SS 454 rear gears

[riverdogs00]

Group,

I wanted to get the groups opinion on rear end gears for my SS.

The car is a low mileage (approx 60k), and a mix of original and reproduction items. It's been repainted, and repo seat covers, carpet,dp's installed. Drive train appears to be original and for the most part untouched. There are a few non stock items - upgraded ignition and wires for example, new "correct" style Qjet, and now P/S pump, and of course the load leveling is gone, but I'm slowly acquiring all of the pieces to reinstall that system.

The car has the highway 2.56's in it, and I'm really torn.

I am thinking of installing something in the 3.31-3.55 range with a posi/limited slip, etc just to make the heavy car a little more responsive around town.

The car is just a weekend cruiser, not a race car. It will not be a 100 pt show car, nor a museum piece, but rather a mostly original/correct fun weekend car that I hope maintains it's value.

There will be some highway 65-70 mph running as well in and around my local area.

I'm torn as i want to keep the car as original as possible, yet enjoy driving it more.

 

The question is this: If I  swap gears, do you think it hurts the value of the car?

Has anyone made this swap with the LS5, and what do you see? Is the difference worth it?

 

 

M

[Canuck]

Both my 71 SS cars had 3.31 from the factory but were changed to 3.73 before I got them. My suggestion is to stay away from 3.73 if you want to run on the highway. I'm at 3,000 RPM at 60 MPH. I would prefer that mine still had the factory 3.31 rear. I think the 3.31 would be a nice all round gear and it is something that could have been ordered from the factory so it would still be "correct" for your car.

[ripleydale]

You will love having lower gears. 3.42 is popular as a compromise. I put an Eaton posi in mine and it all seemed reasonably priced to me. You will still have your old carrier and gears so you haven't lost any value. Just made it easier to melt some rubber.

[Murphy]

Mike, you'll find that the 3.31 gears are hard to find & those vendors who produce them charge twice as much as the 3.42 gears. I've been looking for awhile and am probably going with the Yukon setup (posi & gears). I figure I can now go with a larger tire also and still get the performance I'm looking for...good luck! 

[Sam (Bones)]

the 3.31 is a nice gear if you can find it, IMO...I wouldn't go more than a 3.42 unless you opt to get a overdrive trans

[mrj52]

I put 4.11's in my SS years ago and hated it, Then installed 3.55's with a tall tire and still don't care for it Namely because the first 454 then the 571 ci motor produces a lot of torque, So in my opinion the 2.56 gears were good the long cruise and 3.31/3.42/5.55's.are hard on the highway at 70+ I am going to be installing 3.08"s to reach that magic compromise.

[Mike Brichta]

Hey Mike,

 

I went through the same thought process a few years back.  I did lots of research and listened to many opinions.  What it really comes down to is what you like and how you want to drive the car.  You won't really know what you like unless you try some different ratios.  I currently have 3 Monte's and a 70 El Camino and they all have different rear gear ratios ranging from a 2.67 (I think), 3.31, 3.45 and a 3.55.  Sometimes I like the 2.67 and some days I like the 3.55.  It all depends what mood I am in.  In my daily driver car I have the 2.67 and with a good strong engine I enjoy that one the most.

 

If you are not sure about keeping the car and rear original I would suggest doing what I did.  I pulled out the original rear and bought a real nice BOP 10-bolt posi rear for about $100 and then I tried several rear ratios until I found the one I liked the most for that car.  10 and 12 bolt rears are interchangeable and are not that hard to swap and you can always sell the 10-bolt if you want to later on.  Nice 10 bolt rears in my area are now selling for around $200-$250.  They only seem to go up in value.  That way you can play with different ratios without having to feel guilty about changing the original rear which you can always put back in later on.

 

Just my thoughts from someone who has already gone down the same path.

 

Good luck!!
Mike

[MCfan]

Mike, I don't see how a 3.31 could hurt the value of your SS because that was a factory option.  Fortunately, some of the '70 SS454 models that car magazines tested for quarter mile performance specs had the 3.31 axle, however, many (including mine) were built with the 2.56 cruising gear.

 

When I got my SS, I was used to the 3.31 axle in my '70 402/4-speed so I was originally pretty disappointed that it came with the 2.56 ratio and considered the same swap you are considering,  However, I soon discovered that in combination with the TH400 and the torque of the 454, it wasn't so bad.  It also came with BFG 245/60-15s on all four corners, so that shorter-than-stock tire also helped a bit on the low end.  Best of all, when cruising on the highway, the tach is still reading just under 2,000 at 60 mph.

 

I suppose it all comes down to the primary type of driving you will be doing and how quick you want your big, heavy Monte to move.  Since I have one of each ratio you were initially comparing, I can at least give you some cruising specs to consider.

 

When cruising at 70 mph (upper end of practical, IMO), here are the rpm comparisons for two different rear tire sizes:

 

2.56 rear axle -                                                                       3.31 rear axle -

                         245/60-15 (26.57" diameter) = 2267 rpm                               245/60-15 (26.57" diameter) = 2931 rpm

                         275/60-15 (28" diameter)      = 2150 rpm                               275/60-15 (28" diameter)      = 2780 rpm

 

Fortunately, I have the taller tires on the 3.31 car (which lowers high speed rpms a bit) and the shorter tires on the 2.56 SS (which helps the low end acceleration a bit).

 

There are several great on-line calculators for tire size, speed, rpm and gear ratio that will quickly give you data to compare various combinations - here's the link to one: Advanced Electric Vehicles  Just enter three of the four variables and it will calculate the 4th.  Obviously, you will need to enter your rear tire diameter in inches.  If you don't know it, you can enter your tire specs into this on-line Tire Calculator and it will tell you. Once you enter your tire diameter, then pick the speed you want to use for all comparisons, choose a rear axle ratio and click on Compute RPM.  For example, a 3.08 rear axle ratio @ 70 mph will require 2726 and 2587 RPM, respectively, for the two tire diameters shown above.  

 

What tire size are you currently running and are you planning to change your wheels/tires anytime soon?

 

 

 

[LostnFound]

Mine came with the 3:31's from the factory, still has them and they still looked in great shape when we pulled the cover for inspection, cleaning and new fluid and gasket a few years ago. They seem to be the right gear for my use.

[riverdogs00]

Group, thank you for all of the feedback. My current, and probably continued tire is a 235/60/15.

I agree the 3.31's is probably the best compromise. I would enjoy a posi / limited slip unit and the ability to lay some rubber down on occasion.

The car is not registered or plated just yet. I ran into a snafu in Nevada, and have to have it re-titled in Florida in the widow's name, and of course she has been out for a few weeks. I've only had it out around the block and have not got on it, simply puttering around to get a feel for it.

I took the opportunity to reseal my power steering pump and just finished that today. I bought a new pump and resevoir and was about to put it in when i dropped it and kinked the return line fitting. I just re-sued my original reservoir and a rebuilt pump and it works great.

 

I am sick though.......I had the car on jack stands to cycle the power steering, and went to start it. opened the door and did not realize the door was in a little bind and promptly took a 1" x 1"2 strip of paint right off the leading edge of the driver door. I could have cried.

[Canuck]

I had the car on jack stands to cycle the power steering, and went to start it. opened the door and did not realize the door was in a little bind and promptly took a 1" x 1"2 strip of paint right off the leading edge of the driver door. I could have cried.

 

I did the same thing on my red 71 SS I had when it was on jack stands doing a heater core swap. Nothing worse than chipping paint on your own car. Not noticeable to most people when they look at the car but still bugged me a lot.

[riverdogs00]

I did the same thing on my red 71 SS I had when it was on jack stands doing a heater core swap. Nothing worse than chipping paint on your own car. Not noticeable to most people when they look at the car but still bugged me a lot.

ARRRRGHHH     lol

it's definitely noticeable. I'm going to have to get the door resprayed I think

[Dans '70 Z20]

My 70 SS454 had a 2:56 one-legger in it when I received it (original).  True these big blocks have alot of torque but our cars are alot of weight to move too.  It is true that the 3:31 ratio was the highest available stock.  I ended up going with a clean used 3:31 gear set for my car but when I did my transmission I added a 2:75:1 billet lower gear set.  This way I have the best of both worlds.

 

Off the line my combination compares to a 3:64 gear in first gear,  a 3:42 gear in second and finally when 1:1 ratio in 3rd gear I get my 3:31's.  Its a great combination, and the lower gear set helps get our heavy cars moving easily from a stop.  ( Remember that Monte's with a standard transmission came with an M-21 rather than an M-22 for its lower first gear for the same reason)

 

If you plan on cruising at 70mph often (not possible in NY) you may want to keep the 2:56's and just add the lower gear set when your tranny is rebuilt.  Or maybe go with a set of 3:08's.  With the lower gear set you'll have close to 3:31's off the line but the 3:08's in third gear for 70 mph cruising.

 

Dan

[riverdogs00]

great info thanks!

[riverdogs00]

going with the 3.31's and an Eaton Trutrac. install scheduled for Thursday. I'll get new tires after i have a little fun with the 6yr old BFG's  

[72 LS5]

I put a post up a long time ago regarding the 2.56 and 3..31 gears in the SS cars.  I have yet to find a 70 SS that had anything other than a 2.56......same goes for the 3.31 in 71.  I'm not saying they didn't exist, but  I haven't seen otherwise.  Oddly, the Canadian version of the sales brochure lists 3.31 as the only gear for the 70 SS454, yet all I've seen is 2.56 for 70.,

 

Anyway, I agree with the others that 3.31 is a great all around gear.  With 3.31s, I have found that you can really tweak your highway cruising rpm with tire size.  With a shorter tire, I find myself in the slow lane doing 3000 rpms at about 65, but now I'm running the tall 28" tires (275/60/15), and I cruise at under 3k at 70....in the middle lane!

 

If you are building a low to mid range 454, I think the 3.08 would be the best all around gear for both city and highway....maybe with mild converter.

 

Dennis - those mph/rpm calculations include torque converter loss?  With my mild converter, I take my foot off the gas on the highway and the rpms immediately drop like 400 or 500 rpms.

[riverdogs00]

Turns out I need new axles too, and a wheel cylinder. To be expected I suppose. Any reason to keep any of the old parts?

[overdrive]

Wheel cylinder, no, imo. If the bearing surface is your concern on the axles, you can buy repair bearings that use a different area on the axle, and you won't have to replace the axles.

 

I bought Moser axles from Summit Racing, because the seal surface had some pitting caused when the original owner passed away and the car sat for years in a garage.

 

Dan

[MCfan]

Turns out I need new axles too, and a wheel cylinder. To be expected I suppose. Any reason to keep any of the old parts?

 

Mike, I assume you will be replacing the rear wheel bearings and seals when you replace the axles.  Or, as Dan suggested, you may be able to save your stock axles if you buy offset replacement bearings.  Either way, the axles will have to come out to replace the bearings and seals.  You may be experienced at that task, but if not, you might be interested in a photo journal I made of replacing the rear wheel bearings on my '70 that is accessible at this LINK.  

 

The trickiest part, IMO, is removing the old wheel bearings.  I found it was easier to drive them out with a long shaft (or pipe) from the opposite side (with carrier removed, of course) than to pull them out.  That was a tip I picked up from another member here on the forums.

[riverdogs00]

New gears, carrier, axles installed. I had the shop return my axles and ring/pinion/carrier. I will just box up in case I ever sell the car.

There is a little gear whine, but as i go through the break in period it's getting quieter. Run it easy for 15 min, let sit for 45 min. repeat 4x. change the fluid at 1000 miles.

Now I have to redo the speedo gear. I've been reading the threads and ordered what I hope is the right driven gear.