Does anyone know if an 85 vette batwing would work in a 93? The 93 has the anemic 2:59 ratio rear, the 85 is unknown. Thank you in advance for your help.

 

the 85' (if it came out of an automatic car) is still going to be the D36, the gear ratio is something like 3.07 "at best" for that year (I believe).

the differential and batwing itself should fit fine, the remaining suspension componenets and half shafts measure differntly than the new vettes'.

 

I heard there are very minor differences but not anything to upset the fitment

I looked for an older one also one time, ended up buying gears instead, unfortunately

 

Thanks for the info guys. Do you know if I go to some lower gears for the differential, will it have any side effects on the vehicle electronics or speedometer readings? Any thing I should watch out for?

 

The difference is related to the model year ; not diff type. Later models have a different spindle ( also brakes / shock mount ) which puts the hub 3/4" out further than early models.The camber arm inner bush is larger and the bolts that hold the camber arm bracket to batwing are larger on the late models.
Halfshafts / dogbones interchange
In a early into late swap ;you would use the batwing and chamber arm off the early diff with the rest of the late model components

To to change speedo gear(s) in trans to suit new ratio

 

Hello down under rodj! Just to clarify, so I will know what I am getting into; I have the opportunity to purchase a show polished batwing from and 85 which does not have the differential. If I decide to find a lower ratio differential, would I still need to make the adjustments you mentioned if I installed a later year model differential into this batwing? It sounds to me that I would. If I am understanding you correctly, that would also tuck my ZR-1 wheels inward and I am not sure if I have the clearance inside. Would you advise that I shelve this purchase and stick to later compnents? Again thanks to you and everyone else for the help and information. I have not delved into C4 suspension before now. I do know that the 90 L98 six speed car I traded in on this LT1 seemed to have much more power out of the gate!

 

Nothing changes on the car UNLESS you fit the easly spindles and hubs to your car ( not recommended)
This is all you swap

 

To (hopefully) clarify the question..

You need to know if both parts (batwing and differential) are from the same "family" of differential: Dana 36 or Dana 44.

All automatic transmission C4's used the Dana 36 differential. All Standard shift C4's used the Dana 44 differential. Regardless of model year.

A Dana 36 batwing willl Not fit a Dana 44 differential, or vice-versa.

In other words there are no differences in the batwing (or the differential itself) year-to-year from 1984 thru 1996. A D36 batwing will work with Any year car using a D36 differential. A D44 batwing will work with Any year car using a D44 differential.

Thoughts about swapping a D44 in where a D36 was originally - the C beam is different, mostly at the Front because of the differences between automatic and manual transmissions, but in General you will have to modify/fabricate a C beam to make the differential swap. Other than That it's easy, all C4's, regardless of the differential used, take the same half-shafts and U-joints. The lower camber arm mounts are a bit different on the later year cars (see rodj's posts) but that's minor to deal with.

Changing the Gear ratio in the differential (or significantly changing Tire sizes, for that matter) will require that you then correct the Vehicle Speed Sensor (VSS) signal. This is necessary to fix the speedo display and the speed input to the ECM.

You can either change the reluctor gear in the transmission (not hard, means taking the tailshaft housing off) or splice in an electronic "convertor" box, such as sold by DakotaDigital (gives you a much finer range of adjustment, and can be reset easily over and over). Either way works.

 

Thank you one and all!

 

The trans end of the C beam is the same ; auto v man .The D44 swap requires a shorter C beam because the diff head is longer than a D36.

Use a D44 beam or do this mod.( bottom of page )
http://www.joby.se/corvette/mods/2001-0X11_diff/