58-61 Generator end frames - are they funtionally the same?

[Dan B.]

I have read some of the threads giving good explanations of the VISUAL differences between the shorter Corvette generator end frames on the 043 Delco units, but my question is does the size (height) difference on the commonly found passenger ones (1/4" taller) make a difference in any way relative to the alignment of the generator assuming you are using the correct fan and brackets ect??

If both the front and the rear passenger frames are the same height relatively, can we conclude they should function the same as the Corvette ones but just not appear correctly for judging?? TIA for your replies. Dan

[Ronald W.]

Re: 58-61 Generator end frames - are they funtionally the same?

I ran a 58 power steering generator in my 61 corvette for many years and never had any problems.

[Richard M.]

Re: 58-61 Generator end frames - are they funtionally the same?

Dan, a quick answer to your question is...Yes. It'll work. It's functionally the same.

Over the last several years I've gotten up close and personal to the generator frames. Here's what I've learned from many of the guys here and much of my own research.

Firstly, I have never really understood why the Corvette frames were actually shorter. That 1/4" difference may have been devised as a hood clearance issue but I've never seen it documented for that reason. It's the only explanation I can think of. Maybe the engineers had a tolerance specification to maintain and had to meet that criteria. This is all speculation on my part but it may make sense.

For example, the 1102043 generator "case" used on the 1956 to 1961 Corvettes was also used on many passenger cars. I say "case" because of the current capacity spec. On passenger cars with power steering, the extended shaft of the armature drove the power steering pump. On the Corvette, it drove the tach drive mechanism. When looking for a Corvette 1102043 unit, many just see the tag and assume it's correct for Corvette. It'll work, but it's not what was originally used. A closer look at the frames is needed to get the right one. Many auto electric shops over the years have made mongrels out of the 3 main pieces(front/rear/case) and have left us with so many variations of generators. Some have correct front frames and wrong end frames, and vice versa. This results in generators with their mount planes off by 1/4" with respect to each other. Functionally they work but are going uphill or down hill when mounted. Sometimes it's quite noticeable.

On the Pass cars, the front frame is a cast alloy or aluminum and it's perimeter has several reinforcement ribs. On the Corvette, it's perimeter has no ribs, and the distance from the bearing center to the mount hole center is 1/4" shorter than the pass car frame. They are different part numbers and are easy to spot. However, the rear frame is cast iron/steel and has a noticeable difference in the profile of the area of the mount hole. This "dogbone" shape has a noticeable feature. It's long on the Pass and short on Corvette. Below is a reference showing the visual differences.

A trick I've learned from the guys is when a generator is mounted, stick your finger between the top part of the mounting boss and the bottom of the case.....
If your finger fits in there it's a Passenger car end frame. If not it's Corvette end frame.

The other important difference between types is the 3 5/8" diameter pulley. The Corvette's back of the pulley has a 1/4" space to the fan. This to move it out to align the belt to the crankshaft and waterpump pulley. This due to the thickness of the front engine mount and extra WP gasket and it's necessary harmonic balancer spacer ring. This was for 1958-1962. The 1956 & 1957 did not use the spaced out pulley. I believe due to exhaust manifold mount difference but not sure.

I recently restored/rebuilt a 1102043 generator for a buddy. It's actually a Passenger car version with the longer frame mounts but using the Corvette pulley. It's for his 1960 Corvette. It'll work fine but has the wrong frames. I've installed many on Corvettes with no clearance issues. You can see my rebuild process here. I do this as part of my restorations and I like to document my steps for reference, especially if I forget something.

Below is the pdf document I found long ago showing the frames but cannot remember where I got it. I'd like to give credit to the author but not sure who it is. Also a few other pics for reference. One for the "finger" test(IIRC from Roy Braatz), and mine of the backside of the Passenger car frames.

Rich

[Dan B.]

Re: 58-61 Generator end frames - are they funtionally the same?

Rich, thanks for taking the time to post such a thorough explanation which brings many of the things I have read together. I've used the passenger end frames for years in Corvettes as well with total success but just never understood why GM felt the need to make 2 different sized parts. Your idea of possible minimum clearance issues is the best reason I have seen so far. Also, very good point about checking both end frames to make sure they are evenly spaced and not mismatched whatever the configuration on any given unit. Thanks again for an excellent reply! Regards, Dan