with the new dakota rear end.

 

Modifiying these old cars  can sometimes be a long frustrating learning curve.

Bob

[tom'sB2B]

I have the same set-up and the same problem. I don't seem to get enough leverage with the pull handle to engage the drum brakes. I've wondered if the older floor handle would work. I'm still using the original brake and a block. Hopefully you find a solution.

[Jeff Balazs]

Bob put it pretty well when it comes to mods on these. I too have a fluid drive truck with a later rear axle. I am using the original E brake which I had re lined but the adjustments are a bit fiddly to be truthful. So far so good...... but it could be better.

 

I think if you want to use the E brake function from your later rear axle you will have to build some intermediate linkage to help gain the leverage required to actuate the brakes. It could be something similar to the lever linkage bolted to the original E brake actuator. If you study what the factory did the cable from the hand brake in the cab goes to a lever which incorporates a mechanical advantage as it actuates the brake. You can't eliminate that lever and expect the brake to actuate as easily. I am sure with some experimentation a lever system could be fabricated that would allow the original handle in the cab enough advantage to be used to actuate the new E brakes.

 

Jeff

[Bobacuda]

I appreciate everyone's input (and sympathy) and I will probably do some further "engineering" in the future.  But for right now, I am on a deadline to get the truck back on the road for my son's wedding in April.  I have re-installed the original e-brake and will be adjusting it this evening. 

 

BTW, my digital shop manual has a terrible, blurred photo of the e-brake with the components named, so if anyone has a clear photo of the fluid drive e-brake with the components named, I would appreciate it if you would post it.

Thanks to all,

Bob

Edited January 29, 2015 by Bobacuda

[wayfarer]

As suggested, a bell crank should solve your problem. You will just need to find a suitable location to mount it and then play with the leverage. Something like this should work.

[Desotodav]

 Hand brake diagrams from manual attached. I can email them in larger size if you send me a PM with your email address.

[Plymouthy Adams]

I said this in PM and will say it here..the cables must be pulled in a line from the cable housings..if you pull at an angle to early you will bind the cables on the housing ends..not good...if you were to study the earlier style single pull dual cable axles you will find that they have guides that are loop ended  and connect to the frame..this will allow for a straight pull and allow for the angle at the guide as it crosses through the common captured pull point...by proper position of the cable guides you will have this straight pull and can also set your common pull point to be left right or center....once this is done you should have no problem with your lever soing the job for which it was designed.  Also the easiest setup out there is the 2004  model Dakota...you must get the rear frame mount and will also need to get the front stay..front stay is a quick cut to length fix and the rear brace gets welded in place...the cables can be removed from the modern housing and retrofitted to fit early 8 3/4   7 1/4    8 1/4 and the 9 1/4  axles. 

 

I eliminated the loop guides and made roller bearing capture guide..just a bit neater looking in my opinion.

 

 With the later Dakota it is a straight pull...very very smooth...

Edited January 29, 2015 by Plymouthy Adams

[Bobacuda]

Desotodav, thanks for the diagram.

 

Just crawled out from under the truck after about 3 hours and I got the original e-brake re-installed and adjusted as the manual described.  I had almost forgotten how much fun (and magic) was required to get the band to contract more or less correctly.  I really appreciate everyone's input and I was hoping for a quick fix because I am trying to get it all back together for my son's wedding in April.  So, I will tough it out with the original brake and carry a set of wheel blocks . 

 

I will be using Tim's input later this year when I am no longer up against a deadline and try for "real" e-brakes again.

Bob

[Dodgeb4ya]

The proper type woven brake band lining adjusted accurately all the way around the drum should cause the rear wheels to lock up and skid with the hand firmly applied. 

I purposely nearly locked the rear wheels up  last week testing a 41 pymouth convertible hand brake for a brake safety inspection.

I didn't want to break a U-joint or drive shaft doing a road test.!

Edited January 30, 2015 by Dodgeb4ya

[Merle Coggins]

I agree with Bob. My tail shaft park brake works just fine. I've parked my FD truck on hills with the park brake set and it held firm. If your park brake won't hold there's something wrong with the setup, or linings. It's not a design issue.

 

Merle

Edited January 30, 2015 by Merle Coggins

[Don Coatney]

This is always in the back of my mind when I think about transmission mounted emergency brakes. When I was a 15 year old young and foolish kid I had a hemi powered 57 Desoto with a transmission mounted emergency brake. I pulled the car up on some ramps, set the e-brake, crawled under the car and removed the driveshaft to replace a bad universal joint. As luck would have it I had not yet removed the wheels. The instant I popped the driveshaft off the car promptly rolled off the ramp and pinned me underneath. I was in the grassy yard and nobody was within earshot. I was able to crawl out with only a couple minor scratches and have now lived to be old and foolish.

[Jeff Balazs]

This is always in the back of my mind when I think about transmission mounted emergency brakes. When I was a 15 year old young and foolish kid I had a hemi powered 57 Desoto with a transmission mounted emergency brake. I pulled the car up on some ramps, set the e-brake, crawled under the car and removed the driveshaft to replace a bad universal joint. As luck would have it I had not yet removed the wheels. The instant I popped the driveshaft off the car promptly rolled off the ramp and pinned me underneath. I was in the grassy yard and nobody was within earshot. I was able to crawl out with only a couple minor scratches and have now lived to be old and foolish.

You left out the part when you went inside to change your pants.   If you ever needed proof that someone is watching over you....there it is.

 

Jeff

[Plymouthy Adams]

After a reload of my computer I transferred back some of my pics..this is the 2004 e-brake set up on my business coupe..by far the most effective and easiest one to transfer and connect to original pull handle...again the cable will snap into the older backing plates and cable will affix to the spreader bar..the 2004 cables are ball ended and not bullet..not a game stopper..works just as well

 

It just came to mind looking back at the pics that I also swapped the Dakota pull cable from the foot lever to the 48..length and such allowed install without  original modification and yes it also is a simple bolt in replacement...and for those with a desire to have a brake light I also transferred the switch to the original brake handle...all in what you want...all is easily transferred/modified..

 

 

Ignore the added plumbing that is part of the zero emission fuel system..the componets are no longer exposed to the elements as was factory

Edited January 30, 2015 by Plymouthy Adams

[Jeff Balazs]

That is really interesting Tim. Might have to take a closer look at doing something like this on my truck. When I fitted my Grand Cherokee rear axle I just left off the E brakes that were fitted into the rear discs. Will have to take another look at all this as I think I might prefer this type of brake over the original. At the time I did the swap I was more focused on having 4 wheel disc's and better gearing (which is really nice btw) than I was on the E brake aspect of the swap.

 

Jeff

[Adam H P15 D30]

Plymouthy, What's the pvc pipe under your car for?

[Frank Elder]

X2?

[Don Coatney]

I believe that may be part of the dump system for his shine tank.

[Plymouthy Adams]

I thought I explained that in post 15....it is part of the zero emission fuel system...my car is eco friendly..I have mounted my components out of the weather and off the frame rails...the tube iruns to the engine intake to burn off fuel vapors after start of car and operation temp reached..even when fuel the fuel emissions is almost nil...as long as fuel is being pumped..there is no fumes to the atmosphere..that is why I also have a warning light if fuel cap is left loose..typical 2004 technology..

Edited January 31, 2015 by Plymouthy Adams