Technical Official" 4 speed, performance clutch and bell housing thread''

I have a copy of the 1992 April Super Chevy that has a step by step Muncie rebuild when I get home tonight I can scan and post it.

 

That would be great! This is exactly what I was hoping this thread would become. As far as adding clutch linkages, I'm all for it. You guys add anything that you think will be helpful within the realm of the topic. I will post my linkage in the model A.


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Here's a link to my page with step by step and pictures on building a custom steel bellhousing from scratch... http://grannys.tripod.com/20102b.html

 

Wow...thats pretty.

 

Here's the scan out of the Super Chevy mag I guess you guys can resize it so you can read it.

 

The time it takes for your clutch to lock up is a huge deal if you want an OEM style 4 speed to live at the track. Below is some info i posted for a nitrous sbf/T5 guy on radials, but the general idea applies for Muncie/Saginaw/ST10/etc. If your 4 spd has a 1st gear ratio lower than the 3.35 of the T5 in the example below, your rpm will be even lower at lockup.

Raising launch RPM, adding flywheel weight, or spinning the tires can help eliminate a bog off the starting line, but here is another way that's much easier on your transmission. ***uming 4.10 gears, 28" tire, 3.35 1st gear, accelerating at a 1.65G rate (1.5 60'), and the tires stuck to the track, here's the rpm you will be turning at different clutch lockup points down the track...
...at .3 seconds in 1790 rpm (typical aggressive clutch)
...at .4 seconds in 2387 rpm
...at .5 seconds in 2983 rpm
...at .6 seconds in 3593 rpm
Since it's not a good idea to spray below 3000rpms, you will need to delay the clutch's lockup point until after .5 second into the run if you want to spray off the line.

Raising your launch rpm has the effect of delaying your clutch's lockup point, but it also has the negative side effect of increasing the amount of energy stored in the spinning crankshaft/flywheel ***y. That can easily add another 450ft/lb spike of torque on top of the torque your engine is already making at your staging rpm, not good for T5.

A much better plan is to lower the launch rpm to 3000, reducing that stored energy to something your T5 can handle. The downside to that is your clutch is going to lock up quicker and the engine is going to bog. The answer to that is to simply delay the clutch's lockup point using a "clutch slipper". In this case you are not really adding much clutch slip, here's how that's possible...a clutch slipping from 5500 to 3000 over .3 seconds without a "clutch slipper" represents about 11 revolutions of disc slip. A clutch slipping at 3000 rpm for .5 seconds is going to have roughly 12.5 revolutions of disc slip, so increased wear on the clutch is not as much as you might think. The good news for your T5 here is that the combination of lowering the staging rpm to 3000 and extending clutch lockup until the vehicle speed matches that 3000rpm, there is zero rpm drop, effectively eliminating the added torque spike from the flywheel completely!

Here's a link that explains what a clutch slipper is, how it works, and how it is adjusted for both "initial hit" and the amount of "lockup delay"...clutchtamer.com

This style of slipper also has the benefit of delaying lockup when the clutch is used on upshifts as well, effectively reducing stress on a T5's weak 3rd gear.

 

Great info guys. Thank you for posting! I know I have a lot of homework to do!


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Ive got a ST10, I think its around a '78 model aluminum case behind a 350 and a 3:42 rear gear. I am really displeased about the take off in 1st gear. It bogs the engine and is slow. Once it gets going it is fine but I guess 1st has low ratio. It ****s.

 

^^^You mean it has a HIGH ratio, likely 2.20 or 2.42, when it needs @ 2.64, being limited w/ a high rear-end ratio to boot. Your combo puts a lot of strain on drivetrain components. If you have a heavy foot , have extra clutch discs on hand... at the very least.

 

I think the S t10 could be had with some where around 2.95 first, if not from BW then maybe after market; I think Nash [mid 70's !!] made some low firsts for them...Liberty may still do..

 

That makes sense I have to really ride the clutch to get it going, either that or dump it and peel out. So I guess I need to look for a new trans because that clutch was expensive and I do not want to buy another one anytime soon.

 

Weedburner Thanks for the information.

 

I found this rebuild series on an early t-10 on YouTube. There are 3 parts and its pretty good instruction.

 

You need one out of a 1979 Firebird with a 3:42 1st gear and iron case. Have one in my coupe with 2:89 rear it is great.
The deep 1st gear is cheaper cuz people want the 2 series 1st


Ago

 

Thanks, I need to get on that. Its a real disapointment to drive right now.

 

Well, I'm in. You can probably guess that I'm a four speed guy. I try to have them in everything. I don't know anything about modifying them though. I did just buy one of those oddball A833 derived overdrive 4 speeds with the chevy bolt pattern. I'm hopeful it'll give me some better cruising with 411 gears.. Early nineties I had a 56 Chevy with a 427 and hemi fourspeed trans. I really liked the spacing on those. Thanks for the thread idea---


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Great thread.

I remember reading on here that your first gear and rear end ratio needed to be greater than 9 when multiplied together in order to gibe the motor enough mechanical advantage to get the car moving. Does this sound correct?

 

Here's a different modification for a Muncie M22.
The front of case has a steel "teardrop" shaped insert to stop the mainshaft and the countershaft trying to grow apart in a high torque application.
Done in the days when factory casting numbers were required . I used in an old Road Racing car with 650 ft/lbs getting shoved through it

 

I'm using a muncie close ratio [2.20 low gear] in my lightweight [should come in at 25-2600 lbs] ford coupe with a quick change rear. That way I can run 4.56-4.88 gears around town to save my clutch and in 15 minutes I can change to a road gear for hiway trips. Part of the decision to do this is just to have "coolness". I LOVE the sound of going through the gears with a close ratio trans!

 

I've never run anything besides a manual in a performance car. So much more fun!

That being said, they do have their limitations. The close ratio units like the M21/M22 with a typical 2.20 first really need a 4.10 gear to get moving. The advantage here is that with closer ratios, shift rpm stays closer between gear changes, which really makes a difference at high rpms. The problem is with 4.10 or deeper gears, freeway rpms tend to run a bit high. We put a set of 4.10s behind a close ratio T10 in my sons's car with a 283 and it's great in town, but 4K to run with traffic on the highway. Options that we have looked into include T5's, which are known to be weak. They can be upgraded, but at great expense, and even then, I've not found any internal rail type transmission to shift well. There is a trick where you can add the overdrive unit from a Saginaw 3 speed to a Saginaw close ratio 4 speed, but in the end, you still have a Saginaw that will eventually grenade. I have yet to find a Saggy 3sp+O/D anyway. Used to be every hot rodder had a 3 speed backup under his bench.

Wide ratios are nice for street cars with mild motors, but I seem to run too much cam and compression to make them happy, plus I want my rear gears to be ideal for the 1/4 mile.

Devin

 

I'm in!!!! I used to run 4 speeds in my 68 chevelle. Saginaws, muncies, T-10s, broke em all. ended up putting a liberty proshifted Top loader in. That held up but went through clutches. Now in the process of building a 62 Bel air with a 350 and an old cast case T-10 with liberty pro shifted gears. The rear is a 9" with 3.70s but I also have 4.30s on a spool that I just might use. Also still have the Top loader if I decide I should use it. Should be fun!!!

 

Try these guy's for a stronger Muncie
http://autogear.net/

 

Thanks for all of the great information and links guys. I know I have been all over every one. I cant get enough.

Check this out! Just because Grumpy was the man. I know that its a little late for the HAMB but here is a great video of one of the best in action.

 

here's a great old book I have.....neat stuff in there.....

 

Loved watching the Grump do his little waltz between 1st n 2nd gear


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Here is an interesting article out of my archives that goes back to 1975. This is for Ford top-loader fans who wanted to convert their box into a clutchless 4-speed.

 

Great thread... I'm doing a car with a M20 (2.56 1st gear) and a 4.10 posi rear and it will weigh about 3450 when complete. So it should move off the line well enough for me.

 

Love those 4 speeds, built quite a few muncies , I'm a open wheel / road racer type & gotta say T10 prob toughest economical choice due to their straighter cut gears , almost same degrees as M22. But I love muncies, I used the Italy M22 gears in my 69 Z & love them. Here's a few good Muncie tips p***ed down from an old time mentor to me. To make wobbly inputs engage deeper into 1st gear syncro hub use dorman .030 shim #730-013 on input before installing bearing takes away slop. Try to get old stock USA made bearings not imported ones. N1307L input slop deference in some cases is unreal with cheapo's. Get a "1" wooden dowl or 7/8 if early case to load countershaft needles on , cut to about 8 inch ***emble all the needle rollers n washers & drop into case, then slide real counter shaft in behind it. I've filed worn syncro "collars" but now there are amazing aftermarket ones now which engauge deeper & better than originals "so it won't pop out of gear under high rpm. I use to take one regularly close to 8000 Saturday nights at the track. There are also h/d rear output bearings with more rollers "aka" T10 units u can upgrade to. Just a few quickie tips that'll go far. Invest in a quality bell housing, get a dial indicator setup & check runout. If all is square with the world it'll live longer & not scrub speed as if it were mis aligned. A heavy SFI rating is a must, I've seen some nasty carnage in the pits with Oem units. I run a McCleod, If you can't afford one just sit it out till you can get one. Hard to grow back feet & toes! Also the input nut wrench is worth buying if you plan on more Muncie tinkering. Here's a few pics , some old gm "slick shift" toothless rings, my 2 speed a mod Muncie, & s****s I've bought over the years. Notice the broken ears on lower left one ! Like said I also agree their a road race minded ****** but are some slick shifting ****ers! I've gutted a couple but was always able to fix Em back up. I believe there's some aftermarket Oem case braces out too now. Good luck!

 

A hydraulic throw out bearing is a slick & easy set up too, , here's a ram unit on a a Saginaw 4 speed with r10 overdrive conversion I just put together for dad's 53 235. The saginaws just can't take much abuse from a performance perspective. Under 250 hp n low torque. No clutch linkage under car! Carry on.