3.55 differential

[Lord Iffy]

I am thinking about changing the differential together with the transmission rebuild (I will have plenty of time, so why not to do anything interesting with the car, but I have some question about it. Now I got standard 302 EFI engine, not wide ratio gears in transmission and 3.08 differential (Y code). I use the car as daily driver (some city driving, some higways), but in future I am planing HO conversion and another car, so marquis will bu just fun car.

1) What would be best choice for me? I am looking for solution for reasonable money, easy to do and something what will have some effect. I was thinking about 3.55 LSD differential.

2) What would be the the change in the way the cars runs? Worse mileage is no problem. And in the future with HO? I do not want to do something now and than do it again in different way when I do the HO conversion.

3) What is the best way to do the replace? Just buy another differential and change them? Can also a differential from another car be used?

Thanks

[Nathan in MI]

A 3.55:1 ratio would be fine for a lopo or an HO engine, though the HO might arguably like 3.73:1 even better. For donor axles, you're pretty much limited to ones from other Panther chassis vehicles. I don't know how the selection of Panthers in junkyards is in Germany, but if I had to guess I'd say it's probably pretty slim. So, if you can't find an entire axle to swap, you'll have to swap the ring and pinion or find someone to do it for you.

[Lord Iffy]

A 3.55:1 ratio would be fine for a lopo or an HO engine, though the HO might arguably like 3.73:1 even better. For donor axles, you're pretty much limited to ones from other Panther chassis vehicles. I don't know how the selection of Panthers in junkyards is in Germany, but if I had to guess I'd say it's probably pretty slim. So, if you can't find an entire axle to swap, you'll have to swap the ring and pinion or find someone to do it for you.

And 3.73 in lopo? HO conversion will come earliest in a year.. In the Czech Republic no junkyards with panthers and I think in Germany it is the same. So the only things that have to be changed are the ring and pinion? It is no problem to get Explorer diff here but as I have understood I can not use it as whole, can I then use the ring and pinion out of them? And what about a track-lock?

What would be the factuall difference (in city, going uphills, higway at cca 75MPH, higways uphill...) when I change the gears (I understand the theory but want to here some practical experiences)?

[Nathan in MI]

3.73 in a lopo wouldn't be all bad, but it might be a bit much. 3.55 gears will do quite well with an HO as well, so it's really up to you.

The only things that have to be changed would be the ring and pinion, yes, though it's also a good idea to replace the carrier bearings and outer axle bearings at the same time, since you're in there anyway. The axle shafts could also be worn, so you may want to replace those or else use repair bearings instead of normal outer axle bearings.

Explorer differentials use 31 spline axles as far as I know, and Panthers are 28, so they're out of the question. The ring and pinion from an Explorer diff will work fine - they're all the same. A trac-lock is a good upgrade as well, and anything designed for 28 spline axles will work, regardless of model.

In city stop-and-go driving, the car will accelerate much better and feel far more agile in traffic, and get better gas mileage. Going uphill, it will be less likely to need to downshift in order to make it. On the highway at 75, obviously the engine will be running faster, so the mileage will drop some, though Scott/Lincolnmania claims 21 mpg highway with his HO-powered, 3.73 geared '86 Town Car.

[Lord Iffy]

thank you very much, that is very helpful.

So any Ford 8.8 ring and pinion should fit? The axle shafts have been replaced few months ago, so I hope there would not be any problem.

[Nathan in MI]

Any 8.8 ring and pinion, from any model, from any year.