E30 M42 Serpentine Belt Conversion

[roguetoaster]

Check post 11 for current status. This space reserved for completed project details.

[Andrew325is]

I don't think it would be good to run the A/C belt misaligned. It looks like you may be able to get a new clutch with a serpentine pulley.

[roguetoaster]

I don't think it would be good to run the A/C belt misaligned. It looks like you may be able to get a new clutch with a serpentine pulley.

Yeah, both new clutch assemblies and taking a center section out of a different compressor will probably work. There are even mag clutches that move the pulley to the rear, which may allow for a single belt system. Was also trying to explore as many permutations as possible so others can have more options depending on what they want to run.

[Andrew325is]

Hmm, yeah I'm going to run into this issue putting the M44 in. I guess either try to transfer the clutch & pulley from the M44 compressor to the E30 one or use the M44 compressor and change the ends of the E30 hoses.

[Andrew325is]

I heard from someone who’s done this. He said you need to use the M44 compressor (and bracket) and change the fittings on the E30 hoses to match it. Also drain the oil if using R12 and use a compatible oil.

[roguetoaster]

I heard from someone who’s done this. He said you need to use the M44 compressor (and bracket) and change the fittings on the E30 hoses to match it. Also drain the oil if using R12 and use a compatible oil.

I'm sure there's another way as folks who have working AC probably want to skip the evac/charge steps. That said, if M44 or other compressors are cheaper/more available it's undoubtedly a good way to go, but mine is only a few years old, so I'm trying to keep it one way or another.

Will have more info tomorrow.

[Andrew325is]

Yeah, there could be. If you find a way to keep the E30 compressor I'd love to know how.

[roguetoaster]

Messed around painting parts, replacing little things, and generally spending some quality time on other stuff on the E30. Will be back to the conversion tomorrow when the WP pulley arrives and I get the belt.

For anyone interested, total cost so far on the conversion on the DS would be about $95, if you didnt already have the bits lying around, plus a belt.

Pretty sure the AC side could be perfectly solved with a $75 serpentine equipped clutch, granted that's no name aftermarket. Also exploring other Denso untis that have the belt drive aft, which may allow for an idler/single belt drive, and do have 2 used compressors on hand to disassemble.

[Andrew325is]

I heard from the guy who's done this again and this is what he said, "The M44 compressor uses the same fitting as the M42 compressor for hose ends. The problem is length of the hose, as the fittings are farther back from the clutch face of the compressor on the M44 one." So that's why the fittings will need to be changed.

[roguetoaster]

So, it looks like I may have a solution for the v belt drive, a slight spacing of the clutch ought to work.

Also, serp belts apparently cannot run in a square config without an idler, even with good tension, so I have a provisional idler/hex key tensioner, same style as the M42 AC tensioner. It's mounted with a cut bolt welded to the inside allen fastener on the face of the oil filter housing, with temporary spacers. While I think it will be okay that way, I don't feel 100% comfortable with that mounting, but it was the only one that did not require bracket fabrication.

[roguetoaster]

Several updates on the conversion. Still using the stock alt, PS pump and WP. Have stayed with an M44 alt pulley, an M50? PS pulley, an M44 trigger wheel and an M44 WP pulley (in my case, an aftermarket one). Remember, the PS adjuster nut/stud will need to be removed to allow for belt clearance, and a short 13mm bolt replacement is optimal.

First iteration of the idler/secondary tensioner mount didn't work when I used the stock plug on the oil filter housing and welded a bolt to it. I did have to use the square setup with no idler to move the car to a shop where I could make the second iteration of the mount. This did work with a 46.75" belt with both alt and PS tensioners maxed out, but it would squeal until warm, and would start to slip somewhere around 5500RPM. I suspect that this solution may work with a belt 1-2" shorter, but there is plenty of leeway. Video: https://www.youtube.com/watch?v=zXmYhOa3Nz4

Second iteration took an M12x1.5 (possibly a trailing arm bolt) turned down/threaded to allow the idler (an M44 A/C unit) to be placed in the right spot. FYI, this is a 4 or 5 rib idler, and a wider one would be more appropriate. Video: https://www.youtube.com/watch?v=7ko9KVFo30I



Finally, still working on the A/C fitment, broke my set of snap ring pliers, so will need some new ones to remove the A/C clutch and check spacing, but did reduce the M20? v belt pulley to a single instead of a double, and did my very best to balance it.

[Andre3127]

There must be something I'm missing. It looks like there's almost no wrap around the crank pulley. How will it drive the belt?

[roguetoaster]

There must be something I'm missing. It looks like there's almost no wrap around the crank pulley. How will it drive the belt?

Well, the angle of the shot isn't the best, but it clearly runs the drive, even if the contact patch isn't absolutely optimal, and it's the same crank to water pump setup as an M44, granted the other side is different. Haven't tested it with water or an aged belt, and I suppose there's a chance of an issue there, but so far, smooth sailing.

Edit:

Looking back, the V belt setup runs the same way in very similar ratios with no idler on that side for the main belt, and unless there is something radically different about serpentine setups I think it will be okay.

That said, a bracket could be made off of the AC compressor mount and allow you to have a second idler, but it would not be simple as far as I can see.

[roguetoaster]

Quite a few trips on the setup now, all is working well, did have to adjust the eccentric idler about 250 miles in as I was getting one or two squeaks on cold start. Added a second nut on the idler just in case that was the issue. Haven't had time to mess with the AC setup, but all signs point to being able to space the magnetic clutch assy a few mm, and thus have it work.

[AmosCake]

So these are the parts more or less which I think I’ll need?
M44 Idler Pulley (M44 ac pulley ) - you suggest a better setup

M44 alternator Pulley 12311432988
M50 PS pulley - 32421722555
M44 Harmonic Damper 11231743305
M44 WP pulley 11511739527
crank pulley -?
Serpentine belt size -
ac/crank pulley/ tensioner V belt -

thanks for the help