Anyone with 4.11 gears mind telling me your top speed?

[Vamisk]

It's a franken car, it has at least a 63 motor. I'm assuming the previous owner just bought a R&P from Clark's and threw it in. My current tire size is 175/70/R13. Not sure where i can find bigger tires for these rims.

[bbodie52]

175/70R13

That's about 22.6" diameter (71" circumference) and 921 revs per mile, compared to the standard for Corvair of 829 or so. With a wild (not for street) 4.11 gear ratio you have the worst possible combination! No wonder it gets squirrelly!

RECOMMENDATON: Replace the differential with a 3.55 unit and mount some 14" rims and tires. You will save a lot of gasoline, the car will handle, brake and perform better and will be safer, and your engine will survive and will be happy.

Sizing Corvair Wheels and Tires
http://autoxer.skiblack.com/tires.html

[Vamisk]

That's the plan, i need a new clutch anyway. Are 3.55s common by any chance? can i use any old GM ring and pinion? Does the 3.55 still accelerate decently in your opinion?

[bbodie52]

29 posts and I still cannot tell what part of the country you live in!

As you can see, 3.55 and 3.27 differentials for manual transmissions are common. The 3.55 gives a little more pep to the acceleration and is better if you have a lot of hills to climb. 3.27 is better for lower cruising engine speed and slightly better gas mileage. 1961-1963 should be plentiful, 1964 would work but is more rare due to the transverse leaf spring mount needed on 1964 Corvairs. 1963 and earlier come with a drain plug.

Shipping weight is about 80 lbs. Clark's doesn't seem to have any. Changing th gearset in your existing unit is somewhat complex and a little hard to set up correctly.

The Corvair Ranch is 185 miles north of you in Gettysburg, Pennsylvania. They have a lot of experience and a large inventory of Corvair parts cars, trucks, and vans and should be knowledgeable about your needs

http://www.corvairranch.com/


1079 Bon-Ox Road, ​Gettysburg, ​PA. 17325 USA
​Phone: 717-624-2805
fax us by the same number... ask us to hook up the machine
​Email: findit@theranch.today
Our hours are Monday thru Friday 9 to 5, Saturday 9 to 12
or contact us for an appointment.

New 4.11 gear sets are expensive and rare. Maybe you can sell or trade or something like that to help cover your parts costs and shipping fora standard set of gears.

Part number C5050: 4.11 GEARS*!! (*!*!FOR HIGH STRESS DUNE BUGGY APPLICATION WE SUGGEST C8644 )

Weight: 10 lbs 0 oz
Catalog Pages(s): 126,OT-26
Price: $ 353.65

[66vairguy]

Yes the 185/80x13 is very close to the old 7.00x13

You have not stated your tire size. To find the revolutions per mile, or ROLLING circumference (tires squish) mark the tire and pavement and move the car for two tire rotations (to average out error) and fine the distance of one rotation and post. Then the RPM at 60 can be more accurately calculated.

Changing a ring and pinon set should be done by someone with experience, like the Corvair Ranch mentioned. Let them find the parts as the EM and LM ring bolt pattern is different. They can also find the correct speedo drive gear. A 3.55 is a good all around ratio (why GM used it). Unless you plan on spending a lot of time on the highway the 3.27 isn't needed, and in hilly country it's less desirable.

[Vamisk]

I'm in the southeast corner of Pennsylvania and I've heard of the corvair ranch but never checked them out.

My tire size is 175/70/R13. If it makes a difference to the diameter, they are perpetually squashed in. (They look flat but I can assure you they have the right amount of air).

[bbodie52]

The radial tire equivalent of the Corvair factory stock 6.50-13 bias ply tire is 185/80R13. Your 175/70R13 tires are significantly smaller than the standard.

185/80R13 OVERALL DIAMETER: 24.7" REVS. PER MILE: 842

175/70R13 OVERALL DIAMETER: 22.6" REVS. PER MILE: 919

(Average tire specifications from the Tire Rack website)

195/70R14 OVERALL DIAMETER: 24.8" REVS. PER MILE: 839

205/70R14 OVERALL DIAMETER: 25.4" REVS. PER MILE: 821

(Typical 14" tires fitted to Corvairs)

Left-click to enlarge for better viewing...

RPMs FOR GEAR RATIOS & TIRE DIAMETERS IN HIGH GEAR AT 60MPH

Above data is from Sizing Corvair Wheels and Tires http://autoxer.skiblack.com/tires.html webpage

The Corvair Ranch is about 125-150 miles from your location. I would suggest calling them to discuss your needs and see what they can suggest, either with a differential swap or exchange, or having them change the gearset on your differential.

The Sizing Corvair Wheels and Tires http://autoxer.skiblack.com/tires.html webpage I referred to earlier also lists a number of factory 14" 4-lug wheels in the section labeled: Interchange Information. These used wheels were found on a number of British, Japanese, Korean and American cars. These serviceable used wheels can often be found on eBay or at local swap meets or junk yards. Switching to 14" or 15" wheels for a Corvair can open up a wide range of modern performance tire options that are simply no longer available in the obsolete 13" wheel size.

[Vamisk]

Thanks a bunch, it looks like I have Some work cut out for me.

[66vairguy]

If you check the tire calculators you'll get various numbers, but a 175/70x13 is small and some rough calculation shows a 4.11 axle will hit 4,000 engine RPM at about 65. Again to calculate accurately you have to do a rolling measurement, but a 175/70x13 is small.

If you go to a bigger rim make sure you try to check the backspace to maintain good steering geometry. A lot of recommend the 15" rims for greater tire selections over 14", but even the 15" tire selection is getting slim now. The 14" gives a better ride and the 205/70X14 tire (a good fit) is still common.

Good luck.

[64powerglide]

Keep an eye on this place, they are always changing the price, last week they were $98.00.
https://simpletire.com/maxxis-p185-80r1 ... 0000-tires

[64powerglide]

What is the engine block number? It's behind the fuel pump & what is your timing set at? If it's to high you will lose power at high rpms.

[notched]

Your car is severely over geared if the car in question is the one listed in your profile with the 110. I did that years ago with a set of 3.89's. Those gears are best suited to a heavy vehicle such as a van OR something highly modified with heads and cam that can spin past 6,000 rpms. I would looking into getting another differential with 3.27 or 3.55 gears.

[davemotohead]

My 65 Corsa 140 with 280 isky cam and 4:11 posi 23" tall tires tops out at 126 mph on the radar gun at about 6500 rpm, it will rev to almost 7000,your engine sounds like its only doing about 4000 rpm or less.

[66vairguy]

motohead - you really need to go to a Crown mid-V8 setup. Faster!!

[Vamisk]

It's possible it's not revving that high. I just bought a taco from vatozone but the install will have wait a while. It's hard to guesstimate rpms when the engine is too loud to think over.

[Vamisk]

My 65 Corsa 140 with 280 isky cam and 4:11 posi 23" tall tires tops out at 126 mph on the radar gun at about 6500 rpm, it will rev to almost 7000,your engine sounds like its only doing about 4000 rpm or less.

That makes me wonder about the aerodynamics of a Corvair. Obviously late models have better lines but are these cars worse or better then any comparable cars of the time?