my project is finally buzzing down the road.. just wondering what you olds guys are running in the way of rear end ratios, as well as what kind of MPG i should expect?? the way it's set up now i need to be hauling ass to utilize the overdrive.. anything below 85 and the engine lugs at 1500 rpm.. and hauling ass at 90 is a little too hair ball for me... and i'm getting about 11 mpg that's a combo of hi-way and city driving.. no black smoke, and plugs look pretty good, a tad rich- the engine has around 175 miles on it- i seems like she likes to run around 65 @2300 (4th gear) i used one of those ratio calculators and it seems that a 3.89 ratio would put me where i wanna be (2000 @ 70) i realize that i have pretty much answered all my questions, however i am curious to hear what you guys are running.. 31 CCPU Model A , weighs 2700 pounds 3.70 rear 750 r16 rear tires 56 324 olds, .60 over cam Lunati-.540 intake .549 lift exhaust rochester 4gc carb heads are ported, and set up with chevy 194 intakes valves 160 exhaust stock exhaust manifolds electronic ignition WC t5 thanks guys- Rich-
are you sure about the rearend gear ratio? with that tire and gearing, should be running a few hundred rpm higher.
Good going Rich! Glad to see another Olds going down the road. What did you use for rockers and lifters in that 324? AS for the gear ratio wouldn't you want to be up in the 411 arena? with that overdrive T5.
What is the OD ratio of your trans? I had one with a .53 OD and it acted like yours. Screaming in 4th then lugging in 5th. I thought it was a .63 when I got it. Changed to a .73 OD and a 3.55 rear and it works great now. 2000 at 70 in 5th and 1st is not a granny gear.
85 MPH in OD should show about 2400 rpm. seems like she likes to run around 65 @2300 (4th gear)Rich-[/QUOTE] 4th gear should show about 57 MPH @ 2300 RPM. Something is not reading correctly, or the rear ratio is wrong, as squirrel already mentioned.
If you want to run 2000 rpm @ 70 mph and you have around a 30 inch tall rear tire, you're going to need about a 2:6 final drive. To figure what ring and pinion you'll need you will need to know what high gear in the trans you're running.
4th gear should show about 57 MPH @ 2300 RPM. Something is not reading correctly, or the rear ratio is wrong, as squirrel already mentioned. [/QUOTE] X2 something is wonky
I had a friend take some notes while I drove, this is what we got 1st. 2500 @25mph 2nd 3000 @40mph 3rd 3000 @ 55mph 4th 3000 @ 70mph 5th 2000 @ 80mph To be honest I'm not sure what my od is.. I should be able to get a ball Park by spinning the rear wheels and counting drive Shaft rotation??? And yes the rear end ratio is 3.70 Posted using the Full Custom H.A.M.B. App!
" To be honest I'm not sure what my od is.. I should be able to get a ball Park by spinning the rear wheels and counting drive Shaft rotation??? " No, this won't work for the trans gearing. You might be able to put the trans in 5th and turn the motor one turn and see how far the the driveshaft turns. Or turn the motor 10 times and count the driveshaft rotations. It would probably be a little more precise to check it on the bench but if you are careful to mark and turn everything while its in the vehicle you should be able to get close enough. There seems to be several ratios in the T5 overdrive trannys. With careful measurements of tire height and rotation of the drive train you should be able to figure it out if by nothing but process of elimination. It seems like the 5 speed you are using is a poor choice for your vehicle. Too much of a jump between 4th and 5th. If you gear it where OD is useful, fist gear will be just about useless
Thanks man...it's been a long time coming!! I'm running the stock rocker assembly. . So 1.8:1... Posted using the Full Custom H.A.M.B. App!
Thanks for all the info guys.... Ed, I'll mark and count rotations later today. . As well as check the rpms at the speeds that were listed- Thanks Posted using the Full Custom H.A.M.B. App!
If you have a 3.7 gear your tire OD is 29. here are the ratios calculated from the info above. 2.33 1.75 1.27 1.00 0.58 Some Web WC T5 info; I think rechecking your info is a good idea. Might want to use your phone GPS for speeds. With a 4.30 you will be about 2015 @ 70. Hoop
Using these numbers, finding rear axle/tire diameter by assuming 4th is 1:1, I calculated the following ratio's; 2.33, 1.75, 1.27, 1, .58 What transmission are you using? I'm not familiar with any factory 5 speeds with a close ratio like that. There is a significant drop into overdrive, but with that first gear you could run a lower axle ratio to get your desired cruising rpm. As for mileage, what is the duration and lobe separation of your cam? Based on the lift, I'm assuming it has fairly long duration and tight lobe centers. A "rumpy" cam, not a high efficiency one. I don't think your ever going to get good mileage with a rowdy cam in a non-aerodynamic vehicle. It may pick up a little bit once it's broken in and tuned spot-on.
I. Got the trans through the guy who built my engine. It's a mid 80s camaro gear box with a s10 tail shaft.. and its a fresh rebuild.. ill make a phone call tomorrow, hopefully the builder keeps records. .. Lobe seperation is 108°.. wiyh a 280/290 duration.. pretty hairy.. It stilled needs to be fine tuned.. my plan is to bring the truck to a shop and have them set it up, carb , timing, ignition curve, etc... Fine tuning isn't my specialty! Posted using the Full Custom H.A.M.B. App!
Exactly what efabman said. I originally had a 4:10 rear end a 2:95 1st with a .53 or so overdrive. I thought it was a .63 when I got the trans, never found where .53 was availabe with a 2.95 1st. so someone changed in the past. RPM would drop almost 1/2 from 4th to 5th. Confirmed ratio by rotating motor 2 turns and the driveshaft only rotated a hair over 1 turn. 1st was almost useless, couldn't cross and intersection without having to shift. Used 2nd most of the time. Have 30.5 inch tall tires. I found if you look at most tire specifications, they will give you the rev's per mile (663 for my case) I changed to a 3:55 rear and a .73 OD in the trans. Now there is a pretty even gap between all gears. 1st is usable a 10.47 ratio and final drive in 5th is 2:59. Before I could not drive around town in 4th at 50 to 60 then got to 5th without dropping the RPM's to the point it would bog. I made an excell spread sheet to figure this all out.
<TABLE id=post9499566 class=tborder cellSpacing=0 cellPadding=6 width="100%" align=center border=0><TBODY><TR vAlign=top><TD id=td_post_9499566 class=alt1 style="BORDER-RIGHT: #e5e5e5 1px solid">This for a mph base line ...... "I think rechecking your info is a good idea. Might want to use your phone GPS for speeds." Also put a level on the top of your rear tires to see how tall they are. Dialing everything in will make driving your hot rod a lot more fun. <!-- / message --></TD></TR><TR><TD class=alt2 style="BORDER-TOP: 0px; BORDER-RIGHT: #e5e5e5 1px solid; BORDER-BOTTOM: #e5e5e5 1px solid; BORDER-LEFT: #e5e5e5 1px solid"> </TD><TD class=alt1 style="BORDER-TOP: 0px; BORDER-RIGHT: #e5e5e5 1px solid; BORDER-BOTTOM: #e5e5e5 1px solid; BORDER-LEFT: 0px" align=right><!-- controls --></TD></TR></TBODY></TABLE>
Sounds like you have a: 1st: 2.915:1 2nd: 1.932:1 3rd: 1.323:1 4th: 1:1 5th: .59 gearset so you need to verify tach/speedo. Might make more sense to go to the .72 OD gears (just change the 2 overdrive gears) than changing rear end. That would give you 2162 with your current rear end.
Hoop... I'll varify speed with my gps on the way to the shop today... the tach is fresh from being repaired, as is the speedo.. How hard is it to switch out the overdrive.. in other words can I do it with the trans in the car?? If not it'll be way easier to switch out the rear.... Posted using the Full Custom H.A.M.B. App!
I really don't know about the Trans OD swap, But if you change rear gears won't that leave you with a useless 1st gear and soggy starts in 2nd gear? You'll be in a different boat with the same problem . Or maybe that's same boat but a different problem lol?
A lot of guys are using the 5 speeds so they can keep some of there hard earned money in their pockets so I would disagree unless you are some rich guy that doesn't give a fuck. In my 55 chevy TKO 600 0.64 overdrive (a stupid 5 speed) 4:56 gear 30 inch tall tire 70 mph 2100rpm 25-26 mpg on the highway Saving money for other things. Not so stupid afterall Jay
As 32VwaH says, swapping the rear end doesn't fix your complaint, too much drop 4-5. I'ts pretty easy but you will need to pull the trans, it does fix it though, not swap it for a new problem. jm2c
Thanks Gasser ... although i have been known to not give a fuck, i'm certainly not a rich guy- so saving some gas money sounds like a great plan.. although with my cam i'm not so sure just how much i'll be able to stretch it! thanks for passing your info along..
right on hoop... i'll verify all my specs and #'s again, than take it from there- yanking the trans isn't that much of a pain in the ass- stay tuned! thanks man-
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