Another differential question
06-09-09, 03:47 PM
#1
Another differential question
This all pertains to my S5 GTU
Ok I just bought a LSD equipped factory diff from a JDM half cut for $200. It just said FC3S on it. It's black cast iron and aluminium.
That being said I turn the driveshaft flange and the axle shafts turn the same direction as each other doesn't matter which way you turn it. OK great its LSD good thats why I bought it!
Now I'm looking at the stub axles bolt pattern and the spread is approx. 3-1/8" on the bolts center to center. as I'm looking at it I'm thinking it looks alot like mine last time I was under the car. So I go get the floor jack and lift it up. The stub axles measurement is the same 3-1/8" approx. So cool I can use the axles again ok great. Then I decide to measure the driveshaft flange. It's somewhere around 2-3/4 to 2-7/8". The jdm diff is 2-7/8 as well wtf????
Then I think well maybe someone put the T2 diff in the car already???
I know it only spins one wheel during a burnout so if it is it's broken. I turn the rear wheel on one side of the car. and the other side wheel doesn't budge. I expected it to turn the opposite way of course. I go on the other side and turn that one and the side I was just on doesn't move then. OK wtf? But no matter what side you turn the driveshaft turns......Then if you turn the driveshaft both wheels turn the same way WTF!!!??? In either direction. I guaruntee only one wheel spins if you do a burnout it has been checked many times.
Then I notice there's a sticker on the driveshaft. Its a bit beatup but fairly new it has the numbers 2691-704 on it. I look on mazdatrix website and thats the part number for the aftermarket non-turbo driveshaft with replaceable u-joints. Ok cool I didn't even know I had that. That's a good think. So Di guess I bought a NA LSD rear end? But why does mine act like that is my question I guess.
The JDM one acts just like a regular LSD. Is mine viscous if so I think it was broken along time ago. Is my car really a GTUS? How can you tell? VIN number? If so It may account for why the car seems faster than most NA ones. But I thought all GTUSs came with the turbo sized brakes? Mine has the regular NA brakes. Now I'm really confused. One thing I know without a doubt is the transmission is not a turbo one and the driveshaft is apparently not for a turbo car anyways. I'm gonna take some pics and post them to see if anyone can tell me what the hell is going on here.
Everywhere I looked says you need T2 axles and driveshaft for the LSD rear end. Does the GTUS actually just have a na tran, driveshaft and na LSD rearend?
Ok I just bought a LSD equipped factory diff from a JDM half cut for $200. It just said FC3S on it. It's black cast iron and aluminium.
That being said I turn the driveshaft flange and the axle shafts turn the same direction as each other doesn't matter which way you turn it. OK great its LSD good thats why I bought it!
Now I'm looking at the stub axles bolt pattern and the spread is approx. 3-1/8" on the bolts center to center. as I'm looking at it I'm thinking it looks alot like mine last time I was under the car. So I go get the floor jack and lift it up. The stub axles measurement is the same 3-1/8" approx. So cool I can use the axles again ok great. Then I decide to measure the driveshaft flange. It's somewhere around 2-3/4 to 2-7/8". The jdm diff is 2-7/8 as well wtf????
Then I think well maybe someone put the T2 diff in the car already???
I know it only spins one wheel during a burnout so if it is it's broken. I turn the rear wheel on one side of the car. and the other side wheel doesn't budge. I expected it to turn the opposite way of course. I go on the other side and turn that one and the side I was just on doesn't move then. OK wtf? But no matter what side you turn the driveshaft turns......Then if you turn the driveshaft both wheels turn the same way WTF!!!??? In either direction. I guaruntee only one wheel spins if you do a burnout it has been checked many times.
Then I notice there's a sticker on the driveshaft. Its a bit beatup but fairly new it has the numbers 2691-704 on it. I look on mazdatrix website and thats the part number for the aftermarket non-turbo driveshaft with replaceable u-joints. Ok cool I didn't even know I had that. That's a good think. So Di guess I bought a NA LSD rear end? But why does mine act like that is my question I guess.
The JDM one acts just like a regular LSD. Is mine viscous if so I think it was broken along time ago. Is my car really a GTUS? How can you tell? VIN number? If so It may account for why the car seems faster than most NA ones. But I thought all GTUSs came with the turbo sized brakes? Mine has the regular NA brakes. Now I'm really confused. One thing I know without a doubt is the transmission is not a turbo one and the driveshaft is apparently not for a turbo car anyways. I'm gonna take some pics and post them to see if anyone can tell me what the hell is going on here.
Everywhere I looked says you need T2 axles and driveshaft for the LSD rear end. Does the GTUS actually just have a na tran, driveshaft and na LSD rearend?
06-09-09, 07:06 PM
#2
If you have single piston front calipers, you have a GTU. The GTUs had 4-pot brakes & a 4.3 NA LSD. The S5 GTU had an open diff, and the one-wheel tire fires you mentioned suggest that's what you have. Viscous LSDs are supposed to last just about forever, so I'd say it's unlikely you have a broken TII viscous LSD. It's the clutch-type S4 LSDs that wear out over time, and start to act like an open diff.
As for the similarities in bolt pattern, all I can tell you is that the NA flange is different from the TII flange. If your driveshaft has an NA part number, you've got an NA diff (unless someone frankensteined some things). The TII driveshaft also uses a different yoke, that would not fit in an NA trans.
As for the similarities in bolt pattern, all I can tell you is that the NA flange is different from the TII flange. If your driveshaft has an NA part number, you've got an NA diff (unless someone frankensteined some things). The TII driveshaft also uses a different yoke, that would not fit in an NA trans.
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