Bought An Ebay Dana 36 3.54 Ratio Rear Diff!!

Crossfire Mike

Crossfire Mike

Active Member
Hello all hope I don't receive a piece of garbage, but I do expect delivery today. I pick it up cheap enough that I will get it checked out by a professional before I install it and get it fixed up if any issues are found. I have studied up on what I need to do to correct my speedometer gears and have a new 15 tooth drive gear and a 44 tooth driven gear on the work bench at home. I should really have a 45 tooth driven gear but it seems those are not available anymore. Best I can figure is my MPH will read a bit fast, which is better than reading slow to me. There is also a electronic fix from Dakota Digital that for under a $100 allows me to leave the speedo gears alone and just dial in the correction so that's a pretty good option too if I'm lazy and find more money than time.

Yes it's a mystery on what I will actually receive but I will check it out tonight to confirm the ratio and report back on it and the next steps of actually installing it into the Corvette. I am expecting a 3.54 gear ratio to make a huge difference in acceleration and drive-ability. I may be killing a few top end MPH but the reality is I'm never exploring that side of the speedo anyways. About 120mph is as fast as I ever go and that's rare when it happens.

I'll post some pics later tonight or tomorrow of the diff after I have it at home.
 
I wish you the very best of luck,
my experiences with buying used auto parts from EBAY are .
WELL...FAR less than encouraging to say the least
 
Living life on the edge I guess. For what I paid I at least will have a rear diff that I can purchase gears and have it set up while still driving the car now. I took a risk but worse case is not a total loss per say.
 
They are usually in very good shape Dana 36 C4 Corvette.
Only unknown is condition of Posi clutches.
It's all Dana Spicer built.
I used to built alot of C4 & C3 Dana 44s, they were all raced hard prior, lots of wear !
Not sure if the Dana 35 Jeep Posi clutch is same as the C4 Dana 36 auto.
Everything is still available otherwise last I looked about 1 month ago.
Like Nitro gears.
Near everything is coming from China bad quality.
Nitro gears made in South Korea.
I rebuilt a 2014 Jeep Wrangler Dana 44 and Dana 35 front Diffs got done 2 weeks ago for a local friend.
Used Nitro 5.13 gears.
Setup Beautiful.
Quality like old Richmond Gear was 1980s and 1990s years parts.
5.13 :1 Nitro gearsets with 35 inch tall Mud Street tires.
 
Well here's what I received, and thank you B&R Racing for the informative post. Either I got lucky, or paying my tithing to church does pay off or whatever but I seriously think I scored a good one. It actually looks like it's a gear change thats been sitting on a shelf for a little bit still has the white grease on the gears from the set up. Probably helps that I bought it from a Ebay seller with many years worth of positive sales. I still will drop it by a shop to have a professionals eyes look it over, but it looks fresh and spins freely with basically no slop or play. As of right now I'm very relived and feel happy. I picked this up shipped for a few bucks more than the gears alone would have cost.

Rear Diff and Batwing.jpg Diff Side Shot.jpg IMG-3787.jpg IMG-3788.jpg
 
Looks very good.
The Posi case is 8620 cast steel used.
Better than C3 iron Diffs I think material.
Gary used to do all the Iron C3 Diffs, best at them.
 
Progress update, I have been slowly chipping away at it and doing some cleaning up and couple other small things along the way. The plan for tonight is to support the transmission, disconnect the c-beam or what ever it called, remove the half shafts and finally drop the diff out. I am expecting some Superpro batwing bushings to be delivered on Friday so once I have those I'll determine if I press the old bushings from the batwing original to the car, or use the batwing that came with the 3.54 diff. I'll update next week. One question I haven't been able to find answer too though is does the metal sleeve not get used with the new Superpro bushings? I think it does not, but not exactly sure.

IMG-3796.JPG
 
Crossfire Mike said:
Progress update, I have been slowly chipping away at it and doing some cleaning up and couple other small things along the way. The plan for tonight is to support the transmission, disconnect the c-beam or what ever it called, remove the half shafts and finally drop the diff out. I am expecting some Superpro batwing bushings to be delivered on Friday so once I have those I'll determine if I press the old bushings from the batwing original to the car, or use the batwing that came with the 3.54 diff. I'll update next week. One question I haven't been able to find answer too though is does the metal sleeve not get used with the new Superpro bushings? I think it does not, but not exactly sure.

View attachment 15772
Click to expand...
I am not Familiar with the Superpro bushings.
If they are High End Style Drag Race style it will be a Spherical Bearing to to take well North of 1000 Ft/lbs flywheel power 1000+ Hp.
Wait to remove the Batwing bushings till you those New Racing Bushings in for directions.
Have to work carefully removing bushings on C4 Corvette.
Working with Alcoa Cast and Forged aircraft grade Aluminum.
Set up a stress riser to crack fail later if not careful aware.
 
These are the bushings

25-854369-1.jpg
  • Improves Ride & Handling
  • SuperPro Syntheyic Elastomer Bushings
  • Best Bushing On The Market!
  • No Squeaking
  • No Disintergrating With Age!
  • Fits All 1984 to 1996 Corvettes
  • For The "Bat Wing"
  • Life Time Warranty
Not a racing or very high end bushing but suppose to be a better alternative to the Energy Suspension offering or stock style rubber. I'll wait to see if any instructions are included with them and go from there. These can be bought at Eckler's . Been out working on the car and the diff is actually out finally it fought me a little bit and I feel old and tired now but I won and got it done. I'll post some pics tomorrow when there is some better light.
 
Crossfire Mike said:
These are the bushings

View attachment 15774
  • Improves Ride & Handling
  • SuperPro Syntheyic Elastomer Bushings
  • Best Bushing On The Market!
  • No Squeaking
  • No Disintergrating With Age!
  • Fits All 1984 to 1996 Corvettes
  • For The "Bat Wing"
  • Life Time Warranty
Not a racing or very high end bushing but suppose to be a better alternative to the Energy Suspension offering or stock style rubber. I'll wait to see if any instructions are included with them and go from there. These can be bought at Eckler's . Been out working on the car and the diff is actually out finally it fought me a little bit and I feel old and tired now but I won and got it done. I'll post some pics tomorrow when there is some better light.
Click to expand...
They Look nice.
 
Make sure to get the C-Beam Channel Bolts Torqued down properly with a Torque wrench.
Been a long time I have to look up the Torque specs on my 87 Corvette Factory GM Service Manual.
 
Last edited:
Pics of diff out. Fedex sent notification this morning that the package is on the truck for delivery so hopefully I'll be able to put it all back together Saturday.IMG-3798.jpg IMG-3799.jpg IMG-3800.jpg

It was SUPER greasy so I did some cleanup on it last night and will do more today. I do plan to take the batwing off the diff that came out just to have a look inside and confirm that gear ratio is 3.07 even though I did do the whole spin the tire and count the driveshaft revolutions thing.
 
Well it's all put back together and the Corvette has been test driven. I first while still on jack stands ran the car in 2nd gear for a bit to just spin the new diff so I could listen for bad noises and spot any leaks. Non of either so that was good. Took it out slowly around the block and found a place to do some slow figure 8's and circles to work the limited slip and get the additive in there that went well with nothing concerning. Brought it back home to inspect, still everything looking good then took it out for a "real" test drive.

The car is faster or should I say quicker for sure. Going from a 3.07 to 3.54 is a not as dramatic as if I went with 3.73 or higher so I had to tone down my expectations. I can say though it is worth it and the car does run through the gears much quicker and the RPM seems to drop right in the fat part of the torque curve between shifts. Really good acceleration and where I really noticed is the 4th gear pull. To me that is the most improvement that I can feel right now. I have not done anything with the speedo gears, so my usual MPH mark points did not help on this drive. It's over 100 degrees here in La Mesa right now so I thought I'll take it out later when the sun goes down. Overall this is a good upgrade and the cost and effort to do was worth it to me especially considering how lucky I was to get a good rear diff. Couple pics one is it all buttoned up(looks the same except cleaner) and the other is the Superpro bushing installed on the batwing original bushing sleeves are not used.

IMG-3806.JPG IMG-3807.JPG
 
Last edited:
Nice work .
C4 Corvettes are one of lightest Ever built they dont need low gears unless 1/4 or 1/8 mile drag racing.
They have Relagated to A Neat Cruiser Car what most use them for today.
They also get amazing mpg at speeds 70, 80, 90, 110mph steady high speed cruising. Good car to go on real long rides across state lines if you know the roads are decent no Big pot holes .
 
Evening time drive done, put a few miles on it and runs great faster everywhere. Nice cruise RPM on the freeway with the overdrive engaged. My speedo reads 10mph fast pretty much all the time now also. I'll definitely want to get that squared away soon.
 
You must log in or register to reply here.
Back
Top