Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: BIGDRY on August 03, 2016, 11:16:52 AM
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Hello all, well ive finally got my cj7 back on the road , got a few issues....
first major one to address is the rear drum brakes lock on easily when braking reasonably hard, ive had both drums off and the biggest issue i could see is the brake self adjuster cable is stretched and not providing much tension on the self adjustor - especially on the off side which tends to lock the easiest.... the adjuster lever hardly touches the star wheel at all...
Does anyone know somewhere in the uk that i can buy just the adjuster cables - i see rock auto do such a kit , but id like to get them quickly..
Also any tips in setting up rear brakes so they dont lock easily? :)
thx
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I may be asking the obvious, but are the shoes the right way round and paired correctly?
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Lighthouse do kits of all springs and cables for the rear drums.
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If the rears are locking up this doesn't sound like an adjustment issue to me. I would be looking at the proportioning valve or something else.
The adjuster could still need some work but it doesn't sound like the cause of the problem.
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:iagree:
the adjusters only work when you put handbrake on. And that's when the lever hits the star wheel and gives it a click more. You could run without them..... Just have to get under more to adjust the brakes :icon_twisted:
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:iagree:
the adjusters only work when you put handbrake on. And that's when the lever hits the star wheel and gives it a click more. You could run without them..... Just have to get under more to adjust the brakes :icon_twisted:
Not true on CJs wilwood the adjuster is designed to move the lever when reversing and applying the brakes.
Are your front brakes working okay? Does it seem the rears are doing all the work?
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i adjust the rears on mine when i find its not stopping quickly enough. great round town in the wet going down a hill, certainly attracts attention the sound of a locked wheel and the tyre screaming in protest
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:iagree:
the adjusters only work when you put handbrake on. And that's when the lever hits the star wheel and gives it a click more. You could run without them..... Just have to get under more to adjust the brakes :icon_twisted:
Not true on CJs wilwood the adjuster is designed to move the lever when reversing and applying the brakes.
Well waddyaknow. I was going to say that and then I thought......I bet I'm wrong......but what a thing I now know I would have been right... Trouble is when I had that system on the YJ I always ended up taking the drums off and. Hosing them out before readjusting the brakes manually. I am sure it's a system that only works marginally when you stick to dry roads.... :icon_twisted:
Are your front brakes working okay? Does it seem the rears are doing all the work?
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Sounds like a stuck proportioning valve to me, have you tried pushing the little pin in and out. It's on the pass side chassis rail just behind the engine
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Thanks all for the helpful comments.
I need to check the shoes for sure - when i last checked them i didn't know there was a difference, its possible they are incorrect by PO. but he slack in the adjuster cable isnt a good sign admittedly but i thought that if anything would mean that the shoes wouldn't adjust up as they wear
I seem to get most locking on the offside rear only so i didn't think it was proportioning valve - but as i sit on the left hand side (lhd) i guess it is the most unloaded. Also it could just be that this one brake is more susceptible than the other side. im surprised the rear drums can lock up wheels so easily but i guess the rear of a cj is pretty light.
Does any one know if the proportioning valve is the type that provides less rear bias under braking or is it a fixed bias? thx all again.
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Under heavy breaking the proportioning valve should limit pressure to the rear brakes. The front brakes should always lock up first otherwise you will end up facing the wrong way as the back passes the front.
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I may be asking the obvious, but are the shoes the right way round and paired correctly?
:icon_super: Took them apart today and..... the (ahem) person who fitted the brake shoes had fitted both leading shoes on the right hand side and both trailing shoes on the left. :banghead:
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well at least the problem js now solved
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Well done, Sir.
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Hi All, prob not solved..:( Despite re adjusting a few times now the rear brakes still end up being too aggressive on the rear once they have self adjusted up fully.
i have noticed that the combination;/proportioning valve has it little pin stuck in - i think this is sending too much fluid to the rear all the time.
Anyone else had this? you adjust up the rear brakes and at first its ok , but gradually they settle in and adjust up fully after a few miles then rear brakes are too active.
was thinking of ordering this part? as rock auto/crown etc dont seem to offer this a replacement?...
http://www.ebay.co.uk/itm/1974-86-74-86-JEEP-CJ5-CJ7-PROP-COMBINATION-PROPORTIONING-VALVE-PV2-DISC-DRUM-/262592807096?hash=item3d23c040b8:g:1bYAAOSwhOVXdMFu
cheers
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If you can hold of Dave the sparky he put a manual proportion valve on his and adjusted it what he wanted.
Don't think it was too expensive.
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If i remember correctly the pin should be sticking out in normal operation, it may just be gummed up, but maybe just buy a new one at that price....
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I used one of these on the 8 as i have 11" drums and not the standard 10" but i was also fitting all new brake lines so it may not be a straight swap for you if you bought one as i seem to recall the pipes to the rear brakes are a bigger diameter than the front ones and may have bigger fittings.
Prop Valve Hyperlink thingy! (http://www.rallydesign.co.uk/product_info.php?products_id=15436)
It does work very well and great fun can be had whilst fine tuning it in your nearest flat area/car park so the fronts lock first!
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Just dont set the bias when its wet
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ok rear combination valve ordered. lets see if that helps.
The pipes to the original valve look past their best however.
Does anyone know what flange type and union tyres are fitted to cj7 originally?
I might order flaring tool and unions in advance...
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old imperial ones where you cant get them easily here.
or talk to light house
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Most of them are 3/8 UNF but as i said before i have a funny feeling the rear brake line is bigger.
You need the long threaded ones, standard ones are too short and ignore old 69er they are easily obtained from Ebay. or these guys in lovely non corrosive brass too! :icon_winkle:
https://www.automec.co.uk/products/brass-brake-pipe-fitting-male-3-8-x-24-unf-3-16
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Cheers Dave
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hi all, the aga continues!
Finally got around to try and fit this new brake combination valve that got sent over from the states.
Getting all the old pipes off was great fun, but I managed it without breaking anything!
However the new combination valve supplied has a 9/16 18 tpi 1/4 pipe size female fitting on it where as the car has 7/16 18tpi 3/16 pipe an male fitting...
Does anyone know any where in the uk that sells proper inverted flare, imperial, brake pipe adapters so I can some how reduce correctly down.
Im not 100% sure but i think i will need 2 fittings one to go from 9/16 to 7/16 then another to reduce internal bore down 1/4 to 3/6
I've tried all the local usual suspect such as Pirtek etc but all they do is bring out metric stuff..... thanks
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I'll have a look what imperial brake fittings we have in work later.
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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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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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something like these?
https://www.dormanproducts.com/p-46665-785-432.aspx?origin=keyword
https://www.dormanproducts.com/p-44032-785-434.aspx?origin=keyword
http://brakequip.com/products/hardware/male-female-adapters/
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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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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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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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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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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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:iagree:
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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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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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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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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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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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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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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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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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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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:icon_super:
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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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Thanks for the update. Most useful....