LD20 rebuild procedures/advice

I purchased new piston and crossover seals for my LD20s and have searched on the Internet but have been unable to locate any sort of manual for these calipers, so I really have no idea what I'm doing. The only calipers I've ever rebuilt were off of a 100cc race kart, and that was too long ago to remember anything about the procedure! I know compressed air can be used to help remove the pistons, but beyond that I'm clueless.

Looking for any advice, procedures, and/or words of wisdom from all you FC gurus out there. Pictures help. I'm not too bright. :confused:

Thanks!
Eric

Get a knowledgeable friend/buddy/coworker/ to help you. These calipers are as simple as they come, and all the basic tricks apply.

The brakes are THE moist important system on the car, if you gotta get on here asking for how to's, it's more than a little bit of a :redflag:.

I hope you appreciate my directness on this matter.

Merry Chrismukkah, GC

Quote:

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Originally Posted by glenn cooper

Get a knowledgeable friend/buddy/coworker/ to help you. These calipers are as simple as they come, and all the basic tricks apply.

The brakes are THE moist important system on the car, if you gotta get on here asking for how to's, it's more than a little bit of a :redflag:.

I hope you appreciate my directness on this matter.

Merry Chrismukkah, GC

---

Actually Glenn I was really just looking for specifics around bolt torque specs, pre-treatment of seals, any gotchas with this particular caliper around assembly/disassembly, etc. Maybe I should have been more specific. My bad.

My understanding was that these forums were here for knowledge transfer, which includes helping the new guys to the class along. I completely understand the importance of brakes on a race car, which is exactly why I posed the question in the first place, rather than simply cutting myself loose on the job without a thorough understanding of the specifics.

I'd never changed the gears in a racing gearbox either, but after asking the right questions of those who'd already performed the task, and reading and studying the manual (which is readily available on the Hewland website), I was able to successfully accomplish that task.

I like to think that I'm a relatively competent guy, who simply feels it prudent to do his homework first. I know it's crazy, but I even read instructions before attempting to put something together! ;)

LD19 (CP2505):

• Button head screw:
  
  • PN CP3299-108
  • 0.375” UNF
  • KL44517 copper gasket
• Blanking Plug
  
  • PN 103664
• Bleed screw
  
  • CP3720-182
  • 12.5 ft/lbs torque
• Repair Kit
  
  • CP4508-K
  • piston seal
  • dirt seal
  • dirt seal retainer
  • cross feed seals
  • 1 kit per caliper
• Pistons
  
  • CP2195-14
• Cross feed seals
  
  • CP2485-111
• Assembly bolt
  
  • CP2696-163
  • 0.375” UNF x 1.16”
  • Original bolts not re-usable
  • Torque 30 ft/lbs (40.7 Nm)
• Brake pad retainer, split pin
  
  • CP2696-160

LD20 (CP2485):

• Button head screw:
  
  • PN CP3299-108
  • 0.375” UNF
  • KL44517 copper gasket
• Blanking Plug
  
  • PN 103664
• Bleed screw
  
  • CP3720-182
  • 12.5 ft/lbs torque
• Cross feed seals
  
  • CP2485-111
• Assembly bolt
  
  • CP2696-163
  • 0.375” UNF x 1.16”
  • Original bolts not re-usable
  • Torque 30 ft/lbs (40.7 Nm)
• Brake pad retainer, split pin
  
  • CP2696-160

Eric,
They are not very complicated. my procedure is relatively simple and I rebuild my calipers very often (probably dont need to but...). I prefer to use the rubber grease that Taylor sells, but brake fluid will work, just wont give you the spongy feel at the start.
I have used compressed air to pop out the pistons with the calipers apart and together. I seldomly change the cross over seals unless they are damaged. Clean up the pistons and bores with 400 sandpaper. Apply liberal amounts of grease inside the seal groove before inserting the seal, then spread the excess around the seal and pop the piston n place. Wipe off the excess grease between the bore and the piston with a q-tip. I install the caliper on the car and then attach the outter half torqued to 25 ftlbs with red loctite. I found it is easier to do on the car as opposed to the vise.
When you bleed, watch the fluid for bubbles, as with the grease they will feel spongy, like there is air, but it is the piston retracting back, which is why I rebuild often.
Hope this helps,
John

Eric,
If you haven't split the calipers, I would leave them assembled, left alone, the cross-over seals never leak (or very, very rarely). Second, I would soak the new caliper seals in brake fluid for 20 minutes, as suggested by AP, before installation.
If you seal kits included external wiper seals (OEM part), assemble without them for racing.

Thanks guys, this is exactly the kind of info I was looking for. Sounds like, unless they're known to be leaking, the crossovers can be left alone (at least I now have a new set should I need them). That makes the job MUCH easier. I'll soak the piston seals prior to install.

Eric

Pay attention to Keith! The crossovers rarely need attention, and they can be a pain in the empennage to replace, so unless absolutely necessary, leave 'em alone!

Larry Oliver
International Racing Products

BEFORE you split them, you absolutely must keep the halves together. They are machined to match, and if you mix the halves, the'll never seal. This is direct from AP!!

Iverson

Understood guys. I'm leaving the crossover seals alone for now and just replacing the piston seals. At least I've got them now should I need them down the road. Two calipers down, two to go.

Thanks,
Eric