Brake caliper mounting bolt length

[R N.]

Hello Everyone,

I pulled the brake calipers off my '67 to replace them with rebuilt units and in doing so I noticed I have two different bolt lengths from the same caliper - 1-1/8" and 1-1/4".

I did a search in the achieves but couldn't find the info, so my question is "what is the correct bolt length for mounting the calipers".

Many thanks.

[Alan S.]

Re: Brake caliper mounting bolt length

Hi Kurt,
On my 71 the front brake caliper mounting bolts are 1 1/4" long and the rear brake caliper mounting bolts are 1 1/8" long.The 71 AIM does list 2 different part numbers for the bolts.
Same in 67???
Regards,
Alan

[Rich P.]

Re: Brake caliper mounting bolt length

Hi Kurt,
On my 71 the front brake caliper mounting bolts are 1 1/4" long and the rear brake caliper mounting bolts are 1 1/8" long.The 71 AIM does list 2 different part numbers for the bolts.
Same in 67???
Regards,
Alan

They are the same for 67 1-1/4" front and 1-1/8" rear all grade 8, 7/16-20.

Rich

[Wayne M.]

Re: Brake caliper mounting bolt length

Can somebody point me to a section of the 1965 AIM where the caliper mounting bolts [to the mounting bracket] might be found ? All I can locate is the whole assembly [spindle support, trailing arm, brake assy. (caliper & mounting bracket),etc.] -- all is one part # for LH and another for RH. But then, this is to be expected.

Then I went to my parts books (P&A30B, etc) and can't find the caliper mount bracket or bolts there, either (although I can see the caliper halves, pistons, etc.)

This is driving me nuts; not being able to find the caliper mount brackets and bolts, front or rear .

[Rich P.]

Re: Brake caliper mounting bolt length

Wayne,

I don't think it is there for 65 if you notice some of the refrence pictures are of a drum brake and not a caliper.

Rich

[John H.]

Re: Brake caliper mounting bolt length

Can somebody point me to a section of the 1965 AIM where the caliper mounting bolts [to the mounting bracket] might be found ?

Wayne -

They aren't shown anywhere in the A.I.M., as the calipers were received at St. Louis as part of the front hub/spindle assembly and as part of the rear trailing arm assembly; the calipers were installed as part of those assemblies at Chevrolet-Warren.

[Wayne M.]

Re: Brake caliper mounting bolt length

Wayne -

They aren't shown anywhere in the A.I.M., as the calipers were received at St. Louis as part of the front hub/spindle assembly and as part of the rear trailing arm assembly; the calipers were installed as part of those assemblies at Chevrolet-Warren.

Thanks, John; that's what I suspected. Now if someone could give me the GM catalog group # for (say) the caliper mounting brackets (which may have the [somewhat special ?] bolts closeby, I could check if the bolt part # is in Gr 8.900 Standard Parts section, to get the actual spec's., including length.

[Rich P.]

Re: Brake caliper mounting bolt length

Wayne,

the 69 AIM has the St. Louis assembly line pt #'s, UPC 5 sheet A4 you can see the rear bolt is taged as 5 pt# 3843384 and the front caliper bolts is 3 pt# 186645.
Now my 82 GM Corvette illistrated parts cataloge only has the rear bolt listed (twice) once in the rear suspension section and once in the parking brake section. You can read in both sections it is listed as 7/16-20 - 1 x 1/8" long.

The front bolt is not listed anywhere in the 82 master cataloge. But I know everyone I have ever seen removed or restored from 65-82 has been 1-1/4" long. The are always longer than the rears.

Rich

[Rich P.]

Re: Brake caliper mounting bolt length

2 more pics

[Wayne M.]

Re: Brake caliper mounting bolt length

Wayne,

the 69 AIM has the St. Louis assembly line pt #'s, UPC 5 sheet A4 you can see the rear bolt is taged as 5 pt# 3843384 and the front caliper bolts is 3 pt# 186645.
Now my 82 GM Corvette illistrated parts cataloge only has the rear bolt listed (twice) once in the rear suspension section and once in the parking brake section. You can read in both sections it is listed as 7/16-20 - 1 x 1/8" long.

The front bolt is not listed anywhere in the 82 master cataloge. But I know everyone I have ever seen removed or restored from 65-82 has been 1-1/4" long. The are always longer than the rears.

Rich

Rich -- OK, now I get it. Also (finally ) found the caliper mounting brackets in the P&A30 catalogs, under Gr 5.001. It shows the front caliper adapter (ie. mounting) bracket changing for '68-70 (it's a Jan '70 catalog) from 3864114-6 ('65-7) to 3928649-50 (LH/RH both cases). So maybe this is why a longer bolt was necessary.

Dug into my bolt bin, and the only 5-pointers (300M) I could find were 7/16"-20-1_1/8", but all these were off cars prior to 1968.

Thanks for looking into this. BTW, none of those bolt part #'s that you mention show in section 8.900 [standard bolts] of my P&A30 (Rev 7-1-69), although there are both 1_1/4 and 1_1/8 300M's shown; #s 454972 and 453719 respectively; maybe the part numbers changed often back then.

[David M.]

Re: Brake caliper mounting bolt length

was wonderng the same thing on my 75, what is the correct length bolt? I have 2 different length bolts on my left front, the aim does not show the length of the bolts, nor does the shop manual...

[Rich P.]

Re: Brake caliper mounting bolt length

I have to correct 3 year old info front bolts 1-1/8" rear bolts 1"