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Discussion Starter #1
Anyone happen to have this info handy ?

distance center to center across top
distance center to center across bottom
distance center to center top to bottom

Thanks
 

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same, yes.....the only difference (not sure about the drum brake plate) is that the (disc brake) backing plate ID fits a register on the housing, which I've only seen on the 94-96 8.5" narrow & wide sedan housings. I recall that it is not on the Fleetwood version, but I could be wrong.

I was pretty sure I had posted some info on this in the past:

http://www.impalassforum.com/vBulletin/showthread.php?t=244003

Here are the PN's for sedan housings and drum brake backing plates from 91-96:

Y01 = 7.5/7.625" ring gear
Y04 = 8.5" ring gear

Y01 (drum only)
91-92 (narrow) 26016279
93-96 (wide) 26045300

Y04 (disc & drum)
91-92 (narrow - drum only) 26016278
93-96 (narrow) 26042094
93-96 (wide) 26042092

91-96 drum brake backing plates - 11" x 2" drum 18002392

The point here is that the 4-bolt trapezoid flange pattern on the sedan axle is the same on ALL 91-96 sedan housings--regardless of whether the brakes are 9.5" drum, 11" drum, or disc brakes.

By the info above, the 8.5 housing got the added register in 1993, same year the body rear wheel openings changed, which makes me wonder if the original plan had been to add rear discs in 93 instead of 94.
 

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What's the OD of that housing register? I'm gathering info on the posibilities of fitting these brakes to a Buick rear end.
 

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Welcome, Tomas!

What model & year of Buick are you working with? If it's a sedan, the Caprice/Impala SS rear discs are a straight bolt-on.

The register OD on the 93-96 8.5" (ring gear) sedan housings is 2.828 inches (71.83mm)
 

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Thanks Bill! I have a 1972 boattail Riviera. I find the brakes marginal considering the weight of the car and while the fronts take the majority of the braking it still makes sense to upgrade the rears to discs IMO. The fronts actually match the Impala with roughly the same OD and slightly thicker rotors IIRC. I've already compared the data on rear brake drums and Impala rotors so I know the rotor will drop right onto the axle register. Can someone measure the OD of the driveshaft flange that holds the lugs? What I'd also like to know is the distance between the outside of the driveshaft flange and the axle housing flange to compare to the Buick axle.

Edit: I've attached pics that show what I'm interested in. I already got the "yellow measurement" in a previous post. I believe the red "square" is the common GM pattern, 3.125"x2.687"x2.437".
 

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Vlad - let me suggest to you that even though I see it (and I get an e-mail alert), this is a dormant 5 year-old thread. It really would help to address more clearly exactly what you are after.

1. who are you addressing your request to? (I do not assume it is for "me" - even if that is your intent)
2, in regard to "measure real values", what is meant by this?

We will help all we can, and there MAY be a "lost in translation" situation if English is not your primary language. In watching your posts, it seems you are determined to create an adaptation using parts that are readily available to you that were created for another application - I can understand you may prefer to do that instead of obtaining the original parts that were designed for the axle, but anything you do in the way of adapting a non-production brake component is really NOT something we can guide you through - only in a general sense, and while not being SURE of your location, if a functional park brake is required, the use of something other than the OEM setup is going to be most difficult to help you create a working rear disc brake system.
 

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I know that custom brake plate have successful end.
This is not problem for me.

About "measure real values":
I know 3 OD diameter from my friends: 72.15mm, 72.85 and 68mm.
I made 72.75mm OD register.
Where is true?

Many internet sources shows pictures like this, but
green lines - is absent measurements.
196406



I best case i wated all real mesumets of impala backing plate or flange.
Coz at this moment try to find anybody who have free access to impala rear disk backing plates.
Just do not want remove axle on my caprice to measure this. )
 

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This is my plate, already laser cuted.
Measuments taken from drum backing plate.
Take a look center diemeter and 4 chevy flange mounting holes, closer to register diameter.
Do not matter to other.
196407
 

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the cross dimension (in green on your picture) is 3.865" = 98.17mm - center of housing tube radius to all 4 holes, center of hole to center of hole is the same - 1.9325" = 49.085mm - which you came up with 48.12mm.

Holes are 0.375" = 9.525mm.

Backing plate register (where axle tube extends beyond backing plate flange) is 2.830 = 71.882, which on your drawing is shown as 72.75mm. The register dimension is lifted from an 8.5" Y04 housing, as used on Impala SS. The cast iron backing plates were centered by this register dimension.

The housing end in the photo is not stock GM - it is Moser 7900, made for a no C-clip setup, using larger diameter axle shafts, using a Ford-style sealed bearing with a lock ring. The backing plate was used to retain the bearing & axle shaft in the housing end.

I guess I'm your "nobody" - I have a pretty good stock of disc brake backing plates.

BP2.JPG


boot1.JPG

new axle--no c-clips 007.jpg

new axle--no c-clips 025.jpg
 

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I've re-measured an actual backing plate - here are cross dimensions:

3.76" = 95.5mm - center to center of flange bolt holes - top (wide) to bottom (narrow) diagonally
1.88" = 47.75mm (radius - center of tube to center of any bolt hole) - compares to your 48.12mm on drawing

Stamped steel drum brake backing plates required less critical dimension tolerance, since brake shoes would self-clearance. Disc brake backing plate was held to tighter dimesnions for proper caliper/abutment positioning and interface of rotor to backing plate at edge of drum in hat (DIH) channel in backing plate circumference, which was machine-finished as part of backing plate production.

I am not claiming my measurements are perfect/100% accurate - I'm using a Starrett dial caliper, not digital.
 

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Thank you! Usefull info.
"center to center of flange bolt holes" - yes, but for geek it is not correct ).
from closer radius to closer radius )
like this )<--->(
plus knowlege of bolt hole diameter0.375" = 9.525mm makes true correct measuments.

196417



Can you make this measuments on plates or flange?
 

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Discussion Starter #16
I would beg to differ.
Center to center of holes is the number you want to compare, base work on.

If you measure inside to inside or outside to outside, bolt holes if reamed to size, clearance drilled or some other size is going make comparision impossible.

If measuring existing holes , inside to inside plus one hole dia , is of coarse center to center.

I may have a housing that I can measure.
It is an earlier diff, but it will either be right or wrong by a large margin
 

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take what you can get - I'm not using CMM, scanner, or any high-tech devices. Don't need any coaching on how I list the dimensions I thought your were trying to confirm. The info I provided along with the backing plate you have should be more than adequate to lay out the pattern and adjust/confirm correct print details.
 

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take what you can get - I'm not using CMM, scanner, or any high-tech devices. Don't need any coaching on how I list the dimensions I thought your were trying to confirm. The info I provided along with the backing plate you have should be more than adequate to lay out the pattern and adjust/confirm correct print details.
Yes, i take it. Anyway thanks!
 

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I would beg to differ.
Center to center of holes is the number you want to compare, base work on.

If you measure inside to inside or outside to outside, bolt holes if reamed to size, clearance drilled or some other size is going make comparision impossible.

If measuring existing holes , inside to inside plus one hole dia , is of coarse center to center.

I may have a housing that I can measure.
It is an earlier diff, but it will either be right or wrong by a large margin
Yes please, measure it. Interest to compare.
 
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