TR4/4A TR4 Alternator/Generator

[KVH]

I just returned from a long trip in my TR. It was great, but after my auxilliary cooling fan came on for about 45 minutes on an uphill incline, I believe I noticed a weak battery on start up.

Does a cooling fan deprive the ability of the generator to recharge the battery?

Is that why some people convert to an alternator? Is that complex, inadvisable undertaking? I do like the "stock" look.

As always, thx in advance for all the good help on this Great Board.

 

[Keoke]

You must have been going up Yarnell Hill.Yes a cooling fan can deprive the ability of the generator to charge the battery,which justifies conversion to an alternator.---Keoke

 

[Alan_Myers]

Hi,

Most of those cooling fans put a pretty heavy load on the electrical system. Many use over 10 amps. Some of the larger sizes (16" and up) can use 15 or more amps.

Your stock generator puts out 22 amps, at best. Plus, a generator does not produce very much power at lower rpms, not nearly as strongly as an alternator.

So, probably half the output is now going to the cooling fan and, yes,- if the generator is sub-par, electrical connections are less than ideal, or you are using any other electrical devices on the car, it's quite possible the fan will gradually draw down the battery. The engine, itself, will use some power, too. Add it all up, subtract any weakness in the system and it's marginal if the generator output will be adequate for use with a cooling fan.

I ended up installing an alternator. In addition to a 14" cooling fan, I've got halogen headlights, halogen running lights and an electric fuel pump to be concerned about (but no radio, no heater/fan).

An alternator will not look stock, It's not a straight swap, and most common sizes are about the same weight as the original generator. However, consider that there were special order TR4 with alternators (police specials! just imagine!), and I'd bet the factory racing TRs were mostly fitted with alternators, especially the rally and Lemans cars with all the auxiliary light!

I installed a Delco 7127-3. It's rated at 60 amps, but the one I got has tested to 76 amps. It's a rebuilt unit and cost $50-60 (without a core to exhange). Also, a two wire "pigtail" was needed to make connections to the wiring harness. That's still not done (actually, the entire car has no harness in it, at present).

The Delco 7127-3 is one of the most common and easily installed alternators.

First, remove the front generator mounting spacer and replaced it with approx. 6" long 3/8" bolt. Over that, a approx. 4" long tubular spacer needs to be fitted to go between the front and rear "ears" of the original generator bracket. This provides a solid mounting point for the bottom/front bracket on the alternator and, at the rear/bottom of the alternator, a tab can be welded onto the 4" spacer to accomodate the mounting bolt.

On the top/front the original generator upper/adjusting bracket can be used, but needs to be straightened to align properly (fits behind the mounting lug on the alternator, alternatively, bend the bracket more and fit it in front of the mounting lug). The bottom side of the adjusting/top mount bracket needed a little bit of filing to keep it from rubbing against the case of the alternator. Also, at the bottom/front, about 3/8" of the cast mounting lug was removed from the backside, to move the alternator back so the pulleys alighn properly.

This particular Delco has an internal regulator, so the external one now on your car isn't needed, but might be retained and disabled, used as a connecting point, to maintain a stock appearance.

Another thing needed is either a heavier wire run to the starter solenoid (to handle the higher current output) or a second wire that runs parallel to the original and increases the circuit's load capacity.

You will need to convert the car to negative ground, also (primarily just a matter of swapping the battery leads and swapping the wires on the back of the Amp meter, behind the dash).

Another consideration is the pulley on the alternator. It will come with a narrow pulley that won't work with the original, wide belt. There are wide, conversion pulleys around, occasionally on eBay. That is, if you want to keep the wide belt for original appearance. (I swapped to narrow pulleys and a harmonic dampener at the crankshaft pulley. That's an alternative.)

All this sounds like alot, but it really isn't bad.

You could do the changes in stages. Such as converting the car to negative ground first, then adding the alternator later.

Hope this helps!

Cheers!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[KVH]

Thx for the info. My car is already a negative ground, but the rest sounds like a good possibility if overheating keeps kicking on the auxilliary fan. I'm going to read up on it all, and check the battery power as I go. I appreciate the good information and technical advice.

 

[vettedog72]

I did not realize TR4's had a generator but an alternator has an advantage and a disadvantage. The advantage is much more power out put (charging ability and assory power ability) and less brush wear. The disadvantage is that it will not allow the car a push start when the batt is flat.

If you are going to convert, Pep Boys have Bosch alternators on sale today for as low as $12.00.

 

[Kurtis]

I have an electric fan on my TR4 with a generator. In fact, it's the only fan I have on the car (since the original fan has been removed). If my ammeter is to be believed, my fan pulls less than 5 amps when running, and my generator has never had any problems keeping the battery charged.

 

[MDCanaday]

My experience is like Kurt's , the stock gen is OK for this load as long as its in good shape. I think that the poor old Lucas lup is too much malinged, as long as its properly maintained it does a good job given the designs age.....
Any modern alt will out perform it but you got to want it, cause you probably dont really need it.
MD(mad dog)

 

[Alan_Myers]

[ QUOTE ]
The disadvantage is that it will not allow the car a push start when the batt is flat.

[/ QUOTE ]

Since when? I've never heard that before and I've push started many alternator equipped cars with no problem whatsoever.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[Geo Hahn]

[ QUOTE ]
I have an electric fan on my TR4 with a generator... my fan pulls less than 5 amps when running...

[/ QUOTE ]

Me too. Easy to measure the draw of the fan with an ammeter (or amp setting on the multimeter). I measured it and all accessories on the TRs just to see what sort of load I could get.

If I drove in the rain with the headlights on and the fan on while listening to the radio then the turn signal would put me over the top... but realistically I saw no problem with the fan & dynamo combination.

If you are adding other stuff (driving lights, stereo with big amp) and/or doing a lot of night driving then I think an alternator may be needed.

 

[vettedog72]

Alan:
Since from the beginning of time alternators were release, they do not produce pwr with out an external electrical excitation. You have to have some juice for an alternator to work; they do not have any residual magnatism like a generator has. Alternators need a little priming voltage, some as much as 6 or 8 volts in some cases. You are lucky not to have had a flat batt.

 

[vettedog72]

Kentvillehound:
Just curious about what you decided to do? I'm looking at a 16" fan that will blow 3300 CFM for a big block checy and it pulls about 20 amps continious and about 30 amps to start it. The little fan on my TR6 is a dealer add on when the A/C was installed (before the car was originally deliver to the owner). I wanted to measure the draw but the fan is not operational. I hope it only needs a clean out and relub the bushings.

 

[Dave Russell]

[ QUOTE ]
Alan:
Since from the beginning of time alternators were release, they do not produce pwr with out an external electrical excitation. You have to have some juice for an alternator to work; they do not have any residual magnatism like a generator has. Alternators need a little priming voltage, some as much as 6 or 8 volts in some cases. You are lucky not to have had a flat batt.

[/ QUOTE ]
I agree with Alan. Many alternators have enough residual magnetism to self excite if reved a bit, maybe 1500 engine rpm. Maybe not all alternators will do this, but most will. I believe that Bosch is one of the exceptions.
D

 

[Bob_Muzio]

I installed a Delco alternator and it's a vast improvement. I can, if needed, power the electric fan, am-fm cd player, halogen sealed beams, halogen driving lights, halogen tail lights, etc. without a concern.
If you do switch to an alternator I'd suggest replacing the amp gauge with a volt gauge. They are available and other than a slightly different bezel, match the other gauges quite nicely.
Bob

 

[PeterK]

The Delco "SI" models (7127 is a 12SI) will self excite at low rpms and are frequently used when converting from a generator on tractors.

 

[prb51]

My TR3 generator has no problem with my electric fan and I live at the bottom of Yarnell hill in Wickenburg. Must have a generator problem.
Still, an alternator is an improvement.

 

[martx-5]

[ QUOTE ]
The Delco "SI" models (7127 is a 12SI) will self excite at low rpms and are frequently used when converting from a generator on tractors.

[/ QUOTE ]

Actually, the 7127 is a 10SI. The 12SI (7292 I believe) is a higher amp version of the 10SI. It's dimensions are the same, but there are internal differences. They are easily recognized by the plastic turbo type fan that supplies more cooling air.

In order for a 10 or 12SI to self excite, a self exciting regulator must be installed in place of the standard regulator. Most remanufacturers add an "SE" suffix to the part number to indicate a self-exciting unit. These "one wire" units can be used, but they will not start charging until the engine revs to about 1200 rpm. Another disadvantage is that if the unit sits for a long period of time, the rotor will lose some or all of it's residual magnetism, and no amount of revving will get it going. In that case, the rotor will have to be grounded momentarily through the "D" shaped access hole at the back of the alternator while it's running. On the TR, that might be a real PITA.

 

[PeterK]

I stand corrected; you obviously know more about this than I do. Thanks for the info.

 

[martx-5]

PeterK,

I work for a large electrical remanufacturer as plant engineer, so I get exposed to all this stuff.

Anyway, from your signature, I see you have HVDA after your cars. I imagine that means that you've done Herman's conversion, I just got a Toyota trans, and just ordered the conversion kit. Did you have much difficulty with the TR6 pressure plate mounting to the TR3/TR4 flywheel?? And, how much pedal travel is lost with the hydralic throw out bearing??

 

[PeterK]

I probably should start another thread on HVDA but I still need to take a couple of pics of the 3A with the HVDA installed.

I replaced the TR3 flywheel with one from a 4A so I didn't need to redrill to fit the TR6 B&B clutch cover. The 3A has a much lighter flywheel than the 4A but I doubt I'll be able to tell much. I did need to change out the bull nose starter for a later one though.

The 3A is still on the lift in my shop from the conversion so I haven't driven it yet. Pedal travel with the hydraulic T/O is about the same as before but you have to fabricate a stop to prevent from pushing the new T/O o-rings too hard and damaging them. Hermans manual suggests 1/2" free pedal AFTER the clutch is disengaged, before the stop.

As far as the hydraulics, Herman supplies a AN3 to AN3 adapter that connects the AN3 T/O hose to the MtoF inverted flare adapter on the TR. I didn't like the idea of mating the AN3 37 degree fitting to the 42 degree I.F. fitting without conversion for a proper seal. To fix this, and eliminate the extra fitting from Herman, I purchased an AN3 MtoM bulkhead fitting from Pegasus. This replaces the TR adapter between the TR MC hard line and the TR slave hose. Then, Pegasus sells a 69 cent copper crush tip that snaps on the end of end of the male AN3 to adapt it to the inverted flare coming down from the MC. Works slick and doesn't leak.

I also had issue with the new speedo cable having too sharp of a bend radius and sitting too close to the exhaust pipe. So I found a Toyota adapter that is near right angle and puts the cable more out of the way (better but not perfect.)

If you need any help or pictures, I've btdt so just ask.

 

[martx-5]

Thanks for all the info Peter. I like the idea of using a TR4A flywheel. It would save me the hassle of machining the TR3 one. I'd have to go into work on a Saturday to do that job. /ubbthreads/images/graemlins/nopity.gif

Thanks again... /ubbthreads/images/graemlins/cheers.gif