Engine/Trans Swap Axle Line Up (Page 1/1)
rennaizxance AUG 17, 04:01 AM
Hi all,

I'm in the middle of an engine swap and realized I might have been too hasty with some of the custom mounts I did for the engine and trans. In the current position the axles aren't in a direct line with the spindles. I haven't gotten an extremely good measurement, but currently the end at the trans is about 3 inches forward of the spindle position. This is my first time approaching anything like this so I'm not certain if this will cause any problems down the line. I'm not nearly done so it won't be tremendous effort to correct this, but I'd rather not finish up and have to move things again. Any insight into this?
theogre AUG 17, 04:27 PM
Axle at "rest" the axle want to be straight as possible even car running on smooth pavement.
If not the axle "thinks" is turning all the time and wears out faster. Move angle the worse wear you get. More so w/ inner CV.

Is not as bad as drive shafts w/ uni joints but doesn't like to bend at CV limits either.
Even if CV don't fail itself, the boots can die fast.

Worse... if inner CV spines section moves in the trans swap vs OE trans setup location... Likely have short or long axle(s) now that cause inner CV big problems including destroying it.
Inners only use ~ middle &fraq13; total travel in/out. That can be 1" or often less.
Short axle often pulls out the CV and blows boot and joint apart.
Long axle often pushes axle spines into the trans and can wreck either or both doing that.

This even happen in stock cars w/ bad engine/trans mounts or bought new/rebuilt axle and didn't check length. Is common New/Rebuilt axles don't match OE length and won't fit but install then wonder why new axle fail fast. Often in seconds.

------------------
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(Jurassic Park)

The Ogre's Fiero Cave

rennaizxance AUG 18, 12:27 AM
Helpful as always Ogre. I'll take the time to move the engine.
fieroguru AUG 18, 02:48 PM

quote
Originally posted by rennaizxance:

Helpful as always Ogre. I'll take the time to move the engine.



I wouldn't...

Lower your car 2", you introduce 2" of additional CV angle. Drop the engine/transmission lower in the chassis, it increases the CV angle. Swapping from an auto to manual also changes the CV angle as even GM put the axles in different placements w/o bothering to change the engine mounts.

For a transverse setup using any of the common Fiero engine and transmissions swaps, as long as you don't cut a lot of metal away to fit the drivetrain in the back of a Fiero, the CV angles will be well within their operational limits. There just isn't enough room to get things that far out of position from a CV/Tripot perspective.

The "real" issue is axle length and the need to verify there is no binding or over extension of the tripot joints with the suspension fully extended and fully compressed. If there is no binding, your axles and CVs will be fine... even if they are at an angle!
Raydar AUG 20, 09:18 PM

quote
Originally posted by fieroguru:
...
If there is no binding, your axles and CVs will be fine... even if they are at an angle!



I was thinking of R-Runner's tube-frame IMSA car. When he first built it, using the longitudinal engine / transaxle setup, the axles were angled forward probably at at least 15 degrees, IIRC. I don't think he ever suffered any ill effects due to this.