Restoring Some 105/115 Rear Calipers...

[PMB_Performance]

Hi Gang,

Many here have been extremely helpful when I was searching for some specialty calipers for a rally car. Found them I did and I figured I'd pay back the list with a little "how-to" thread.

I came upon the fact that the 105/115 calipers would be what we were looking for. Originally we wanted the vented rotor kit that was offered by an Alfa supplier but they decided that would be a rules violation so we stuck with the solid rotors. The upgrade for this car is now little more than switching from a 35mm piston to a 38mm piston.

Here's what we started with, it's a pair of 105/115 rears that were stuck tight. With stuck pistons we use a high quality grease gun to literally "pump" the pistons out. You can find the 10x1 adapter fitting at McMaster Carr. I like to use white lithium as it cleans up easier:





The pistons simply push and "plop" out. With fluid there is no high compression/pressure you find with air. It's very safe and effective:





For the second piston I use the same process and block off the now open bore. I use a block off plate made from sheet steel and a round rubber gasket (large rubber washer found at Lowe's). The plate sticks down in the vise and the top is clamped shut with C-Clamps.

Once the pistons are out I begin to dismantle the calipers. Be "VERY" careful with any and all of the M7 hardware on these calipers. They use Ribe heads and they are irreplaceable. There are no sources for Ribe M7 fasteners (or virtually "any" M7 through bolt fasteners for that matter... trust me). Use the proper "Ribe" bit, which is an R5 in this case, to hold the head while turning the 11mm nuts with a fairly large impact. They can be tough. If you have to fight them with a smaller wrench or a hand wrench, use heat in the form of a MAPP torch.







Once the fasteners are out of the way you can take the bleeders out. Be careful here, bleeders can get stuck. Do not use a 7mm open end as it will simply strip the bleeder. Use a deep 7mm or simply use a pair of small Vise-Grips set VERY tight. If they give you trouble, go back and use the MAPP torch to heat the bleeder and surrounding area first.



Once the shells are stripped I take a hooked dental pick and remove the seals and it's off to the platers for a fresh coat of yellow zinc.

[PMB_Performance]

Back from the platers we have what appear to be brand new caliper 1/2's. I really encourage this step for any of you looking to rebuild you calipers. Google some local metal refinishers and drop off your calipers and have them done right.

Here you see the caliper 1/2's in yellow zinc and the fasteners have been brought back to a new look with black oxide treatment. New rebuild kits wait patiently by:







When they come back from plating they'll need to be honed out to prep them for new seals and the pistons. Enter McMaster Carr again (McMaster-Carr) as they supply the 3-stone brake cylinder hone. You can usually find these at Pep Boys as well for around $16.00:



Once the bore is honed the seal goes in...:



...and once the seal is in I slather the bore with caliper grease. Make sure you use caliper grease or caliper assembly lube when you put the calipers back together as other greases will swell the seals and ruin your nice new rebuild:



Now we're moving on to pistons. For pistons, I like to clean the tops and then use POR-20 manifold grey paint. This is their high temp paint and it's extremely durable. Once it dries I take the pistons and polish them with a bench top polishing wheel:



With the dust boots installed we're now ready to press them into the caliper 1/2's. The notch in the piston top needs to face into the oncoming rotor movement by 20 degrees. To determine the proper angle simply run an imaginary line through the middle of the caliper and place the bottom notch on this line.This helps angle the pads into the oncoming rotor and reduces squeal:



Once they are in position I use a bench arbor press to push them into place. You can also use a vise and a suitable socket to help with this step.



Finish it off with a dust boot clip and that part is now behind us:



Finally, it comes time to bolt everything back together. First I put the caliper 1/2 seals (these do not come in rebuild kits) in the nose section of the caliper. Then I install an outside fastener to use as a starter/guide post:



Then I drop the back 1/2 of the caliper down on the nose and start spinning on 11mm nuts:



TIP: Once I start spinning on the nuts I like to have an 11mm socket on a 3" extension nearby. You can hand tighten and arrange the caliper 1/2's prior to torquing them down.

Finally; they get torqued together (sorry for the bad picture). Use the following sequence and number the nuts from left to right:

Torque to 7 ftlbs. 2-3-1-4

Then torque to 17 ftlbs. 2-3-1-4



Finito!

[PMB_Performance]

Next we'll dig into these for Brian...

[ossodiseppia]

That's very impressive work, Eric. I just looked at the pricing for this service on your website. Prices seem pretty reasonable for the amount of work that's put into the rebuild.

[jburning17]

This is fantastic!

This should get a sticky for sure!

[PMB_Performance]

Thanks Guys,

Brian, your's are all apart. They were in excellent condition. The adjuster shaft seals were hardened and there was some old grunge/sludge type fluid in there but overall great shape. One of the bleeders appears to have been damaged in shipping (bent a little) but it came out fine. One of your outer adjusters was missing the lock clip so I'm sourcing that and the outer adjuster seals (which are larger than the ones we normally see).

My only concern with these IHB (integrated hand brake) types for the Alfa is the cable attachment cam/pivot. They are pot metal and I need to hand deliver them to the platers so he knows about it before dipping them. If they went through the normal acid cleaning process it would be gone when it came out of the tank.

ATE had made some tremendous leaps with these compared to some of the Porsche 914 and 914-6 and the Ferrari 308 calipers. One is the worm gear adjustment mechanism. The other is increasing the size of the outer adjuster from 4mm to 5mm. The 4mm adjuster on those calipers "always" stripped.

I'll start posting some pics soon. I'd expect them to go into plating next week.

[rawr]

i have a quick question. if i "split" my rear left cal (82 gtv6) is it now "thrashed and ready for the trash"? by the way, what you have posted up here is great! thanks

[kengta]

Quote:

Originally Posted by PMB_Performance Back from the platers we have what appear to be brand new caliper 1/2's. I really encourage this step for any of you looking to rebuild you calipers. Google some local metal refinishers and drop off your calipers and have them done right. Here you see the caliper 1/2's in yellow zinc and the fasteners have been brought back to a new look with black oxide treatment. New rebuild kits wait patiently by: When they come back from plating they'll need to be honed out to prep them for new seals and the pistons. Enter McMaster Carr again (McMaster-Carr) as they supply the 3-stone brake cylinder hone. You can usually find these at Pep Boys as well for around $16.00: Once the bore is honed the seal goes in...:

[1750GT]

Very nice job Eric...you're lucky to have a plater near you willing to work with small quantities. In our area, not many will undertake to plate parts for less than $200....so one needs to do a big batch of parts at one time in order to make it worthwhile.

[PMB_Performance]

We usually send in a large batch every week... PM me if you want some calipers plated. The USPS Flat Rate boxes make it doable.

[PMB_Performance]

Quote:

Originally Posted by rawr i have a quick question. if i "split" my rear left cal (82 gtv6) is it now "thrashed and ready for the trash"? by the way, what you have posted up here is great! thanks

[1750GT]

Quote:

Originally Posted by PMB_Performance We usually send in a large batch every week... PM me if you want some calipers plated. The USPS Flat Rate boxes make it doable.

[valvebounce]

Totally awesome! Thank you!