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Author Topic: cj7 rear brakes locking easily  (Read 6971 times)

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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #25 on: October 16, 2017, 05:51:01 PM »

hi Jonny thanks you are a Gent. really seem difficult to go from 1/4 to 3/16 pipe for some reason!??
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Jonny Jeep

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Re: cj7 rear brakes locking easily
« Reply #26 on: October 16, 2017, 10:40:59 PM »

Sorry, can't help. Couldn't find anything with a thread that big.

Edit:
Just a though but could a 14mm bolt with a shank be cut down and threaded 9/16" and center drilled? ...if so would a 3/16" pipe work or could 1/4" tube be slipped over 3/16" pipe and the pair flared together?

I'm going to have to look for 14mm shanked bolts at work now. Trouble is a 14mm bolt has a 22mm head. Would you have room to work with that?
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Dave69

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XJ 2.5 diesel - dead. XJ 4.0 6" lift - sold to some lucky person
CJ7 4.2 auto standard(ish)
Alfa 147 jtdm

BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #28 on: October 18, 2017, 01:18:41 PM »

Many thanks all, for input.

The thing I don't understand about these adapters, even if you can find the correct thread types (brakequip bq123), is that the center bore is 1/4 or 3/16 all the way through.

Surely the 1/4 flare size boss is bigger than a 3/6 boss? or does the smaller flare of the 3/16 actually still fit on the flare of larger 1/4 boss?

How can you reduce from 1/4 to 3/16 center bore- maybe you don't need to as the pressure will balance out in the system?

maybe I'm thinking about  this all too much and the bq123 will do the job?
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Dave69

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Re: cj7 rear brakes locking easily
« Reply #29 on: October 21, 2017, 10:43:25 PM »


not 100% on brakes as its been some years since i played around with them.

basics is that the tubes are there to transfer the pressure fromt he pedal to an expansion cylinder then to the brake shoes, so a larger bore to the front exerts more pressure than a small bore pipe to the rear brakes, so that the rears dont lock before the fronts.

one posssible solution is to run the same size pipe to the front and the rear pipes keeping the installation simple and uniform in regards to fittings. Include a brake bias valve so that the pressure to the front and rear can be adjusted to suit the vehicle. either a 50/50 split or a 75/25 split to the front.

either have the adjuster in the engine bay or pay that little bit more and have a remote adjuster in the cab so that it can be tuned to suit while your driving rather than a stop adjust start process.

if you have power brakes then the current master cylinder should be able to cope with this installation
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XJ 2.5 diesel - dead. XJ 4.0 6" lift - sold to some lucky person
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Dave The Sparky

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Re: cj7 rear brakes locking easily
« Reply #30 on: October 22, 2017, 09:28:13 AM »

The pipe seals on the taper of the outlet and the angled face it sits on to has a smaller hole than you would think.
But you are correct if the angled face has a hole that is too large it will never seal properly and you would need to step down using fittings or buy a different valve.
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3.0TD (proper fuel) Toyota powered CJ6, 1981 4.2L "Montana" blue CJ8,1982 "Cack" Brown CJ8 slowly getting a Chevy V6 and a lot of welding...

BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #31 on: November 01, 2017, 11:39:11 PM »

Gents Im beginning to think that this new valve body is never going to fit properly - believe me if I could find the correct valve i would buy another  - its odd how this is the only part of the cj7 that it seems you cannot buy  and no one makes them in same spec anymore...

i have now cleaned out the original body as it was full of crud and seized and now looks like it might do the job  - unfortunately the pressure switch in the center has disintegrated so now i d need one of these to reuse - Anyone got an spare old one to sell???

Or should i just drop by Lighthouse Jeeps personally (I've given up with their telephone manner and lack of responses...)

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Mike Pavelin

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Re: cj7 rear brakes locking easily
« Reply #32 on: November 02, 2017, 10:37:09 AM »

The other option would be to stick a manual bias valve in the rear line. Readily available from Demon Tweeks and the like.
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Dave69

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Re: cj7 rear brakes locking easily
« Reply #33 on: November 12, 2017, 11:08:35 AM »

 :iagree:
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XJ 2.5 diesel - dead. XJ 4.0 6" lift - sold to some lucky person
CJ7 4.2 auto standard(ish)
Alfa 147 jtdm

BIGDRY

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Re: cj7 rear brakes locking easily - 99% solved
« Reply #34 on: April 18, 2018, 02:35:06 PM »

Hello all, i thought as you were all kind enough to give me your time with responses id  update this thread in case anyone else has similar issues.

Suffice to say I think the main issues to correct rear drum operation were that the pads on the backing plates for the drums had worn surfaces – under more careful inspection I found lots of groves and uneven wear.
I welded and ground them back to best part of flat that I could.

I also have found issue with the square shaped coil springs that fits the center bar that runs across both shoes were found to be 2-3 mm wider that necessary and this had caused the springs to slip one side down the center bar. So much that the bar was no longer tensioned correctly.
Older correct fitting parts were refitted.

All these  coupled with careful cleaning  and derusting of the metal blades that fit into the star wheel adjustors made a massive improvement as being rusty they were too wide to fit correctly . The pedal is firm and the rear brakes do not drag or make any odd random screechy noises.

Long, door less, roofless  test drive in the sun today is needed for further testing  :greggmo:
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5536paulj

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Re: cj7 rear brakes locking easily
« Reply #35 on: April 18, 2018, 09:42:08 PM »

I've always found that the springs in new brake drum kits don't fit and you always end up using the old ones.....
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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #36 on: April 22, 2018, 08:38:43 PM »

Well looks like i spoke too soon... despite everything working correctly with the brakes now, Im finding that the nearside rear drum is heating up for some reason. its not binding when jacked up and the jeep rolls back when on a  slight slope  when driving and is easy to push around workshop, but that nearside drum is getting far too hot after only a few miles (far too hot to touch, whilst other side is fine).
I have noticed that the nsr drum has a slight warp and very, very lightly rubs the brakehoes in one section, i need to check with dti as it might be a bent axle or hub. Any experiences with slightly warped drums, axles etc causing brake rub that would make this sort of heat that make the drum too hot o touch after only a few miles? thx
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bgbazz

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Re: cj7 rear brakes locking easily
« Reply #37 on: April 23, 2018, 05:18:07 AM »


Can you back off the adjuster on the bad side...just enough to stop the shoe contact when it's in the relaxed position?
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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #38 on: April 23, 2018, 12:51:37 PM »

Hi, I've done that but it still seems to generate heat even when backed right off.... i wonder if its possible that the drum can rub maybe at the top of the shoes when loaded up somehow (if the bearing  have excess play or axle /hub/drum is bent. )
I actually drove the car without the rear shoes and rear flex hose clamped, and no heat was generated - so I'm pretty sure the axle bearing is fine friction wise and that the heat is coming from brake drag somehow.

I think i need to check run out of hub/drum/axle but not sure if measuring it wheels up in the air on a lift gives you the whole picture as the axle isn't loaded.

I don't understand how so much heat can be generated and yet the car is free to push back and forth makes no sense....
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bgbazz

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Re: cj7 rear brakes locking easily
« Reply #39 on: April 23, 2018, 04:08:47 PM »

What you wrote makes the problem even more curious. I would be looking closer at the axle bearing now...can it/or does it move sideways under load...are there any wear marks on the inside of the drum which might indicate contact between the edge of the shoe and the drum (not to be confused with the normal contact faces). Are the shoes and the drums compatible? ie. are they the ones you had on previously?

Apart from all the above (learned in the school of hard knocks), make sure that all the components are squeaky clean and fit into their respective positions neatly (wire wheel on a bench grinder is handy) and a light smear of white grease on all connecting surfaces (excepting the drum and shoe, obviously), might help you out. You would be surprised how a little ridge of rust or grime can affect a smooth operation.

Other than the above, I have no clue how to help.

 :icon_winkle:
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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #40 on: April 24, 2018, 08:30:02 PM »

Bazz you read my mind - i have been checking axle movement when jacked up and there is indeed a lot of play in axle bearings.
I can make it actually touch the drum on the shoes when jeffin' on it, making a nice knocking noise...
Movement in and out on the axle i think is way over max tolerance, must be 2-3mm at least and vertically its more - Oddly it spins fine with not really any real worn bearing noises and i can't hear any real odd noises whilst driving (but i guess cj's aren't that quiet to really tell!)
I think when the vehicle is on its wheels the drums must be moving about dragging randomly on the shoes (despite there not being much witness marks on them to prove this).

Looks like its new bearings time and possibly a one piece axle conversion whilst I'm there!... :icon_rolleyes:
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bgbazz

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Re: cj7 rear brakes locking easily
« Reply #41 on: April 25, 2018, 05:45:33 AM »

Replacing the bearings would be a good move IMHO. It's quite difficult to determine how much movement (in any direction) can occur when the whole assy is under load and moving.

Keep at it mate...you'll win in the end.   :icon_winkle:
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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #42 on: April 25, 2018, 10:31:50 AM »

 Cheers Baz will do!

must admit i was loving driving it even if for a short time, in the sun the other day!
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bgbazz

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Re: cj7 rear brakes locking easily
« Reply #43 on: April 25, 2018, 03:28:27 PM »

 :icon_super:
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BIGDRY

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Re: cj7 rear brakes locking easily
« Reply #44 on: June 20, 2018, 03:21:17 PM »

OK an update for those interested.
It seems I've finally sorted out my wayward rear brakes.

I fitted a new one piece axle kit and completely new rear wheel bearings, seals,  brake shoes, cylinders and drums. Unsurprisingly they now works properly....
But I actually think the biggest hurdle was the play in the rear wheel bearings.It was such that the drums would rub on the bottom on the drum. So if you are getting odd rear brake performance, heating up regardless of actual braking, grabbing under braking, or dragging rear brakes regardless of all your adjustment attempts , I'd heavily recommend checking condition of rear bearings. Also i found that wheel cylinders that look in great condition can be sticking and rusted inside. Onwards to dodgy dash gauges now!...
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johnnyboy

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Re: cj7 rear brakes locking easily
« Reply #45 on: June 30, 2018, 01:03:02 PM »




Thanks for the update. Most useful....
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