A15 w/ Auto Revs too high!

[leosnake]

I've been driving my 210 with a rebuilt mild camshaft (lopes at idle) A15 and automatic transmission for 2 weeks now...Haven't driven an auto for a LONG TIME over 2 years! I don't remember if this is normal but this thing revs too high I believe...

50mph 3200rpm

55mph 3600rpm

60mph 4000rpm

65mph 4300rpm

70mph 4500rpm

Tires are 195/65/14 and maybe the 3.89 rear...It runs great...but mileage sucks since I drive mostly on the freeway!

Any other A series automatics out there with a tachometer for comparisons...??

[Mini-L320]

That seems Correct. Automatic is only 3-speed. I have a 4-speed Manual and at 115mph im doing 6000 RPM's.

[RAlly_DatoB210]

Mines bone stock but winds out higher than my friends 4 speed he runs out of gears about 75 and I can wind mine up just a little Above 90 I feel really hittin all the gears there worth about 30 mph but that's some hard revs. After a few trans swaps thanks to N-D ghetto automatic burnout shifts but it has always wound up hard before it senses it needs to shift so idk I flog my engine and have for thousands of commuting miles non stop on end at eighty I wouldn't worry about it but I'm no expert

[Nicholas7620]

I have a 4spd with 205/70 by 14's on the rear, I get 55 mph at 2900, 65 mph at 3400 and 75 mph at 3900. I get 35 mpg on the freeway and 25 mpg city driving.

[datzenmike]

.It runs great...but mileage sucks since I drive mostly on the freeway!

 

Define 'sucks'. I had a '76 B-210 and only twice did I ever get the mileage below 30. I had to drive the living piss out of it for a whole tank full.You should be in the high 20s at least.

[Stupid_fast]

After a few trans swaps thanks to N-D ghetto automatic burnout shifts but it has always wound up hard before it senses it needs to shift so idk I flog my engine and have for thousands of commuting miles non stop on end at eighty I wouldn't worry about it but I'm no expert

Learn to stall-launch. I can do epic burnouts in my toyota(Not that I have tried yet... only some launches) without ruining the gearbox! :D

And about your gear ratio's, are the rear end diff's on the 210 interchangable with anything? You could swap for a better ratio maybe?

[RAlly_DatoB210]

I wouldn't know about swapping the gearing I don't see why not though. I'm pretty happy with stock gears for a dd. It really takes abuse of rainy wester Washington parkinglots sliding around and melting tires. Glad Aberdeens mall sucks. Really go there it's absolutely empty. Parking lot is begging to be messed with though. Wouldn't brake boosting it be just as hard on it internally? Ok off topic sorry for the blab

[Master-O-Turbonics]

Ya I put 2 gallons of 110 octane gas in and filled the rest up with regular and drove the living crap out of my A14 5 speed 210 and I still got 31mpg! I get ~35mpg on average with an even mix of city and highway driving.

I'm guessing the little bit of 110 gave me an extra 10% hp so thats like 6-7hp?

 

I run 185/60R14 tires now but am about to go to tall rally-cut winter tires and a 4.11 rear gear.

[leosnake]

Okay...Here is more data...167 miles on 7.96 gallons = 20.97 m.p.g. (1st fill up on an empty tank was 8.01 gallons 2nd fill up was 7.91 gallons...average 7.96 gallons) That's why I stated the gas mileage sucked...I was comparing it to my 200sx 2.2 Napsz /5 speed hatchback which has more power, and gets better gas mileage!

The owners manual states a 13 1/4 capacity fuel tank but they fill up with 8 gallons! :blink:

[RAlly_DatoB210]

i know the answer to that last statement! here is how my gas tank breaks down....

from dead empty it takes about twenty bucks to just above the e line. i use premium so still there is atleast 5 gallons after i says empty. i have made it easily another hundred miles. then its another fifteen to the half tank and between 5 to ten bucks and its topped off full. usually 30 bucks will "fill" it but there is way more under the e line

[datzenmike]

Wouldn't brake boosting it be just as hard on it internally? Ok off topic sorry for the blab

 

There are no 'gear changes in an automatic. It's in all 4 gears constantly and clutches are engaged or disengaged to select the gear you want.

 

1/ The Neutral Start: If you select neutral the clutches are released, you rev the motor to 6K and select Drive. The 1st gear is engaged suddenly with great and irresistible force and any slack in the u joints, gear lash in the crown and pinion or spider gears is taken up with a severe shock.

 

2/ Brake Torque Start: With brake on to hold vehicle, select Drive or 1st. Tranny shifts into gear, you hold brake and apply the gas. Motor revs to just under 2K at which point it reaches it's stall speed and can't rev any higher against the fluid drive. Between engine and brake drums the drive train is loaded with stored energy straining against the brakes. Release the brakes and floor the gas. Torque is smoothly and evenly applied to the tires at once.

 

Any time the brakes are held and the motor revved while in gear the torque converter will start to over heat. HEAT is the number one cause of automatic failure. It runs on hydraulic pressure and the specific lubricating properties of the ATF used. It's like cooking oil it can get hot enough that it changes the chemical friction modifiers in it and the clutches will start to wear. The fluid will change from bright ruby red to a duller brown and eventually black. The discoloration is lost clutch material that can't be put back.

[datzenmike]

I've been driving my 210 with a rebuilt mild camshaft (lopes at idle) A15 and automatic transmission for 2 weeks now...Haven't driven an auto for a LONG TIME over 2 years! I don't remember if this is normal but this thing revs too high I believe...

50mph 3200rpm

55mph 3600rpm

60mph 4000rpm

65mph 4300rpm

70mph 4500rpm

Tires are 195/65/14 and maybe the 3.89 rear...It runs great...but mileage sucks since I drive mostly on the freeway!

Any other A series automatics out there with a tachometer for comparisons...??

 

It works out to 3,800 (and change) for 70 mph... add a couple hundred for auto tranny slip and say 4,000 @ 70 MPH. 4,500 seems a bit high. I worked it out for a 4.11 rear end just to see and still too high so I tried it if stuck in 2nd gear and that's like 5,500 @ 70 so unlikely it's that.

 

So either the torque converter is no good, the tach is reading wrong or the speedo is wrong....

 

Check the fluid color. Bright see through red???? Cloudy red/brown???

[Driftastic210]

I got a 3 speed auto and it seems to start revving high around 65-70, but with no tach i have no way to tell. I will hopefully be purchasing a tach over the holidays.

[leosnake]

Found my camshaft specifications...280 degrees duration with .457 lift ...with a 109 degree lobe centers

runs really good...so bear this in mind with the gas mileage i'm getting!

As far as the actual reading of the revs...I have a factory tachometer...so as far as accuracy..who knows?!

[datzenmike]

So either the torque converter is no good, the tach is reading wrong or the speedo is wrong....

 

Tach could be fine and the speedo off. Drive beside someone at 70 and look at yours.

[ggzilla]

Those RPM to MPH figures seem right on. You have low profile tires.

23.9" tall, stock B210 is 22.8". Add torque converter which by design lets the Revs jump a few hundred RPM. And B210 speedometers are off.

 

Your mpg is off, but the RPM seems OK.

[deltapeco]

my 3pd auto gets 25 mpg on high way if I,m lucky.60 mph seems to as fast as she likes to go any faster than that the revs are just to high. Don,t have a tach but ya sure can here the revs ay 70.

[RAlly_DatoB210]

weird... my friend has a 4 speed hatch with similar badmilage. he wont take it past 70 cause it sounds like its gunna explode. ill take mine up to 90 before i run out of gears. have clocked it with a new car next to me too. read 87 but had a mile or so to milk oout of it