Hi Andy,
I'll share a little experience with gearing. I have two Tigers, one has a
high-revving 6800 RPM (no snickering, Buck) 289 with the standard close ratio
Toploader, a 3.23 rear end and 205/60-13 (22.8" diameter) tires. The other car
is a low-revving (5800 RPM) 331 stroker with stock 2.88 but with the wide
ratio gear set in the Toploader and 205/60-14 (23.7" diameter) tires. In
either case the cars will easily overcome available traction with much spin
and hop. I have a set of Hoosier R6s for the 289 car and those tires have a
lot of bite but still spin like hell.
When I built the stroker car I went with the wide ratio to keep the stock rear
end and therefore lower RPM at motorway speeds. I had the opportunity to flog
both cars last weekend through some of S.E. Ohio's famous back roads and
actually preferred the 289 car with the close ratio box, it was a better
combination for tight roads when running 50 to 70 mph. The stroker car is all
about torque (over 325 lb-ft from 2100 to 5700) and was more comfortable when
I just left it in fourth and powered out of the turns, with an occasional
downshift for switch-backs and to blast past the errant Amish buggy. In short,
the close ratio was more fun and more involving to drive, the wide ratio was
more relaxing and less fatiguing. Two different kinds of quick. On the
Interstate the 331 car with the bigger tires and 2.88 turns about 500 rpm
lower so is more relaxed and less stressed on long trips.
So what to do? If your engine has a broad torque curve, the wide ratio is the
way to go, this also preserves the 2.88 rear end for those 80 mph I-35 runs,
plus it keeps your car close to original. A 5-speed would be the best choice
but you either go cheap and modify the car's sheetmetal or spend cubic dollars
and use Tom Hall's T-5 kit or the new Tremec drop-in kit from Bill Martin.
Also keep in mind what you plan to do about tires in the future. There simply
are no more decent 13" or 14" tires out there, so the jump to 15" or 16" will
change your running diameter and your effective gearing. Your current tire is
about 23.2" in diameter, a 205/50-15 is right at 23" dia, a 225/50-15 is
23.8", all part of the equation.
For Toploader parts I have had great service from David Kee Toploaders in San
Antonio TX, I have bought gear clusters and complete rebuild kits from him. He
will also rebuild yours with a nice wide ratio cluster. Be aware that to
rebuild a Toploader with a new gear cluster and bearing kit will be north of
$1100.
Good luck,
Bugz
-----Original Message-----
From: tigers-bounces@autox.team.net [mailto:tigers-bounces@autox.team.net] On
Behalf Of Andy Walker
Sent: Tuesday, August 06, 2013 11:44 PM
To: 'Tiger's Den'
Subject: [Tigers] Gears and rpms
Hey, guys:
I've got a question for some of the more mathematically proficient in the
group. I'm considering making some changes to my Tiger pertaining to the rear
end gear ratio. Can anyone tell me how to figure what kind of rpm difference
there would be at, say 70 mph, between a Tiger equipped with a stock 2.88:1
rear end and one equipped with first a 3:07.1 and then a 3:31.1 rear gear?
Surely there's a formula out there that can figure that. Can
anyone point me in the right direction?
The bottom line here is that I need something that will get my car off the
line a bit quicker without completely destroying my highway cruising
capabilities. I currently am running an Edelbrock F4B and a Holley 465 cfm
carb, a hydraulic version of the old Ford hi-po cam, and 13" LAT 70s with
185/70 tires. The car currently has a 2:88.1 rear gear and that makes it a
bit sluggish off the line. I've heard it said that a 3.07:1 gear was about
ideal for a stock Tiger, but with the cam and carburation my car has, would a
3.31:1 be a better alternative?
Thanks for any advice,
Andy Walker
Edmond, OK
B382001600LRXFE
TAC #740
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