Guys
(This post relates to all Jaguar V12 engines fitted with the GM400 gearbox)

A few days ago the old car's starter motor quit. Happily at the house rather than miles from home, proof, if proof were needed, of the existence of a God!

The starter was last renewed in about 2000 (when it failed in an underground car park in the middle of London!) and the OEM modified starter with the external solenoid on the top, was fitted in place of the huge original.

I have purchased a more modern 'gear reduction' starter (which everyone recommends as being better) made by PowerLite, to replace the non functioning one. So the question was, how to remove the starter motor? This being a known pain to do, as the top starter bolt is notoriously hard to get a socket on.

I am lucky enough to have a lift, so up the car went. I knew from the relatively recent gearbox change that the starter fixing bolts are incorporated as part of the gearbox bellhousing-to-engine fixing bolts. I also knew the two fixing bolts are NOT the same:

Top starter bolt at the top; bottom starter bolt at the bottom of the photo


Out of focus close up of the top starter bolthead

As can be seen from the closeup above, the head of the top starter bolt is NOT a normal hex head, but a 12 point head. This type of head requires a 12 point (ie double-hex) socket to be used to undo it, the size required being 7/16ths A/F. That is, one of this type:

12 point (double hex) 7/16ths socket required on top starter bolt.
If you try any other type of socket you will ruin the 12 point head, and in that case an engine out and massively difficult drill-out or starter motor flange cut out is in your future!

WARNING: The special top bolt, Jaguar Part number BH506271 - Bolt is NLA. And none of the aftermarket suppliers have them. However, I have found out that ARP make a suitable bolt, 3/8ths x 16 thread (UK 3/8ths UNC) with 2 inches length below the flange. This bolt requires a normal 3/8ths 12 point socket socket but the socket size is is 3/8ths rather than 7/16ths. It is otherwise identical and will work perfectly, link here: Or this USA supplier has a 12 point bolt in the right dimnsions, using a 3/8ths 12 point socket:
https://boltsandnuts.com/products/3-...ws-black-oxide

Now, as in all matters pertaining to the V12 as installed in the XJS, access is the problem. Here is a shot of the side of the gearbox on its own showing the grooved location of the top starter bolt, and a shot of it installed in the car installed in the car:

The red ring shows the groove in the side of the bellhousing and the small hole through which the top bolt has to go to screw into the starter motor's threaded hole


This is a shot of the installation in the car. The red ring shows the top starter bolt hole, the bolt has been removed in this shot. NOTE to get even this amount of access, the gearbox has to be lowered as explained below. Note, if you do what I did, you will not have to remove the dipstick tube or any items other than those mentioned below.

This is what I did to get the starter out, having first disconnected the battery:

1. removed the exhaust pipes under the car, the ones between the downpipes and the over-axle pipes.
2. removed the heat shields
3. supported the gearbox under the gearbox sump with my transmission jack
   
4. Using the G in F four bolts method, removed the Y shaped exhaust bracket, AND the bracket that covers the propshaft UJ. Link here: https://www.jaguarforums.com/forum/x...itting-145478/
5. This now allowed the transmission jack to be lowered somewhat, just enough to be able to get enough access to get the socket onto the top starter bolt. I used a 21 inch long extension with a short wobble bar on the business end, onto which the 12 point 7/16ths socket was fitted.
   
   
   Without a wobble bar near the socket it seemed impossible to engage the socket on the top bolt. I have read that people have managed to undo this bolt without doing any removal of the gearbox mount or lowering the gearbox a touch. All I can say is that this was impossible on my car. More to the point, I cannot see how one could re-engage the bolt when fitting the new starter without better access.
6. Undoing the bottom bolt is easy, and then the starter can be removed, having disconnected the cables and solenoid activating wire connected to it.
7. The starter motor can be wriggled free once the bracket holding the transmission cooler pipes to the sump has been undone from the sump. Note that the old fashioned original huge starter would not be able to be removed without removing more items to give access. The gritty lane I live down explains the crud on the bracket!
   
8. The starter hole from the engine side
   
   

The old and new starter motors shown in these photos. Because the attachment points for the cables to the new starter are in different positions from the old one, I have been warned by that noted optimist BenKenobi that I may have to alter the cables to get them to fit. Time will tell.

Old motor at the top, new one at the bottom.

Closeup of new starter. It may be that the heatshield fitted to the engine above the starter has to be modified to clear the more bulky top part

Old starter closeup

Powerlite are the makers of the new gear reduction starter.

The next stage, once one or two tractor related items have been attended to, will be the trial fit the new starter and see what is required to hook it up. Stay tuned.

 

Great detailed write up.

 

And if that doesn't scare you nothing will 😊😊

 

I believe the bolt is the same for the 6.0 engine with the 4L80e transmission. When my starter failed, rather than replacing the 12 point bolt, I used an Allen hex socket bolt. That was easier to put on the end of a socket and get started.

I found that the oil and dirt that was on the 12 point bolt didn't allow a socket to seat properly so I partially stripped the bolt head trying to remove it. After removing the downpipe, I'd suggest a good cleaning before trying to remove the bolt to ensure the socket seats properly.

 

Same. I have some extras if anyone needs one.

 

Both those original bolts look like 3/8"-16 coarse thread, which surprises me as it seems every other bolt I have found on my car is fine thread. That 12 point head is typical aircraft fodder, but aircraft is all fine thread, so an easily obtained 3/8"-24 aircraft bolt wouldn't work.

Doug

 

I am not sure you can lower the rear of the trans on an H&E convertible conversion due to the body stiffeners added under the rear of the trans and drive shaft. FWIW. But you don't have that issue

Doug

 

It's typical Jaguar practice over the decades. Any thread into steel is fine thread, into aluminium is coarse.

There is a greater contact area on a fine thread, which makes it stronger in steel, but in aluminum the shear strength of the material governs, so the coarse pitch prevent the threads from pulling out.

 

Fantastic writeup, excellent photos and details....
Wow.

 

Refitting the new high-torque gear reduction starter motor:

Post 1 above finished with the old OEM post-1987 version of the V12 starter having been removed. Yesterday I bravely offered up the new version, which as you can see from the pics below is more bulky:


Old motor, above, is less tall that the new style


Powerlite is taller top to bottom and overall more awkwardly shaped than the original

The old motor could be wriggled out with just the sump to gearbox cooler lines bracket being undone. The new motor was a 100% PAIN to get back into the space. I tried to get it in but there was no possibility of so doing, gearbox cooler line attached to the gearbox. So I had to undo the gearbox cooler lines from the actual gerabox and pull them down out of the way (which later meant more pain see below).
Then I still struggled to get the starter in place. In the end it went in as follows:

• offer it up vertically, flange end upwards, to get the flange above the sump line and above the downpipe, flanges in a fore and aft orientation
• then swivel the flange end rearwards thus swinging the body of the starter up and forwards. It will just go in.
• the attached pdf diagram, run up for me by my friend Pablo Picasso gives you some idea.
• once in place it is best to do up the bottom bolt, which is easy to get to, while you fiddle about with th wiring etc.

NOTE:

1. I have no doubt that a modern gear reduction high torque starter motor is better than the original. BUT, it will be FAR easier to replace the original with an identical type, and if I knew then what I know now, I think I would have purchased the original type!
2. Warning: If you have a car with cats in the downpipe, I think (repeat think) it would be just about impossible to mount a high torque motor without removing the downpipe.
3. The connections on the Powerlite are not in the same position as on the original. Instead of being on the end, they are on the side. This does not present a problem for the firewall main cable as the new motor's connection is marginally closer. The alternator connection is marginally further away. If you have the OEM alternator cable this may need extending. I had replaced mine during my rebuild (2009 to 2011) with a single large cable and I had enough slack to fit it.
4. The solenoid trigger wire from the starter relay (white with red trace) has an eye on it OEM, and this is connected to the OEM starter with a small bolt with a slotted head. The Powerlite has a male Lucar connector, which requires a female Lucar connector to be fitted to the trigger cable. This I regard as a definite failure-in-waiting when the Lucar female connector on the trigger wire falls off the male on the starter owing to vibration etc etc. Herewith closeup of the male Lucar terminal on the starter and of the alternator and firewall cable post:
   
   The trigger wire is pushed onto this male terminal as shown here:
   
   The red arrow shows where the female Lucar terminal fitted to the relay trigger wire gets pushed onto the motor's male. The BLUE arrow shows where I fitted a tiny self tapper through a 2mm hole I drilled through the male and female connectors, to ensure it could not come free accidentally
   I then gunked up the hole so it was kept clean and dry, you can just see the gunk in this photo:
   
   Blue ring shows the connector area gunked up. Under this gunk there is a small self-tapper where the red dot is placed, which locks the Lucar connectors together, thus avoiding the push-on connector shaking loose.

Here it is all cables fitted:

Silver cable is from the firewall post, red cable from the alternator, small red wire with blue connector from the starter relay. The relay wire has been cable tied to the firewall cable to stop it flogging around as shown in the next photo


Heat shield:
OEM there is a decent heat shield fitted that helps protect the starter from the manifold and engine heat. It does not need modification to fit the high torque motor, at least on my car. The shield goes from the engine upwards and over the top if the motor, quite a distance above it, and is fixed on the main firewall/gearbox heat shield just outboard of the downpipe, pics from below here:

Top of the photo is the outside, bottom shows the arch of heatshield above the starter.

Better shot of the top of the heatshield arch

Engine side of the heatshield. The bottom edge is about level with the top of the bottom barrel of the starter.

Refitting the starter fixing bolts:
The bottom bolt is easy, 9/16th A/F. Fit it first and leave it just so the motor can be moved with a little effort. Assemble the extensions as shown here:

Wobble bar near the end

Minimum 21 inch extension

Take your 12 point 7/16ths socket:


and jam the special bolt in the end by using a bit of garage paper or tissue round the end of the bolthead. This will ensure that while you are persuading it into the hole and to start threading, the bolt does NOT fall out into some irretrievable place! Get it started and done up.

From this point on it is a matter of refitting the gearbox mounts, exhaust heat shields and the exhaust.

BUT in my case, and very likely yours, the gearbox cooler lines have to be refitted to the gearbox. The lower one went back fine, that is the easier one...
The top one, which is awkward as I was too lazy to remove the dipstaick tube, would NOT go back. What to do?
Many years ago I was teased by the late lamented Orangeblossom for buying a flare tool as I only needed two flares, making them cost about 75 UKP each. This was to make my own rack pipes, as those now sold, at least those I bought, were absolute RUBBISH. Into the garage corner to unearth the plastic box labelled flare tools.

I cut the top gearbox pipe, made up an 10 inch length of 5/16ths cunifer pipe and used one of the lovely brass flarenuts also in the box. I tried the nut first, which thankfully confirmed the female in the gearbox threads were fine. A nice 5/16ths SAE double flare later (having re-read the instructions as I had completely forgotten how!) and a length of OEM cooler flexible, and all is well:



Talking on the Franco/Oz hotline to the Great XJS Prophet (turn to the Southern Cross and bow) I made sure as instructed to fit double clips. Here they are, Grant!!


Double clips and loctited!

 

Wonderful thread, Greg! Great ingenuity and resilience!

I so hope that I never have to change a V12 starter motor!

Paul

 

Impressive feat Greg!

Replacing the starter is the last time I have paid someone else to work on the XJS, and frankly I was glad to do it because of how difficult a task it is. The guy who did it (sadly now retired) said he had a special trick for doing it that makes it easier but he wasn't forthcoming on what his trick might be.

I can't imagine getting a starter that is actually larger than the original into that space, but well done. The Bosch gear reduction starter I bought was actually smaller than the original Marelli starter from the factory, but I'm not sure if it is still available or not.

 

Final assembly and test:

Today I refitted the gearbox mount, so for the sake of having all this in one thread, below in words and pictures the way I do it using four threaded rods.

The first step when refitting the gearbox mount is to push the gearbox upwards into the correct pisition it would be in were the mount to be fitted. I use a transmission jack for this purpose, but an ordinary jack plus a length of 4x4 wood, if the car is high off the ground, will do the job.
Then the "half moon" plate has to be attached first. This is shown on the left in this rather unclear photo, the curved "half moon" part is shakily picked out by the red line; the blue circles show where the hard to fit tunnel bolts go. This bracket is there to ensure the propshaft, in the event of a U joint failure, does not drop and pole vault the car.


This bracket has 8 bolts to secure it, three on the flat each side, and one each side up in the tunnel fitting horizontally. You need a 1/2 A/F ratchet spanner to tighten them:

Tunnel bolt on half moon bracket

Ratchet spanner to tighten

1/2 A/F ratchet spanner


Half moon bracket in place.

Next up the Y bracket containing the gearbox support spring. This shot shows the GiF four rods method of fitting it. The front two rods are 5/16ths UNF fine thread and the rear two are 3/8ths. Why they are not all 3/8ths is one of the many mysteries of Jaguar production!


Y bracket plus spring and sponge damper


Offered up and held in place by the four rods, the rods are screwed into the threaded captives on the body. You screw up the nuts on the rods to push the bracket up into position.

Ensure the gearbox support rod is central in the bracket

Before final tightening, knock the bracket about with a hide hammer to centralise it on the gearbox rod

One at a time the rods are removed and replaced by the fixing bolts. Do not forget the spacers at the rear where the Y bracket bolts up to the half moon bracket.

Then the final part of the gearbox assembly: the bottom "tongue-shaped" piece:


The tongue shaped piece, note hump UPWARDS, at the bottom. Then the special washer (mine being a beautifully made stainless piece run up by Louis the Lathe King) yours being the low rent Jaguar two-welded-washers version!. This is indented to allow the tubular spacer, next item up, to sit in the indent. On top is another special washer which is rounded on its edge. This MUST be in top of the tubular spacer (the Jaguar diagram which shows it below the tubular spacer is WRONG).

All in place and the front nuts on the tongue also fitted and tightended.



If all is correct, you should be able to push the gearbox tail up and down an inch or do on its spring.

So now the gearbox is supported, I lowered the car (before fitting the heat shields and exhaust) to test if the starter worked. I disabled the ignition feed to the coil and gave it a go. IT WORKED!!

 

I have just tested the car after fitting the exhaust, which is always a total pain. Someday I am going to fit under-axle pipes!

The Powerlite High Torque gear reduction starter motor is FANTASTIC. You only have to look at the key and whoomp, off she starts!
As long as you can stand the fitting, a great improvement on the traditional starter.

So thanks to Jack at Manners for advising me to buy one - the pain was worth it.

 

Great write-up Greg, and so pleased that it was worth all your effort. Should be pasted as a sticky, imo!

Paul

 

I put under axle pipes on a few months ago. 2.5" all the way back. Since they are tight mounted to the differential plate, i put some expandable bellows in , in front of the first set of mufflers. I calc'd that the pipes would expend a maximum of about 3/16" in length from engine to axle, during high heat conditions.

Pardon the ugly welding, I need to get under there and spray it with aluminum color paint. I didn't give up much ground clearance, I could have gotten another 1/2" clearance at the rear of the under axle section, but I was working with purchased pieces, and had no access to a tube bender. I am not going four wheeling off road, anyway.

Doug





Doug

 

Doug,
No urgency, but could you post a few closeups of the way the exhaust is attached to the car, before and on the cage please?

 

I will get a close up when it up on the lift next week.

I also added a couple commercial rubber isolated hangers AFTER the differential, inside the rear of the rear wheel wells in front of the rear mufflers.

The attach to the differential protection plate is via some modifications i made to the two U-bolts clamps.

I welded a horizontal plate about 1" wide, 1/8" thick and 1.5" long to the top of "saddle" of the u-bolts. That plate extends onto the front shelf of the protector plate and allows the exhaust pipe on the bottom, and the added extender plate to clamp the pipe tight to the protector plate when the u-bolt nuts are tightened. No drilling or nut removal on the protector plate was required.

I tought about using the two lower forward bolts of the protector plate as a an attachment if necessary but decided not to,as the clamp type arrangement worked out fine

There is no other exh attachment to the car forward of that, just the exhaust manifolds.

Doug

 

Tanks Doug, pics of all that please!

 

Sorry for the delay in catching up - we've had a crazy month. But I have just added this great thread to the Stickies. Thank you, Greg, for the great photodocumentation and taking the time to share this great information with the forum!

Cheers,

Don