Accidental removal of caliper bridge bolt
 

Were going to change brake pads in a haste. Starts screwing and (:banghead:) I have loosened the upper bridge bolt of the caliper. As it says in the workshop manual,
https://www.rx7club.com/attachment.p...1&d=1316281047

Anyone have experience from this mistake? Do I need a new caliper? Or is it okay as I only loosened one bolt? I found some horror stories about people who had loosened all four bolts.

:banghead:

you must remove all the bolt now for change the 4 viton o-ring between the 2 half of the caliper.

It's have work for me in the past when i made the same mistake.

I take the viton o-ring in a hydraulic shop for 4$

I have plenty of low mile used calipers on the cheap...and can ship to sweden

I have to try the new o-rings approach. Brake fluid has to be removed before disassembly of the caliper right?
Is any kind of sealing needed when the caliper is put together again?

You not need to remove brake fluid but you will make a big mess if you dont.

No you dont need any sealant

If they haven't seen a lot of heat......become flexy and make noise when the brakes are applied - I'd just nip them up again.

You'll have to make an educated guess on torque value - loosening one of the others to see what the break-away is, might be an indication, I used 50lb/ft for some shcs replacements with hardened washers after some dropkick on this site sold something he half arsed put together.

Those lathe cut O rings in the halves are just about impossible to find, at least here - and don't really deteriorate. One of the weird things, Mazda actually have a part # for the bolts, although they don't seem to sell it!

Good used calipers are a dime a dozen. Don't take a risk, just replace the caliper. The braking system is something you don't want to mess with.

Dale

You guys make it hard for me to decide...

You mean If they have been warm it wont work to screw it back. Or that if they get warm again they will start to separate?

It's 100 bucks in freight cost too, but I guess it is cheap compared to crashing. I have to look around some...

Repeated high temperature cycles changes the heat treat of the alloy, essentially why calipers become disposable over time.....and why you often see high-end ex-race calipers offered on ebay for a pittance, that have only seen an event or two.

The calipers will bolt together fine, if the car has only seen street duties, that's the way I'd go, on the other hand if they've been heavily tracked, change em out. Down here, a pair are normally in the 150~200 range from the front cut importers (assuming 294mm set).

I removed all 4 of one of my calipers when painting them before i saw tha fsm, i replaced the 2 o-rings at the top & bottom for the fluid channel & used plenty of thread lock when tightening them back up & they have been fine since, although they have not seen a lot of use since

I purchased my FD with power steering fluid contamination in the brake system. I took the calipers apart to clean and re-build them. I replaced the master since it was not maintaining pedal pressure.

I took the calipers completely apart including splitting both sides so I could sand blast them, then power coat them.

I put the 2 o-rings aside for each caliper and once i was done i put everything back together and I have been driving the car for 6 months issue free.

You will be fine if everything goes back together like it was and the seals are new or in like new condition.

If you need Calipers, I just replaced mine with RB BigBrake kit...
so I could ship mine to sweden if you want to..

I don`t know what they are worth... but I think we can find a price :-)

I´m located in germany. So that shouldn`t take too long.

regards
Marc

I would def remove that brake fluid at the caliper rather than push it back into the brake system. It all takes but a few seconds at that.

Only thing you should be using on the caliper slides if anything is a small film/dab of anti seize or silicone based lube

Where can you get these o-rings? Had my brother working on one side of the car while I was doing the other and he took all the bolts out. :(

I split my orginal calipers apart for powdercoating. Put back together with out problesm and used for years before change out to'99's. The '99's I just painted and so didnt break apart.

My view on splitting was that the temps and current flow during PC priocess could be more damaging to the O-rings that reassembly process.

Most has been said here, but wanted to chime in.
I split my calipers for inspection and managed to loose one of the rings, dont ask me how.
I just went to a company where i live, and brought one of the viton seals with me.
The company supplies sealings, hoses, connectors etc. for the onshore/offshore/deepsea drilling industry. I asked em if they had an O-ring like this in their database, and they had. Got all mine replaced for a few bucks, cant remember the price.
It was chemically usable with brake fluid, and my logic dictates, if its good enough for this industry, its good enough for me :)

Does anyone know the o-ring size? I went to the local places I could find and none had square-cut orings. I see mcmaster-carr sells them but I don't know which size to order.

sorry to put this tread back up,i did that mistake and i just wanna share and you could comment :)

It happened to me 2 years ago, since then, I did 15 000 kms and put some heavy braking into. I did loosen the 4 bolt untill i see fluid coming out and then i retighten them to unknown torque(because unspecified). Then i bleeded this caliper just to remove air.

2 years later, no brake fluid coming out and it seams okay

this is a idiot mistake i made because changing those brakes are easier than it seams

I rebuilt a set of Z32 brakes which are very similar to the FD brakes. In fact the bridge bolts are the same size and thread pitch (not sure on length). Here is a guide that I used
http://www.zmods.org/index.php?page=caliper_rebuild

They recommend 60 ft lbs which is what I did and mine have been good for 3+ years and lots of hard use.

There are reports of the calipers splitting open at some point down the road... to me that small risk is not worth the reward. If you have money I would (a) buy new (good used) calipers or (b) rebuild. The thought of my caliper(s) splitting in half during hard braking is not worth saving one or a few hundred bucks.

Edit: I accidentally loosed the bolt myself on one of them. All appeared fine and I tightened it back up but chose to replace with newer condition JDM parts from Japan2LA. If I was broke I probably would have left it... but then again in that case I probably shouldn't own this car.

From an engineering standpoint that makes no sense. If these bolts were torqued to stretch then I could see a problem with re-tightening, but they aren't. Also, plenty of Mandeville brake kits were sold and worked on track FDs. They required splitting the caliper and rebuilding using a shim and new longer bridge bolts.

Edit: I actually took measurements and used a bolt torque calculator.
http://www.futek.com/boltcalc.aspx?mode=metric

Bolt:
M10 x1.25
Grade 8

Caliper Threading:
27mm length
Aluminum (all three grades on that site came to the same conclusion)

Answer:
Recommended Torque
62.61 N-m
(6.388 kg-m)
(46.18 ft-lb)
Resultant Tension:3192 kg

Maximum Torque
83.48 N-m
(8.518 kg-m)
(61.57 ft-lb)
Resultant Tension:4256 kg