5-speed transmission or diff: Which should I install first?
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
5-speed transmission or diff: Which should I install first?
I have a Keisler RS500 PerfectFit transmission and hydraulic clutch kit on order for my ‘80. My diff has been leaking pretty badly from both sides and there is quite a bit of in-out movement on both side yokes, so I decided to have the diff rebuilt while I’m at it. Hopefully the WhileImAtIt disease doesn’t spread much further.
As of last night, the entire drivetrain is out from the block and clutch back. I removed the transmission after I removed the diff with the driveshaft attached. I detached the driveshaft from the diff after the diff was out because getting at the strap bolts above the front diff mount looked like a nasty job. I could hardly see the strap bolts.
The diff will be done quite a bit sooner than the transmission. I can either install it when I get it or wait until the new transmission is in.
Should I install the transmission before I install the diff? Or should I install the diff and then the transmission and driveshaft as though the diff had never been removed?
I’d especially like to hear from those who have already done a 5-speed upgrade.
As of last night, the entire drivetrain is out from the block and clutch back. I removed the transmission after I removed the diff with the driveshaft attached. I detached the driveshaft from the diff after the diff was out because getting at the strap bolts above the front diff mount looked like a nasty job. I could hardly see the strap bolts.
The diff will be done quite a bit sooner than the transmission. I can either install it when I get it or wait until the new transmission is in.
Should I install the transmission before I install the diff? Or should I install the diff and then the transmission and driveshaft as though the diff had never been removed?
I’d especially like to hear from those who have already done a 5-speed upgrade.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
For those who upgraded to a 5-speed...
Let me put the question a different way:
If you upgraded your transmission to a 5-speed, do you think the install would have been easier if the diff had not been installed?
If you upgraded your transmission to a 5-speed, do you think the install would have been easier if the diff had not been installed?
Melting Slicks
Joined: Jun 2005
Posts: 2,239
Likes: 74
From: Palatine, Peoples Republic of Illinois
St. Jude Donor '09-'10-'11-12-'13-'14-'15-'16-'17-‘18
NCM Sinkhole Donor
Did mine together but it wouldn't have mattered. Enjoy the ride! I went from a 4 speed to a 5 speed TKO and from a 2.73 to 3.36 gear. Like driving a different car!
Safety Car
Joined: Nov 2008
Posts: 3,720
Likes: 557
From: Seattle Washington
Keep in mind that if You rotate the Tires with the Trans in newtral You will never have to get to a U-Joint Strap Bolt on top. I probably would of driven the car with the new Trans first before rebuilding the rear, in case You didn't like the Gear ratio. Your 80' should have the 3.07 so it should be OK. You didn't mention what You were doing to the Rear, just Seals or redoing everything including Gears.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
I thought attaching the driveshaft to the diff would be easier with the diff out. I did see how I'd get up in the tunnel to get at the strap bolts, so I pulled the diff back with the driveshaft attached. The bolts had 12-point heads, and all I had for 1/4" 12-point was a box end wrench. The new bolts will be 6-point, so I won't have that limitation.
Apparently attaching the driveshaft with the diff installed was no big deal because the opinion is unanimous: Diff before trans.
Thanks guys!
Apparently attaching the driveshaft with the diff installed was no big deal because the opinion is unanimous: Diff before trans.
Thanks guys!
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Keep in mind that if You rotate the Tires with the Trans in newtral You will never have to get to a U-Joint Strap Bolt on top. I probably would of driven the car with the new Trans first before rebuilding the rear, in case You didn't like the Gear ratio. Your 80' should have the 3.07 so it should be OK. You didn't mention what You were doing to the Rear, just Seals or redoing everything including Gears.
The gears weren't noisy and the 3.07 ratio seems to work well with the RS500 gears, so I wasn't planning to change the gear ratio. Paul (the local Corvette drivetrain expert) named a few other things that often go wrong in these diffs and said he'd replace any of the usual parts that wear.
We discussed all that before he showed me a brand new diff and made me an offer I couldn't refuse. He offered to "cook" and inspect the batwing, mount the new diff, and fill it with fluids for a couple hundred $$ more the cost to rebuild my old one.
Deal!
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Pro
Joined: Jun 2007
Posts: 688
Likes: 1
From: Stevens Point WI
I thought attaching the driveshaft to the diff would be easier with the diff out. I did see how I'd get up in the tunnel to get at the strap bolts, so I pulled the diff back with the driveshaft attached. The bolts had 12-point heads, and all I had for 1/4" 12-point was a box end wrench. The new bolts will be 6-point, so I won't have that limitation.
Apparently attaching the driveshaft with the diff installed was no big deal because the opinion is unanimous: Diff before trans.
Thanks guys!
Apparently attaching the driveshaft with the diff installed was no big deal because the opinion is unanimous: Diff before trans.
Thanks guys!
insert in trans....pull back to attach to rear....
Race Director
Joined: Feb 1999
Posts: 19,659
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From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
I knew that I had a lot of side play in the side yokes and the seals were leaking on both sides. Other than that, I didn't know what else needed to be done inside. I was going to put in a new clutch pack while it's open so I don't have to open it again.
The gears weren't noisy and the 3.07 ratio seems to work well with the RS500 gears, so I wasn't planning to change the gear ratio. Paul (the local Corvette drivetrain expert) named a few other things that often go wrong in these diffs and said he'd replace any of the usual parts that wear.
We discussed all that before he showed me a brand new diff and made me an offer I couldn't refuse. He offered to "cook" and inspect the batwing, mount the new diff, and fill it with fluids for a couple hundred $$ more the cost to rebuild my old one.
Deal!
The gears weren't noisy and the 3.07 ratio seems to work well with the RS500 gears, so I wasn't planning to change the gear ratio. Paul (the local Corvette drivetrain expert) named a few other things that often go wrong in these diffs and said he'd replace any of the usual parts that wear.
We discussed all that before he showed me a brand new diff and made me an offer I couldn't refuse. He offered to "cook" and inspect the batwing, mount the new diff, and fill it with fluids for a couple hundred $$ more the cost to rebuild my old one.
Deal!
Rick B.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Once the driveshaft is slid back to the diff, the u-joint needs to be attached to the diff with straps and two bolts in each. Wouldn't it be easier to attach the driveshaft to the diff with the diff on the bench?
They were sure easier to get them off that way. We just took the straps off the trans end of the driveshaft, and pulled the diff back with the driveshaft attached, set it on the bench, and rolled it away.
When everything was assembled, I could hardly see the straps and bolts let alone get a 1/4" 12-point box end wrench up there with enough room to move the wrench.
So, you guys are saying:
It is easier to attach the driveshaft to the diff with the diff already installed in the car
than to
attach the driveshaft to the diff with the diff sitting waist high on a bench and installing the driveshaft and diff as one unit.
Really? Maybe, if my car wasn't on a lift.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Second, "cooking" was his word for "boiling", like engine builders do with blocks before a rebuild.
Sorry to bother you.
Instructor
Joined: Sep 2007
Posts: 198
Likes: 0
From: Colorado Springs Colorado
I think the easy way to connect the drive shaft to the diff. (with the diff. in the car), is to use a coupla long 1/4" drive extensions (about 2' long), and go at the bolts along side the drive shaft. That way you are beyond the crossmember, and not trying to put a wrench in that little space. You can spin the shaft to get at all 4 strap bolts. Works great, and only takes about 10 minutes or less.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
I think the easy way to connect the drive shaft to the diff. (with the diff. in the car), is to use a coupla long 1/4" drive extensions (about 2' long), and go at the bolts along side the drive shaft. That way you are beyond the crossmember, and not trying to put a wrench in that little space. You can spin the shaft to get at all 4 strap bolts. Works great, and only takes about 10 minutes or less.
Thanks for that idea.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
So, you guys are saying:
It is easier to attach the driveshaft to the diff with the diff already installed in the car
than to
attach the driveshaft to the diff with the diff sitting waist high on a bench and installing the driveshaft and diff as one unit.
Really? Maybe, if my car wasn't on a lift.
It is easier to attach the driveshaft to the diff with the diff already installed in the car
than to
attach the driveshaft to the diff with the diff sitting waist high on a bench and installing the driveshaft and diff as one unit.
Really? Maybe, if my car wasn't on a lift.
Thread Starter
Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
Sure, I could turn the driveshaft to get the wrench on each bolt, but working the bolts with a 6" long 1/4" box end wrench in that cramped area sucks. There is more room to wrench ahead of the cross member.
Instructor
Joined: Sep 2007
Posts: 198
Likes: 0
From: Colorado Springs Colorado
I have found that you'll still have to tighten the strap bolts down with the box end wrench, because at the angle you tighten them down (with the extensions & 12 point socket) won't allow you to get a good torque on them. Still under 10 minutes to do!
Le Mans Master
Joined: Oct 2006
Posts: 8,941
Likes: 35
From: El Cajon California
