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wewantutopia
Samba Member
Joined: September 23, 2004
Posts: 29
Location: Woodstock, IL
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 Posted: Wed Aug 06, 2025 7:42 pm Post subject: Which alternator and cooling boot? |
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Hello, I'm working on a 76 Riviera with a CV 2.0L type 4 engine. I'm assuming this bus originally had a 55 amp alternator, because I have this cooling plate
but, installed on the engine was this alternator
Am I correct in assuming that this alternator is an original "high output" 70 amp style alternator and not the one that Bus Depot is selling that is 70 amp but "directly replaces stock 55 amp unit"? If so, does anyone know the part number?
This alternator wasn't connected properly, it still had the original shaped cooling boot, which of course didn't work, and it was connected via that crappy flex aluminium stuff that is visible in the pic. Is this the correct boot for this alternator? Part number 022-903-655?
Thank you!!!!
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Pics from a duplicate thread:
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dodger tom 
Samba Member
Joined: March 25, 2013
Posts: 1957
Location: Central Coast, CA, but we're all still Ukrainian and Californian
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| Posted: Wed Aug 06, 2025 8:03 pm Post subject: Re: Which alternator and cooling boot? |
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try loading your photos into the samba gallery. it makes it much easier to respond to you.
https://www.thesamba.com/vw/forum/faq.php?mode=gallery#2
i’m no expert, but that doesn’t look like my 70-amp.
_________________
1978 Champaign Edition 2 Westfalia
Would never find the time to keep up another classic air-cooled. |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42797
Location: at the beach
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| Posted: Wed Aug 06, 2025 9:22 pm Post subject: Re: Which alternator and cooling boot? |
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EDIT: I missed that you are really trying to do an alternator swap, which is really what you are asking.
Most original alternators were 55 amp. Your photo looks like 55 amp. The 70 amp setup is different and requires different parts. For most applications the 55 amp will be fine. It requires more than just the larger alternator. You also need the cooling in place for it. And, 70 amp alternators are harder to come by. I believe that they use a different pulley and rubber elbow too.
To use that backing cover you will need to make gasket between the metal cover and 55 amp alternator. Keep in mind that earlier buses used a 30 amp and 38 amp generator, and they were fine with that. The 70 amp is used mostly in buses that have auxiliary heaters, auxiliary batteries, and are campers. Many people today simply get a LIPO4 power station, charge it off shore power while at home, and then use it camping. Ask Robbie about that if you want to go that way. He has it down to a science.
If you put a 55 amp alternator back in you MUST check stud length on alternator B+ to make sure CANNOT hit cover. If this happens, and it is common - poof
The boot you need has a part number but finding a boot with that part number does not guarantee it is that part number. It is one item that is a real pain to chase down. There are different size openings in the fan shroud also so it will depend if you have the original fan shroud of not. Look at the serial number on it and on the case. See if they match. If not go with the number on the shroud to see what it is off of originally. I think yours should start with GD but if it is an early 1976 then it would be something else.
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" 
Last edited by SGKent on Thu Aug 07, 2025 10:59 am; edited 1 time in total |
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Wildthings
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Joined: March 13, 2005
Posts: 52499
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| Posted: Thu Aug 07, 2025 10:36 am Post subject: Re: Which alternator and cooling boot? |
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You do not need or want the cover that goes with the 55 amp alternator and do not want the 55 amp style alternator boot either. You need a boot for the stock 70 alternator such as used on Porsches and (some?) Canadian buses.
Note that there are two different fan shrouds used on these rigs, one style has a larger hole for the alternator boot than the other, so you might possibly have a fitment issue there. |
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poundman
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Joined: April 05, 2024
Posts: 434
Location: Sugar Land, Texas
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| Posted: Thu Aug 07, 2025 11:55 am Post subject: Re: Which alternator and cooling boot? |
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This is the 55AMP boot I purchased recently
https://www.busdepot.com/021903655b
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Restoring a 1972 Bay Window Bus that has not be registered for the road since 1981.
Sugar Land, Texas |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42797
Location: at the beach
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| Posted: Sun Aug 10, 2025 11:23 pm Post subject: Re: Which alternator and cooling boot? |
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edit: if it doesn't fit, try this https://914rubber.com/alternator-cooling-boot
you'll have to try it to see if it fits. My 1977 55 amp takes the /D boot. The bus depot one is a /B which is the smaller hole in the shroud so it falls out on the large hole shroud like my 1977
If it is correct it will be easy to install. If it does not fit then it is the wrong one. There is not a simple solution to this problem because even if you get a part with the correct part number on it, that does not mean it is the correctly designed part. I can tell you this because I got a NOS one from VW about 5 years ago. I also ordered one from a bunch of different vendors. Only the VW one fit right. And some of the reproductions had the same parts numbers as the original VW one. The differences were major and not petty.
| eche_bus wrote: |
I just got off the phone with Jim at Airhead Parts. Jim is directly involved with parts procurement and the Ventura Wharehouse Group, and the reproduction of parts such as the alternator boots we've been discussing. I learned A LOT.
Ventura makes both the -B suffix 55A boot as well as the one for the 70A alternator. They sell these to VW Heritage. As we already know, the part numbers that VW Heritage is showing for these two parts are wrong. Jim looked at VW Heritage's website while I was on the phone and agreed, as he knows what Ventura sells them. If you buy a boot from VW Heritage, you're going to get the same part you could have bought from Airhead Parts. This is not opinion, it is fact.
It turns out that Jim knows quite a bit about these boots. I was told the reason they decided not to reproduce the -D suffix boot was that contrary to what's been assumed here, this boot is the exception, not the rule. His experience has been that the majority of 75-79 shrouds had the smaller hole that fits the -B suffix boot. He was baffled as to why this would be, too. Much fewer shrouds were made with the larger hole, requiring the -D boot, and he couldn't justify the expense of reproducing it for such a limited market. This came from a guy that has personally owned quite a few late bay buses.
Warning - speculation: My thought is that around '75 when the 70A alternator became an option for USA-delivered buses, VW created a shroud with a larger boot opening, along with new boots for both 55A and 70A alternators. They still had plenty of old shrouds to use up, and for vehicles that didn't use 70A alternators, the old shroud was used along with the -B boot.
So I asked Jim about using his repro round 70A boot with a 55A alternator. He confirmed that the shroud end of the 70A boot is larger than the -B suffix 55A boot, but in his opinion I'd have a heck of a time getting it to seal on the 55A alternator. I'm still going to go ahead and try it though.
Furthermore, I've heard back from sources in the UK that confirm I can order the -D 55A part from VW Classic Parts in Germany through them. There is no reason to believe this is the same part as either of the ones made by Ventura/AirHead. It'll take several weeks, but I'm going to do this too and will report back with results. |
| eche_bus wrote: |
Under suggestions from a couple of members, I thought I'd try one of the repro 70A alternator air boots to see how it would work with my 55A alternator.
In short, it doesn't. It's not so much that the part can't be squished by the clamp to seal around the 'D'-shaped alternator fitting. It's not that it doesn't fit pretty well in the fan shroud hole - the 70A boot most definitely has a larger fan shroud end. It's that when you mount the alternator to the shroud and then try moving the alternator along the arc of the adjustment bracket, it pulls the boot right out of the fan shroud hole. Yes, the boot was held in the hole by the "C-clip" wire.
I'll show you why. The -B 55A repro boot is on the left, my original -D 55A boot in the middle, and the 70A repro boot is on the right. I've positioned all three so they're sitting flat on the fan shroud end and rotated to the same orientation.
You can see how different the angles and heights are, especially between my original 55A part and the 70A one.
Here's a photo showing the same parts from the top. You can see more differences between them.
It might not seem like that much difference, but trust me (I've fit and tried them all), unless the part used is the right one for BOTH the fan shroud and the alternator used, it'll simply pop out of the fan shroud hole as soon as the alternator is adjusted.
Sure had hoped the 70A boot would do the trick. I'm waiting on the correct part to arrive from VW Classic parts. |
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42797
Location: at the beach
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| Posted: Mon Aug 11, 2025 11:47 am Post subject: Re: Which alternator and cooling boot? |
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I ordered two spares since the oem VW one I have is on the engine and I have no spares. This is the /D one. They shipped this morning. I have nothing to compare them to except memory, but one review did say that they were larger than the small hole /B one so they should be the correct part. I'll post a photo when they come in. Save your old spring and band to reuse them.
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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wewantutopia
Samba Member
Joined: September 23, 2004
Posts: 29
Location: Woodstock, IL
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| Posted: Thu Aug 14, 2025 8:16 pm Post subject: Re: Which alternator and cooling boot? |
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Thank you all for the replies! Sorry, life got busy as I'm sure you all can relate!
I'm going to start a new thread to clarify my question.
Thanks again!! |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42797
Location: at the beach
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| Posted: Thu Aug 14, 2025 8:28 pm Post subject: Re: Which alternator and cooling boot? |
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use the same thread. Duplicates will get locked.
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42797
Location: at the beach
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| Posted: Fri Aug 15, 2025 7:17 am Post subject: Re: Which alternator and cooling boot? |
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| dodgertom wrote: |
looks like a 70-amp alternator without the 70-amp pulley.
but, that’s just a wild guess.
_________________
1978 Champaign Edition 2 Westfalia
Would never find the time to keep up another classic air-cooled. |
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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