Don't weld the AWD VCU - Page 4 - 3000GT/Stealth International Message Center

sipe16 · 10-07-2004, 07:28 AM

Quote:

Originally Posted by Bret Brinkmann

The 5 and 6 speed VCUs are interchangable though.

are you 100% sure on that? I noticed that the lip on the top of my 6 spd's vcu unit itself is much larger/higher than that of my 92 (18 spline)'s vcu. I thought that the 25 spline output shaft was larger than that of the 18 as well, and since it runs through the vcu would'nt they be different? I never counted the teeth going through the vcu before it was stolen, so I can't give a definate answer if that's 18,25 or neither. But I would think that only the 25 spline's are interchangeable with the 25's and 18's with 18's. correct me if i'm wrong.

Bret Brinkmann · 10-08-2004, 10:06 AM

sipe16 - I welded the planetary gear to each other AND to the carrier. I had an 18 spline, 25 spline, and six speed in my shop a while ago and all three VCUs looked identicle when I held them up to each other. I was even able to swap output shaft between the three center diff assemblies with no problem. I had thought there would be a difference at least in the 18 splines but perhaps only some of them are different? In any case, all the ones that I have compairedthus far are identicle. I'll see about getting up with Bill at CRS. He has a spread sheet about which parts where changed over the years and when they were changed. Maybe I can get him to fax me a copy and I'll see about posting it. He is hard to get a hold of so no one hold your breath on this.

ES 3000TT · 10-08-2004, 10:26 AM

Brett The 18 spline shaft I got and the 25 spline shaft i just cut off were totally different! The 25 spline can't be replaced with an 18 because the shaft is smaller and will wiggle around inside the transmission. Then the 25 spline wont fit inside the 18 because its too big. The 25VCU compared to the 18VCU I received as well was different. The lip on the bottom was longer. opposed to the 25 spline VCU that had no lip. I ended up hooking my fathers AWD back up on his 25 spline transmisson but it took some grinding of the old 25 spline vcu middle gear set and eating away some of his inner teeth on top of the 18 spline VCU. The Middle gear sets are different. the 18 is longer and the 25 spline is shorter. The 18 gearset also has the teeth all the way up to the set where the Planetaries run on. Opposed to the 25 spline middle gear set that the teeth end like 1/4 inch before the teeth for the planetary gears. The 18 vcu also has the inner teeth all the way up and down the inside. opposed to the 25 that doesn't. This is all on the five speed! haven't cracked a 6 speed open yet! 18 spline shaft is thinner then the 25 spline thicker shaft

sipe16 · 10-08-2004, 01:11 PM

I believe that the answer to the shaft fitting through the vcu lies in the piece i'm holding up below:

http://test.x5racing.net/vcu/images/P8130326.JPG

When i looked at my 6spd's vs my 5spd's i could have sworn that it was different, and now that it's brought up I think that the thickness of this piece is different. The middle area is smaller (making the piece thinner) for the 25spline, and vice versa for the 18 I THINK. I'm going off of memory, but I'm almost certain.

Edit:
Looking at that picture closer, I KNOW that they're different. The 6spd/25spline is much thinner. I'll take a picture of the 25spline one later tonight.

ES 3000TT · 10-08-2004, 08:22 PM

If its like I think you said . 18 spline is thinner and 25 is thicker for 5 speed

Bret Brinkmann · 10-09-2004, 05:04 AM

I have an 18, 25, and six speed in my possesion at this time. I'll take a look at them and compair them. I'll take pictures of all three side by side also. I'll get back to you all on the results.

Bret Brinkmann · 10-13-2004, 03:57 PM

I just looked at the Japan version of CAPS. When they switched over to the 25 spline output shaft they also changed the VCU, sun gear, and pinion shaft (front output shaft). As some one posted earlier about the diameter being smaller for the 18 spline shaft parts I'd be interested in knowing if you could use the 25 spline parts in an 18 spline transaxle. Given that the center diff housings are the same for all years I would think you could use a 25 spline VCU with an 18 spline shaft so long as you use the 25 spline sun gear. But I may be wrong.

Bret Brinkmann · 10-18-2004, 08:16 PM

Here is what I got out of JDM CAPS. With the change from 18 to 25 spline output shafts they also changed the VCU, sun gear, and pinion shaft, bell housing, and output shaft seal. If you switch from an 18 spline to a 25 spline you will need the follow parts.

25 spline output shaft
25 spline output shaft seal
25 spline bell housing
25 spline sun gear
25 spline VCU
25 spline pinion shaft

sipe16 ws correct about the differences in the VCU, sun gear, and pinion shaft. I'm working on pics but probably won't be able to post them until I get home. (Away from home for 2 weeks for work related training.) But in a nut shell the diameter of both the pinion shaft and sun gear are smaller for the 18 spline. Also, the placement of the splines in the VCUs are different. The 18 spline has the spline more towards the pinion shaft while the 25 spline has them more towards the sun gear. With the defference in VCU spline placement the 18 spline has a taller sun gear and shorter pinion shaft than the 25 spline. The planetary carier and center diff housing are the same through out the years.

NOTE: You can use an 18 spline output shaft with the 25 spline VCU but you HAVE to use the 25 spline sun gear AND 25 spline pinion shaft. If you change either one of those three you HAVE to change to other two also. Obviously you can't use a 25 spline output shaft with the 18 spline VCU/sun gear/pinion shaft because of clearance issues. Also, the 5 and 6 speed 25 spline transaxles have different pinion shafts and bell housings (among other things) but they use the same output shaft, output shaft seal, VCU, and sun gear.

sipe16 · 10-18-2004, 10:41 PM

that's good information to know. Thanks for the definate answers.

MilkyClr69 · 11-01-2004, 10:55 AM

Just need a quick question answered, hopefully i can help an AWD guy in the process and save my broke-ass a buck or two...

I have a 92 18 spline tranny and i'm converting it to fwd via welding the vcu. So I'd rather trade it for a AWD guys bad vcu and help him out and make a buck for myself. What VCU's will fit into MY tranny to weld, and what trannies will MY VCU fit into so i can trade it to someone.

I read most this thread but i just got confused...heh.

10-08-2004, 10:06 AM	#32 (permalink)
Bret Brinkmann Gear Head Join Date: Mar 2001 Location: Charlotte NC Drives: Rear wheels only... Trader Rating: (4)	Re: Don't weld the AWD VCU sipe16 - I welded the planetary gear to each other AND to the carrier. I had an 18 spline, 25 spline, and six speed in my shop a while ago and all three VCUs looked identicle when I held them up to each other. I was even able to swap output shaft between the three center diff assemblies with no problem. I had thought there would be a difference at least in the 18 splines but perhaps only some of them are different? In any case, all the ones that I have compairedthus far are identicle. I'll see about getting up with Bill at CRS. He has a spread sheet about which parts where changed over the years and when they were changed. Maybe I can get him to fax me a copy and I'll see about posting it. He is hard to get a hold of so no one hold your breath on this. __________________ When asked what the best thing to come out of Italy is, most Italians will tell you Ferrari.... But if you ask me it was Super Mario Brothers. 250 RWHP If you want the exploded views of both 5 and 6 speeds or pics e-mail me at SavagTiger@AOL.com. 94 VR-4 Panama Green Tan Interior RPS II, gutted cats, flipped BPV, 3SX control arms, 3SX shift bushings, Red Line, Auto-Meter. Rebuilt TC, transaxle, steering rack, heads, and turbos. 360cc's blue printened with in 1%. New short block. RWD convertion and welded rear end.

10-08-2004, 10:26 AM	#33 (permalink)
ES 3000TT 9B's Try me in 3rd!!! Join Date: Jan 2004 Location: Orlando Drives: ES 3000TT Trader Rating: (25)	Re: Don't weld the AWD VCU Brett The 18 spline shaft I got and the 25 spline shaft i just cut off were totally different! The 25 spline can't be replaced with an 18 because the shaft is smaller and will wiggle around inside the transmission. Then the 25 spline wont fit inside the 18 because its too big. The 25VCU compared to the 18VCU I received as well was different. The lip on the bottom was longer. opposed to the 25 spline VCU that had no lip. I ended up hooking my fathers AWD back up on his 25 spline transmisson but it took some grinding of the old 25 spline vcu middle gear set and eating away some of his inner teeth on top of the 18 spline VCU. The Middle gear sets are different. the 18 is longer and the 25 spline is shorter. The 18 gearset also has the teeth all the way up to the set where the Planetaries run on. Opposed to the 25 spline middle gear set that the teeth end like 1/4 inch before the teeth for the planetary gears. The 18 vcu also has the inner teeth all the way up and down the inside. opposed to the 25 that doesn't. This is all on the five speed! haven't cracked a 6 speed open yet! 18 spline shaft is thinner then the 25 spline thicker shaft __________________ ES 3000TT Soon something else!! 2 of 2 in the US!

10-08-2004, 01:11 PM	#34 (permalink)
sipe16 3000GT SL TT Join Date: Aug 2003 Location: Silverdale, WA Drives: 95 VR-4 & 94 Base TT Trader Rating: (1)	Re: Don't weld the AWD VCU I believe that the answer to the shaft fitting through the vcu lies in the piece i'm holding up below: http://test.x5racing.net/vcu/images/P8130326.JPG When i looked at my 6spd's vs my 5spd's i could have sworn that it was different, and now that it's brought up I think that the thickness of this piece is different. The middle area is smaller (making the piece thinner) for the 25spline, and vice versa for the 18 I THINK. I'm going off of memory, but I'm almost certain. Edit: Looking at that picture closer, I KNOW that they're different. The 6spd/25spline is much thinner. I'll take a picture of the 25spline one later tonight.

10-08-2004, 08:22 PM	#35 (permalink)
ES 3000TT 9B's Try me in 3rd!!! Join Date: Jan 2004 Location: Orlando Drives: ES 3000TT Trader Rating: (25)	Re: Don't weld the AWD VCU If its like I think you said . 18 spline is thinner and 25 is thicker for 5 speed

10-09-2004, 05:04 AM	#36 (permalink)
Bret Brinkmann Gear Head Join Date: Mar 2001 Location: Charlotte NC Drives: Rear wheels only... Trader Rating: (4)	Re: Don't weld the AWD VCU I have an 18, 25, and six speed in my possesion at this time. I'll take a look at them and compair them. I'll take pictures of all three side by side also. I'll get back to you all on the results.

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10-13-2004, 03:57 PM	#37 (permalink)
Bret Brinkmann Gear Head Join Date: Mar 2001 Location: Charlotte NC Drives: Rear wheels only... Trader Rating: (4)	Re: Don't weld the AWD VCU I just looked at the Japan version of CAPS. When they switched over to the 25 spline output shaft they also changed the VCU, sun gear, and pinion shaft (front output shaft). As some one posted earlier about the diameter being smaller for the 18 spline shaft parts I'd be interested in knowing if you could use the 25 spline parts in an 18 spline transaxle. Given that the center diff housings are the same for all years I would think you could use a 25 spline VCU with an 18 spline shaft so long as you use the 25 spline sun gear. But I may be wrong.

10-18-2004, 08:16 PM	#38 (permalink)
Bret Brinkmann Gear Head Join Date: Mar 2001 Location: Charlotte NC Drives: Rear wheels only... Trader Rating: (4)	Re: Don't weld the AWD VCU Here is what I got out of JDM CAPS. With the change from 18 to 25 spline output shafts they also changed the VCU, sun gear, and pinion shaft, bell housing, and output shaft seal. If you switch from an 18 spline to a 25 spline you will need the follow parts. 25 spline output shaft 25 spline output shaft seal 25 spline bell housing 25 spline sun gear 25 spline VCU 25 spline pinion shaft sipe16 ws correct about the differences in the VCU, sun gear, and pinion shaft. I'm working on pics but probably won't be able to post them until I get home. (Away from home for 2 weeks for work related training.) But in a nut shell the diameter of both the pinion shaft and sun gear are smaller for the 18 spline. Also, the placement of the splines in the VCUs are different. The 18 spline has the spline more towards the pinion shaft while the 25 spline has them more towards the sun gear. With the defference in VCU spline placement the 18 spline has a taller sun gear and shorter pinion shaft than the 25 spline. The planetary carier and center diff housing are the same through out the years. NOTE: You can use an 18 spline output shaft with the 25 spline VCU but you HAVE to use the 25 spline sun gear AND 25 spline pinion shaft. If you change either one of those three you HAVE to change to other two also. Obviously you can't use a 25 spline output shaft with the 18 spline VCU/sun gear/pinion shaft because of clearance issues. Also, the 5 and 6 speed 25 spline transaxles have different pinion shafts and bell housings (among other things) but they use the same output shaft, output shaft seal, VCU, and sun gear.

10-18-2004, 10:41 PM	#39 (permalink)
sipe16 3000GT SL TT Join Date: Aug 2003 Location: Silverdale, WA Drives: 95 VR-4 & 94 Base TT Trader Rating: (1)	Re: Don't weld the AWD VCU that's good information to know. Thanks for the definate answers.

11-01-2004, 10:55 AM	#40 (permalink)
MilkyClr69 Forum Member Join Date: Jul 2003 Location: Pittsburgh Trader Rating: (11)	Re: Don't weld the AWD VCU Just need a quick question answered, hopefully i can help an AWD guy in the process and save my broke-ass a buck or two... I have a 92 18 spline tranny and i'm converting it to fwd via welding the vcu. So I'd rather trade it for a AWD guys bad vcu and help him out and make a buck for myself. What VCU's will fit into MY tranny to weld, and what trannies will MY VCU fit into so i can trade it to someone. I read most this thread but i just got confused...heh. __________________ 96 SL MagnaFlow Catback, K&N Intake, 18 x 8 ADR Sterling, 245 40 18 Ecsta Supra, Limo/15% window tint, Cross-drilled and slotted rotors, 12" sealed IDMAX w/ 1000 Watt Hifonics amp. Infinity & JBL speakers powered by Hinfonics amp, Alpine 7893. TT engine/tranny swap Fixing a few problems and she'll be back on the road!