Question: Im wondering if I can use an alternator for an 88 xjs in an 86. The reason I am asking is I would like to have a higher amperage alternator. Current one is 75 amps and it has a bad voltage regualtor (major voltage fluctuations from 12 volts to 18+ volts) and I think this may be due to too much current draw. I know the heater blowers take quite a bit of power (50amp fuse) and I also have a few accessories that suck the juice as well.
Any help is appreciated...
Thanks

Answer: Yes using a BOSCH 115 amp AL192X alternator will be a direct fit replacement for your 75amp LUCAS alternator. The only difference is the pulley (usually has a groove belt pulley, will swap over tothe V-Belt style no problem). Swap it out and enjoy the power.

 

If its a Lucas alternator, yes, it would be a drop-in....but I'm not sure it has any higher amp rating. My '88 XJS V12had a Lucas 75 amp as well.

Somewhere along the line, maybe late '88/early '89, they went to a 115 amp Bosch unit. That's probably the one you're looking at. It uses a grooved drive belt rather than a regular v-belt. I'm pretty sure there's a way to make it all work but I don't know the details. Somebody will chime it.

Or you can convert to a GM alternator for more amps. Johns Cars in Texas makes an adapter kit....a popular upgrade for those wanting more amps.

Don't be thrown off by the Brit fuse ratings, which are different than USA ratings. Those 50amp fuses are "30 amp" in USA-speak. Still a lot of amps, though, due to dual blower motors.

Cheers
DD

 

I tried a 35amp fuse in the Jag and it melted it. It didnt blow just got real hot. Put a 50 amp fuse in and all is good. Dont ask me... But it worked.

 

But back to the alternator issue:
I just need to make sure that the pulley will swap with out a problem.
If so I may just be purchasing a new alternator real soon

 

The factory fuses are 30a continuous, 50a blow. They get so hot that often times the solder on the end caps deteriorates and the filament goes open circuit. So I wouldn't worry, beyond keeping a spare.

Back to the alternator: If the Bosch armature shaft diameter and length was appropriate to accept the Lucas pulley, everybody (particularly rebuilders)would know about it. I have never tried it, I'm sure it can be done but it won't be 'no problem'.

What would be is to install the correct alternator: PRS rebuilt units are great, releatively cheap and, as of about a year ago, still covered by a lifetime warranty. Justkeep in mind that the dash voltmeter is not accurate enough to trustfor much, they almost always read 1v low.

 

Thanks jagtech,
That is exactly what happened to my fuses two in row. The solder melts right out and even melted the fuse holder.I fixed it by using a two fuse fuse holder and using 2 25amp fuses linked together. Havent had a problem since.

Iknow about the voltmeter on the dash and as far as a correct alernator I have a new rebuilt autolite that came has a bad voltage regulator. I am just worried that I may have burnt out the Voltage regulator by drawing too many amps hence the reason for a more powerful alternator. If this doesnt sound like the case then maybe I can just order a new alternator and be done with it.
THANKS FOR THE HELP

 

No problem, you're already on the case. Splitting the feeds is what Jag eventually did. If you wired yours that way, maybe put an ammeter on each one and see if one motor is excessive? Sure sounds like it.

I'm pondering your point about the possible effect on the voltage regulator, I don't know if it's valid or not. Think about it this way: when you jump one of these cars with a toasted battery, the alternator can handle the load without pukingwhile it is powering everything at max output. I don't know where the weakest link is, but the alternator is pretty stout. I have seen a few that cooked the early style spade connectors on the alternator terminals, that's about all I can add. Unless it's because of your billion megakickin' power amp?

 

I am pretty sure one of the motors at least is overdrawing. It gets pretty cold here in WI and that is when I started having problems. I think possible some moisture got in tot he fan motor then iced up, causing the motor to work a little harder that usual which made it draw more amps that normal as well. Possible any way, a stretch but possible. Could just be an old *** motor starting to break down. I will look in to it sooner or later.

As far as accessories in the car they do draw about an additional 10-15 amps. And of course with head lights on and everything else, I am a little concerned. I would like to just go with a heavier duty alternator anyway to stay on the safe side. Most cars only come with a 75amp alt, but cars with a lot of electronic accessories usually require something more.
I talked to an Ebay vender that is actually an alternator repair shop and he said an alternator from an 88 XJS should work fine. I just wanted a second opinion so that I dont get stuck in the middle of a repair job.

 

OK just reporting back.
Just got done swapping out my alternator.
I had a stock Lucas alternator but wanted a little more juice.
I decided to try and use a BOSCH 115amp alternator from a later model xjs (88). IT WORKED GREAT. Mounted perfectly, pulleys swapped over fine. Everything seems to be a go right now. I can no longer see a reason to install an alternatorconversion kit from john cars, the alternator he recommends costs more than the one I bought (ebay but a very good seller) and the BOSCH is capable of 20 additional amps than the 94 amps GM model.
Anyway,
Thanks for the help...
Andrew

 

Cool, good job ! Good to know that the pulley swaps over with no problem

Cheers
DD

 

That's great, thanks for the lesson! I would have thought for sure a direct interchange would be common knowledge, there's no reason not to uprate the output if you're changing out a bad unit.

Are you certain that the belt alignment is good? In cases like this I'd lay a straight edge in the pulley grooves to make sure everything looked square up. But if the belt looks to you like it's tracking OK, I'd say you built a better mouse trap. Thanks again for reporting back withyour solution.

 

Greetings,

The self-proclaimed poobah of XJS on another forum has recently posted that the Bosch alternator will not fit the Lucas mount for this alternator.

Your post says that you interchanged these alternators with no other modifications or problems.

I'm not playing "pick a winner" here, I'm trying to avoid having a customer's car stuck on my lift while I scramble to find something that fits on his car. Do you have any other information to provide? Thanks in advance.