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Re[2]: engine/trans compatability ?

To: <Carmods@aol.com>, <Curtis_Fisher@smtp.svl.trw.com>, <laifman@flash.net>
Subject: Re[2]: engine/trans compatability ?
From: nicholsj@oakwood.org
Date: Mon, 03 Nov 97 13:20:33 -0500
     'Found an article in April, 1966 "Ford High Performance",'
     
     April, 1966????, where is Phil LeBrun, the accuracy watchdog, when we 
     need him? 
     
     Jeff 
     
     
______________________________ Reply Separator _________________________________
Subject: Re: engine/trans compatability ?
Author:  Steve Laifman <laifman@flash.net> at INTERNET 
Date:    11/3/97 9:46 AM
     
     
Carmods wrote:
> 
     
> .How about a Tremec transmission?
> 
> Tremec transmissions have torque capacities of  350 lb-ft  to 500 lb-ft verses
> 265 lb-ft to 330 lb-ft  for the World Class T-5's . the Tremec will bolt to
> Lakewood or Ford 6 bolt flywheel housings. It is however larger than the T-5
> and will require some the additional minor work of widening of the rear of the
> transmission tunnel and  modification to the body "X" member for the rear
> mount.  Steve, from what you say, I assume the bearing retainer hole must be 
> machined in the flywheel housing.
     
> 
> John Logan
     
     
John,
     
No, the larger bearing retainer reference was to Ford/Tiger Top Loader 
for the 5 bolt, vs 6 bolt design. All these new ones have the 6 bolt 
wider retainer.
     
With reference to the TREMEC:
Tremec Trading Company
DSA of America
23382 Commerce Drive
Farmington Hills, MI 48335
(810) 471-3200
Dealer Info: (800) 442-8011
     
I spoke to Julio, who was very informative. My first introduction to 
this box was in search of a 5 spd for my Mustang. Most transmission 
specilaists warned me away from the T-5 to the "World Class T-5", but 
also suggested the Tremec was much better.
Found an article in April, 1966 "Ford High Performance", and acquired 
Tremec brochure. There is a basic problem with all 5 speed OD 
transmissions, manual or automatic. While the 4th gear is a direct drive 
(1:1), the OD is ususally in the 0.63 to 0.68 range. This is quite an 
RPM drop. Just multiply the RPM you now have at your cruising road 
speed, (say 72 mph @ 3,000 rpm with 185/70 13) and you get a drop to 
1890 to 2040 RPM, with these two examples. Drive up a mild hill in your 
current top gear, at 2000 rpm, and accelerate from just a little to full 
power, and you will get the idea about what your car will be like in 
5th, only worse because of tire and air drag. The normal "performance" 
OD ratio is 0.8, and this is used in most sports car applications. That 
would be a drop to 2400 rpm, in the example. a lot more torque available 
here, yet still a comfortable rpm. The reason these manufacturers use 
such a low number is to acheive the government decreeed C.A.F.E. 
(Corporate Average Fuel Economy), not because it's the good choice for 
the car. Tremec says they have a set of "racing" gears available, that 
include 0.8 5th.
     
There are at least two models of the aluminum case Tremec. The standard 
is the TR3550, the other is the TKO. Here are the specs:
     
TR-3550/TKO:                1st - 3.27; 2nd - 1.98; 3rd - 1.34; 4th - 1.00; 5th 
-
0.68; Torque (ft-lb) 400/490
T-5/World Class:        1st - 3.35; 2nd - 1.99; 3rd - 1.33; 4th - 1.00; 5th - 
0.68; Torque (ft-lb) 265/330
     
I have been quoted costs of $1125 to $1338 for the Tremec, $1400 for the 
TKO, and about $1100 for the World Class T-5.
     
The TR-3550 has three "top load" covers, and shifting linkages bolt into 
any of them, but only the rear comes standard. The center location would 
be the one Cobras use. Shift Kits are available to move it. The Tremec 
has a 3 1/4 inch spacing between the main shaft and the countershaft, 
like our top loader, which allows (and requires) larger diameter gears, 
which are also wider. Instead of bushings, like the T-5, the Tremec uses 
tapered roller bearings on all shafts, and needle bearings on the speed 
gears (like our top loader), and brass blocker rings. The input shaft is 
the same dimensions as the T-5, as well as the front bearing retainer. 
Unlike the T-5, the Tremec has a positive stop on the clutch teeth of 
each speed gear, so the transmission cannot be "overshifted". The input 
shaft on the TKO is 1 3/4 inch diameter with 26 splines. The output 
shaft is a heavy duty 31 spline that uses a C-6 yoke. The TR-3550 is the 
same as stock 302 Ford. The transmissions come with the rear-top mount 
shifter, not the side-shift type on our Tiger, and various length and 
ratio levers are available, as well as location change kits. The 
over-all length of the transmission, from mounting face to end of tail 
stock, is 24.07 inches (611.5 mm). The stock rear-most shifter is 19.52 
inches (495.8 mm) from the dual 4-bolt pattern front face. The front 
face to rear engine mount is 15.8 inches (401.4 mm). The TKO (and 
perhaps the TR3550) input spline is 7.47 inches from front mounting face 
to end of pilot shaft. I know of early Mustang installation kits that 
worry about linkages (mechanical), "adapter plates" for input shaft 
length, and revised rear mounts. Some drop the rear mount to clear the 
drive tunnel, but this increases the driveshaft angle (not a good idea). 
I have seen installations where the floor transmission cover is neatly 
cut around the firewall, and down the sides to about the Mustang gear 
lever hole. The front of the floor cover is raised a few inches, 
allowing a taper back to the end of the long cut. A piece of sheet stock 
is welded back in, in a "V" shape alongside the tranny, and around the 
firewall. This is very neat, gives the required tranny space without 
widening the tunnel, and allows the rear motor mount height to remain 
the same. Chevrolet uses T-5's stock, and rotates the tranny 
counter-clockwise to position the shifter towards the driver.
     
I have no interest, financial or otherwise, in any product except our 
Air Force/ NASA Space Launch Vehicles. This information comes from Bob 
McClurg's article and my phone calls to "Julio". Since I sold the 
Mustang and bought the Tiger instead, I have had no hand's on 
experience, but all the pro's I've talked to like the Tremec.
     
I hope that answers your questions.
     
Since this information is a little over a year old, I would double-check 
today's specs and prices. They may have released their 0.8 5th (my 
recommendation) for a reasonable price.
     
     
Curtis Fisher, <Curtis_Fisher@smtp.svl.trw.com>, asked about ratios with 
5 spd, close ratio top loader, wide ratio top loader, rear end ratio's, 
etc. He is interested in fast street action and autocross. He currently 
has a HiPo 289 with a 3.31 posi. I will try to answer his questions, as 
best I know, but realize there are a lot more friends out there who have 
BTDT, and should add their 2 cents worth.
     
1) Calculating speed vs rpm in any set of transmisssion, rear end, and 
tire size is relatively simple, and the formulas are available on web 
sites and in Tiger Shop Notes. I will send some to you, if you want. The 
difficult part is transferring your torque-vs rpm data, tire friction 
capability, clutch capability (and your tolerance for replacement)  and 
drag vs speed data into this model to make selections. My general 
comments, based upon my own experience, is that the choice of ratio's is 
very camshaft dependent. If your car idles like a wet dog, and doesn't 
"fire-up" it's torque until 3500 rpm and above, then that's where you 
would want to keep your engine. Choose the combination that keeps you in 
that FAT TORQUE range. If you've got a more streetable machine, like the 
stock or mildly modified Tiger, then I believe your activities are the 
key. For road racing, where you spend your time above 40 mph, the 
factory close-ratio is pretty good with the stock rear end and slightly 
oversized tires. For around town stop-light drags, and freeeway on-ramp 
acceleration, the close ratio gets you about 60 mph in first. This can 
put a higher slip in the clutch on rapid take-offs, and you take a while 
getting up to the rpm the motor likes. The MKII Tiger, with the "wide" 
ratio top loader, is more suited to this activity. Shift speed is about 
52 mph, instead of 60, giving you less clutch load (slip) and faster 
initial acceleration. Getting out of first at 52 isn't too shabby anyway 
(used to be 20 mph in my MG). Since you'll be putting effectively 20% 
more torque on the road, your acceleration will be better. Shifting at 
about 5-6,000 you get an rpm drop of about 1,000 rpm in the next gear up 
(or vice-versa if your downshifting). This keeps the "operating band" 
around 1,000 rpm - you choose the band nominal by your choice of when to 
shift. The wide ratio will drop about 1200 rpm. This broadens the torque 
band, and is ok if you've got a 1200 rpm "good" band. You won't "bog 
down" on the shift, and will keep accelerating smoothly if you've got 
the torque set up by
cam/carbs/valves/springs/ports/ignition/compression/gas. Trouble is that 
adding 20% more torque at dead stop take off is the tires may spin, 
getting you nowhere, or you can wind-up the suspension, and chatter down 
the road with 1 foot burn marks. I'm sure you've seen that Tiger II 
picture. While a Traction Master is supposed to help here, it really is 
a poor design. The original doesn't have a good structural connection in 
front, although newer replacements do (Tiger Technologies, Sunbeam 
Specialties (maybe-ask Rick). Trouble is there are two many pivot points 
trying to control your axle, and the harshness of this geometry 
competition is harshness when your not on-it, as well. The LAT bolt-on 
the spring system is smoother, but the load will shorten your springs 
life. The really best solution is Dan Walter's design axle locator, 
which only requires two holes (I believe) to install. It locates the 
axle with a rigid pair of long arms, is well thought of, but is not 
original factory or LAT option (if this is important to you. I would 
believe not, considering your use, but I would check with classification 
on Autocross events before changing anything that will take you to a 
competition level your not prepared for.
     
I hope this answers your questions, without confusing you more. These 
are not simple questions, and require trade-offs only you can make. The 
factories spend hundreds of engineering and track testing for each 
change they consider, and EVERYTHING is a compromise between what you 
want, can afford, and are living to live with the other side of each 
choice.
     
Steve
     
     
SORRY about the length, but there were a lot of questions out there.
     
-- 
Steve Laifman         < One first kiss,       > 
B9472289              < one first love, and   >
                      < one first win, is all >
                      < you get in this life. >
     
     
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