I know this is an old topic but here's the situation. I am currently rebuilding my trans after catastrophic differential failure. I am doing the rebuild myself and am good with that. The thing is that this is my second differential, the first one only killed itself; the current one forces a complete tear-down and rebuild. I think that my axles may be too long. I used the stock manual hubs with the appropriate shafts per Ryan and then followed up with 4T65E-HD cups. Based on the fact that the bearing formally behind the differential is obliterated, I feel there is excessive loading during suspension motion. I saw a post recommending installing without snap-rings and boots and checking swing (with strut spring removed), and I like that idea. I just wanted to know if anyone had the axle actual lengths that they have used successfully and if this has happened to anyone else. I am using a drop out from a 00 Bonn SSEI with Purple Rein mounts.
Thanks.

[This message has been edited by olchap (edited 09-11-2012).]

The axle length required will vary based on where and how the powertrain is mounted. The shortest axle is the TranSport Van driver side axle at about 20". Take your axles apart and measure the axle bar. Then you can decide what size to use. Certainly sounds too long to me. I had a problem when I did my swap using the GTP axles.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

I used two Fiero manual passenger side driver side axles with the tripots centered between the hubs. This left 1/2" clearance in the bottom of the tripots.

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Project Genisis Lo Budget 3800SC swap

88 Coupe under construction.

[This message has been edited by hercimer01 (edited 09-14-2012).]

Sounds like good advice. Thanks.

Driver th125 axle for drivers and fier manual axle with gtp inner for passenger

[This message has been edited by FriendOfYours (edited 09-12-2012).]

quote Originally posted by FriendOfYours: Driver th125 axle for drivers and fier manual axle with gtp inner for passenger

?? These are two different diameter axles with two different size tripot rollers for different size tripots.

Edit: GTP tripots are correct

[This message has been edited by hercimer01 (edited 09-12-2012).]

Olchap check your PM

quote Originally posted by hercimer01: ?? These are two different diameter axles with two different size tripot rollers for different size tripots. Edit: GTP tripots are correct

GTP inner tripot will fit the Fiero man axle

quote Originally posted by FriendOfYours: Driver th125 axle for drivers and fier manual axle with gtp inner for passenger GTP inner tripot will fit the Fiero man axle

Yes, but you stated that the driver side AUTO axle for the driver side. The auto axle wont fit the tripot. The rollers are smaller.


I was wrong in saying the passenger side manual axle should be used. It should be the driver side manual. here is what i did. I couldn't find another manual fiero axle so I made one from a Cadillac axle.









These are 4T65EHD tripots from a 1998 GTP



The Fiero manual driver and Caddy driver auto axles are the same.




I did set up the control arms and hubs with dry tripots and measured 1/2" clearance left with the hubs perpendicular to the tripots with the trans centered in the car. Again this is not what most people do. This just what I did.

[This message has been edited by hercimer01 (edited 09-14-2012).]

quote Originally posted by hercimer01: Yes, but you stated that the driver side AUTO axle for the driver side. The auto axle wont fit the tripot. The rollers are smaller. I did set up the control arms and hubs with dry tripots and measured 1/2" clearance left with the hubs perpendicular to the tripots with the trans centered in the car. Again this is not what most people do. This just what I did.

The fiero auto drivers side plugs into the 65E, tulip and all.

I also used 2x fiero manual axles, as my trans is centered in the cradle.

quote Originally posted by MRose: I also used 2x fiero manual axles, as my trans is centered in the cradle.

Me too...

quote Originally posted by hercimer01: I used two Fiero manual passenger side axles with the tripots centered between the hubs. This left 1/2" clearance in the bottom of the tripots.

Did you mean drivers side? PS manual axles are WAY to long...

quote Originally posted by MRose: The fiero auto drivers side plugs into the 65E, tulip and all. I also used 2x fiero manual axles, as my trans is centered in the cradle.

So depending on how the engine/trans is mounted in the cradle, stock Fiero axles can be used with the 4T65E-HD trans without modification?

Jonathan

quote Originally posted by Boostdreamer: So depending on how the engine/trans is mounted in the cradle, stock Fiero axles can be used with the 4T65E-HD trans without modification? Jonathan

The driver's side Fiero auto axle fits directly into the 4T65E-HD, however there is no 100% direct fit Fiero axle solution for the passenger side of the 4T65E-HD.

When people say they used 2x Fiero manual DS axles, it is implied that the Fiero axles are inserted into the 4T65E-HD tulips. The Fiero manual axles will not directly fit in the 4T65E-HD, but the lobes are the same size so you just pop the fiero axle apart and stick it into the 4T65E-HD tulip.

The 2x Fiero manual DS axle approach only works if your transmission is centered, but it gives a nice symmetry and is easy-ish to obtain.

[This message has been edited by MRose (edited 09-14-2012).]

quote Originally posted by ALJR: Did you mean drivers side? PS manual axles are WAY to long...

Yes, Sorry. I meant drivers side.

quote Originally posted by MRose: The driver's side Fiero auto axle fits directly into the 65E, however there is no 100% direct fit Fiero axle solution for the passenger side. When people say they used 2x Fiero manual DS axles, it is implied that the Fiero axles are inserted into the 65E tulips. The Fiero manual axles will not directly fit in the 65, but the lobes are the same size so you just pop the fiero axle apart and stick it into the 65E tulip. The 2x Fiero manual DS axle approach only works if your transmission is centered, but it gives a nice symmetry and is easy-ish to obtain.

Does anyone have a pic of an engine compartment that has an L67/4T65E-HD that has been centered for the use of Fiero driver's side manual axles on both sides of the trans?

Jonathan

I Know this is off topic, but the manual axles DO work in the pass side of the NON-HD version of the trans, if anyone finds this in the future while searching for axles.

[This message has been edited by Jncomutt (edited 09-14-2012).]

quote Originally posted by Boostdreamer: Does anyone have a pic of an engine compartment that has an L67/4T65E-HD that has been centered for the use of Fiero driver's side manual axles on both sides of the trans? Jonathan

My 3800SC/4T65eHD powertrain is centered and uses two equal length CV axles. I forget the exact forumula that my axle shop used but the following may help.

CV Compressed Axle total lengths axle on bench, pushed together and measured
Fiero Manual driver side 21"
1995 Beretta (all trans) 20 1/4" drivers side 21 1/4" passenger side
(1995 Corsica also uses the same axles)
1995 TranSport auto 20 1/4 " drivers side 23.3/8" Passenger side
1998 Lumina 3.8 (auto) 20 3/8" driver side
1998-up Grand Prix Drivers (auto) 21 7/8" drivers side
2002-2004 Cavalier (auto) 21 3/16: drivers side.

By the chart I assume that the 1995 TranSport or Lumina axles should be the ones used if you center your powertrain and change the outer CV joint to Fiero manual units and the inner passenger side to the GTP tripot. While two manual Fiero axles might work I'm not certain if they would provide enough inner travel clearance when the control arm pushes the axle into the maximum point.




------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 09-14-2012).]

quote Originally posted by Jncomutt: I Know this is off topic, but the manual axles DO work in the pass side of the NON-HD version of the trans, if anyone finds this in the future while searching for axles.

Good to know, I've edited my previous post to be more specific.

Just wanted to post an update. My pass axle is in fact 1" too long. I had a Fiero manual driver's side axle on the shelf and that is clearly the axle that I need to use. I have done a dry fit with strut springs removed and I get a good fit through out all ranges of suspension movement. When I tried the original axle, the differential was fully loaded; I think the cause of my failure has been clearly found. Thank you to all of your inputs and suggestions. This is been a long process due to a business trip and waiting for various transmission parts to arrive. I completely rebuilt my transmission with a new differential and torque converter. I just have to get everything re-assembled and flush my trans cooler and then should be back on the road.

[This message has been edited by olchap (edited 10-21-2012).]

quote Originally posted by Boostdreamer: Does anyone have a pic of an engine compartment that has an L67/4T65E-HD that has been centered for the use of Fiero driver's side manual axles on both sides of the trans? Jonathan

I would be curious to see a pic of the motor centered AND how close the Bonny dogbone mount lines up with the stock fiero dogbone?

This type of DB mount

[This message has been edited by ALJR (edited 10-21-2012).]

quote Originally posted by ALJR: I would be curious to see a pic of the motor centered AND how close the Bonny dogbone mount lines up with the stock fiero dogbone? This type of DB mount

Well I got my motor in and the dogbone is not even close to lining up... Not a big deal, time to relocate the chassis DB mount...

quote Well I got my motor in and the dogbone is not even close to lining up... Not a big deal, time to relocate the chassis DB mount...

If the fit is just a little off, that can be corrected by making an "offset"dogbone. Cut the two sides from round tubing to fit Poly dog bone bushings.t in place and then weld in a piece that connects both ends. The resulting dog bone may look a bit like a Z shape but it will work. If the fit is way off then you will need to modify the engine dog bone mount for correct alignment.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: If the fit is just a little off, that can be corrected by making an "offset"dogbone. Cut the two sides from round tubing to fit Poly dog bone bushings.t in place and then weld in a piece that connects both ends. The resulting dog bone may look a bit like a Z shape but it will work. If the fit is way off then you will need to modify the engine dog bone mount for correct alignment.

Prior to installing the motor I was thinking I might need the "Z" dogbone; after the motor was in I confirmed that. However, I am "trying" to make the swap look as OEM as possible. I removed the chassis dogbone mount and reshaped it (moved it closer to the strut tower). So now the chassis DB mount looks "almost" like the Fieros AND I can use the stock DB...

If I were to do it over again, I would NOT do what I did. Removing that DB mount is a ROYAL PITA! But I was fairly well commited and didn't want to turn back. Reshaping that DB mount was also allot more difficult than I envisioned and I also had to repair my trunk wall because it got chewed-up a bit from tha air chisel. Im in the home streatch now (reattaching it) and have about 8 hours into it. 8 Hours to make a stupid bracket...

Next time (if there ever is) I will just make a new 3800 DB mount, rather than using the stock aluminum one...