Dismantling transaxle for painting

1008 Views 7 Replies 7 Participants Last post by Gubi, Sep 24, 2015

Trooper

Discussion Starter · Sep 21, 2015

Hi forum: I got a complete, lightened (gears) transaxle for my 1982 GTV6, which came originally from a 1984 GTV6. I have two questions regarding the overhauling I want to do:

1-Can I disassemble the differential portion of the unit so I can have the external aluminum cast case for cleaning and powder coating, WITHOUT NEEDING TO RE-ADJUST BACKLASH OF CROWNWHEEL TO PINION TEETH OR OTHER ADJUSTMENTS?

2- Since I have the original speed ratios for a 1982 on the car and now I got a 1984 fully functional transaxle, any changes of gears (1st and 2nd maybe) to makie it more driveable for street use?

Your opinion will be appreciated.

Thanks,

Trooper

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Milanoguy

· #2 · Sep 22, 2015

Painting a Transaxle case

Hi Trooper

You said
1-Can I disassemble the differential portion of the unit so I can have the external aluminum cast case for cleaning and powder coating, WITHOUT NEEDING TO RE-ADJUST BACKLASH OF CROWNWHEEL TO PINION TEETH OR OTHER ADJUSTMENTS?

The short answer is YES. The differential comes out as one piece. Take the side cover off, slide out the differential, put the side cover back on, and paint away.
The side to side placement of the differential is set by shims in the main case and side cover where the stub axles enter. As long as theses shims aren't interfered with the differential can be R&R (Removed & Reinstalled) without concern.
Now lots of people powder coat transaxle cases without any apparent problems. It makes me a little nervous. I worry the high temperature involved, that the case is going to distort slightly. Ask the powder coating guy, how hot the powder coating oven gets. If it's over 240F, I wouldn't do it.

2. Since I have the original speed ratios for a 1982 on the car and now I got a 1984 fully functional transaxle, any changes of gears (1st and 2nd maybe) to makie it more driveable for street use?

You can swap the entire set of gears and the matching layshaft from one transmission to another. However this will mean getting a new main shaft shim, and re-setting the crownwheel to pinion backlash, and dept. I'd farm this job out.

Hope this helps

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racingswim2006

· #3 · Sep 22, 2015

Trooper said:
Hi forum: I got a complete, lightened (gears) transaxle for my 1982 GTV6, which came originally from a 1984 GTV6. I have two questions regarding the overhauling I want to do:

1-Can I disassemble the differential portion of the unit so I can have the external aluminum cast case for cleaning and powder coating, WITHOUT NEEDING TO RE-ADJUST BACKLASH OF CROWNWHEEL TO PINION TEETH OR OTHER ADJUSTMENTS?

2- Since I have the original speed ratios for a 1982 on the car and now I got a 1984 fully functional transaxle, any changes of gears (1st and 2nd maybe) to makie it more driveable for street use?

Your opinion will be appreciated.

Thanks,

Trooper

A few things:

Is the transaxle you sourced originally an 84 transaxle? Just because it was installed in there doesn't mean that's what it is.

1) You can do this but WHY? Just paint it when it's assembled. Just asking for extra trouble and getting dirt into bearings, etc. Paint it after masking the vent tube, seals, etc. As Milanoguy says, I'd avoid powder coating altogether. I don't even paint these cases as I like to get all the cooling I can from the case itself. There are plenty of heat issues back there and painting/powder coating only insulates the case further.

2) The transaxle gear ratios are identical from 1982-1985 (early). They had stump puller first gears, even shorter than the Alfetta. Only the final drive changed practically (the pinion shaft itself is different as is the ring gear obviously). There is no advantage to changing any of the gears around between the two transaxles if they are true 82 and 84 units.

If you have it out of the car it's very easy to renew the synchros and inspect the dog teeth etc.

-Rob

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Trooper

Discussion Starter · #4 · Sep 22, 2015

kyou Rob and Milanoguy for replying. I am not sure the 84 transaxle is really a 1984 issue, but I got the number on the bottom of it. Can that be matched to a year of production? I believe it starts with 060 or 60???.

I hear you about the heating and my only concern was trying to clean it good for a plain paint job. So I wanted to piece it appart for sandblasting, as the whole transaxle is too heavy and too large for closed cabinet blasters (unless I can find one of those walk-in blasting units services out here).

I'll probably check inside guts, rings, synchros and then clean the s**t out of it with solvent and give it a thermally conductive paint job.

Thanks,

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Alfar7

· #5 · Sep 23, 2015 (Edited)

Paint?

Why are you painting the transaxle. The bare aluminum transfers heat effectively. Not so painted!

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alfasrule

· #6 · Sep 24, 2015

I did the opposite with my 85 GTV-6 I Obtained an early transaxel and moved my gears from the 85 to that gear box. Very TALL gearing, best change ever. You may have gone low in your ratios cause I believe the gears are lower in the early models because of the diff gear. While your doing 80 your car is screaming mine is purring. Painting STUPID who's gonna see it? It's a gearbox, who cares if it's painted.

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alfaparticle

· #7 · Sep 24, 2015

Years ago I started a new job as a maintenance engineer and the boss asked me to investigate the high failure rate of electric motors in one part of the plant. The operations people were painting everything, including the motors, as make work during slack periods. The paint caused the motors to overheat and fail. Most paint is a lousy conductor of heat.

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Gubi

· #8 · Sep 24, 2015

Listen to the guys: they're right. No need to coat aluminum, and you're really going to hurt the heat transfer and potentially cause overheating.

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