T-56 hard to shift at high RPM - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old Oct 22nd, 02, 02:55 PM Thread Starter
 
Join Date: Jun 1999
Posts: 306
Wondering what is normal for T-56 shifting effort. While driving around town and shifting between 4-5K the ease of stick movement is light, buttery smooth. However, when shifting at cam shaft red line of 6500 rpm stick effort is noticably increased. Sometimes it feels like I have to literally slam it into gear. Currently there is Mobile 1 synthetic ATF as the lubricant with about 1000 miles run time. The shifter is a Hurst Pro Billet, their top of the line if that means anything. I don't think the clutch is sticking but uncertain how to check that. The clutch is a Centerforce Dual Friction with their billet flywheel. The tranny was rebuilt by a good shop and told it was in great shape so don't think the syncros are shot, if it even has syncros (goes to show how much I know about T-56 trannys). Any ideas what is causing the high shift effort in the upper rpm range?

------------------
Joseph

1969 Camaro
404 SB w/ 10.3:1 Eagle 4340 assembly in Dart Little-M block, AFR 210's, Crower #00350 short track solid cam 238/244 @ .050" on a 107 lobe center and .530" lift w/ 1.6 rockers, Holley 750 vac sec, Victor Jr., custom 1.75" headers, Spintech 2.5" exhaust with x-pipe and Sportsman XL mufflers, T-56, CenterForce Dual Friction clutch and billet flywheel, Guldstrand Mod., Landrum 600# front springs and adjustable spacers, Hotchkis 1.125" front bar, Detroit Eaton 175# rear springs, Bilstien shocks.
1971 Ford Bronco
Stock 302, 4" rock crawler suspension lift, 1.5" body lift, NP435 tranny, 4.11 gears, Detroit Locker rear diff., Power-Lock limited slip front diff., 33" BFG MudTerrain tires.
Joseph is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old Oct 22nd, 02, 03:33 PM
 
Join Date: Oct 2002
Posts: 2,045
It is "CenterForce Dual Friction" related. The weights are the culprit, you spin the engine up that much and you'll find it doesnt really want to release. That type of pressure plate wasnt really designed to release at that RPM. 6500-7000 is where you will find most of your clutch related shift problems.
chicane67 is offline  
post #3 of 8 (permalink) Old Oct 23rd, 02, 03:04 AM
Senior Tech
 
Join Date: Sep 2001
Location: Elizabethtown, PA
Posts: 980
Send a message via AIM to Spames
So, you are telling us that one of the best high perf. clutches out there isn't any good at higher RPM's? It just doesn't make any sense to me. I almost don't believe it.

I have shifted my 4-speed at 6000 without any change in shifting effort (dual friction clutch).

------------------
68 Coupe, 350 4-speed
Jim's Camaro Corner

[This message has been edited by Spames (edited 10-23-2002).]
Spames is offline  
 
post #4 of 8 (permalink) Old Oct 23rd, 02, 04:39 AM
Tech Team
Wally
 
Join Date: Dec 2000
Location: Frederick Maryland
Posts: 91
Not the clutch. I pull the handle with a Center Force clutch at 7500 and my muncie shifts like a hot knife through butter.

It's the trans, those shift rails just won't shift like a Muncie or ST-10.
muncieman is offline  
post #5 of 8 (permalink) Old Oct 23rd, 02, 07:59 AM Thread Starter
 
Join Date: Jun 1999
Posts: 306
Humm, conflicting opinions as usual.
In any case, seems I'm stuck with the problem if opinions above are indeed the cause as replacing the tranny or clutch assembly with a different models is not possible at this time. Infact, I'm pretty disappointed because when I fully researched the T-56 swap never was there mentioned any draw back such as this. I'd just as soon build another car than replace the trans. That gives me another reason to enlarge the car collection. When I burn up the clutch I'll try a McCleod or something else to see if that helps. Any other opinions out there?

Joseph
Joseph is offline  
post #6 of 8 (permalink) Old Oct 23rd, 02, 10:24 AM
Senior Tech
 
Join Date: Sep 2001
Location: Elizabethtown, PA
Posts: 980
Send a message via AIM to Spames
Have some patience. Maybe the trans just needs a little more break-in time.

Maybe there's someone out there that can shed some light on the clutch adjustment check?

------------------
68 Coupe, 350 4-speed
Jim's Camaro Corner
Spames is offline  
post #7 of 8 (permalink) Old Oct 23rd, 02, 11:09 AM
 
Join Date: Oct 2002
Posts: 2,045
Spames, noticed how you have stated 6000 RPM. And as for one of the 'Best' high perf clutches, that is an opinion.....

Muncieman, I agree, I too can shift beyond that (now that I dont use a Centerforce pressure plate) but it really has more to do with the linkage, the pivot ball height, type of fork and sometime requires a 'Z-Bar' leverage change. I also agree with your statement of it being an internal rail shift design, that it will never shift like a Muncie or a S-T10. I have over 80 hours "in" my Muncie, and all of this also has to do with certain tricks and modifications inside the trans itself.....above 7000 RPM.

Having built road race transmissions (from Muncies, S-T10's, TopLoader's/Jerico's, ZF-6 speeds and the BW T-56) and typical street cars, I have noticed A-LOT of clients (of mine and other trans builders) have complained about shifting at 7000 and up.

These and many other transmissions were never designed to shift at that RPM with a diaphram pressure plate. There are numerous articles, and even the manufaturers state this....and they both recommend a Borg and Beck type pressure plate over a diaphram at that RPM. And then considering the centrifugal weights, this just adds more to MOST high rpm shifting woes. This is one reason why Liberty and Jerico have gone to designs like 'Dog ring sliders' so that you dont have to use a clutch while at that RPM.

Joseph, give "Red" a call at McCleod.....I did a some of R-n-D on the 'Street Twin' clutch with him. He/his knowledge of this would amaze/rival even the most die hard gearhead and he will have an answer for you addressing this issue. It might even be a hydraulic problem....I have had/seen problems associated with increasing pressure plate loads (also associated with the centrifugal weights) over coming the stock clutch master in high perf applications.

[This message has been edited by chicane67 (edited 10-23-2002).]
chicane67 is offline  
post #8 of 8 (permalink) Old Oct 23rd, 02, 11:49 AM Thread Starter
 
Join Date: Jun 1999
Posts: 306
Thanks Chicane67, I'll give Red a call.

Joseph
Joseph is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome