The Lotus Grand Tourers

Hi,

I am looking for a workshop manual for my 1985 Excel. I guess it's not part of the parts manual... Does anyone know where I can get one ?

What I need at least is a camshaft belt schematic (with pulley timing marks). I found one on Lotusespritworld.com : http://www.lotusespritworld.com/EGuides ... belts.html

...but it does not look complete (I am not an expert...) and I am not sur it fits with my Excel's 912 engine.

Many thanks in advance for your tips !!
Bruno

For some reason Lotus called it "service notes" rather than a workshop manual.

You can buy then here http://www.thelotuscentreonline.co.uk/e ... A089T0327J

Carl

Bruno,
What is the engine's current status? Operational, and you're just contemplating a timing belt replacement? Or the engine is apart, and you're trying to get it together? Have you ever replaced a timing belt on any engine before?

The timing belt & pulley schematic on LotusEspritWorld is 9XX-generic, and is from the many Lotus manuals. It's as correct for your Excel's 912 engine as it is for any Lotus 9XX. It does not include the specifics of any one engine... like the 912LC or 912HC.

Both Excel engines, LC & HC, use 104 MOP cam pulleys. On the forward facing rim of the cam pulleys, there should be round dimple timing dots filled with green paint. On the Front face of the intake pulley, the green dot will be adjacent to a nearby "IN" mark cast into the pulley spoke area. Similarly, the exhaust pulley's green dot should be adjacent to a nearby "EX" mark cast into the spoke area.

For each green dot on the front side of the pulleys, if you follow the tooth it's on to the back side, you'll find a second green dot on that same tooth. If the front dot is near an "IN" mark, then the rear dot will be near an "EX" mark... and vice versa.

If the green dot on the front of the Intake cam pulley is next to an "EX" mark, then that pulley is on backwards. It must be removed, flipped over front-to-back, and re-installed. You cannot begin to time the cams until both pulleys are correctly installed...
Green dot next to an "IN" mark facing forward on the INtake cam.
Green dot next to an "EX" mark facing forward on the EXhaust cam.

Rotate the crank clockwise to Top Dead Center (TDC). If the green timing dots are on far opposite sides of the cam pulleys, then rotate the crank CW through one more full revolution and back to TDC. The dots should now be adjacent to one another, and on the imaginary centerline between the two cams. If the dots are aligned, but above or below the centerline, then the cams are not correctly timed. The dots must be BOTH aligned with one another, AND on the centerline between the cams.

*~*~*~*
The Auxiliary Pulley drives both the oil pump and distributor. In order to get the distributor timing right (at least by the Lotus book), the Aux Pulley must also be set correctly on the timing belt. For that, there's another dot on the rim in addition to the cam timing green dot. It must be toward the bottom of the Aux Pulley rim, and on the imaginary centerline between the Aux Pulley and the Crankshaft. That is also illustrated on the LotusEspritWorld schematic.

However, the distributor's function doesn't really care how the Aux pulley is set. The Aux pulley rotates the distributor's shaft, and the rotor on the end of the shaft. But no matter where the rotor ends up, the distributor body can be unclamped and rotated into alignment with the rotor. The "Distributor Function" itself doesn't care where the Aux pulley is.

The only problem is that in some positions, the spring clips that retain the distributor cap may face the cylinder block, and become very difficult to snap or unsnap. Also, in some markets, the distributor uses vacuum advance. In that case, the big vacuum capsule on the outside of the distributor can interfere with the bottom of the carbs, intake manifold, cylinder block and oil filter. There's just a narrow sweet spot between the oil filter and the carbs where the vac capsule will fit. If you align the Aux pulley timing dot as shown in the schematic, everything fits without interference.

The belt & pulley schematic is a generic, one size fits all drawing, and was used in all Lotus 9XX 4-cyl engine manuals. Depending on the MOP of the pulleys used, the end result can put the vacuum capsule so close to the oil filter that you can't get your hands in there to get a good grip on the filter when you need to replace it. In that case, I prefer to rotate the Aux pulley a couple of teeth clockwise (as viewed from the front), moving the vacuum capsule as close to the carbs as possible short of causing an interference there. That gives the best working room around the oil filter. It's a judgement call, and you can work it to your best advantage. Or, you can simply set the Aux pulley timing dot on the centerline between the Aux pulley and crankshaft, and call it good. That will work, and you just have to live with the details you could have improved upon, but didn't.

If your distributor doesn't have a vacuum capsule sticking out of it's side, then rejoice... you have great latitude in how you time the Aux pulley. Or, it wouldn't kill you to simply align the dot as shown in the schematic.

Regards,
Tim Engel

Thanks so much Tim and Carl for your swift and comprehensive replies !!

The Excel and its engine are 100% operational. I bought the car about 2 years ago. It was an opportunity : no more than a few have be imported to France. It was in pretty good shape, just needing basic mechanical works and a good overhaul as it did not run often (+ some body work still to be done).

Tim, I am going to try and translate your message and hand it over to my mechanic. I would like do it by myself but I have not enough time ...and above all I fear I could do it the wrong way despite your accurate tips

I will also consider investing in the so called "Service note" for further uses !

Kind regards
Bruno

Bonjour Bruno,

I have the service notes and can confirm the description is very much the same as for the Esprit. The only thing missing is description of the automatic tensioner on some earlier cars (Excel as well as Esprit). This needs to be locked in position when removing the belt.

I can understand you don't have the time to do it yourself, but make sure your mechanic WILL take all the time necessary, preferably without overcharging you. It's all quite easy and clear, but you don't want to rush it, especially first timer around. I'd feel more confident doing it myself, the advice over here and on TLF tells you everything you need to need, including some tricks you wont find in a manual .

Greetz,

Filip

Thank you Filip. I am quite confident in my Mechanic (an old fashion one...) but you can be sure I will double check that he follows the precious recommandations and warnings I got here
Amicalement
Bruno

907/ 910/ 912 Spring Loaded, Semi-Automatic Timing Belt Tensioner
REMOVAL and REPAIR

Removing the Spring-Loaded Tensioner:
Disconnect the battery and remove the alternator in order to gain top-side access to the tensioner.

The semi-automatic, spring-loaded tensioner’s plunger must be retracted and pinned prior to removing the timing belt.

To facilitate inserting the locking pin, first slack off the belt tension by backing-out the tension adjusting screw until there is approximately 12mm of exposed thread (ie, per Lotus Technical Service Bulletin 1973/1 and subsequent printed Workshop Manuals). Ignore the jam nut, and measure the exposed thread from the end of the housing. Don’t screw it out too far or the threads will disengage and the internal springs will shoot themselves and the adjuster screw across the room. Do not have your head down in the line of fire.

There were two types of adjuster screws used...

1) Adjuster screw with a flat outer end and a screwdriver slot:
The 12mm exposed screw measurement is measured overall, tensioner housing to the end of the screw, ignoring the jam nut. The screw is 26mm (1.024") long with an M18-1.25 thread.

2) Adjuster screw with a raised, smaller hex head on the outer end:
The 12mm exposed screw measurement does NOT include the hex head. Measure only the threaded, cylindrical body, ignoring the jam nut and hex head. IMHO, if you have to order a new adjuster nut, and have a choice, buy the one with the hex head drive. It’s much easier to use.

• In order to release even more belt tension to make inserting the locking pin even easier, I turn the adjuster screw out a little further than Lotus suggests. Of course, going too far and having it pop out will only add to your work load, so use the following info at your own discretion.

• The screw with the flat, slotted end is 26mm (1.024") long. Screwing it out to 12mm of exposure per the book leaves 14mm still engaged. With a 1.25 thread pitch, that means there are 9.6 threads/ turns of engagement. That’s a lot.

• In order ease installing the locking pin even more, I routinely turn the adjuster screw out until 19mm (3/4”) of thread is exposed beyond the tensioner housing. That leaves 7mm (.276") or 5.6 threads (turns) of engagement. That’s more than enough.

• Note that turning the screw out beyond 12mm only makes it easier to insert the locking pin into the tensioner. It provides no additional belt slack to make removing or installing the timing belt any easier. This step is only about making it easier to install the locking pin.

There’s a 4mm (5/32”) hole in the front side of the tensioner through which the locking pin is to be inserted in order to engage a groove cut around the piston, locking the piston in place. The hole’s location changed through the model years. It may be above or below the piston bore, it may be exposed and to the right of the lower mounting bolt, or it may be hidden under the upper mounting bolt’s washer.

If you need to remove one mounting bolt to gain access to the pin hole, then first give the other bolt a good twist of torque to ensure that it’s tight enough to hold the tensioner firmly in position. Remove the bolt and washer that is hiding the locking pin hole. Start a 4mm (5/32”) pin in the hole (I use a drill bit shank), wiggling it while pushing it inward. Make certain the pin goes all the way into the hole and bottoms out. It needs full engagement with the plastic plunger.

A loose fitting pin is easier to install, but DO NOT go there. The groove around the plunger is shallow. If you use a slightly small pin, the engagement will be less positive, and the plunger can squeeze by in time (it's plastic, and can distort over time). Once it gets past the pin, you're job just got a whole lot more difficult. Use the largest, tightest fitting locking pin you can install with finger pressure. Do not hammer it in.

Place one hand on the timing belt mid-way between the intake and auxiliary pulley and push down firmly. The additional pressure on the belt will retract the tensioner’s piston into the bore. Vary hand pressure as required to align the piston’s groove with the hole, then the locking pin should slide in… with some effort and wiggling. Make certain the pin is fully engaged (bottomed-out in the hole), then release the hand pressure on the timing belt.

With the timing belt now fully slack, slide it forward off the two cam pulleys, the auxiliary pulley, the tensioner roller, and the crankshaft sprocket. Then remove the one remaining mounting screw from the tensioner, and remove the tensioner from the engine.

NOTE: The plunger/ piston is plastic, and it can ‘creep’ (ie, cold deformation under pressure) to get past the locking pin. A close-fitting pin will hold for a while, but not forever… it’s not permanent. If you wish to set the tensioner aside for an extended time, or if you’re going to start the rebuild right away, then remove the pin and ‘dis-arm’ the tensioner now.

Slip the tip of a large flat blade screw driver, or a “Wonder Bar” style pry bar into the gap next to the hinge pin, between the tensioner bearing and the housing/ fork that holds it. Then use the leverage to fold the tensioner, pushing inward on the plunger to relieve the pressure on the locking pin so it can be withdrawn. With the pin out, carefully allow the tensioner to unfold fully. The plunger will pop out of the end of it’s bore, but will bind against the bearing/ roller and not shoot across the room.

Hold a wad of rags around the adjuster screw and unscrew it fully from the housing. The remaining bit of spring pressure will still shoot it out, but with far less energy that before the piston was released. The wad of rags will catch it.

Rebuild the Spring-Loaded Tensioner:
The tensioner bearing fits between front & rear yokes. Bosses cast into the inward faces of the yokes slip into the bearing’s bore. The assembly is secured by two bolts & nuts. One through the yoke’s bosses and the bearing’s bore, and the other through bottom corner flanges on the yokes. Remove the bolts & nuts and separate the yokes in order to free the bearing/ roller. Simply install a new bearing and bolt it back together, except…

Separating the yoke halves also slides them off the hinge pin, making this a very good time to replace the plastic bushings in the hinge. DO NOT get lazy and skip replacing the inexpensive little bushings every time you replace the tensioner bearing/ roller.

Early spring-loaded tensioners’ hinge had a steel pin that ran directly in bores in the aluminum housing/ yokes. That had a history of unreliability. Later tensioners were fitted with replaceable plastic bushings in the bore. Replace the bushings whenever wear becomes apparent during inspection, or whenever the tensioner is disassembled to replace the ball bearing/ roller.

It’s not necessary to remove the hinge pin just to replace the bearing or hinge bushings (just separate the bearing yoke halves). But if the hinge pin ever needs to be replaced, note that it is locked in place by a tiny roll pin. About half way along the hinge’s width you will find a small cross-drilled hole in the housing. A small roll-pin is driven through both the housing and the hinge pin. Drive the small roll pin out, then drive out the larger hinge pin.

Don't just press the new bushings into the bores. They’re soft plastic and can cock a bit in the bore, yet still go in. And once they're cocked, it may be difficult to get them to slip onto the hinge pin. Instead, start the bushings just enough to hold them, slide them onto the hinge pin, then use a vice to squeeze it all together at once.

The TENSIONER BEARING is a double wide, purpose-built, timing belt tensioner roller & bearing assembly. The same bearing is used on all “Lotus” 900-Series 4-Cylinder engines with either eccentric or spring-loaded tensioners. Early Jensen-Healey 907 eccentric tensioners used different bearings.

1.2205” (31mm) = Inside Diameter
2.4803” (63mm) = Outside Diameter
1.1811” (30mm) = Thickness / Width

Part No. ...... Source .... Comments
414871A ...... SKF ........ Excellent quality, strongly recommended.
FS03299 ...... Flennor ... Sold by JAE (2016-onward).
1500004 ...... Ford ....... 1977-86 Ford Transit Van (hard to find in North America)
VKM 14300 ... SKF ........ ?? In general, SKF is a quality brand.
531 0098 20.. INA ........ ?? In general, INA is a quality brand.
TKR 9841 .... Timken .... ?? Timken production is in China.

The plastic bushings electrically insulate the tensioner roller and it's hinged yoke arm from the engine, and the rubber belt rolling/rubbing on the steel roller acts like a Van de Graaf generator. It can generate a spark that will cause pitting of the bearing’s race and balls. There's a short ground wire that bridges across the hinge joint... don't forget to re-install it.

Tension the Timing Belt:
Only on a cold engine normalized to 15° - 25° C (59° - 77° F) ambient temp for 8 hours.
Rotate the crank a minimum of one turn clockwise, stopping with #1 Cylinder at TDC.
Check/ set timing belt tension midway between aux & inlet cam pulleys - no where else !

For BLACK OEM & aftermarket timing belts, both trapezoidal and HTD....
Burroughs = Krikit KR-1 ranges (my judgement, not Lotus approved – tim engel).
....... <82 = 45 Park it... drive it at your own risk.
........ 90 = 50 Normal minimum tension.
........ 95 = 52 For re-tensioning a USED belt.
... 97-100 = 53-55 For installation of NEW belts, in order to allow for initial stretch.
..... >105 = 58 Too tight.

The Krikit KR-1 has two scales. ALWAYS read the Krikit’s POUNDS scale.

If you use the Gates Racing BLUE timing belt, either HTD or Trapezoidal tooth, then all the above tension specs DO NOT apply. There is no factory support for the Blue belts, not from Lotus, and not from Gates. So strictly from user experience, the appropriate BLUE BELT tensions seem to be:

Burroughs = Krikit KR-1 --- Gates Racing BLUE, HTD & Trapezoidal
..... 83-85 = 34-35 NEW Blue belts, to allow for initial stretch.

One of the Gates Racing blue belts' advantages is that they're very stable with regards to tension. Once set, you'll rarely have to re-tension a blue belt while it's in service.

Regards,
Tim Engel