shinzon1

iTrader: (1)

i just swapped a th350 in to my 89 camaro. i'm having trouble getting the speedometer gears right. i'm pretty sure that i have all my info right but i cant find anything on the speedometer revolutions per mile. everything i've read says that most modern cars from 1965 and up turn 1000 times per mile. is that the case for 89 camaros? need help!

AlkyIROC

What's you tire size? What's the gear ratio in your diff?

ed o

that's funny.
the 700r4 (built since 1982 not 1965) has a .7:1 overdrive, so it differs in revolutions per mile than say a th350 with a gear ratio of 1.0:1
stephen is correct, get some valid info on the car
a 26"tire x3.14=81.64" per revolution, divide by 12 to get feet=6.8feetper revolution, 6.8 divide by 5,280(a mile)=revolutions per mile is 776.47 times your rear gear ratio (3.55 guess times 776.47=2,756 revolutions of the output shaft per mile, 1:1 trans,
not even close to your predictions!!!!!!!!!

AlkyIROC

It's a speedo gear output speed. If you were doing 30 mph in any gear, the output speed would be the same telling the speedo that you are doing 30 mph. In first gear the engine would be screaming, in OD it would be at an idle.

1000 rpm per mile is a common speedo speed but there are also other speeds. Traveling a mile at 30 mph or 60 mph the speedo will still turn 1000 rpm per mile providing it's been calibrated properly with the proper speedo gears or an adapter.

shinzon1

iTrader: (1)

my tire size is 26 inches. the axle code tells me that it is a 3.42. i went online and ordered drive and driven gears for 26" tires with a 3.42 ratio and 1000 revolutions per mile speedometer, but the speedometer reads way too fast. i havent had a chance to find what it reads at actual 60mph. i'm gonna open up the rear end and make sure it has a 3.42 in it.

shinzon1

iTrader: (1)

i pulled the cover off and counted the teeth on the ring and pinion. 41 on the ring and 12 on the pinion. it is definately a 3.42 gear. so the only thing that leaves me with is something wrong with the speedometer the speedo drive gear is red with 7 teeth and driven gear is black with 19 teeth. any ideas as to whats going on?

shinzon1

iTrader: (1)

and the speedometer reads about 105mph when i'm actually doing 50.

AlkyIROC

7 and 19 should be pretty close. At least within 5 MPH.

shinzon1

iTrader: (1)

thats what everyone i've talked to and every website i've found said. but with 26" tires, a 3.42 gear, 7 tooth drive gear and 19 tooth driven gear the speedometer reads about 105 mph at actual 50 mph. i count figure it out. i started to take the speedometer out and ended up braking the shaft that the pointer rides on. so i'm gonna end up getting another speedometer anyways, but if the next on does the samething then i'm lost.

ed o

how did you check the drive gear teeth? as they are hard to see with the housing on? maybe your count is off, the gears have been made different tooth counts with different color/manufacturers, so you can't judge a book by its cover so to speak. if you used a color chart to determine tooth count it is probably wrong.....

shinzon1

iTrader: (1)

i ordered the gears online. when they came in i counted the teeth. i built the transmission myself. i know its a 7 tooth drive and 19 tooth driven.

shinzon1

iTrader: (1)

the car used to have the 2.8 v6. the speedometer is the 110mph one. i'm going to a couple of junk yards around here and i'm gonna try to find a different one.

shinzon1

iTrader: (1)

figured out the problem. thanks for eveyones help!

ed o

yes?

shinzon1

iTrader: (1)

it was actually my fault. lol. i had two gears drive gears sitting byside and i grabbed the wrong one when i put it on. i felt like an idiot when figured it out. when i grabbed the first one i just grabbed the one that looked cleaner thinking it was the newer on, but it of course wasnt.

B Roger

I have an '86 Berlinetta with the Digital Dash but can't find the RPM/Mile specs for it. (1K p/mile RPM?)

I just swapped out the 14" Berlinetta wheels for the 16", '86 IROC wheels and a 245/50 tire (ended up with a 25" diameter).

I have a 3:42 posi diff.

How do I figure out which speedo gear set to put in the 700R4?

Roger

Samdweezel05

iTrader: (1)

I will add a question to this as well. Does the cable from the 700r4 hook up to a TH350 directly or is there some kind of an adaptor that is needed. I am going to be doing this in the near future with a project car. Thank's

Phil

shinzon1

iTrader: (1)

here is link that should take you to site where i figured mine out. http://www.transmissioncenter.net/sp...n_______va.htm

shinzon1

iTrader: (1)

the speedo cable will attach directly to the th-350. and it is 1000 revs per mile.