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Topic of the Month: John’s philosophy on questions. February 2009
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John’s philosophy on questions. February 2009
Gang – Hi again! I am going to get a bit philosophical this month instead of technical. We get a lot of questions on British transmissions, overdrives and differentials – and a lot of other things as well! Don’t get us wrong, we welcome your questions and appreciate your calls and your trust in our answers. But most people start their statement with “This is probably a stupid question, but….”
Let me say this about questions – Don’t be afraid to ask them! Here are some famous quotes on questions.
- The only stupid question is the one not asked. From my main man Confucius!
Question everything. Learn something. Euripides
- Answering what seems to be a stupid question is a lot easier than fixing the stupid mistake that will inevitably be made by not asking it. – me!
- A wise man can learn more from a stupid question than a fool can learn from a wise answer. – again my main man Confucius!
- Not asking the question is asking for trouble. – me!
- Each question asked generates at least two new questions! – me!
- We learn more by looking for the answer to a question and not finding it than we do from learning the answer itself. Lloyd Alexander
- The power to question is the basis of all human progress. Indira Gandhi
- It is not the answer that enlightens, but the question. Eugene Ionesco
- The key to wisdom is this - constant and frequent questioning, for by doubting we are led to question and by questioning we arrive at the truth. Peter Abelard
- To really ask is to open the door to the whirlwind. The answer may annihilate the question and the questioner. Anne Rice
- A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of ideas. John Ciardi
And in the inimitable words of Yogi Berra “I wish I had an answer to that because I'm tired of answering that question.”
This is what happens when you have a minor in Philosophy!
Hope you enjoyed the lesson – there will be a test!
Keep ‘em coming!! - John
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Topic of the Month: June Topic
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Topic of the month for June 2005 – Overdrive oil recommendation
Gang – I apologize for not writing an article for some time, but between
the rough winter and everything else going on, it was impossible!
I want to express our experience and opinion on the topic of the proper oil
for use in the Laycock de Normanville overdrive units. We constantly get into
discussions( and sometimes heated debates!) with British car owners on this
subject. This month’s discussion will invariably get some interesting
responses as it seems to be a rather emotional (and not necessarily logical)
discussion item for British car overdrive owners.
Let’s start out with history. Historically even the recommendations from
various car manufacturers are confusing. Some say to use multi grade oil (MG
manuals), some hypoid oil (Triumph manuals), some non detergent oil and some
even recommend automatic transmission fluid! No wonder everyone is so confused!
Many years ago (in a land far, far away (OK it wasn’t that far away or even
that long ago)) we ran an experiment on overdrive oil. We rebuilt an A type
overdrive unit and initially ran it with 30 weight non detergent motor oil. When
spun up on our test bench at 1,000 RPM, it reached a normal pressure of 400 PPSI.
When shifting the pressure dropped to 300 PPSI and quickly recovered to 400 PPSI.
All was right in the world of overdrives.
We then drained the oil and replaced it with 10W30 multi grade oil. When spun
on the test bench, initially it tested fine. However, after a few minutes of
running, the oil pressure dropped to 300 and when shifting, to 200. Upon
observation of the internals of the operating overdrive we found bubbles
developing in the oil pump body and oil pump output passage. We surmised that
the detergents in the oil were causing the oil pump to cavitate, and develop air
bubbles as it pumped.
We then drained the oil again and replaced it with 90 weight hypoid oil. This
time the oil pressure jumped to 600 PPSI! When shifted, the pressure dropped to
450 PPSI, which made the shift immediate and harsh. After a few minutes of
running the oil pressure actually began to climb even higher. (Which made no
sense since we thought the oil would thin out and the pressure would drop). We
finally shut it off at 750 PPSI as we did not want to damage the unit. Even
though the overdrive unit was now in the non overdrive position (solenoid
disengaged), the overdrive was now stuck in overdrive and would not come out.
The higher pressure had driven the sliding clutch member so hard into the brake
ring that the clutch return springs could not return it to the non overdrive
position. A tap on the brake ring with a hammer (the universal overdrive release
tool), shifted it back into the direct drive position. After running a number of
these test with the same result we found what was happening. The oil holes in
the accumulator sleeve are very small. The 90 weight oil was so heavy it could
not escape from the accumulator chamber as fast as the oil pump could pump new
oil into it. So even though the accumulator piston had passed the oil hole
relief position, the pressure continued to build up because the oil could not
leave the system as fast as it was being pumped in. The accumulator piston
actually bottomed out in the sleeve (similar to coil bind on valve springs).
When removed we found the accumulator spring had been compressed and was no
longer useable.
After replacing the spring, we then tried automatic transmission fluid. We
saw the same results as we did when we used the 30 weight non detergent oil.
We then tried synthetic oil and the unit also worked OK although it began to
leak from all sorts of places it had not leaked from before.
Based on these tests we have since and continue to recommend the 30 weight
non detergent motor oil as the best oil to use in the overdrives.
Some other experiences with customer overdrives over the years have
reinforced this choice. For example, we found a Jaguar compact overdrive with a
broken accumulator piston and bent spring when it had been used with 90 weight
oil by the owner. When the piston and spring were replaced and the unit filled
with 30 weight non detergent oil, it functioned normally. A customer LH
overdrive unit that was filled with 90 weight oil "pulsed" between
direct drive and overdrive without even being switched on electrically. When the
oil was flushed and replaced with 30 weight non detergent oil the unit worked
normally.
Other noted problems with overdrives filled with 90 weight are excessive wear
on the oil pump plunger wheel and the eccentric cam, probably due to the higher
pressures developed. Also the clutch lining seems to be more deteriorated in
units with 90 weight oil than those with 30 weight oil.
The use of non detergent 30 weight oil does not seem to affect the
transmission parts or function. Bearings, synchros, gears and hubs do not seem
to function any less effectively with the non detergent 30 weight oil as with 90
weight gear oil.
So there it is gang, our scientifically based rationale for using and
recommending 30 weight non detergent oil in Laycock overdrives. I welcome
further discussion and feedback on this topic by anyone interested. As always,
thanks for reading this article!
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Topic of the Month: February Topic
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Upgrading the TR3B/TR4/TR250 and early TR6 to the steel bush mainshaft gearset.
We have seen some unbelievably destroyed TR2/3/4/250 and TR6 transmissions lately! (What are you guys/gals doing out there!) Most of these are primarily due to the layshaft wearing out and the layshaft bearings (especially the first gear end) disintegrating (see an earlier discussion on this topic). However, we are now seeing more transmissions that have been damaged due to the weakness inherent in the bushing design on the mainshaft. The second and third gear on the mainshaft ride on bushings and their overall clearance is set by an adjustable thrust washer between the rear of the second gear and the mainshaft shoulder for the first/second sliding hub. The entire assembly is held in place by a spring steel circlip at the forward end of the third gear splined washer. In transmissions prior to 1973 (I do not know the serial number breakpoint, possibly chassis prior to CF12501), these bushings were made of bronze. The second gear bushing is shaped like a “top hat” and not only is the bushing for the second gear but also provides the spacing and clearance between the second and third gears. This bushing seems to normally take the brunt of the punishment and is prone to fracturing at the joint of the bushing part and the spacer part and after further wear breaking at this point and eventually completely disintegrating (see accompanying photo). This damage seems to be caused by gradually increasing play in the entire mainshaft gear clearance due to normal wear on the components, especially the softer bronze bushing parts. Also, eventually the second gear adjustable thrust washer fractures and disintegrates due to excessive clearance and loading and then all hell breaks loose.
Fortunately this wear and damage normally manifests itself in the symptoms of grinding the second or third gear on shifting or popping out of second or third gear on acceleration or deceleration. These symptoms gradually get worse until both gears are completely lost and major damage to the gears, sliding hubs and even the mainshaft itself can occur. However, some customers say they never experienced any symptoms until the complete loss of the second and/or third gear has occurred (with accompanying expensive noises from the gearbox).
The Triumph part number of the bronze second gear bushing is 129939, the third gear bush is 129940. The adjustable thrust washers come is sizes from .118 to .113 (part numbers 129941 to 134670) to allow proper setting of the gear assembly clearance (.003 to .006) The second gear numbers vary depending on the year and serial number.
In 1973 Triumph finally addressed this problem by replacing the bronze bushings on both gears with steel bushings. (The Stag transmissions all came with steel bushings) This upgrade seems to have solved the problem as we have only seen one later transmission with gear damage, and that was due to excessive clearance because the circlip wore out, not the bushings.
Unfortunately, they didn’t make it easy to upgrade the earlier transmission to the later thrust washer/bushing set. (So what else is new?) The second gear thrust washer is much thicker (.197 to .208) than the earlier one (.118 to .133) and has a small indent cut out on the inside of it. The later mainshaft has a small ball bearing inserted into it where
the steel second gear bushing cut out rides in order to prevent it from spinning on the shaft. The combination of the thicker thrust washer and the ball to prevent spinning also improves the life of the entire assembly. The later second gear was modified to compensate for the thicker thrust washer and the steel “top hat” bushing is also correspondingly shorter. Additionally, the oil flow holes are located at a different point inside the second gear and bushing. To make it even more confusing, the later second gear has a different gear tooth angle, requiring a different second gear wheel on the cluster gear assembly. You MUST also change the third gear bushing to the steel bushing. (It is asking for trouble to have a bronze bush up against a steel bush!)
You must therefore replace 5 parts to properly upgrade the mainshaft bushing set. The original Triumph part numbers are the later second gear, TKC454, the matching second gear cluster wheel, 155047, the third gear steel bush, 153238, the second gear steel “top hat” bush, UKC956 and one of the adjustable thrust washers, UKC958/959/960/961 depending on the mainshaft clearances.
We do this modification for all Triumph racing transmissions, as they get quite a beating from higher horsepower loads and harder shifting requirements of the race track. Although it is relatively costly and the parts are beginning to get scarce, this modification is also highly recommended for street cars where reliability and extended use are needed. I hope this article helps you if you are thinking about improving your transmission. As always, feedback is welcome! John
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Topic of the Month: November Topic
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Required changes to convert a Volvo J type overdrive to the TR6
Although the Volvo and the TR6 J type overdrives may be similar in manufacturer and name, there are some differences that must be overcome in order to use the Volvo unit on the TR6. The TR6 unit came with 25% overdrive reduction, the Volvos came with 25%, 27%, and 28% depending on the year and type. There were also 4 and 6 cylinder versions of the Volvo unit.
The following identifies the changes or additional items required so the TR6 owner can know what must be done to use the Volvo overdrive in his TR6
Parts that should be acquired from the donor Volvo J type overdrive transmission
- J type overdrive unit, complete with solenoid and rear flange
- Driveshaft matching front flange and hardware.
- Mainshaft eccentric oil pump drive with spring clip and woodruff key.
Minimum additional parts required to install the Volvo unit into the TR6
- TR6 J type overdrive transmission 3rd motion shaft (transmission output shaft). It should be noted here that the TR6 J type overdrive third motion shaft uses the later "free caged" type spigot bearing. If you try to convert an earlier transmission with the pressed in spigot bearing, you must also replace the input shaft and corresponding cluster gear wheel with the later type.
- TR6 J type overdrive to transmission adapter housing and one additional short attachment bolt
- If the TR6 is prior to 1973 commission number CF1, a transmission conversion mount kit is required as the chassis mounting plate is different for the J type.
- Interrupter/isolator switch for the Triumph shift tower
- Speedometer cable right angle drive and spacer
- Transmission and steering column overdrive wiring harness set
- Steering column escutcheon and overdrive switch.
- Shift tower reinforcement bracket and mount stud
Modifications to the Volvo unit required to install it in the TR6
- The speedometer drive gears and bushing must be removed and replaced with the TR6, 20 tooth speedometer gearset, bushing and attachment ferrule as the threads on the Volvo are coarse and the TR6 are fine and the speedometer gear ratios are different.
- Some Volvo overdrive rear housings are properly drilled for the TR6 vertical-mounting studs, but some are not and must be drilled and tapped for the TR6 mount studs or replaced with the TR6 rear housing. An alternative is to use the TR6 J type mount kit for the earlier cars (pre CF1) instead.
- There were at least (by our count) three different types and two different size rear flanges used on the Volvo units. One is identical to the TR6 in size and the flange bolt pattern and inner locating circle diameter and can be used without modification. The second type is identical in size, but uses a different bolt pattern and internal locating circle and requires professional machine work to adapt (or you can use the original Volvo driveshaft front flange in place of the TR6 driveshaft flange. The third type is smaller in diameter than the TR6 and should not be used or modified and must be replaced completely with a proper TR6 rear flange as it is too small to take the TR6 torque loads.
Modifications to the TR6 4 speed to convert to J type overdrive
- The original TR6 4-speed transmission must be completely dismantled in order to replace the 4-speed output mainshaft with the overdrive mainshaft. This is generally a good time to inspect and replace any worn, damaged or questionable parts in the transmission.
- The TR6 shift tower must be drilled and tapped on the third/fourth shift rail boss for the interrupter/isolator switch. All TR6 third/fourth shift rails were set for the overdrive switch, so no other modifications are required.
3. The TR6 shift tower used must be of the later type with the breather hole in the front left corner of the tower. There is no transmission breather on the J type overdrive unit itself. The 4-speed transmissions had two breather hole points. On the earlier cars it was on the tailshaft only. On the later cars it was on the tailshaft and on the shift tower. If there is no provision for a breather hole on the transmission, pressure will build up inside the transmission and overdrive and will blow out significant oil past the front and rear oil seals and any gaskets with weak mating surfaces or gaskets.
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Topic of the Month: April Topic
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How to properly shift an overdrive
Well, do I shift the front overdrive first or the rear one first?"
April 2003 – Topic of the Month – Proper shifting of a Laycock overdrive
OK everybody, calm down out there. We have received some interesting emails over the last few months asking (and telling) us about the proper way to shift in and out of overdrive on the Laycock deNormanville overdrives as used on the British cars (A, J, LH, D and compact A types). We received some spirited responses – use the clutch, don’t use the clutch, etc. I would like to express our opinion on the proper method to shift in and out of these overdrive units.
First let me admit that when I had cars with overdrive, especially Big Healeys, I did not shift the recommended way. It is way too cool and impossible to resist the temptation to pull up next to someone at 50 or 60 MPH and, as you shift into overdrive, accelerate away into the great beyond. This usually gets very interesting and surprised looks from the other drivers and passengers and really impresses the people who are with you in the car. What was that, warp drive? Like, you still have another gear? How many gears does his car have???!!!!
It is also way too cool to kick down from overdrive at 50 or 60 and watch the expression on the faces of other people as the engine revs on the downshift. This is especially true on the Big Healey, as the 6 cylinder really sounds great at speed. You get the fantasy of what it must feel like downshifting at the end of the straight at LeMans.
Anyway, back to the proper way to do it. Let’s think for a minute why overdrives were put in cars in the first place. I mean after all, anyone can put in a 5th gear on a transmission, why an overdrive? First of all the British never do anything the way we expect or anyone else does it. This was especially true in the 40’s, 50’s and 60’s and is why we have such interesting cars from that period. Laycock overdrives are really like a manually initiated mini automatic transmission. (I personally think a guy named Rube Goldberg had a major part in their design). The important thing to remember is that it was added as an option on most cars in order to reduce engine RPM (and consequently wear) on the highway and increase fuel mileage. Secondarily it was also used to increase the number of speeds forward, giving a better selection of gear ratios for driving.
Given this objective, we can understand that the proper way to shift into overdrive is to reduce the engine RPM’s, not increase the road speed of the vehicle. In fact, it is somewhat damaging to the overdrive clutch to accelerate under power during the shift process. This is akin to slipping the clutch or power shifting during the normal shifting of a regular gear. It can tend to lead to premature overdrive brake ring and clutch wear and failure. You do not need to use the regular clutch pedal at all. Get to a reasonable speed, say 45 to 50 MPH. Activate the overdrive switch. As the overdrive engages, feather the throttle so that the road speed of the car remains the same and the engine RPM’s are reduced. Voila, you have shifted the overdrive with minimum stress to it and now are cruising at a lower engine RPM. Objective achieved. Now you can accelerate to any cruising speed you desire as the overdrive is fully engaged. It is not recommended shifting into overdrive at too low a speed as this also can cause stress on the clutch and lugging the engine is not a good practice either. In fact the early overdrives had a mini Lucas centrifugal type regulator on the output shaft of the overdrive that would not allow the overdrive to be engaged below a specified speed
Shifting out of overdrive is the reverse of this process. Turn the overdrive switch to the off position. As the overdrive disengages back to normal drive, push down on the throttle to keep the car’s road speed the same and increase the engine RPM until the overdrive shift is complete. This again minimizes wear to the overdrive clutch and brake ring. You can now decelerate the car as you would normally. Again, you would not want to shift out of overdrive at too high a speed as you could over-rev the engine and cause damage to it as a result.
As you can see, the basic objective of proper shifting is to reduce the wear on the clutch during the shifting process. This can easily be done with some practice and will significantly increase the life of the overdrive unit.
We have determined this shift procedure from observing many overdrive units and the wear on the key overdrive clutch components, as well as just plain common sense.
We hope this will clear up any questions on the proper way to shift these overdrives to reduce the wear on them and keep them running longer. Most likely we will generate a new set of questions on the procedure, but that is what it is all about! As always, comments and feedback are welcome! Thanks! John
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