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Freespeech

Freespeech

Freshman Member
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(This was also posted on New Member intro forum)

Hi all. I have a nifty 1975 1500 that I've gone way overboard modifying, and of course, it never ends....
Here's what I've done so far:
APTFast stageII radical cams;
+020 pistons;
Pacesetter/Monza header and exhaust;
Crane electronic ignition:
PRI quad-carb Keihnins;
Koni's and Minilites.

This car shifts at 6000 like it's nothing. I suppose I ought to put roller rockers in...

Anyway, it turned out so much more torque that I put in a taller diff from a GT6 which is nice on the highway, but I lost the initial acceleration, which leads me to the following:

I am looking for an OD transmission, and I'll switch back to the shorter differential gearing. Make sense? I'm open to a non-Triumph tranny it that works..

Also, I want to reduce weight, so I want to lose the bumpers and am having a dickens of a time finding a decent air dam for the front.
Any suggestions are really appreciated...
Charles Glasser
cglasserbloomberg.net
75 1500 Spitfire
70 E-Type FHC
84 SIII XJ6
 
Re. gearbox, you could fit a Spitfire 1500 overdrive box, alternatively, there is a readily available conversion kit to let you fit a Ford 5 speed box, this has the advantage of not taking a few HP in use, as the overdrive box will.

As for adding lightness, a few possibilities for you:
Alloy diff housing
Alloy bell housing
Alloy engine plates
Alloy water pump housing or replace with EWP
Gutted doors,
perspex side windows,
Smaller alloy alternator
hi-output pre-engaged starter motor, (Ted Schumacher)
alloy roller rockers (Ted)
tubular chrome-moly pushrods (Ted again)
alloy valve caps
alloy front hubs
lightest possible wheel/tyre combination - nitrogen in tires?
lightweight alloy flywheel with extra two holes and ARP studs
lightweight front brake calipers
alloy water radiator
small battery (seen in back of hod rod magazines)
alloy engine back & front plates

Sure there are probably things I have missed, but it is a start for you.
 
Speech,
You may want to check out the recent posting asking about overdrive gearboxes. There was a fair amount of debate on the subject and I think the consensus was that overdrive was more fun than a five-speed!
Regarding weight-loss. The best modification for my TR3 would be for the driver to go on a diet!
Nick
 
Oh, and a thought about your air dam. There is a guy here in the UK thinking on doing a run of air dam as seen in the pic below, in carbon fibre.

tri04_53_8192.jpg


https://crazyspitfire.blogspot.com/2007/12/spitfire-mk1-2-3-and-gt6-mk1-2-valances.html
 
how do you like the Kehins from PRI, I bought a triple set of Mikunis and could not get them set up for my TR6 and Chris was no help at all, so much for life time help, seems like once some get your money they forget about you, so now I have a triple set of mikunis and triple webers on the car
 
SpitBang said:
Re. gearbox, you could fit a Spitfire 1500 overdrive box, alternatively, there is a readily available conversion kit to let you fit a Ford 5 speed box, this has the advantage of not taking a few HP in use, as the overdrive box will.
Click to expand...

Do you have a name of a source for this conversion?
 
Anytime you shift into any gear other than direct in a conventional trans you will lose HP... so a 5 speed with an OD gear will take more HP when in 5th OD...
 
YankeeTR said:
Anytime you shift into any gear other than direct in a conventional trans you will lose HP... so a 5 speed with an OD gear will take more HP when in 5th OD...
Click to expand...

But an electric overdrive has additional losses - such as the power to drive the oil pump - that a 5-speed doesn't have.


Bryan
 
BryanC said:
But an electric overdrive has additional losses - such as the power to drive the oil pump - that a 5-speed doesn't have.
Click to expand...
True, but the losses are small. My drill motor will supply enough power to turn the OD & it's pump and I would be very surprised if it will develop 1/4 hp.

Plus it's at least possible that the planetary OD gear configuration is more efficient than the single spur gear used in a 5-speed.
 
Deleted
 
amcboy said:
Now, driving an oil pump is something else.
Click to expand...
True for the main engine lube oil pump. However,
In this case, I think we are discussing the OD operating oil pump. It is a tiny cam & plunger type pump that puts out moderately high pressure & practically no volume. I seriously doubt that it requires more than 1/4 hp as was stated.

Nelson Riedel calculated the power to drive this pump at 0.1 hp.
D
 
amcboy said:
Your oil pump robs your engine of at least 25hp.(!)
Click to expand...
SUURE it does. We're all bolting on overdrives that burn 25 of our precious 100 bhp, and no one has noticed yet.
 
A 5-speed consumes less power than an OD. If that were not the case, OD would be the preferred system both for power and fuel efficiency. OD was great technology in the '50s and '60s, but modern 5 and 6 speed manual transmissions are more durable, simpler, consume less power and are more fuel efficient. Originality is great if that's your thing, but the only mechanical advantage OD holds is that it can be engaged in more than just top gear.

Ernie
 
amcboy said:
This is to reduce the overall noise the gears make while engaging. It also moves some of the input energy into longitudinal thrust on the gearset.
Click to expand...

I had learned that the hypoid bevel gear was designed because as engines became more powerful the straight cut gears were not strong enough. The reason being that the bevel gears contacted more than one tooth at the same time. This also made them operate much smother as you said. Either way they were a vast improvement.

I believe that Jaguar was the first to use hypoid gears. Another of the many innovations first found on LBC's.
 
shining_armor said:
A 5-speed consumes less power than an OD.
Click to expand...
I would really like to see some measurements that back up that assertion. I'd settle even for temperature measurements showing they run cooler. Even one horsepower loss amounts to quite a bit of heat (the little heater in my office that glows red even with a fan blowing through it consumes less then 2 hp) so if the OD is sapping more power it should get hotter.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]If that were not the case, OD would be the preferred system both for power and fuel efficiency.[/QUOTE]Which might explain why a great many cars today have overdrives with hydraulically controlled clutches actuating planetary gearsets. The difference in fuel mileage is trivial and generally disappears once you compare apples with apples (no fair comparing a 4-speed auto to a 5 speed manual); plus frequently better acceleration.

Many of the top racing transmissions today also use planetary gearsets (tho generally OD is not needed).
https://www.api-racing.com/
https://www.nealtrans.com/

And, look under the surface of "high efficiency" cars like the Toyota Prius, and you'll find planetary gearsets. More expensive to build, but more efficient (and lighter weight). Many cordless tools use them too, for the same reason.

I agree, comparing a nearly 60-year-old gearbox to a modern one is unfair, but it's not because the technology is inherently flawed.

BTW the descendent of the Laycock overdrive is still being sold and used today, in spite of it's cost and complexity.
https://www.gearvendors.com/
 
Deleted
 
amcboy said:
You're not comparing apples to apples.
Click to expand...
I disagree. Heat is heat, and if the transmission is wasting power, it's by generating heat.

I'm deleting the remainder of my post ... obviously neither of us is going to change our minds.
 
No Trolls.

No Problem.

I apologize for my earlier posts and the obvious ire they have caused.

I will NEVER enter into another debate on this forum where facts are taken as opinions.


I do not want to be tossed.


I do want to support the group at large and to that end I will from time to time chime in.

Otherwise, consider me a lurker.

I may ask a question again, and I hope you as a community will consider it.

I will not look at this thread ever again, and I'm sorry if you think I hijacked it for my selfish personal gains.


To the original poster I will say this:

Regardless of what route you choose to take, you will likley have fun. The journey is the reward not the end result.


To Randall I will say this:

I am sorry we do not seem to agree. I am sorry I took so much of the thread to try to show my POV. I am glad you were convinced enough to post your replies. It made me re-think what I know and check (for like 2 hours) my references. I have a great deal of respect for you to try to learn whats happening out there.

The only stupid questions are those that go unasked.


To CTC76828LO: Consider my PMs checked.
 
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