The benefits of overdrive

[67440Dodge]

With 3.91 gears and 3spd auto
587

3.55 gears and 6-spd auto
588

[ws27]

You forgot to mention the computer controlled engine management which will allow higher load/torque at lower RPM. I don't think we can do that with our old engines they'll knock themselves apart.

Besides, they won't sound as awsome.

[67r/t4speeder]

I am still planning some sort of OD in Max. I think the kits are still $2,000 for a OD 4th

85mph 2100 rpm Mike I likey

[markz]

Oh yeah baby! My new GTX build is getting a Gear Vendor's OD! It will drop the 4.56 gears to an equivalent 3.55.............

[67r/t4speeder]

This going to be the drive it to the track race it drive it home car Mark?

[markz]

This going to be the drive it to the track race it drive it home car Mark?

That is the plan! I tow the race car daughter drives the GTX.

[honcho]

Yea overdrive is so awesome

[thebankerstoy]

I know very little about these new OD units, so please excuse what might seem like a stupid question by those who have researched these units, but I'm a bit confused about one thing concerning these OD units for our older muscle cars. I run a 3.91 gear ration in my 66 Coronet and Mark says that he will be running a stout 4.56 gear ratio, so won't there be a fair amount of heat build up on our older rear differentials with lower gear ratios even with an OD unit in place when running at highway speeds on longer trips? The engine will be running at a lower rpm range, but those healthy rear gears will still be spinning at their usual rate per rear tire revolution, so how will the extra heat be dissipated?

Richard

[markz]

I know very little about these new OD units, so please excuse what might seem like a stupid question by those who have researched these units, but I'm a bit confused about one thing concerning these OD units for our older muscle cars. I run a 3.91 gear ration in my 66 Coronet and Mark says that he will be running a stout 4.56 gear ratio, so won't there be a fair amount of heat build up on our older rear differentials with lower gear ratios even with an OD unit in place when running at highway speeds on longer trips? The engine will be running at a lower rpm range, but those healthy rear gears will still be spinning at their usual rate per rear tire revolution, so how will the extra heat be dissipated?

Richard

Very good point but I will be running very close to the same highway speed just the engine rpm will be lower. I will be running 4:56 gear because the tires that showed up today are 30 inches tall. Without the OD I would be turning around 3350 RPM at 65 mph. With the OD it will be around 2600 rpm.

So I don't believe additional heating will be factor.

[thebankerstoy]

I'd be a bit worried with that 4.56 gear ratio driving longer distance trips myself Mark, but I will be very interested in hearing how this set-up works out for you. I hope that you will update us after it's all in place and will let us know how you like it.

Richard