86 c10 brake upgrade 1.00 to 1.25 question

[obrut]

Hi, I have a 86 c10 2WD shortbed with the 1" front brakes. I would like to lower it and have been doing a bunch of searches to figure out what I want to do. I just bought a set of flip brackets from board member specialtyretail and I was going to do drop spindles and cut one coil from the stock springs.

I found a set of belltech drop spindles for sale locally for a decent price. They guy said they were off a 81-87 2wd c10. He said they are stamped 31200. From what I've read this could be for 70-72 or 73-87 trucks. Either way they use the 1.25 rotor. He also has new 1.25 rotors, calipers, backing plate and rubber hoses they he will include for a little more money.

My question is;
To convert from 1" to 1.25" brakes I need the rotors with bearings, calipers and rubber hoses but what about the proprotioning valve, master and booster will mine work?
How can I tell if the spindles are for 73-87 and not 70-72?
These will work with the factory 15x8 rallie wheels right?
Anything else I need to know if I do the swap?

Thanks,
Tim

[mgchevyparts]

No need for change to your booster/master.
No more then 4" back space or else you will need spacers with drop spindles.

[mattcrp1]

Not to hijack, but I kind of have the opposite problem. I just installed my used drop spindles and they appear to be for the 1.00 rotor, and my 76 has the 1.25. It looks as if the grease seal is the same and the 76 HD caliper will bolt up to the spindle. The bearings are totally off in size.

Has any one just swapped rotors and bearing between the two? Or is a caliper swap needed as well?

[SCOTI]

Originally Posted by mattcrp1

Not to hijack, but I kind of have the opposite problem. I just installed my used drop spindles and they appear to be for the 1.00 rotor, and my 76 has the 1.25. It looks as if the grease seal is the same and the 76 HD caliper will bolt up to the spindle. The bearings are totally off in size.

Has any one just swapped rotors and bearing between the two? Or is a caliper swap needed as well?

Different calipers as well.

[lolife99]

Belltech Part #31200 is a 71-72 only drop spindle.
Save yourself ALL the headaches and get the correct 73-87 HD spindle for your truck.
They are only $229 most everywhere.
Belltech will be slightly higher.

[obrut]

Originally Posted by lolife99

Belltech Part #31200 is a 71-72 only drop spindle.
Save yourself ALL the headaches and get the correct 73-87 HD spindle for your truck.
They are only $229 most everywhere.
Belltech will be slightly higher.

I hope not, I bought everything. I won't have time to install it until the spring. I couldnt find info saying 31200 is for 71-72 only

[lolife99]

Originally Posted by obrut

I hope not, I bought everything. I won't have time to install it until the spring. I couldnt find info saying 31200 is for 71-72 only

It is.
http://www.summitracing.com/parts/be.../applications/

71-72 spindles use a different upper balljoint and a different outer tie rod.

[lolife99]

Belltech HD 73-87 3" drop spindle is part # 3100.
Belltech Light Duty 73-87 3" drop spindle is part # 3200.

[obrut]

Originally Posted by lolife99

Belltech HD 73-87 3" drop spindle is part # 3100.
Belltech Light Duty 73-87 3" drop spindle is part # 3200.

Carp, well I guess ill through them back on craigslist with the rotors calipers and brake lines. Thanks for the info.

[lolife99]

Keep the rotors and calipers and brake lines,... since you already have them.
Just buy 73-87 HD drop spindles for 1.25" rotors.
Done.

[obrut]

lolife99 in your experience what are my spindles worth, they look almost new if that counts.

[lolife99]

Originally Posted by obrut

lolife99 in your experience what are my spindles worth, they look almost new if that counts.

Used parts are worth 1/2 of new price,... or whatever you can get someone to pay,..

[obrut]

I found some of the post I read before I bought these. Maybe I'll call belltech tomorrow, seems like there is some conflicting info out there.

read the last post
http://67-72chevytrucks.com/vboard/s...d.php?t=237574

read the last post on this one too
http://67-72chevytrucks.com/vboard/s...d.php?t=375970

[obrut]

I called Belltech today and I was told that part# 3100 and 3200 both have the same casting# 31200 on them. Belltech gave me these specs to measure to verify the spindles I have.

Pin length - distance from the end of the threads to the spindle - 4.41"
Inner bearing surface on the spindle diameter - 1.38"
Outer bearing surface on the spindle diamrter - 0.843"

He said that if my measurements match these then I have spindle part# 3100 I checked my spindle measurements and sure enough they match - so I'm good to go.

I wonder if the 31200 is a cast number for C10 trucks, and depending on the pin thats installed and the final machining determines the final part number; 3100, 3200 or 3120?