since I will have my CJ car back on the road here soon I have been considering a gear change. Car has the stock 14" Gt wheels and with the tire I have it tachs a little high for my taste on the highway. I checked the speedo and its correct within 2mph and was told the car has a 3.50 gear so what would be a better gear to run so the car could b driven at highway speeds? As it sits now I see almost 3k at 60 i would have to drive it again to double check but beleive thats close. I just cruise with the car and have a little fun now and then in town so not to worried about loosing a little grunt down low
Basically your choice is between 3.25 and 3.00 gears.
August 17 2012, 3:02 PM
There are other ratios, but those are the most common in the range your looking at. IMO, going to a ratio numerically lower than 3.00 would kill acceleration toooo much.
So if you have 3.50's now, and are running about 2930 rpm at 60 mph, going to a 3.25 will drop the rpm to about 2720 at 60 mph. Going to a 3.00 gear will drop you to about 2510 rpm at 60 mph.
It's just a matter of what you want.
edit: Put another way, each drop in ratio, from 3.50 to 3.25 and from 3.25 to 3.00, will also drop your cruise rpm by about 200. It's your choice, but to make a really noticeable difference I think I'd go to a 3.00 gear. A 3.25 gear will make a less noticeable difference and may not be worth the effort and expense. It could also depend on your combination. Stock? Modified? Again, JMO.
This message has been edited by Paul_Lovett on Aug 17, 2012 3:15 PM
I like the 3.50 or 3.70 ratios for Pure Stock drag racing. On the highway most traffic around here runs 70 - 75. I like a 3.00 open for that, so I have a spare pumpkin with that in it. Takes about two hours to swap pumpkins.
Although a 3.00 gear change will knock your cruise RPM down around 400-500 RPM, it will also make you think somebody swapped out your 428 and installed a 351 in its place. Joe, is your Mustang an automatic or 4 speed? The combination of a close ratio toploader and 3.00 gears makes for weak acceleration and an unhappy clutch in stop & go traffic, especially starting off on a hill.I agree that having 2 complete 3rd members is a good compromise, a set of 3.00 or even 2.75s would be good for really long freeway trips, but if freeway use is infrequent, I never liked anything taller than 3.50s myself. On my old 70 428 4 speed Mach 1 I made several 2-3 hour freeway trips with 4.30 gears, and my 69 428 C6 Mach 1 regularilly seen 3 hour trips to the closest (at the time) dragstrips, with 3.50 & 3.70 gears. For myself, the performance loss of taller gear ratios was not worth the trade off. If you never drive your car hard, the 3.00s may not bother you too much, but I`d be cautious about any stoplight action for fear of embarassment.
428 powered Fairmont drag car, Best ET:[email protected], best 60 ft: 1.29
59 Meteor 2 dr. sedan 332, Ford O Matic
74 F350 ramp truck 390 4speed
Curious if U ever made any runs at the strip with the tall gear to compare to the others. I realize if it was a 3.00 open that might complicate the comparison, even a 3.00 would light up the right rear pretty easy in those Cougars.
OK, if you want to have fun, sure, have a true freeway flyer PIG, with tall gears, and a cruising. street racing Pumpkin, or a bracket night pumpkin, tuck away in a clean 3rd member box
If you pick a new gear, get one that has a speedometer gear available, richmond makes a bunch of fine steps in 9'' ratios, you probably know this
But hey, Doug Nash raced some good friends back when, and built a strong 4 + 1 5 speed that we must have used over 100 times in the 80's and 90's on fast, light to moderately heavy cars. Get a LONG shifter, or let a good guy modify it if you want.
We have one on a fast personal car, beat to death, works great, takes a pounding.
You can do some serious freeway racing with one and piss off a lot of Porsches which is such fun. We do it late at night sometimes with only collector extensions...no mufflers...too fun....
We have had a few friends blow their mufflers off back when, hilarious.
You get the best of both worlds with the correct rear gear. A hard enough launch, and a road warrior MPH with a good street tire, front and rear sway bars, balanced spring rates and power.
On your tires, short roll out? Low aspect ratio? Have 50's or something? A taller tire or 15'' wheels should be factored in too
How hard does this boy hook? What do you do with it? How much ooomph ?
Go To 15" Wheels and Larger Tires Even Bigger in the Rear
August 17 2012, 6:38 PM
Going to a taller rear tire will be like going to a numericialy lower gear ratio. Use this calculator to determin size difference and effect on final drive ratio. You may realy enjoy the new look with the bigger wheel/tire package. ww
you should probably call to see if they still make it.
I had a close ratio toploader I had swapped into a 351C 73 Montego.
Since it needed all new parts, I converted to a wide ratio. And
since I was paying for all new stuff, why stop at 2.78 when you can
have a 2.90 1st gear? Does it make a noticeable difference over
what a 2.78? I assume so, but I never drove that car with a close (2.32)
or 2.78 so I can't really say. That car isn't great for torque to
weight, so I knew I needed as much gear as possible.
With a slushbox changing to 3.00's wouldn't be that terrible but with a Toploader it'll suck. Gord has the right idea with a lower first gear in the toploader (or change to a Doug Nash/Richmond) and the other way would be to swap to a tranny with an overdrive like a Tremec and leave the 3.5's alone.
Taller tires would help but again you get into reduced first gear if it's a stick.
With an auto, it's not that bad in a relatively light car with a big motor. My old `62 Falcon wagon with a 10.5:1 351 would still eat a 5.0 for lunch with a 2.79 open on 29" tall tires. The COM had a stock convertor in it and the launch was still good but softer than a dedicated drag car. On the other hand, I could cruise the highway at 20mpg doing 65 or so (back when 55 was the federal max) and take all kinds of stuff in a race even when they had me off the line.
A rower would make it a completely different game but traffic levels vary and would matter a lot. What I could handle floating around in northern Arizona would drive me up the wall here in LA.
That said, 3.00's won't be bad with an auto in a 'stang with any FE over a 352... Whole different world in a Gal or truck. Then again, I have truck with a granny gear 4spd and 3.00's with 31" tall tires that I have no problem driving... If the motor has good torque at idle, it might not be a deal breaker even with a stick.
`67 F100 Custom Cab
So the 360 runs but... it's a 360.
The Last Dance 428 is next.
with 255/60 15 tyres, about 27" diameter. I was going to go with lower gears just for fun at one time, but now the motor makes some good torque, I'll stick with the 3.25's. they suit this particular car very well. lots of variables. I certainly wouldn't go to any taller gear for highway use, just drive slower... of course, a tremec or whatever would be nice, but my pockets only have a certain depth
I apprecite all the input guess it would have helped to give you guys more info on the car lol my mustake. Car is a 68 428 CJ R code Torino with a c6. I want to be able to drive the to maybe KC or somwhere that distance so would like to be able to at least cruise around 70 on the highway to make the trip bearable lol. Tire size in the rear now is 235/60/14 sucks cause there isnt alot of options in a 14 that give you a wide tire with good height so I know the tire size doesnt help. I do drive the highways here in wichita quite a bit so just dont want it reving to death lol. Yeah a different soze whel and tire would help just dont want to ditch the stock wheels at the moment. Guess I should just deal with it for now and save my pennies for a gear vendors unit lol.
Rory et al are right about his comments with a stick car, 3.00 and a 2.32 top loader make even a big block a dawg, I ran one like that. On the other hand, the car was a quiet loafer at 60mph cruise and got 21mpg up there (tho it was a 429 set up for MPG and not a 428cj). About 2000rpm at 60mph with h70x15 on the back.
If you have stock era tires and traction I actually dont think it will hurt performance much either tho you might not be able to do as Fierce of a burnout but so what.
it shows that each 1" increase will save you about 100rpm.
find a 27" or 28" tire and you'll be happier. get some
15" magnum 500s: they look great as well as look factory correct
(even if they were never an option on your particular
combination, no real Ford guy ever complains about a set of
Here is "stock w/revised cam" 428scj car running at Milan from a 5-car comparison (Buick won!!?!?) in the Jan 99 MuscleCarReview
13.87 at 101.57
With 3.91 gesrs, matching traction, Gonkulator says (I did assume the c-cam and a good loose build)
9.03 at 80.5
13.87 at 101.6
Swapping in your current 3.50 gears, no other changes, Gonkulator said
9.05 at 80.4
13.92 at 101.2
Swapping in 3.25 gears, no other changes, Gonkulator said
9.08 at 80.6
13.95 at 100.7
Swapping in 3.25 gears, no other changes, Gonkulator said
9.12 at 80.1
13.99 at 100.5
The gears dont help much on those factory tires. Of course this Gonkulator comparison is no guarantee - I asked Royce if he ever tried this swap in his Cougar. How bout go get some timeslips, then swap in a 3.00 and compare and post back? Even if it's a tenth or two, given your use I bet you will be way happier cruising with the 3.00's and have a 3.50 or even 3.89 handy with some sticky rubber for fun days.
I have a Frankland quickchange in my '64 Galaxie and it is quite road worthy. I usually run around with 3.80's or so, but I can switch to super tall freeway friendly gears in a snap. It has full floating hubs as well.
I recall watching a Nascar race about ten years ago when one of the Ford's i rooted for snapped the pinion leaving the pits, they pushed him behind the way and a dozen guys thrashed about and had the third member changed in maybe five minutes. I think the caution flag was still out when they were done. Amazing what teamwork and preparedness can do.
With a full floating rear end the axles slip out of the rear hub, and the tires and brakes do not need to be pulled, that is why the rear gear was changed so fast. I used to change the pumpkin in my dirt modified between the heat race and the main in about 15 minutes using a floater 9" Ford rear end.