Rear Caliper Piston Issue

Djaniero

Member +
Hi guys,
Just when I thought my GT had stopped testing me.
I was building my rear callipers back up today and for some reason, one of the pistons wouldn’t screw back on to the thread.
I thought it may have been the piston thread that was at fault, so I tried to fit both pistons on to the other caliper thread and they both went on fine.

To the eye the caliper piston thread looks fine and I removed the piston with ease a few days ago.
Does anyone have an idea as to what the issue may be?

Thanks
 

SKINY

Lifer
Does the other piston fit both sides bud, dirt or thread damage but I'd say we can rule dirt out since you are rebuilding them.
Fortunately for my time working at cars I've so far avoided the screw in rear calipers, phew lol
Maybe pay Jay to fix mine........ :)
 

Djaniero

Member +
Yeah mate. As said above, I swopped the actual pistons around to a see if it one them at fault, but it’s definitely the thread.
Really strange as it doesn’t look damaged and I cleaned everything properly as I rebuilt the callipers.Really strange.I thought the Guru aka @Jay may have come across this before.
 

Djaniero

Member +
Never had to deal with it myself but the thread could be damaged (think it's a reverse thread IIRC).

You might be able to order the part separately going on this diagram, part number is 47407-16010 :

http://www.japan-parts.eu/toyota/jp...707_rear-disc-brake-caliper-dust-cover#47407A

I've avoided removing that so far, looks a pain in the ass..
Awesome, thanks Jay. I don’t blame you..it looks like a nightmare to remove that circlip to get that part out. My circlip pliers were way too big to remove them.
Idiot question, but do both rear caliper pistons turn clockwise? I was doing some digging online and apparently on some cars, the piston turns clockwise on 1 side to tighten then anti-clockwise to tighten on the opposite side?
 

Jay

Admin
You'll obviously need to download and rotate them then run them through Google translate but here's the 1990 gt turbo workshop manual version. Goes a little more indepth.
 

Attachments

  • 20210916_060509.jpg
    20210916_060509.jpg
    113 KB · Views: 3
  • 20210916_060514.jpg
    20210916_060514.jpg
    112.9 KB · Views: 3
  • 20210916_060527.jpg
    20210916_060527.jpg
    109.7 KB · Views: 3
  • 20210916_060532.jpg
    20210916_060532.jpg
    107.9 KB · Views: 3
  • 20210916_060545.jpg
    20210916_060545.jpg
    121.6 KB · Views: 3
  • 20210916_060550.jpg
    20210916_060550.jpg
    112.8 KB · Views: 3
  • 20210916_060607.jpg
    20210916_060607.jpg
    89.9 KB · Views: 1

Djaniero

Member +
Thanks a lot for the the guides lads.
It seems to be the inner rubber seal on the cylinder that is causing the issue. Once I removed it, - and they’re a bitch to put back in - the piston slots in fine and winds back ok.

To my knowledge that seal only comes as part of a rebuild kit, you can’t buy them separately?
 

Djaniero

Member +
Quick update.
It was the inner seal as I suspected. It had overstretched some how when compared to a new set I bought.
Piston inserts and winds back perfectly now.
Thanks again for the info peeps.
Hopefully the thread can help any others who come across this issue in the future.
 

Djaniero

Member +
Thanks lads.
I don’t think this car wants to venture back out off my drive lol.
I’m now having issues with the new rear bearing. The bearing seals in the nee kit are rubber where as the originals look like copper.
So once you tap the new seals on to the back of the disk and push the disk onto the rear spindle, the bearing pops out as the rubber seal doesn’t hold the bearing in place in the disk.

FF to 9mins 45secs in this vid.
Will makes more sense.



Had enough for today, will get back on it tomorrow.
 
i was wondering if the excess grease where the seal is suppose to sit may be the issue
next time try wiping that excess grease away...so the seal has a clean surface to seat itself to.
you would have already put a thin layer of grease on the seal anyways, so that is enough to help you install it...with tight tolerances, i'm not sure the excess grease is helping the issue and may be forcing the seal back out under pressure/tension

i could be wrong, but that my thoughts on the matter after view the video
 

Djaniero

Member +
i was wondering if the excess grease where the seal is suppose to sit may be the issue
next time try wiping that excess grease away...so the seal has a clean surface to seat itself to.
you would have already put a thin layer of grease on the seal anyways, so that is enough to help you install it...with tight tolerances, i'm not sure the excess grease is helping the issue and may be forcing the seal back out under pressure/tension

i could be wrong, but that my thoughts on the matter after view the video

Hail Gorgan. That wasn't actually my video, it was just one I found for reference off youtube. As Jay said below the rubber seals don't work...they simply fall out , so I just reused my old ones in the end :cool:
Rubber seals?

I don't fancy that, I'd reuse the old metal ones before trusting that sort of thing.

What discs did you go for?

Spot on Jay. The rubber seals were a waste of time. Luckily I didnt damage the old metal seals I removed from the old discs so just reused them.

I just went for oem rear discs and bought the bearing kit off ebay. The the ad showed the seals as being metal but when they arrived they were rubber.:rolleyes:

Funny thing Idworkz and other places who sell the bearings kit....they're pictured with rubber seals not metal ones?
 

Jay

Admin
Half the people who land down with rear discs to be fitted usually forget them so I've gotten used to re-using the old ones by now lol
 
Top