PFF - Pennock's Fiero Forum, PDA Edition

Getrag transmission problem on low mileage Fiero GT (Page 1/17)

Moar

OCT 16, 05:54 AM

Hi,

as some members may already know I have bought some new Fieros (´87 and ´88 Fiero GT) in the last few months.

In the meantime I have sold the blue Fiero GT and the yellow Fiero SE for getting more space.
It was hard to sell my fresh restored ´87 Fiero SE, but I needed a free garage for the new ´88 GT.

My ´88 Fiero GT:

I thought my new ´88 GT is in good shape, but unfortunately I´ve found out that there is
something wrong with the transmission/differential (after I´ve sold the yellow Fiero)!

Like the ´87 Fiero SE also my ´88 GT has the Getrag MG-282 5-speed manual transmission.

I´ve recognized some gear whining noises under heavy acceleration, and I have also found out that there is a drive shaft seal leak, too.
Then I have checked the Getrag output shafts for any signs of wear/clearance.
There is excessive clearance in all directions on both output shafts!

So I assume that the carrier bearings are gone?

Now I´m interested in the root cause for this problem.
I´m still using the stock engine in the ´88 GT, while others are driving a V8 powered Fiero!
Why do these diff. bearing fail in a low mileage stock Fiero (only 76000 km)?

Next questions is “How I can get this fixed in Austria for low money”?

Thanks,
Patrick

[This message has been edited by Moar (edited 10-25-2017).]

Rodney

OCT 16, 07:20 AM

When you move an axle around there is always some play even if the differential bearings are 100% tight. Move one axle and watch the other axle. If the differential is loose the other axle will move some.

If it is whining it is worn enough to be pushing against the pinion gear (machined into the intermediate shaft) which means the bearing in the bell housing end is being damaged along with the surface the bearing rides on of the intermediate shaft.

You will possibly/probably need a good intermediate shaft. Plus the bearing/race in the case and new differential bearings. If it has only started whining it may be good enough to reuse the intermediate shaft. drivetrain.com should have many of those intermediate shafts on hand. They bought up like 600+ NOS Quad 4 Getrags and took them apart. I'm not sure if any or all of these Quad 4 transmissions were the 3.94 ratio. If they are and the 3.94 is all they have then you would also need the 3.94 ring gear.

------------------
Rodney Dickman

Fiero Parts And Acc's Web Page:
All new web page!:www.rodneydickman.com
Rodney Dickman's Fiero accessories
7604 Treeview Drive
Caledonia, WI 53108
Phone/Fax (262) 835-9575

Moar

OCT 17, 03:57 AM

There is really excessive clearance on the axles.
• When I move one axle in axial direction, I see some small movement on the other axle!
• If I rotate one axle forth and back, I also some AXIAL movement on the other axle!

This indicates that there is axial clearance on the diff carrier.

So it looks like that I have run into a big problem, because for the repair I gotsta get engine and transmission removed!
If I decide to rebuild the MG282 transmission I will need a lot of parts and special tools.

In the meantime I have done some research regarding needed parts and tools:

Required special tools:
• Bearing separator kit
• Transaxle shim selector kit (Kent Moore J26935)

Spare parts:
• Pro-King trans rebuild kit (BK234)
• Diff./carrier shim kits (GM # 8672903 / #8672904 / #8672905)

I hope I don´t need to replace the intermediate shaft due to pitting on the pinion gear.
I think it´s maybe not necessary, because the whining noises are quite seldom to her.

Do you know if the bearing race (which I´ll probably need for the intermediate shaft) is also included in the Pro-King trans kit BK234WS?

I have found a thread on RealFieroTech about someone using this Pro-King rebuild kit:
http://www.realfierotech.co...opic.php?f=3&t=16004

Hope this is all what is need for a Getrag MG282 rebuild?
(I don´t want to spend more money than an used replacement transmission will cost)

[This message has been edited by Moar (edited 10-31-2015).]

Rodney

OCT 17, 04:48 AM

You do not need the shim tool. If you do this repair the differential can be shimmed by someone who sets up differentials. Someone that sets up differentials knows how tight to shim the bearings. You take the ring gear off. Put the case back together, tighten the bolts and rotate the differential. The person that does differential work will know if it is shimmed too loose, too tight or just right by feel.

Silvertown

OCT 17, 07:31 AM

quote

Originally posted by Moar:

Hi,

as some members may already know I have bought some new Fieros (´87 and ´88 Fiero GT) in the last few months.

In the meantime I have sold the blue Fiero GT and the yellow Fiero SE for getting more space.
It was hard to sell my fresh restored ´87 Fiero SE, but I needed a free garage for the new ´88 GT.

My ´88 Fiero GT:

So I assume that the carrier bearings are gone?

Next questions is “How I can get this fixed in Austria for low money”?

Thanks,
Patrick

Could be low on trans oil causing it to whine due to the leak? I suspect Joel Goodman or Ferris Buller are the culprits.

[This message has been edited by Silvertown (edited 10-17-2015).]

Moar

OCT 17, 01:50 PM

Since I´m the owner of this ´88 Fiero GT all the oil levels are just right (also as I have gotten the car).
I check oil levels very often (especially the trans oil level due to the axle seal leak).
Of course, I don´t know how often previous owners have checked the transmission oil level.
I guess they have NEVER checked the tranny oil, because in Austria most drivers only check
engine oil and noting else. (other things are checked at annually service by mechanics - hopefully).

I have recognized that there is a small difference between the ´87 and the ´88 Fiero
Getrag transmissions - they have "improved" the oil filler cap on the newer Getrags!
They have changed out the old aluminum filler cap with a quick release plastic cap.
The problem with this new plastic cap is that it does NOT SEAL PROPERLY!
For this reason someone has added some RTV there!

Maybe one of the previous owners has lost some oil over this plastic cap while driving, which
caused critical low oil level and accelerated wear of transmission internals?

Actually this might be the root cause for this early differential bearing failure?
(I´m not quite sure if it´s possible to lose so much oil over this plastic cap)

I think the axle seal leak couldn´t be the root cause for the bearing failure, because this
seal usually gets leaky after the diff bearings are gone (the radial runout kills the seal).

[This message has been edited by Moar (edited 10-28-2015).]

Patrick

OCT 17, 03:52 PM

quote

Originally posted by Moar:

I have recognized that there´re is a small difference between the ´87 and the ´88 Fiero
Getrag transmissions - they have "improved" the oil filler cap on the newer Getrags!
They have changed out the old aluminum filler cap with a quick release plastic cap.
The problem with this new plastic cap is that it does NOT SEAL PROPERLY!
For this reason someone has added some RTV there!

I assume the cap you're referring to is the same style as is on my 5-spd '88 Formula. Eventually, that lever assembly fails to compress and widen the rubber plug enough. Rodney sells a shim especially made for that, but I made a suitable shim in two minutes from a bread bag plastic clip. Works just fine.

Moar

OCT 19, 12:18 PM

quote

Rodney sells a shim especially made for that, but I made a suitable shim in two minutes from a bread bag plastic clip. Works just fine.

"Bread bag plastic clip" - What the hell is this?
I have never seen this before!

I´m afraid that this kind of "bread bag plastic clips" is not available on the Austrian marked.

However, this is a good idea and I´ll search for an alternative plastic/steel shim for a "DYI flip up lever dip stick repair".

hobbywrench

OCT 19, 01:54 PM

A few years ago I attempted a rebuild on a salvaged Getrag. These comments may help if you are not experienced with such work. I had lots of time so went slowly. You will need a hydraulic press and many round adapters for gear and bearing replacement. I also used an upright hydraulic press frame for a holding fixture. Read and reread the Getrag assembly manual and you will see repeated references to special tooling , especially for alignment in final assembly. I made some assembly aids and did get together. Alas the transmission was binding upon completion. I have about $300 in parts and , of course, the enjoyable labor sunk in the unit which sits in garage storage.

I did not touch the ring pinion gears so did not have to worry about mesh and tooth pattern there. Before I disassembled the unit the output shaft could be turned by hand with some effort.. After assembly there was significant drag, and unacceptable. I bought a Beretta salvage unit . It turned easily and lives today in my 85.

Take away? You will hear it many times. Especially with ring pinion set up--experience needed. Another thought after my problem. I remember seeing a Porsche trans case being rebuilt . Careful checking of shaft and case alignment. It is possible the unit I worked on was distorted from overheating.

My advice is to have an experienced shop do the work, or buy a salvage unit and hope in either case. Good luck. I bet there is a good Austrian mechanic eager for work.

[This message has been edited by hobbywrench (edited 11-02-2015).]

Rodney

OCT 19, 02:37 PM

quote

Originally posted by hobbywrench:

I did not touch the ring pinion gears so did not have to worry about mesh and tooth pattern there. .

You never have to worry about ring and pinion mesh. All transmissions of this nature are self aligning. The pinion gear runs parallel to the ring gear. The clearance between the ring and pinion gear is set by the machining of the cases. It can not be changed (it can be changed but the case has to be welded and re-machined to move the ring gear towards or away from the pinion gear).