Getrag/Muncie HM282

Post by **PrecisionBoost** » Tue Feb 10, 2004 5:25 am

Speaking of information, do you know if the Grand Am turbo came with a Getrag 5spd ???

It was mentioned somewhere that a Getrag 5spd was coupled with the Grand Am turbo so I really wanted to get to the bottom of which tranny model it was.

I always thought it was an Isuzu 5spd but this other site said it wasn't.

Any clarification on type and model would be greatly appreciated.

pontiacjeff · Post by **pontiacjeff** » Tue Feb 10, 2004 3:46 pm

The 5-speed turbo engine in the Grand Am and Sunbird used the Getrag 5-speed. This is the only performance trans available in N. America. Europe and the U.K. have a 5-speed, 6-speed, and even AWD!

Post by **PrecisionBoost** » Tue Feb 10, 2004 5:05 pm

Good so we can confirm the existance of a Getrag 5spd in the Sunbird and Grand Am turbos.

Do you know what model?

The LeMans came with an F16 but since the 2.0L turbo output is significantly higher than the N/A 2.0L I'm guessing it was an F20 (which would be sweet).

Do you happen to have the gear ratios in your user manual??

I've also looked into European F20's and F28's but it would be so much easier to get a 5spd from here

GsiTurbo · Post by **GsiTurbo** » Tue Feb 10, 2004 5:39 pm

I am arguing here...take a quick peek to compare:

Sunbird/Grand Am gearbox:

Getrag F20

Getrag F28 6 speed

Also, the sunbird gearbox (manual) is using hydraulic clutch, and its cable-driven (as far as the gearchange goes). The mounts are not compatible with the Lemans/Lanos.

Please correct me if I am wrong.

pontiacjeff · Post by **pontiacjeff** » Tue Feb 10, 2004 10:56 pm

The picture you have of the Sunbird box is a generic picture. It is actually showing the GM/corporate bellhousing, not the Opel bellhousing. It is a Getrag 282, which is that? It looks just like the picture of the F20.

I wanna 6-speed!!!!

Post by **PrecisionBoost** » Wed Feb 11, 2004 1:15 am

Ok.... now I feel like an idiot

It just occured to me to look in my Factory Sunbird Manual and what did I find??????

N/A 2.0L Sunbird comes with the Isuzu 5sp ( RPO MK7 )

The Turbo 2.0L Sunbird has a Muncie/Getrag HM282 5spd ( RPO MG1/MG2)

Even better is the fact that there was a "strengthened" HM282 called an HM284 5spd

It can be found coupled to a 3.4L V6 in a 91-92 Grand Prix,

This tranny is rumored to be able to handle 400lb ft of torque in it's stock configuration....where as the general consensus about the HM282 is that it's good for around 200 lb ft of torque.

Even though the HM282 bolts up to the C20GET in the Sunbird it's hard to say if it would fit into the Lanos.

Post by **PrecisionBoost** » Wed Feb 11, 2004 1:31 am

I just checked and both the Gear Selector and Clutch are cable actuated on the HM282 (no hydraulics)

I was confused about why they call is a Getrag/Muncie but I guess it's because it's a Getrag design built in the Muncie Indiana plant in the USA. (correct me if I'm wrong)

Unfortunatly the "76mm (5spd) Muncie manual transaxle" only has 7 pages on it and doesn't go into much detail where as the Isuzu 5spd has 24 pages on the MK7/MT2 including detailed gear diagrams.

The HM282 gear ratios are as follows....

1st 3.50
2nd 2.05
3rd 1.38
4th 0.94
5th 0.72
Final Drive 3.61:1

GsiTurbo · Post by **GsiTurbo** » Wed Feb 11, 2004 4:36 am

Ok, here is another picture of the Muncie HM282 gearbox:

On a further note, a fellow tuner in Edmonton is currently installing the C20GET/Muncie gearbox into the Lemans. He has run into the following problems:
- gear linkage/gearknob mounting plate
- hydraulic clutch
- custom gearbox mounts
- custom-build front axles (shortened & rebalanced Sunbird axles)
- front hubs conversion to accept larger-diameter driveshafts
- speedo drive
- small-clearance areas

My yet another 5c

Post by **PrecisionBoost** » Wed Feb 11, 2004 7:32 pm

I realize it would be a pile of work but I'm considering the HM284 due to the power levels I'm going to be making.

I was thinking about the F28 but it's a pain to import and I was under the impression that some of the mounts had to be changed anyways.

As for the modifications I figured on replacing the gear linkage and stock shifter box anyways.

The clutch shouldn't be a problem to rig up.

I was thinking about making some heavy duty axles anyways and I'm sure I can design them fit the stock hubs. (even thought that hub connection will be the weakest point on the drivetrain )

Speedo shouldn't be a problem, just run it to a rotary encoder....take the encoder output and use a cheap $4.00 PIC microcontroller to give an analog signal to the spedometer. ( this also allows me to make adjustments to the spedometer voltage for different tire rolling diameters)

My only concerns are the clearnance and mounts.

I was also considering the idea of turning my Lanos's 5spd into an semi-automatic tranny by using two high power stepper motors to shift and engage the clutch. ( thought about using paddle shifters )

It would be a unique setup and domestic replacement parts are readily available incase I damage the tranny.

I can pick up an HM-282 for $75 but I have a feeling the HM-284 might be very hard to find.

Who knows it might be fun

Post by **PrecisionBoost** » Wed Feb 11, 2004 11:01 pm

With my estimated gear ratio vs speed calculations for the Lanos with the HM282 5spd would be:

1st 56KPH
2nd 96KPH
3rd 142KPH
4th 208KPH
5th 272KPH

These are using the same formula from the other link so it gives a rough idea....but a modified C20GET should be able to rev a little higher so I would imagine you could probably get over the 100KPH mark in second