BJ74 Clutch Booster Question

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I just used flat head screw driver, gently prying & lifting, it let go pretty easy, it came out a little warped but with a little finger moulding, it returns to original shape, and pressed back in, the ring has little extended feet that push against the wall within the pot to stay in place?
I took the clip out while booster was still in firewall, if I had spare seal on me, I would've taken seal out as well, and replaced if possible before contemplating of removing booster from inside cabin,as I didn't have spare, I didn't bother, at this stage, as it's working again for now??
 
Is it normal to hear some vacum when you first place your foot on the clutch pedal, prior to engaging, or should there be no noise ,
Prior to my issues I had the vacum noise, and after I started playing around it, the noise is no longer there, I bit confused whether the vacum noise is a leak or is it vacum building within the booster ??
 
Well that didn't last long, it's not turning off again, Is it possible to change/ replace this seal while booster is in firewall,
I also checked clutch stiffness while the piping from canister was not hooked up, no change in clutch resistance, doesn't seem to hard at all, can you just plug the canister outlet, in order to facilitate shut off, but does this have any other consequences ?.
 
Its not a particularly stiff clutch to began with even without the booster, its actually quite soft IMO. With the booster it should be almost effortless. If you plug the hose going from the vacuum pump to the booster your truck should shut off normally, assuming that the booster is your problem. Short term it wouldnt be a problem but I seem to remember reading a long time ago that Lowenbrau had the pedal brackets fail after running without a booster for a while
 
When I bought my truck it came with a broken pedal bracket. I repaired it (not thinking particularly about the cause) and continued to run without a booster... actually, none of that is quite true...

What actually happened is, when I bought the truck the clutch actuation was shot, so without much investigation I bought a new booster from China and got the master cylinder stainless steel sleeved, figuring that fitting all new components ought to fix any and all problems.

So when it came to refitting the booster, I spent hours skinning knuckles and swearing because it seemed to be impossible to get it all to line up. I eventually worked out that pedal bracket was broken. So I pulled it out, welded it up and reassembled everything (with new booster and rebuilt master).

The clutch now had a proper pedal but the booster didn't work at all. I just assumed that I'd somehow managed to destroy the new booster whilst levering it this way and that way trying to assemble everything with the broken bracket.

Fast forwards 18 months and the pedal suffered catastrophic failure. I limped it home and pulled it out, my original repair was fine, but the bracket had fatigue cracks in no less than three difference places, one of which had finally ruptured through completely. The bracket is *very* light, being made from about 0.8mm thick steel.

This spurred me on to look at fixing my clutch booster, so I took my 'dead' chinese booster to BHSS at Capalaba in Queensland, Australia. For ~$300 they rebuilt it with a new diaphragm etc. I welded up the clutch pedal bracket again and reassembled.

Still no boosting... Bugger... So I looked a bit further and discovered that a previous owner had pushed a ball-bearing into the hose to the booster, presumably after the original booster failed, which in turn was probably why the pedal bracket originally broke.

At this point I stole the hose off my brother's BJ74 (his booster was leaking you see...) and it fixed my issues. I then got his booster rebuilt by BHSS (another $300), pushed the ball bearing out of the hose and I am back to two fully functioning clutch systems.

The other thing I really should do, is replace all of the pedal pivot bushes... one day...
 
Thanks Gemini, I have removed booster from rig and identified the shot seal, found a replacement seal on the booster, bench tested the vacum, which holds to shut off engine, that's all good now, but once pushrod is depressed the vacum is lost via from the diaphragm, thus I still have no booster for clutch pedal, so after all this, I will get the whole booster overhauled, quote$220, I would like to do it myself, but not keen on the idea of cracking open the booster myself, ansd potentially damaging, as overhauling don't look to challenging, and then once it's done hopefully I'll get another 300k klm
I checked the pedal bracket while it's out, it's still in great shape,
 
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If you replacing just the seal, I wouldn't take booster out, would do it left in the firwall, just take master off, remove the clip in the booster, rip out seal put new seal in, pug the clip back in, attach master, bleed up happy days .
 
@Oldtoy74, thanks for the info. I just got the little seal in the mail today from @beno and am planning to tackle this tomorrow or Friday.

To be clear you are suggesting to remove the clutch master cylinder and then what clip are you referring to? Will I have any trouble removing and replacing this? Sounds pretty simple, but I'd like to make sure I can get the truck in and out of the garage on the same night :)

Also is it fine to reuse the gasket?

Thanks!
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The clip is inside the booster, engine side, where master sits against booster
To remove clip, shine a torch and have good look at what your attempting to remove, it quite simple, slowly pry bit by bit , until you can pull out, be careful not to bend on removal.
If you bend you can re shape it if need be prior to putting back in.
On the gasket, I just used gasket gu
Good luck
 
Thanks for all the help everyone! Was able to get this completed this afternoon and it appears to have solved my intermittent won't shut off problem and heavy clutch. Just a quick spin around the block but all seems well.

Oldtoy pretty much spelled it out, I was able to remove the master and pry out the metal clip with a very small thin screwdriver. I put a light coat of grease on the new seal and pushed it in place, then used a 24mm socket to lightly tap the metal clip back in place. Scraped the old gasket off and used some RTV to create a new one.

Photo of the new and old seal and the clip:
ImageUploadedByTapatalk1428784211.178475.webp


ImageUploadedByTapatalk1428784229.346137.webp


FWIW, my neighbor came to the rescue with a MightyVac speed bleeder which was very helpful. I fear my wife would've tired of the pump pump push routine pretty quickly.
 
Excellent repair info. Glad to know the booster does not have to come out.
 
Seem to have a nasty squeak now. Sounds like somewhere near where the fork goes into the tranny? Sprayed some silicone lube liberally in that area to no avail. What would the next step be? Push back the book and try to get some grease in there?
 
Throw out bearing?? Does the noise change when you engage or partially engage the clutch?
I would not be putting grease or other lubricants inside your bellhousing. You will contaminate your clutch and flywheel
 
No. The noise is only when you engage the clutch, starting from about the halfway point and then until it's fully depressed. Same squeaking noise whether engine is running or not. It might be unrelated to the other efforts today, i pulled the interior last night so the noise is much more apparent with no carpet in place.

Any ideas what it might be?
 
And also, thanks for the tip about keeping the lube out of the bellhousing. Might be a little late though, I already hit it with silicone spray lube. I'm just a shadetree mechanic if you couldn't tell already from my sub-shadetree line of questions! :)
 
Great result on the seal,
Regarding the squeak, the only squeak I had was the clutch pedal bracket that's sits inside the firewall above booster, it had copped a hiding due to no booster, once the booster was repaired the bracket was still twisting a fraction causing a squeak, I then proceeded to undo and then reinstall the bracket bolts up inside the upper mounts of the bracket to ensure it was tight and solid, = squeak gone.
If not above look to re bleed clutch again,
P.S how find you go trying to thread the metal clutch line on top of master, was it just me or was it pain for you as well, as it requires downward straight pressure on metal thread line to get it to align and grab on the to master thread?
 
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