REAR END SWAP

[Duke5A]

One thing to consider is using a 727 and anything over 550 horsepower you have a bomb under your feet asppesally after a ring gear failure! A transmission blanket is a minimal defence and should be a requirement for all automatic cars on the track, I'd say put one on your hot street car.

I've seen the carnage photos on Moparts. I'm right at the edge of that power level, but not running sticky tires on the street. Upgrading the axles over the winter to minimize the possibility of the axle letting go; which seems to be the root cause of sprag failures. I've seen it recommended on Moparts to upgrade to an aftermarket drum in the trans as well.

My only concern about running a blanket on the street would be making the trans toasty. Don't have any real world data to back that up though.

 

[Oldiron440]

That's why you need a big cooler.
I had a friend that ran stock axles in his 8.75 for years , 4000 lbs 300k running mis 11s. He would paint a stripe down the axle and when it had about a quarter turn in it he'd replace the axles. What breaks on the 8.75 is the passenger side bearing support and cap.
Sometimes it's just the ring and pinion but the case will fail. I personally had problems with ring and pinions until I started using synthetic gear lube, I use Strange 4.86 pro gears and pull them after about 400 runs.

 

[Oldiron440]

As far as the transmission goes don't ever power out of a burnout, so your burn out get off the power then release the linelock and let the car roll forward. This is for all Torque flite transmissions.

 

[BudW]

My only concern about running a blanket on the street would be making the trans toasty.

I would think a transmission blanket would not cause a transmission to overheat for street usage – sense the torque converter is the primary source of heat in a transmission (on acceleration or during stall).
BudW

 

[Oldiron440]

Raced with a guy that would drill two 2" holes in the back of the bellhousing, he swore his transmission ran 30 degrees cooler.

 

[volare 77]

Trans guy I worked with many years ago would leave the converter dust cover off when running a stall converter saying it would help keep the trans cooler. Probably did but I didn`t like the idea of all the crap getting up there since I drove mine on the street.

 

[Oldiron440]

I've always left the shield off.

 

[BudW]

For race use – I wouldn’t worry about the dust shield.

For street use – well it depends.
I would use the dust shield - unless it is already a “clunker”, for it does keep a lot of “stuff out of the area.

The main purpose of a transmission cooler (the one inside of the radiator) is to warm the fluid – for ATF works best between 150-200’ F (65-93’ C) or thereabouts. Cooling the fluid is its secondary purpose.
The ATF temp after radiator "should" be in the 150' F (65' C) range.

I would say having transmission temperature in that range is also very good for racers, sense “hot” fluid takes less energy to push than “cold” fluid does.
I don’t think this would make a huge difference on the track – but each couple of ten-thousandth of a second does add up.


Now for street racing, for someone with an extra heavy foot, for someone who tows a lot and for those with a non-lockup converter – having an external transmission cooler after the radiator cooler is a VERY GOOD idea.

Lockup converters will generate just as much heat – but stops the heat production, just as soon as the lockup is applied – so transmission temps drop pretty quick. An external cooler would be very nice for those with a heavy foot, for police or for towing.
I don’t think many FMJ bodies will be used for full-time police vehicles anymore – but there are some of us who road race.
There I do recommend a huge external cooler – after the radiator cooler.

For most of us who get on the gas every occasionally, or only take cars to shows/occasional drag race, I wouldn’t worry about anything other than using stock parts.


Having a temperature gauge (either mechanical or electrical) for transmission is very good idea. The best place for it is in the transmission cooler line (the line at front of transmission, heading towards the radiator) – but having it in the pan is OK.

A transmission will not live long if temperatures get to, or stay above, 250’ F (121’ C) often.
If you see temps at 225’ F (107’ C) often, you need to add an external cooler SOON.
BudW