• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR4/4A TR4 alternator conversion mounting

Share this page

drooartz

drooartz

Moderator
Staff member
Gold
Country flag
Offline
Well, I'm settled in the new house and found all my tools, so it is time to get back to tackling my non-alternating alternator. As a quick recap, with help from this group, I have tracked down my non-charging problems to the alternator conversion the PO did. After finally getting it through my thick skull how an alternator works, I think I've got too loose of a belt. The alternator top mount uses the old generator bracket, slightly cut down. It mounts the alternator way out by the wheel well (almost touches). There is no way to move it closer, since the arc of the bracket is not the same as the arc of the alternator.

The PO used the pulley from the generator, and put on one of those temporary belts (red, with links). I'm sure it slips some, and it is quite loose. From my reading, it would seem that an alternator needs a much tighter belt setup than a generator, so this might be my problem.

The simple solution would seem to be to modify the bracket to give a wider range of adjustment, and get a real belt. Thoughts? What have have folks done for that top bracket? With that generator pulley, can I use a standard TR4 belt?
 
Hi,

Let me make sure I've got this straight... all the pulleys are the wide version, including on the alternator, right? If so, yes, you should be able to use a stock "wide" TR4 belt.

My concern would be how well the generator pulley swapped onto the alternator. I am not certain that would be a good fit (have never tried it and the misc. parts in my stash are boxed and in storage right now, so I can't go take a look). There are special pulleys made to adapt alternators to use the wide belt, leading me to think the original generator pulley won't fit well on an alternator. This might be part of the problem you are experiencing.

Using a proper belt instead of that temporary one will likely move the alternator away from the wheel well, toward the engine. (Keep the temp belt in your trunk for an emergency, though.)

You said there is no way to do that, "since the arc of the bracket is not the same as the arc of the generator". Be sure to loosen all of the mounting bolts and then try moving the alternator closer to the engine (loosening the belt in the process). On my car, the long bolt underneath and both bolts at either end of the adjusting bracket must all be loose, or the alternator will not budge.

I'm using the stock bracket too, straightened, with Delco 7127-3 alternator on my TR4. The bracket attaches to the rear of the alternator lug and I did find the underside of the bracket would rub against the body of the alternator, so had to grind the bracket a bit to gain some clearance. That helped the alternator to move closer to the engine.

From the overall description of the installation, I'd suggest you check as carefully as possible that all three pulleys are in good alignment, that the belt isn't rubbing hard against one or more edges. If your alternator were the same as mine, I can tell you that about 3/8" of metal needed to be removed from the rearward side of the lower/front mounting lug, and that the now-straight adjusting bracket has a couple washers under it at the engine mounting end, to shim it forward slightly. However, each alternator installation will likely be a little different, so these dimensions may be of little use to you.

Also, the wide belt can be a bit difficult to get "just right" on tension. In my opinion, because of all the extra contact area it has, it should be run slightly looser than a modern narrow belt. Don't overtighten it! Just a little too tight with that wide belt and it will wipe out the alternator and/or water pump bearings. It only needs to be tight enough to not slip. Any tighter starts heading into dangerous territory. You might consider a thin belt conversion at some point. It's a little easier to work with and modern width belts are a lot easier to find.

Whatever belt you use, whenever a new one is installed be sure to recheck the tension a couple times during the first 100-200 miles of use. Belts tend to stretch/loosen quite a bit initially, then settle down.

Hope this helps!
/ubbthreads/images/graemlins/cheers.gif
 
Were you aware that the AC Delco can be modified to bolt on with the stock brackets??? You must remove the lower standoff mount and bolt straight to the front of the motor.
A small bit of metal must be removed to line up the pulleys(you have the stock pully reamed to fit the delco). This unit comes in so many flavors you just pick what you need and go, cheap too...
MD(mad dog)
 
As MDCanaday says, the stock pulley bore has to be enlarged. I measured a TR3 generator I have, and it has a 15mm shaft (6202 bearing), and the Delco 7127 alternator has a 17mm shaft (6203 bearing). It is possible to get a 17mm wide belt pulley to use on the 7127 without having to bore out the original pulley. Delco made a ton of versions of this alternator for various farm, truck and industrial applications besides those for automotive use, and many had the wide 3/4" belt. Any local rebuilder should have one in his parts bin.
 
[ QUOTE ]
Were you aware that the AC Delco can be modified to bolt on with the stock brackets??? You must remove the lower standoff mount and bolt straight to the front of the motor.

[/ QUOTE ]

Yes, that's correct. That's exactly what I did, bolted it on with the stock brackets.

A long 3/8" bolt is used for mounting, with a spacer tube in between the two original TR mounting brackets. I also welded a tab on the spacer tube to provide a rear/lower mounting point for the 7127-3. And, once the original generator mounting spacer is removed from the front engine plate, the hole is oversize. The new spacer/tube can take care of that, too, as a sort of bushing.

[ QUOTE ]
A small bit of metal must be removed to line up the pulleys(you have the stock pully reamed to fit the delco). This unit comes in so many flavors you just pick what you need and go, cheap too...
MD(mad dog)

[/ QUOTE ]

Also what I ended up doing. The metal is removed from the rear side of the front/lower mounting bracket on the alternator housing. I took off about 3/8", I believe.

The rebuilt 7127-3 cost me all of about $50, and that was without a core to exhange. Prossibly could be found cheaper with some searching.

There are some websites out there with photos and illustrations on them. VTR has it in their archives, if you can get to that.

Cheers!


Cheers!
 
Thanks all for your insights. The PO did this installation, and I'm not sure that I trust what was done entirely. I may wind up going back to the generator for now (it came with the car) and dealing with the alternator later if necessary.

Mostly just want to get this cleared up, since I'm thinking of passing the car on to someone else (to pursue a different LBC). I want to make sure it is solid before I hand it off.

-Drew
 
Why wait until later. If the car is not your daily driver a Utah winter is a great time to straighten it out.
 
I guess I'm a little scared about messing with this sort of conversion. I've never done this before, and have minimal fabrication skills or equipment. I would prefer to get this alternator working, though, since it's already on the car and is a nice upgrade.

I'll try to take a picture of the alternator with the pulley that's on it later today, so that I can get settled where it is from.
 
Back
Top