My other car, a 72 Buick Skylark, now has a rear diff change which using the phone's GPS speedometer puts it off by 17 percent. (If my math was correct) 17% of 70 is 11.9 The car currently requires 82 mph on the gauge to go 70 actual mph. ....or should it be a percent of the 82?
I hope to get the TH350 speedo gears changed out sometime, maybe in years...but in the meantime couldn't a printed out speedo with a 17% increment change be made? It could be cut into an arc shape and let me know what actual speed is. Otherwise I was going to pretty much just tell myself its about 10mph off, but at 35 mph its off by less, so...
Maybe its more of a can it be done thing.
Anybody good with math and a graphic program?
I suppose we'd the the gauge face diameter...
[This message has been edited by 2.5 (edited 07-08-2016).]
go to your local g.m. dealer and get the correct gears..
hope this helps, then just go to your g.m. dealer or trans shop and get the gear or gears if needed this is a bolt in /on fix, really easy if you only have to change the driven gear, if you have to change both, you only take off the tail housing (4 bolts) and one pin/clip and slide off the gear and in with the new put clip/pin back, bolt housing back on and bingo you are done, well you have to put the driveshaft back but that's a whopping 4 bolts.. It will take less time and energy to do this than take the stock gauge apart and reface it.. while milking the work it'll take under an hour.. even with a break to have a beer or two
go to your local g.m. dealer and get the correct gears..
hope this helps, then just go to your g.m. dealer or trans shop and get the gear or gears if needed this is a bolt in /on fix, really easy if you only have to change the driven gear, if you have to change both, you only take off the tail housing (4 bolts) and one pin/clip and slide off the gear and in with the new put clip/pin back, bolt housing back on and bingo you are done, well you have to put the driveshaft back but that's a whopping 4 bolts.. It will take less time and energy to do this than take the stock gauge apart and reface it.. while milking the work it'll take under an hour.. even with a break to have a beer or two
Maybe. Well, I've been crawling on V8Buick.com, gathering info, and it seems like its not so easy to identify the part you need. People were confirming that though a certain number of teeth gear was supposed to be a certain color, it didn't hold true. Plus I don't know for sure if my trans is a 1969 or a 1972. Also I read that certain drive gears only fit in certain housings so it spossible a new housing is required? I don't really want the car sitting out of commission for any length of time until November when off season starts. I only get limited time to work on things. Every once in a while my speedo will make a scratch sound and wobble some like it slips, (around 35mph) so unless that was a gear thing maybe I need a new cable too.
So I need to take it apart before I can determione what to buy then. Need to get: Tire size,= 27.05 inch Diff ratio, = 3.08 The teeth count of the drive The teeth count of the driven Drive gear clip size, Drive gear shaft size.
So I need to take it apart before I can determione what to buy then. Need to get: Tire size,= 27.05 inch Diff ratio, = 3.08 The teeth count of the drive The teeth count of the driven Drive gear clip size, Drive gear shaft size.
See if its a large or small driven gear.
That tells me what I have in it.
buick uses the larger gear shaft dia.. the chevy th350 uses the 1" and the larger clip as the shaft dia is larger.. it does have a buick engine in it ..
Chevrolet transmissions use a 1" diameter steel driven gear housing located in the tailhousing on all two-wheel drive applications. Buick, Oldsmobile & Pontiac transmissions use a 2.078" diameter driven gear housing. Two housings, each made from either aluminum or plastic, are available for driven gears with 34 or more teeth. One fits gears from 34 - 39 teeth and the second one fits gears from 40 - 45 teeth.
[This message has been edited by E.Furgal (edited 07-08-2016).]
You said your cell phone has a GPS speedometer. So stick a phone holder on your dash. DONE.
But seriously, if it says your speedo is 17% off, that's 17% of your actual speed. So your speedometer is reading 117% of the actual speed (117% of 70 is 81.9). To reverse that effect, you would need to expand your speedometer (i.e. make the hash marks further apart) by 17%.
Since your gauge needle only moves so far, that means your new gauge face won't go up to as high a speed as your old one. Take your existing maximum speed and divide by 1.17. For example, if your old gauge face went to 100 mph, the new one would only go up to about 85 mph (100 / 1.17 = 85.47).
It shouldn't be hard at all to make a custom gauge face. There may even be software to do just that. All you should need is the diameter of the gauge (if it's round), the sweep of the needle (in degrees), and the maximum speed.
[This message has been edited by Blacktree (edited 07-08-2016).]
You said your cell phone has a GPS speedometer. So stick a phone holder on your dash. DONE.
Thats is seriously what I did....I had over sized tires on an F150 about 5 years ago, it would read about 15-20% off at highway speed---I picked up a refurb Tom-Tom for about 40 bucks, mounted it over the speedo and called the job done.
Mind ya, I used that truck mostly on the highway anyway and drive with the traffic flow so really the only time I needed to check a speedo was those times I was alone on the road.
[This message has been edited by MidEngineManiac (edited 07-09-2016).]
Thats is seriously what I did....I had over sized tires on an F150 about 5 years ago, it would read about 15-20% off at highway speed (tom-tom said I was doing ---I picked up a refurb Tom-Tom for about 40 bucks, mounted it over the speedo and called the job done.
Mind ya, I used that truck mostly on the highway anyway and drive with the traffic flow so really the only time I needed to check a speedo was those times I was alone on the road.
You in a truck with over-sized tires? I'd never have figured you were the type...
