Richmond vs. T-56

[Mike C]

I would hazard it is mostly expense, although the Richmond case is larger than the T56. Plus of the richmond, more gear ratio options and only a single overdrive. (I think the concept of two overdrives misses the boat in a high torque application, actually any application.) The T56 is readily available for about $1500 while the Richmond is nearly double that. Another plus to the T56 is the low maintenance internal rail shifter. I think that a set of 3.36 or 3.54 and the Tremec is just about the best combo available. Plenty of gear down low as well as an acceptable overdrive.

[Guest Anonymous]

I think as Mike mentioned, the internal shift rail is a factor, it takes up less tunnel space than having four sets of shift rod linkage running outboard of the transmission. Also as mentioned difference in ratios, doesn't the richmond not get into overdrive until 6th gear? The T56 is in OD by 5th gear and 6th is basically to let the motor run slightly above idle on the freeway for great economy. I'm sure the richmond is hell for strong though and probably usable, clearance and a bit of pounding might be required and I'm not sure how the bellhousing works but its probably old style like the m21/22 which would probably work just fine with a pusher slave. I suspect those are the reasons the T56 is seen as the best alternative though, price and ease (well its not exactly small either) of fitment. *shrug*

 

Regards,

 

Lone

[BLKMGK]

IMO the twin OD is NOT an advantage in our cars. Often the RPM is so low in 6th at any reasonable speed that the engine hates you. I thought a double OD would be awesome however now having driven a car with 6speeds and a single Od I can tell you that if the ratious are right it flat out ROX!

[Guest Anonymous]

Depends on your motor's torque curve. But your right, 6th doesn't like 50 mph for example. On the other hand is there a rule that says we must shift to 6th when going under 65-70? Its still over drive right?

I've been into 5th easily on even surface streets but my motor isn't radical. If you have a cam that doesn't come alive till 2K or more, you'd be hating 6th I'd imagine and anything under that RPM.

The problem I'd see with the richmond is if it is the same box as the old 5sp nash, 1st gear is going to be even shorter than our T56 because it was made for cars to run 3.00 gears or there abouts and still get a good take off. If the 6sp is the same way then our unavailability of gear ratios of that nature would be a problem. But I know jack about the 6sp richmond gear ratios so I'm probably wrong as usual. I will admit Jim though that double OD's are a bit overkill for our cars, but our options are rather limited as you know for a strong OD box. (and you've voiced a dislike for the tremec before.. )

 

Regards,

 

Lone

[Guest Anonymous]

I've noticed in nearly every post about 6-speeds, everyone discusses installing the T-56. I don't see the Richmond ever mentioned. Is this a matter of preference, better fit/easier install, or expense? Just curious. Thanks for the attention.

[pparaska]

Just a datapoint. My Tremec has 3000 miles on it and it shifts fairly nicely. And I've gotten used to it surely. To me, it's not a problem at all, and I've yet to miss a gear.

 

I'd agree that the .50 overdrive is probably not very useful if you have a lopey cam, etc. But heck, just use the first 5 and be done with it!

[Mike C]

There has been a lot of discussion about minimizing low gear multiplication in Z's, which I find counterintuitive. The more low gear multiplication you have, the more torque. The added torque is more easily modulated with the power potentiometer (accelerator pedal) than a car with less gear multiplication. (this is why offroaders run so much gear in the rocks, it allows for very smooth application of power.)Traction is about torque vs. tire and with lower gears you can back off the gas and still put the same torque to the ground, just enough to not bust the tires loose. 3.54 gears and the 3.27 first of the Richmond give an 11.58 first gear ratio, compared to the 4.10s and 2.62 in my Camaro which is a 10.7 overall first. The biggest concern I would have is making sure the ratios stay in a range that keeps your particular combination from falling out of the torque curve when shifting gears. It seems that most people I know with a later model 6 speed F body winds up with 4.10 gears in there car anyhow, which makes the final overdrive of the 6 speed about the same as the Tremec or Richmond overdrive with a 3.54 gearset. The overall 1st of this combo is 12.177. The 2.97 of the T56 and the most often used 3.7 of the LSD gives a 10.989 overall first. The newer T56 with .62 OD yields an effective ration of 2.29 in 6th. The Tremec and its .68 overdrive is almost the same as the T56 and the slightly wider gear ratios make a better use of the high torque of a v8. A lot of speculation I suppose, but I still believe in an overall first gear of 10.5-11.5 to one being optimum for a street car and no lower than a 2.3-2.5 final effective ratio for a carbureted car. The "redundant" 6th gear of a T56 is designed for emissions and not performance for performance, at least with the stock 3.23 gears. With 4.10 it is useable, but 5th is basically redundant at this point, and obviously cruising in 4th provides for maximum transmission life since power is diverted from the cluster gears.

[jeffp]

I have looked into both trannies. The Richmond tranny is not as strong as you might think. I called and asked andthe comment was that guys are trying to get power in 6th with a 502 crate motor and they cant handle it. Also the shifter is off center and that is a big problem for our cars , especially if you want to keep it looking stock like me. The gear ratios are very close. I did the tranny calculator and between 2nd and 3rd you gain only 20mph, fifth is 1:1 and 6th is .780 or so. So there really is not benefit to using that unit.

The T56, well again there is not allot advantage to using that tranny. I also did the calculator on that unit and you HAVE to run the chevy tranny, NOT the viper tranny. You have massive modifications to do. I found a guy that would do the bell housing for 600.00 and then you have to buy the tranny. The unit is rated at 425 foot pounds of torque so since I am already over that figure UI dont think, for me I should bother with it.

NOW the tremec T5 TKO (ford unit) is looking like the winner. it has the gear ratios that are close to the T5 stock for the turbo cars, it will handle more Torque, and I can run it on the strip, so for me, it's the TKO and that wil be what I install in my car.

[jeffp]

Ok here are the calculations. The wheels are 245X45X15 on my car and the engine RPM is 7000. The rear gear ratio is 3.71

 

Tremec TKO with .83 overdrive:

1st) 3.27=41mph

2nd) 1.98=67mph

3rd) 1.34=99mph

4th) 1.00=133mph

5th) 0.83=160mph

 

Tremec TKO with .68 overdrive

1st) 3.27=41mph

2nd) 1.98=67mph

3rd) 1.34=99mph

4th) 1.00=133mph

5th) 0.68=195mph

 

Standard Borg Warner T5 in 280ZX

 

1st) 3.50=38mph

2nd) 2.144=62mph

3rd) 1.378=96mph

4th) 1.00=133mph

5th) .780=170mph

 

That is about it on the T5 and the TKO tranny. I would like to keep the .780 overdrive in the car, but I guess I can live with the .68 overdrive. I just may be able to swap out the gears from the standard Nissan T5 with the gear set from the TKO unit, but I would have to check on that one.

[Mike C]

There is nothing shared between a Tremec TKO and a BW T5. Unless this is a race car, overdrive is for cruising and I think you will be real happy with the .68. If you want a little more top speed without the overdrive, you can swap the LSD into a 12mm 3.54 housing.

[jeffp]

I was looking at the docs on the parts and it is looking like they will not work together at all, oh well. I think I am going to go ahead and go with the .68 fifth. I do like the topend, I would rather have a 170 topend and gain a little torque, but I dont think that is going to happen. I have mentioned before what I would like to run in the 1/4 for top speed of 150mph, but that is an ideal right now.

I like the 3.71 diff gear, but the 3.54 gear would do exactly what I want it to, but since I just dropped 1800.00 to have a Quaife bought and setup with the 3.71, I am going to keep that.

Really I am looking at another significant round of upgrades for the car. I am waiting on a few parts, but I want to knock out all of the upgrades at once. Tranny, clutch modified for the tremec, radiator(aluminum) harmonic dampener, oil pump drive gear(brass gear) turbo, manual rack & pinion, differential, comp oil pan, and that should be about it until I can get with JWT to finish up the upgrades to the fuel management. THEN, the car will be done, I swear LOL

[Guest LT4Justin]

The newer T56 with .62 OD yields an effective ration of 2.29 in 6th.

Actually it was the T-56's from the 93 and 94 F-bodies (M28 and M29) that had the .62 overdrive... except for the 1LE cars which all came with the .5 OD MN6, but odds of finding one of those in a boneyard is slim (less than 200 produced a year)... 95 and up F-bodies all had the MN6.

 

93 and 94 6-spd F-bodies had the same rear gears as the autos (2.73 standard, optional 3.23's), then got their own 3.42 ratio from 95 on, with GM having the tranny ratios altered accordingly.