99 Black Bird TA

I've noticed my 72 vette seems to have a lot of drive line friction. For example coasting in neutral the 72 will quickly slow from 65 mph to 40 mph or less when compared to my 91 Camaro, 99 Trans Am or 06 Tundra 4WD.

Over the last few years the brakes have been over hauled. Hawks pads & VBP rotors stock size. The TH400 was rebuild with shift kit & Yank 3200 converter. Rear gear is 3.08. The engine is a fresh custom Dart 400. The suspension was up dated with the full VBP front & rear composite spring kit. The car weighed 3180 with full tank of gas.

What steps can be taken to reduce drive line friction?

The wheel bearing have all been greased and that helped a little. All of the universal joints were replaced and that didn't make much difference.

New tires helped a little bit.

Would replacing the steel rally rims with a lighter rim help?

Any ideas?

chevymans 77

a couple things that need to be addressed will be the alignment and the removal of the caliper piston springs.

The springs are to maintain pad contact with the rotor (peddle travel control), if the run out is under control then the springs can be removed to reduce roll resistance.

Neal

Shark Racer

When you compare the two are you comparing all the cars in top gear?

If the 91 Camaro is stock and a V8, it's the best car to compare. You should be using the 1:1 gear of your newer cars. If the Camaro is a 4L60 (4spd auto) car, compare in 3rd gear. Looks like the 5-spd manual cars (T5) have 4th as 1:1 so that owuld be the one to compare. Same with the Firebird, compare 3rd gear in an A4 or 4th gear in an M6.

Freeing up the exhaust will help as well as lightening up drivetrain components and getting rid of the drag on the brakes, but you need to start by doing a fair comparison if you are not.

mikem350

The OP said he compares in Neutral

I would check, as said, alignment and tire pressure.

Then..jack all 4 wheels and check each one for dragging.

Parking Brake releasing?

Here is what I do at the shop...Drive the car for couple miles and check each wheel, brake caliper and bearings for heat. Compare to opposite side. Also check rear diff for excessive heat. Shoot whatever you can with a IR thermometer.

Bottom line, friction = heat = problem

'75

I'm guessing the Th400 is making all the drag. I switch to a 2004R and the reduced drag is incredible.

Gale Banks 80'

It might be crude but just try pushing the Car. I have always thought my C3 is hard to push and when You do it always has the sound of dragging brakes. Besides that the C3 has a lot more u-joints.

cv67

taller sidewall wider tires heavier wheels tire pressure non od trans etc all are suspects
Older transmissions or drivelines in general arent nearly as efficient as whats out today
Lower compression helps lol


Too expensive to chase add that extra $5 to your tank and enjoy

doorgunner

I could hardly get my '68 to move by pushing it........after I used the "String Alignment" on all four wheels now I only need to lean against the bumper to make the car move.....and need only one hand to keep it rolling (30 lbs. of air in each 225-15 front tire and 245-15 rear tires.......Toe-in set at 1/16" for less rolling resistance)

Shark Racer

Thanks

99 Black Bird TA

The park brake is weak but it seems to release. I will get the 72's wheels in the air and check each one. I've done that before and the 15 inch wheels are harder to turn than the Camaro's 16 inch wheels or the Trans Am's 17's. I suspect the springs need to come out of the calipers that sounds like a given source to reduce friction.

This is really more to free up some lost up that get a little better mpg but more mpg is nice too.

Will also change differential oil to synthetic & GM additive.

I need to get a temp gun to check things with.

Eventually, I'd like to replace the TH400 with a 4L60e or 200-4R but that a long time away. The car could do with an alignment check. It was set to VBP specs in 2010 when the suspension was done.

Thank you all for the suggestions.

gkull

I vote for brake problems. pull all the rotors and have them resurfaced and then shim to near Zero run out. I've coasted a long ways in the past. I also move my vette around by myself in the garage.

You see this is highest between these two points