Ring and Pinion

[vms4evr]

Hi folks, (sorry this is a little long)

Ok. I'm pretty well decided now and only need to dig up the money... What else is new. I want to replace the factory ring & pinion to get better street performance. This kinda continues that Stang topic recently posted. Dismal 0-60 performance...

I have the 2.59 rear axle with auto trans. Chris M had some ideas on different ratios. I'm down to 3.54 or 3.75. I've done the calcualtions on RPM/MPH and either will work. I still need highway cruising with reasonable gas mileage as I commute on the highway with this car a bunch. Once I make the swap it stays that way. So... :confused

Any comments about whether to go with Richmond, GM or other brand?

Is there any real noticeable difference between 3.54 / 3.75 for 0-60-100 performance?

What other new parts should be put in when the ring & pinion is replaced?

How much can I expect my gas mileage to drop?
(i'm getting 19.5-20.5 on ave now)

About how many hours of labor would you think it takes an experienced mechanic to do the job?

Yes I know I want it all ...

Thanks, Graham

 

[Hib Halverson]

You can't have both a substantial performance increase and good mileage.

If you commute and want mileage, don't install 3.54s, much less 3.75s

A switch to the factory performance axle ratio, 3.07 will give you a modest performance increase without a large decrease in mileage.

 

[JT ZR-Won]

Graham,
In the '85 I used to own, I (actually a speedshop) swapped the 2.73 gears with Richmond's 3.75's. I went with Richmond because they specialize in rear end gears and have been around for quite some time. With 3.75's you will notice a big difference in performance, especially coming from 2.59's
I have never been in an automatic car with 3.54's so I have nothing to compare these to. I went with 3.75's because I wanted more of a quarter mile car. My car was not much of a highway cruiser anymore with the lower gear. At 75mph, you'll be spinning about 2400-2500rpm's. At 85mph, you'll be spinning closer to 3000rpm's. Unfortunately, the L98 motor only revs up to around 5K anyway, so you can see how you won't have a lot of highway capabality.
Gas mileage didn't really change around town at all.......not that I could notice anyway, probably because I'd be in overdrive at about 35-40mph. I probably lost a few mpg on the highway due to the higher rpm's.
My suggestion would be to not go with 3.75's if you do a lot of highway driving. On the up side though, if you're looking for awesome performance from a red light, you might want to think about it
Good luck and keep us posted.

Jay

 

[vms4evr]

Thanks Jay and Hib.
I think I've found a way to see what I can expect for gas mileage commuting. The 3.54 in OD is about the same as the 2.59 in D. So for the rest of the week I'll leave it in D on the highway. The RPMs workout right so this should be close enough.

I spoke with Richmond and they told me I need to add an installation kit and expect 4-7hrs install labor based on the mechanic and whether he has problems.

Jay, On the Richmond gears. Some people had told me that they are noisey and you can hear them whine. That seemed to be the only complaint I've heard. Were yours noisey ?

Thanks, Graham.

 

[Corvette-Pilot]

Thanks Jay and Hib.
I think I've found a way to see what I can expect for gas mileage commuting. The 3.54 in OD is about the same as the 2.59 in D. So for the rest of the week I'll leave it in D on the highway. The RPMs workout right so this should be close enough.

vms4evr

What were the results of your mileage test?
I am also considering the same change myself ?????

 

[vms4evr]

Pilot,
I changed from the 2.59 to the 3.54. I used to average about 20.5mpg over the course of the week. I'm now averaging about 19.0mpg.
It swings a little but at worst it would be 2mpg drop.
For the performance increase it is an easy choice for me. I love the 3.54s.
Have you hugged your gears lately ;-)
Graham

 

[Skant]

If the axle gears whine, it's because they weren't installed properly.

I've had to deal with a shop that gave me that 'its normal for these kinds of axles to whine' thing when I found that the front axle I'd had them change from 3.07 to 3.73 on my K-5 Blazer was whining.

When I pointed out that the front and rear axles on the Blazer are exactly the same... and that the rear was not whining and that neither axle had ever whined before... the guy just yelled at me and told me they didn't need customers like me.

Yeah. I guess they only needed customers who would happily accept shoddy work.

The shop really doesn't want to have to do the work all over again. So if they mess it up, don't be surprised if they say it's normal.

I think if I ever have work like that done again, I'm going to make sure I know what the shop's remedy is up front if it whines after they've done their work. I figure if they won't guarantee that it won't whine, go somewhere else.

If it whines, it really does mean it wasn't installed right. And it will suffer a shorter life span because of it. Possibly very short.

PS: That bad shop, btw, is Santa Clara Truck in the San Jose area. Needless to say, they never had my business again after that.

- Skant

 

[69MyWay]

With the six speed in my 90 (note, I am running the miniram so I no longer have the rev issues of the L98--more like a LT1) the 3.75 gears are fantastic. I don't recall at the moment what the ZF final overdrive ratio is, but I am only up about 7 or 800 RPM or so from where I was with the 3.33 gears. Highway cruising is still smooth and quiet.

I have not driven it enough yet to see the results of the MPG, but I know it will be less.

Now, with a auto trans, first gear is already strong. If you drop to a 3.75 rear you will have neck snapping sprints from zero to the moment that it upshifts into second, attempts to break tires and go sideways, then beyond. It will put a smile on your face a mile wide.

I put 3.73 gears in the 1936 Ford that I installed a 1996 LT1 and auto trans from a Trans Am. This vehicle was very heavy (all steel body), but would/will explode from a dead stand still like nothing you have ever felt. Up to 80 to 100 mph it will take your breath away!

So, my vote would still be on the 3.75 gears. Let me tell you also from experience that Richmond is not the "cheapest" source of those gears. The folks at www.tpis.com can also get a nice gear set that comes with more stuff to make the complete swap.

I had a local drive line specialty company build my diff. The labor charge including four bearings and seals was about $200.

Make sure whoever does yours has plenty of experience with Vette diffs first. My shop actually did not have as much experience (admitted it when I was picking the diff up). They took three extra days because they destroyed the first couple of sets of new pinion bearnings trying to get the depth set, etc. At least they did not charge for them.


Hope that helps!

 

[vms4evr]

I don't know who TPIS buys their gears from but the price of about $400 for the whole kit is pretty good.
It cost me about $450 for my kit. I went with Strange (US Gear) and the master install kit. That has everything in it that TPIS shows plus the synthetic gear oil.
The price on the 3.54 and the 3.73/3.75 gears is the same.
If I wasn't on the highway 4 days a week I would have gone with the 3.73 gears.
Chris is right about the acceleration down low. The 700R4 in my92 has such a low first gear that coupled with beefier rear gears the acceleration is like night and day. The car truly jumps when it shifts into 2nd gear. The ASR will kick on for a second or so depending on how good the rubber is and whether the car is going in a straight line. It pulls hard in 2nd gear too and will get your 0-60 time a solid boost.
You definetely want a shop that has done Vettes before. IT took me a while to find the shop I went to. The guy who installed the gears has been building C4s for racing since they came out. He told me the Dana 36 with those thick gears in it is a royal PITA to get the gears set right. He spent way more time than he had planned on but he is also picky about what he does. Good for me of course.
I do have some driveline whine though. I'm not sure it is in the gears. You hear it and it sounds like it is in the tranny and rear. It sounds like my old SS did when I ran 3rd gear and coasted to a stop. The gears have been checked and the wear pattern appears to be centered like it is supposed to be. It is not a bad sound but it isn't as quiet as when I had the 2.59 gears. You couldn't hear those at all. Thing is now the gears are higher (numerically) you actually get braking force from the engine like you were driving a stick. The car will slow down when you let off the gas. With the 2.59s it seemed like it would coast forever...
Graham

 

[vettn94]

here is my 02.
I changed from a 2.59 to a 3.54 in my 94 convertible.
The car ran a best of 13.82@101 with the 2.59 gear on street tires. With the only change being the 3.54 gear the car ran a new best of 13.23@105.91mph. I didn't notice any significant change in gas mileage, if there was one it's barely noticable and who cares?. I know this may **** some people off but I always say if you're concerned with gas mileage go buy a Honda.
The performance gain of over a half second off your ET and +5 mph in the 1/4mi will make you forget about gas mileage really quick.
Changing to a 3.54 or 3.73 gear it will be the best mod you do to your LT1 period.
Don't waste your time with 3.07's, I think you'll be dissapointed.
There isn't going to be all that much difference between the 3.54 and 3.75 as far as crusing rpms, but I would recommend the 3.54 for a couple reasons.
The way I understand it is the3.54 has a 12 tooth pinion gear where as the 3.73 has a 11 tooth gear. The problem with the dana 36 is that under a lot of torque it will try to flex and the pinion gear will pull away from the ring gear.
Also I just prefer the mid 3 series gear, it has always worked well for me, especially with the addition of a higer stall tq converter.
I bought my 3.54 complete rear end (minus the cover) from
Ed Portner at http://www.partsforvettes.com/partsforvettes/index.html
I think I paid around $1200 for the complete rebuilt rear section which included all new parts including brand new gears. Great guy to do business with. That price was outright, no core reqd.
good luck with whatever you decide

 

[BlackNBlue95]

I bought my 3.07 (completeDiff w/cover) for about 365$ with shipping.. I bought it because it was a cheap upgrade.. I am thinking of going 3.54 or 3.73 later.. but I'm pretty happy with my setup now.. I can spin my street tires.. for half a block hee hee given its cold out and I can't hook but it's much much better then the onld 2.59s

I can't agree more if you want gas mileage don't drive a vette.. it's a toy... not a rice burner...

 

[Hotred94]

I've heard the Richmond gears tend to whine because they are cut in a way that makes the teeth stronger, but the cut also makes them noisier; just like you can get cam gear drive setups with "quite" or "noisy" gears. As the whine, in this case, is a function of operation and not an indication of a problem, I just wouldn't worry about the noise. That's how it is when you put on high performance parts. Of course, all GM factory gears are cut for quite operation.

I've got the 2.59 gears and have been thinking about 3.07's or 3.54's. Cost is always a big factor. It seems like anything you want to buy for the Corvette costs 2-4 times more that it does for any other car. Blacknblue95, if you are interested in moving up to new gears, I'd like to talk to you about your 3.07's. I really believe the 3.54's would be a better setup, especially with the 315 tires I have on the rear, but if opportunity knocks, I'm ready. If anyone has a set of 3.54's they want to get rid of, I'd also like to know.

I've had a set of 4.11's on another vette, and they were awesome, but you really need an engine that can rev for gears that low. I got about 14 mpg with them when I took it easy.

 

[BlackNBlue95]

I've heard the Richmond gears tend to whine because they are cut in a way that makes the teeth stronger, but the cut also makes them noisier; just like you can get cam gear drive setups with "quite" or "noisy" gears. As the whine, in this case, is a function of operation and not an indication of a problem, I just wouldn't worry about the noise. That's how it is when you put on high performance parts. Of course, all GM factory gears are cut for quite operation.

I've got the 2.59 gears and have been thinking about 3.07's or 3.54's. Cost is always a big factor. It seems like anything you want to buy for the Corvette costs 2-4 times more that it does for any other car. Blacknblue95, if you are interested in moving up to new gears, I'd like to talk to you about your 3.07's. I really believe the 3.54's would be a better setup, especially with the 315 tires I have on the rear, but if opportunity knocks, I'm ready. If anyone has a set of 3.54's they want to get rid of, I'd also like to know.

I've had a set of 4.11's on another vette, and they were awesome, but you really need an engine that can rev for gears that low. I got about 14 mpg with them when I took it easy.

It will be a while till i get a new gear set I need to save for the laptop and LT1 Edit to re calibrate my speedo.. but when I'm ready I'll pass the deal I got along.. because I'm probably going to put the new gear set in my factory diff case and sell the complete 3.07's but it will be a while I just put them in.. and only have put a couple 30 or 60 miles on them..

 

[vettn94]

I bought my 3.07 (completeDiff w/cover) for about 365$ with shipping.. I bought it because it was a cheap upgrade.. I am thinking of going 3.54 or 3.73 later.. but I'm pretty happy with my setup now.. I can spin my street tires.. for half a block hee hee given its cold out and I can't hook but it's much much better then the onld 2.59s

That may be true but remember you also added a tq converter
and gutted cats at the same time.
Zip products also sells the 3.54 in the $800 range but you have to send them your core so plan on spending a few bucks more for shipping.
Keep in mind it's going to cost you about the same to buy a set of gears and have them installed, you'll also need a new carrier, as it will to just buy a complete rear section.

 

[-=Jeff=-]

I don't recall at the moment what the ZF final overdrive ratio is,

6th gear is .50 or .49 I cannot remember the exact #

 

[69MyWay]

I drove her again today.

I do have some noise coming from the rear. The question is, how much of this is a concern? The reason I say that is I went with the solid poly bushings in my diff to frame mount, and there was a warning with this product that it would cause drivetrain noise in the car.

So, since I am more or less solid mount, I am getting a whine that is speed sensative, and I can tell a minor difference between coasting to a stop in neutral or allowing the engine to brake torque to a slower speed. I can't hear it at 70, but between the flow masters and other drive line noise that is to be expected.

I will have to keep an ear on it, and get back with VB&P to find out what kind of drive train noise is expected.

 

[BlackNBlue95]

I drove her again today.

I do have some noise coming from the rear. The question is, how much of this is a concern? The reason I say that is I went with the solid poly bushings in my diff to frame mount, and there was a warning with this product that it would cause drivetrain noise in the car.

So, since I am more or less solid mount, I am getting a whine that is speed sensative, and I can tell a minor difference between coasting to a stop in neutral or allowing the engine to brake torque to a slower speed. I can't hear it at 70, but between the flow masters and other drive line noise that is to be expected.

I will have to keep an ear on it, and get back with VB&P to find out what kind of drive train noise is expected.

You didn't drive it before installing the solid poly bushings did you?
Just trying to see if this is something that came up as a result of the bushing or if your not shure (which is what it sounds like) because you installed them before driving the car..
-Rick

 

[69MyWay]

You didn't drive it before installing the solid poly bushings did you?
Just trying to see if this is something that came up as a result of the bushing or if your not shure (which is what it sounds like) because you installed them before driving the car..
-Rick

Exactly. I did both mods at the same time, so I don't know if the drive line noise is normal (as the disclaim did indicate there would be noise), or if it is a sign of any problems with the gear install.

 

[BlackNBlue95]

Exactly. I did both mods at the same time, so I don't know if the drive line noise is normal (as the disclaim did indicate there would be noise), or if it is a sign of any problems with the gear install.

without hearing it it's hard to say.. I would talk the manufacturer of the bushingand maybe whoever either installed your gears or the manufacturer.. and see what they tell you..

 

[Corvette-Pilot]

Exactly. I did both mods at the same time, so I don't know if the drive line noise is normal (as the disclaim did indicate there would be noise), or if it is a sign of any problems with the gear install.

This seems like it makes sense.
If you put the harder bushings in then any vibration and noise will transfer more easily to the body of the car. Where the rubber bushings have a lot more absorbsion that helped to isolate the car from the drivetrain.

Just my $.02 as I was not able to stay at a Holiday in last night.