Alternator upgrade for pre '88 3.8L?

Topic: Alternator upgrade for pre '88 3.8L? (Read 16587 times) previous topic - next topic

Re: Alternator upgrade for pre '88 3.8L?

Reply #60 – June 06, 2005, 10:58:48 AM

Why couldn't you use the front half of the case off the 3.8 alt and bolt it on to the newer style 3g alt. I 've got an 88 3,8 cougar that had that same alt. If I remeber right It looks to be the same. Also I have looked into the 3g swap for my 84 T/c and I found threre are 2 alt that are the 130 amp. At oreilly I believe the numbers are 01-0200, 01-0201. one of them is cheaper. Also with my older style v-belt set up I sont have to do any grinding like all the write ups i've seen

Re: Alternator upgrade for pre '88 3.8L?

Reply #61 – June 06, 2005, 02:40:44 PM

Quote from: Bird351

Success! Only major hangup was that this alt had a smaller top bolt hole than the original.

I forgot to mention that because I took the bolt that came with the alternator I pulled from the salvage yard. The factory setup had a third mount that went into the back of the alternator, which is why the top bolt is smaller. I'm going to do some calculations to see what bolt strength is needed to get back to factory specs. Probably a 12.9. The other option is to tap/helicoil a larger bolt. You could also leave it alone and it might never break, but I have bad luck with leaving things "good enough".

Re: Alternator upgrade for pre '88 3.8L?

Reply #62 – June 06, 2005, 02:43:01 PM

We just dug around in my friend's bolt collection until we found something that fit and fit snug. Don't know how well it will hold up.

Re: Alternator upgrade for pre '88 3.8L?

Reply #63 – June 07, 2005, 08:52:28 PM

The original bolt is a 3/8" fine threaded grade 5.1. The bolt that goes with the 3G case is an 8mm fine threaded 9.8.
Going from my machine design book, the new bolt needs to be 44.5% stronger than the old one to keep the same safety factor. A 10.9 bolt gets you most of the way there (98%). An 8.8 bolt gets you 71% of the required proof load. A 9.8 gets you 77% of the way there. A 12.9 gets you 115% of the load.

In reality, this application requires somewhere between a grade 2 and grade 5.1 bolt. I'll leave y'all to decide what is appropriate. I am going to throw a 10.9 in mine.

Re: Alternator upgrade for pre '88 3.8L?

Reply #64 – June 07, 2005, 08:57:32 PM

Wish I had a bunch of good bolts laying around. Unfortunately, I have nothing in that department. Not even sure if I should be looking at a hardware store or auto parts store for one.

Re: Alternator upgrade for pre '88 3.8L?

Reply #65 – June 07, 2005, 11:34:10 PM

Yeah I would think that a good hardend bolt should do the job as long as you don't strip things out.

Re: Alternator upgrade for pre '88 3.8L?

Reply #66 – June 22, 2005, 05:13:06 PM

Two little things I thought I'd list in the thread.

One, I finally looked at what the bolt was that I was using. It's a Grade 5, I think.. the one with three lines on the head. I'll have to look for the correct (and stronger) bolt when I can get to a parts store again. Best off going to a hardware store or an auto parts store for a stronger bolt? Also, it's possible that this bolt isn't quite right for the application.. like the threads may have been a little bit off. (I didn't put it in, the friend that helped me did it while I was cleaning up the work area, if I recall) Is there anything I can possibly do to ease the load on this bolt in the meantime, or if a proper replacement isn't found anytime soon?

Second.. if the picture in this link is accurate, is this another possible alternator for this application? You had 300 I6 parts listed on your spreadsheet.. and this came up in a search for 4.9L stuff:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7933640016&fromMakeTrack=true

Re: Alternator upgrade for pre '88 3.8L?

Reply #67 – June 28, 2005, 05:57:22 PM

Uh, the alternator uses a metric bolt.

No wonder the threads aren't right. I'd just pick up something from Lower/HD and call it a day.

Yeah, if that e-bay link is showing an accurate picture...that is a viable alternator.

Re: Alternator upgrade for pre '88 3.8L?

Reply #68 – June 28, 2005, 07:56:29 PM

Well, our only source for a bolt that day was my friend's spare hardware collection.. so we're lucky to have even found a grade 5. Had it been at my house, I would've been without a new alternator.. because I don't have any bolts like that at all unless I happened to find one on some other part of one of the two project cars.. and at the time, that was the only car available to us.

Alternator upgrade for pre '88 3.8L?

Reply #69 – January 14, 2006, 09:05:37 PM

Bringing back the dead. I want to upgrade my alternator on my 86 t-bird which is a 3.8, external reg so I guess it's a 1G. According to that spreadsheet I only see 3 models that have a 95 amp alternator. I had wanted to go with a 130 amp orignally, but I guess there isn't anything out there. So I was wondering if there were anymore models that I can look for at a local wrecker for an alternator that is at least 95 amps? Thanks

Jason

Alternator upgrade for pre '88 3.8L?

Reply #70 – January 14, 2006, 09:22:12 PM

The models in the spreadsheet are the only ones I know of.

Alternator upgrade for pre '88 3.8L?

Reply #71 – January 28, 2006, 08:25:43 PM

None of the local wreckers had any alts in. I'm not in a rush so I will just wait till they do. I was wondering if you wire up the alrernator plug like on page 2 with one of these alternators the same? Thanks

Jason

Performance Upgrade to Alternator

Reply #72 – February 05, 2006, 03:01:38 PM

The great research in this thread certainly helps me know what to do to replace my alternator. I do not know enough to understand if you guys are doing it to get a performance gain or simply because a new alternator is needed and you are looking for compatible replacement. Thx.

Alternator upgrade for pre '88 3.8L?

Reply #73 – February 06, 2006, 01:26:56 AM

yeah uh just thought I would throw this out,.... How did you get an alt for a 5.0 1990 tbird?

Alternator upgrade for pre '88 3.8L?

Reply #74 – February 06, 2006, 10:58:12 AM

Quote from: thunderblunder

I do not know enough to understand if you guys are doing it to get a performance gain or simply because a new alternator is needed and you are looking for compatible replacement.

I did it mainly for a performance gain. The factory 2G alternator is rubbish. The headlights, MVAC fan, and the radio would max out the 2G at idle. I don't have that problem with the 3G.

Quote from: Haystack

yeah uh just thought I would throw this out,.... How did you get an alt for a 5.0 1990 tbird?

I pulled the alternator from a local junkyard. [My posts says a '90 T-bird, but it was actually a '91] You can use car-part.com to get one too.