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Bronco II Drive Shaft Replacement/Measurement


ab_slack

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I been digging and have come accross different pieces of information which has been getting me confused. So I expect this has been answered, but I don't know that I am understanding what I have read.

I have 87 Bronco II, 2.9L, 4WD, 5 spd manual trans and manual transfer case. I have no idea as to exact model trans or transfer case. It is an essentially stock vehicle with no lift.

I fairly certain I have a problem with my rear drive shaft. I get a great deal of clicking when accelerating or going up hills. As I understand the OE shaft is a CV joint type shaft that was prone to failure. Most of what I been finding for replacement have been like the A1 Cardon 65-9821 labeled as GKN conversion design. Looks like this has a U joint at each end.

First question, is there any issue with a conversion such as this?

Second, assuming this is the correct item, I find there are two A1 Cardone models that have the 4 bolt flange at each end (like my existing shaft) that are for standard transmission. From what I can tell the differences are the length. The model 65-9821 is 32 11/16" long while the PN 65-9825 is 36 5/8" long.

A crude measurement of my existing shaft gave me a flange to flange dimension close to 33 inches. To me this is very close to the 32 11/16" shaft but even though it was a crude measurement it does seem slightly longer than that dimension. On the other hand 36 5/8" seems way too long so it probably can't be that, BUT

BUT my understanding is that this shaft telescopes for lack of a better word which I believe is to allow for dimension change due to suspension travel. So is this dimension specified by the manufacturer a fully compressed length, fully extended or a nominal length? If a nominal length the 32 11/16 seems just about right. If a compressed length the 32 11/16 seems like maybe too tight, but I don't know how much movement there is and the 36 5/8" would obviously be too long. If it is the fully extended length however, the 32 11/16 would be appear to be too short so perhaps the 36 5/8" one is the one I want.

I am tending to think the 32 11/16 is the nominal operating dimension for the shaft, but I seen a few things that say how to measure and there seems to be no single standard.

Can anyone clarify this for me?

Thank you.
 


4x4junkie

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Driveshafts are nearly always measured at their nominal length (usually at mid-travel of their slip or telescoping section).
 

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