Dana 36 Gear Upgrade

[Doutdoor]

I have a 92 Coupe with the 2.59 gears & automatic transmission. I'm interested in upgrading the gears to a 3.73 or 3.54 ratio. The 3.54's seem to be a better choice, a little better gas mileage & higher top end. Please provide your feedback as to what you think the best choice would be on the gears.

Thanks,
Dave:cool

 

[vettl83]

3:54's will get you better mileage and top end. There will be a noticible difference over the 2:59 gears you have now. However if your looking for some tire shredders the 3:73's will get you there. 84 Cf 91 ZR-1

 

[vader86]

3.54 if you drive alot of hwy miles. 3.73 otherwise.

In a Dana 44.

 

[UB2 SLOW]

I went from the 3.07's to 3.73's. I love them. I lost 2 mpg in town and 1 on the highway, but the difference in jumping off the line and the acceleration was worth it. I agree with Vader about the differences in 3.54 and 3.73's. I would add that the 36 is gonig to usually be cheaper than the 44's so you need to evaluate your application. If you plan on doing allot of drag raceing and plan on doing more mods later, go with the 44. If you plan on doing just a couple of mods and dont plan on allot of racing go with the 36. There are allot people who have both and will argue for both.

 

[RubyDropTop]

I'm in the same boat as you, Doutdoor. I have the lovely 2.59 grocery-getter gears as well, and do not like them at all.

Based on the research that I have done, I hope to go with the 3.54 set up and keep the Dana 36 rear end. I have heard people say that if you are looking to upgrade to the 3.73 ratio, you are better off with a Dana 44, which will obviously cost more.

With the automatic you do have the overdrive, so you should not be screaming down the highway if you choose to go with the 3.73 ratio.

 

[Doutdoor]

Thanks for the replys.

I have heard that the Dana 44 is a stronger assembly than the Dana 36. Since my car is an automatic, I'll probably stick with the Dana 36. It sounds like the 3:54's are probably the way to go for me. It will give the car better driveability and gas mileage on the highways, but still provide some "seat of the pants" acceleration as well. I don't plan to do much racing if any, other than some punk kid who pulls up next to me in a Ricer or a Rustang . Plus, I think the only other mods I want to do is a chip and magnaflow mufflers. I already did the K&N & open air box.

 

[rich95]

If you change from the 36 to the 44, does this involve changing axleshafts, driveshafts, etc?
rich95

 

[92ghost]

Thought I would throw this into the discussion. This is from Graham who frequents this sight often. I think something like this should be a part of this sight if possible (are you listening Rob) it is that well presented.

Again, I did not put this together, but I wish I had it is that good.

"Ok, seeing as how this comes up a bit with "What is the speed/rpm with a given gear?" Here's the answers I got when doing the math for my gear change.

Assumption: Tire Diameter = 25.7in (275x40/17), Drive Ratio is 1.0, Overdrive Ratio is 0.7 (this is for an auto of course). 5400rpm is max with factory PROM/Chip.

In Drive (ratio is 1.0)

Ratio 2.59 3.54 3.75

MPH RPM RPM RPM
----- ------ ------ ------
45 1524 2083 2206
55 1862 2545 2696
65 2201 3008 3187
75 2540 3471 3677
85 2878 3934 4167
95 3217 4397 4658
105 3555 4860 5148
115 3894 5322
125 4233
135 4571
145 4910
155 5249
165

In Overdrive (Ratio is 0.7)

Ratio 2.59 3.54 3.75

MPH RPM RPM RPM
----- ------ ------ ------
45 1067 1458 1544
55 1304 1782 1888
65 1541 2106 2231
75 1778 2430 2574
85 2015 2754 2917
95 2252 3078 3260
105 2489 3402 3604
115 2726 3726 3947
125 2963 4050 4290
135 3200 4374 4633
145 3437 4698 4976
155 3674 5022 5319
165 3911 5346


The formula works as follows:

For Drive (ratio 1.0)
RPM = ((RE Ratio * MPH) / Tire Diameter) * 336

For Overdrive (ratio 0.7)
RPM = (((RE Ratio * MPH) / Tire Diameter) * 336) * OD Ratio

So if you want to calculate different rear gears or final drive ratios just plug it into the formula. Or use the tools on this website or many others.

Graham



Again, I did not put this together, but wish I had it is that good...

 

[Doutdoor]

That is very useful information Graham. I see a bigger difference in RPM's at the lower scales. A much smaller difference at the higher scales. I figured for the 3.73 vs. 3.54 gears, there is only a 286 RPM difference at 165 mph in overdrive. That would put the 3.73's at 5632 RPM, only slightly higher than the red line for my 92 LT1. I thought there would be a bigger difference in RPM's from the 3.73's to 3.54's, but this proves it.

Dave :cool

 

[hotrodd]

I have 3.73 in a 82 with overdrive.It was the single best upgrade that I have done so far! The driveabilty is so much better. It is especially nice if you have a little bit of cam,crusin at 70 m.p.h. is right where the sweet spot is on mine anyway, about 2250 rpm vs. about 1700 with the 2.72 that it had. Just my .02

 

[FordNoMore!]

Remember the Gears need to be changed in the tranny also for proper speddo calibration, I remember a while ago I inquired about this and vms4evr gave in detail the speed sensor and Drive gear, and driven gear that is needed, I copied this info thank God,These gears were for the 2.59 to 3.54 conversion.Speed sensor(3 series) 10456089,Drive Gear,15-tooth(grey)8642620,,Driven Gear, 43 tooth(purple) 25513050,,Hope this helps..These gears go in the tailshaft of the Tranny, check with your Shop and make sure they do both jobs, I have found out that some will put the rear gears in and wont touch the Tranny, Kinda silly to me, I never did get there explanation of why they wouldnt but , I would make sure also, Those Gears listed I do believe are the GM part numbers from the dealer,Unless Im mistaken, Maybe vms4evr can elaborate if I missed something.

 

[Doutdoor]

Thanks for the info Ford No More. I just joined a Corvette club where the club meets at a place called Corvettes of Auburn, WA. It's a corvette repair/restoration shop. The guy has changed-out many rear ends and was familiar with the gear swap necessary at the tranny tail end section. I couldn't imagine someone doing a rear end swap and then not completing the rest of the gear swap to make it work properly.

:cool

 

[JT ZR-Won]

3.54 if you drive alot of hwy miles. 3.73 otherwise.

I agree

Jay

 

[Corvette-Pilot]

Anyone ever try the Ekler's rebuilt pumpkins?
They have 2 options of New ring/pinion or original ring/pinion.
Both with a 3 year unlimited mile warranty.

Thing I can't find out from them is in the description for the original r/p they say they use genuine GM parts.
I called them and the guy on the phone was no help.

It could either be that they rebuild it with new GM gears or they reuse the original GM gears??
I think they reuse the old gears as long as they are in good shape.

I think the Dana 36 3.57 original gears was about $700.

Not knowing a shop that could handle this job locally might this be a safe way to go??
How does the cost compare?

 

[FordNoMore!]

Ecklers rebuilt differentials are 995.95 for the 3.54 automatic , plus a 400 dollar core charge, so 1400 bills, for 400 buks I would prefer to keep the old case and gears and keep them intact just incase ya ned them for an emergency.

 

[Corvette-Pilot]

Ecklers rebuilt differentials are 995.95 for the 3.54 automatic , plus a 400 dollar core charge, so 1400 bills, for 400 buks I would prefer to keep the old case and gears and keep them intact just incase ya ned them for an emergency.

http://www.ecklers.com/product.asp?dept_id=1859&pf_id=43835&mscssid=M7EMLBW89US92LQJ00N0SM2EPKWUF5L4

You are correct.
The $700 one was the 3.07

What is involved with pulling this thing out to change?
The pumpkin that is.

 

[92ghost]

Hey Doutdoor. See if Brady of Brady's transmission is still in business there in Auburn. He does tranys and rear ends (I think) and is very good and priced right too. Don't ask how I know this guy being in New York. It's a long story...

 

[vms4evr]

Well first off. Thanks for the kind words guys
The reasoning for putting those calculations together is just what you are going through. I actually have them in a spreadsheet. Like some of you my concern from 2.59 to 3.54 and 3.73 was based on how much more RPM I would use up. I too was a little surpised that it was not a big difference from 3.54 to 3.73. But I backed down on the 3.73 becuase I am on the highway most of the time. The 3.54s work out well. And at 74mph my tach is sitting almost right on 2500rpm. Slightly off from the formula but that is due to speedo error and that the speedo gears don't match up perfectly.

As fordnomore said. You do need ALL 3 speedo gears to go from 2.59 to any 3.xx gear. If you already have a 3.07 (G92) then you do not need the VSS gear. And that is the most expensive part. The 2 plastic gears that go in the tail are cheap. If I remember right it was about $20 for the 2 gears then about $40 for the VSS. The guy who did my gears said I didn't need it. I told him I did and made him put it in. There are 2 reasons. 1. The VSS is in a 2.59 gear car is considered a 2-series. 3.07 uses a 3-series. So for 3.54 and 3.73/5 you must have a 3-series to get the speed sensor to record acurately. 2. Most important reason. The 2-series will not lign up properly with the 2 new plastic gears in the tail. Run your car with it and they will break!

If you read that thread I did in detail on the change you have all the parts and costs to do the job. I opted on the complete pumpkin simply because I had no intention of going back. So it cost me less money to use my existing pumpkin. But I did buy the master install kit. I highly recommend you do that if you upgrade. Don't save a $100 and only buy the gasket kit. Bad idea. The master install kit has all new bearings, seals, sleeve, and fluid. Everything needed to do the job right.

I've been running the 3.54 gears for a year now and can definetely say that it is an awesome improvement and lets the LT1 wind up like it should. You can run it intown in D and get great acceleration. Then in OD on the highway you have an easy time moving into the passing lane. You don't need to mash the pedal just to pass someone. And just for entertainment run the highway in D. You'll be running about 3200rpm cruising along. Hit the gas and the car jumps. Way too much fun

Graham

 

[Doutdoor]

Fantastic responses from everyone and a wealth of information. You guys have been a big help.

Graham,

Did you do the work yourself? I, like Corvette-Pilot,would like to know how complicated it is to R&R the rear end assembly. A place called Randy's Ring & Pinion in Everett, WA told me about $700 to rebuild the unit with 3.54's. I would need to remove the unit, take it to them and then reinstall it. I'm not sure if I should attempt it.

92 Ghost - I will check on Brady's if I decide to have a shop do the work.

Thanks again!
Dave :cool

 

[FordNoMore!]

From what I have seen, the complete Job, Gears and master install kit intalled runs between 1000 to 1300 buks with the new gears, at least that is what I ahve seen here in Vegas. Good Luck!