Hot Rod Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
131 Posts
Discussion Starter · #1 ·
I am gathering all the information I need to do a tranny upgrade on my 74 Nova. I have looked at a few kits and think I can settle on one that mostly supplies what I need. I do have one question about dial indicating the bellhousing. Should I first measure the runout and only then order the proper dowel pins? I believe the dowel pins come with specific offsets and hence I would only know which ones to get after I know what to offset my bellhousing by. Am I understanding it correctly?
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #3 ·
I am also a bit confused as to whether I need a pilot bushing or bearing for the Tremec. I do not know what my 350 currently has. Is there any way to find out without dropping the current trans and looking at it?
 

·
Registered
Joined
·
443 Posts
It really doesn't matter whether you use a bearing or a bushing as long as you get the correct one. Personally I always liked bushings as they are less prone to moisture causing any problem and they last longer than your clutch will. Others prefer the bearing. The main thing is that the centerline of your trans input shaft and your crankshaft be as concentric as possible. Also, know that truck bellhousings have a bigger hole in them than passenger car four speeds need. That will let your trans go in place mis-aligned even if the bellhousing is concentric. So be sure you have a passenger car housing. I would just order which ever one you want because they both fit. Unless you have a high HP vehicle this is all going behind a rebuilt clutch should work just fine. The Tremec should bolt into the car just like your old trans and the stock clutch linkage should work fine.

The offset pins work by turning them because they are slightly eccentric.

1. You put the bellhousing in place.

2. You attach a magnetic base to the rear of the crankshaft.

3. You attach the dial indicator to the magnetic base and adjust the indicator so it touches the inside of the bellhousing hole.

4. Rotate the engine by hand with a flywheel turner and see how far off you are and then set it a little closer.

5. The easiest way is to try to get the indicator close to some mark in only two directions. Either up/down OR side to side (don't worry about perfect yet)

6. Now work on the other direction (do one plane at a time and its easier to do)

7. Now repeat 5 and then 6 to get really close. (You may actually find that one axis is zero both ways while the other cannot be zeroed.......yet)

8. The TOTAL runout you are getting is TWICE what you need to adjust the housing. Turn the dowel pins and see which way makes it better.

9. Set the dowel pins where you think is best. May just need to move one.....or maybe both.

10. Now try re-zeroing your indicator.

11. You may have a bellhousing that does not have a perfectly round hole. Generally thats ok. You just want to get the housing so that you read the same variation side to side or up/down. Thats called "best condition" Don't worry if you can't get it perfect. Most aren't.....but you need to be in single digits like maybe .005-.007

I would go to Youtube and watch some videos on dialing in a bellhousing and then when you do your own it will be easier.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #5 ·
Great info. Thanks. Yeah I have watched like 18 videos on the alignment and I do believe I got the theory of it down cold. The practice will show how easy or hard this really is.

I do wonder though, even if I have the bellhousing hole perfectly centered, what if there is a tiny runout created by how the trans is mounted to the bellhousing? I mean how can I assume the bolt holes are precisely where they need to be on the housing and/or transmission?

The other question I had was the Tremec TKX seems to be on back order just about everywhere. However, Speedway Motors swears up and down they have it in stock and ready to ship. Has anybody dealt with them before? Are these guys reliable?
 

·
More for Less Racer
Joined
·
20,935 Posts
Speedway Motors has a pretty good reputation, been around for 50+ years.

Bolt pattern on trans or bellhousing doesn't have anything to do with alignment.....the center bore in the bellhousing makes a tight fit to the bearing collar on the front of the trans to locate it.....the bolts just hold it into place.

Thats why the bellhousing center hole has to be matched to the trans collar.....and why you can't mix the smaller car collar with a larger opening truck bellhousing, it won't align anything that way.
 

·
Registered
Joined
·
5,225 Posts
When I advise clients on bellhousing alignment, this is the video I send them.
Its easier to calculate the amount of offset you need and which way it needs to go, than to try different things and see what happens.

It absolutely does matter if you use a bearing or bushing. Or, better said, it probably matters in 1 regard. Tremec often has various warranty requirements, including bushings or bearings. At least they did with the TKO, so I'd check.

Not seen in the video: When you're done checking the bore for runout, pull the dial indicator up (out of the bore) and rotate it so the plunger is now resting on the back face of the bellhousing (the surface the trans will mount up against). What you're doing is checking for parallelism between the back face and the flywheel. This is often missed, but in a world of stamped housings and powdercoat? It can cause problems. Problems that necessitate pulling the gearbox to rectify.

I prefer the RobbMC dowel pins if you haven't bought any.
 

·
Registered
Joined
·
443 Posts
While Autogear and I (respectfully) have a difference of opinion about whether it makes a difference whether you use a bearing or a bushing, I'll add a few comments.

BOTH can go bad. I feel that the environment that they must operate in subjects them to moisture and sometimes directly to water. If a bearing gets any water in it, it's demise over time will cause looseness and not keep the input shaft steady. I have seen some bearings that were like that. With a bushing, water basically has no effect. That leaves the interaction of the shaft to the bushing/bearing as another consideration. When the engine is running and the input shaft is sitting still (at a red lite) the bearing removes any rubbing (as long as its in good shape) while the bushing does do some rubbing. Once the bushing has worn in its pretty minimal. There are pros and cons and I respect others choices. One thing to consider though is that these transmissions are used in a lot of "conversions", and when you bolt them behind an Olds, Pontiac,Hemi, Flathead, etc., there are not going to be bearings available all the time. I have a 500 Cadillac that I'm putting a Tremec Magnum 6 speed behind. Cads don't have a provision for a pilot bearing as they were all automatics. I could drill the crank for one, but luckily I found a company that makes one that fits without modifying the crankshaft. Its not a roller bearing.

If as Autogear suggests the mating surface on the back of the housing is not flat when you check it, check your mating surfaces for debris and try again. A few thousandths won't hurt, but if its too much, then the housing needs to be machined. My guess is you won't have a problem.

As for the shims, no you should not need them. You can change the relationship of the fork to the bearing by using an adjustable pivot or different length pivot.
Gas Automotive tire Wood Automotive wheel system Household hardware

Automotive tire Motor vehicle Product Hood Automotive design


Gas Engineering Motor vehicle Auto part Machine


This last picture is an engine stand I made that lets me invert an engine and install a transmission. I can set up a hydraulic clutch (or manual) and see what how clearances are working. It has a master cyl on the other side so I can actually push a pedal and see it work before I put it in a vehicle.
 

·
Registered
Joined
·
5,225 Posts
I don't think we have a difference of opinion. I prefer bronze; when required, we make oil-impregnated, non magnetic sintered bronze bushings for customers. I also am a Tremec PARTS vendor with "Elite" status through Tremec, and occasionally handle warranty work for Tremec (Bob Hanlon/ Hanlon Motorsports and Rockland Standard Gear handle most of the east coast).

Im only saying if the TKX literature specifies a needle bearing; or a block of cheese...then he should make himself aware of that and follow the mfg course of installation, because this is a serious investment time and money-wise.

With respect to bellhousing : flywheel parallelism; +/- 0.002 is about all you've got when using a tapered bearing gearbox (TKX/T56/TKO/T45/WC T5/ TR6060/ T56 Magnum/ZF etc. A Ball bearing/caged roller gearbox (Muncie/T10/Jerico/Saginaw/ etc.) can TOLERATE about 2x that, but closer to parallel is always better. Bore concentricity should be +/- .005 for a high performance application, or a tapered bearing gearbox. Ball bearing/ caged bearing gearboxes can work closer to 0.010. But using a .007 dowel pin is going to knock that 0.010 down to 0.003; so why not make it that much better.

Problems with alignment will have symptoms like popping out of 4th gear, artificial RPM ceiling for 3rd and 4th gear, poor pilot bearing life, poor input bearing life, cracked throwout bearing tubes, cracked clutch forks and short throwout bearing life. Its my most common technical installation question and complaint when installing a gearbox.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #11 ·
While Autogear and I (respectfully) have a difference of opinion about whether it makes a difference whether you use a bearing or a bushing, I'll add a few comments.

BOTH can go bad. I feel that the environment that they must operate in subjects them to moisture and sometimes directly to water. If a bearing gets any water in it, it's demise over time will cause looseness and not keep the input shaft steady. I have seen some bearings that were like that. With a bushing, water basically has no effect. That leaves the interaction of the shaft to the bushing/bearing as another consideration. When the engine is running and the input shaft is sitting still (at a red lite) the bearing removes any rubbing (as long as its in good shape) while the bushing does do some rubbing. Once the bushing has worn in its pretty minimal. There are pros and cons and I respect others choices. One thing to consider though is that these transmissions are used in a lot of "conversions", and when you bolt them behind an Olds, Pontiac,Hemi, Flathead, etc., there are not going to be bearings available all the time. I have a 500 Cadillac that I'm putting a Tremec Magnum 6 speed behind. Cads don't have a provision for a pilot bearing as they were all automatics. I could drill the crank for one, but luckily I found a company that makes one that fits without modifying the crankshaft. Its not a roller bearing.

If as Autogear suggests the mating surface on the back of the housing is not flat when you check it, check your mating surfaces for debris and try again. A few thousandths won't hurt, but if its too much, then the housing needs to be machined. My guess is you won't have a problem.

As for the shims, no you should not need them. You can change the relationship of the fork to the bearing by using an adjustable pivot or different length pivot.
View attachment 618996
View attachment 618997

View attachment 618998

This last picture is an engine stand I made that lets me invert an engine and install a transmission. I can set up a hydraulic clutch (or manual) and see what how clearances are working. It has a master cyl on the other side so I can actually push a pedal and see it work before I put it in a vehicle.
Ah, I see how I can adjust it. Makes sense. Btw, I will be installing everything without taking the engine out. That's the plan anyway.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #12 ·
When I advise clients on bellhousing alignment, this is the video I send them.
Its easier to calculate the amount of offset you need and which way it needs to go, than to try different things and see what happens.

It absolutely does matter if you use a bearing or bushing. Or, better said, it probably matters in 1 regard. Tremec often has various warranty requirements, including bushings or bearings. At least they did with the TKO, so I'd check.

Not seen in the video: When you're done checking the bore for runout, pull the dial indicator up (out of the bore) and rotate it so the plunger is now resting on the back face of the bellhousing (the surface the trans will mount up against). What you're doing is checking for parallelism between the back face and the flywheel. This is often missed, but in a world of stamped housings and powdercoat? It can cause problems. Problems that necessitate pulling the gearbox to rectify.

I prefer the RobbMC dowel pins if you haven't bought any.
Ok, I will also check the face of the bellhousing for parallelism. The question is what to do if it's not parallel. I don't think a dowel pin can pop the housing out a 0.001 of an inch, can it? Will i need shims of some sort?
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #14 ·
It really doesn't matter whether you use a bearing or a bushing as long as you get the correct one. Personally I always liked bushings as they are less prone to moisture causing any problem and they last longer than your clutch will. Others prefer the bearing. The main thing is that the centerline of your trans input shaft and your crankshaft be as concentric as possible. Also, know that truck bellhousings have a bigger hole in them than passenger car four speeds need. That will let your trans go in place mis-aligned even if the bellhousing is concentric. So be sure you have a passenger car housing. I would just order which ever one you want because they both fit. Unless you have a high HP vehicle this is all going behind a rebuilt clutch should work just fine. The Tremec should bolt into the car just like your old trans and the stock clutch linkage should work fine.

The offset pins work by turning them because they are slightly eccentric.

1. You put the bellhousing in place.

2. You attach a magnetic base to the rear of the crankshaft.

3. You attach the dial indicator to the magnetic base and adjust the indicator so it touches the inside of the bellhousing hole.

4. Rotate the engine by hand with a flywheel turner and see how far off you are and then set it a little closer.

5. The easiest way is to try to get the indicator close to some mark in only two directions. Either up/down OR side to side (don't worry about perfect yet)

6. Now work on the other direction (do one plane at a time and its easier to do)

7. Now repeat 5 and then 6 to get really close. (You may actually find that one axis is zero both ways while the other cannot be zeroed.......yet)

8. The TOTAL runout you are getting is TWICE what you need to adjust the housing. Turn the dowel pins and see which way makes it better.

9. Set the dowel pins where you think is best. May just need to move one.....or maybe both.

10. Now try re-zeroing your indicator.

11. You may have a bellhousing that does not have a perfectly round hole. Generally thats ok. You just want to get the housing so that you read the same variation side to side or up/down. Thats called "best condition" Don't worry if you can't get it perfect. Most aren't.....but you need to be in single digits like maybe .005-.007

I would go to Youtube and watch some videos on dialing in a bellhousing and then when you do your own it will be easier.
I have a question regarding the car vs truck bellhousing comment. It doesn't seem like the parts retailers distinguish between the two. What am I looking for when I am shopping for a bellhousing? For example, if I am buying this one: Lakewood 15000LKW Bellhousing, 1958-Up Chevy
What should I check to make sure it's for a car and not for a truck?
 

·
Registered
Joined
·
5,225 Posts
I have a question regarding the car vs truck bellhousing comment. It doesn't seem like the parts retailers distinguish between the two. What am I looking for when I am shopping for a bellhousing? For example, if I am buying this one: Lakewood 15000LKW Bellhousing, 1958-Up Chevy
What should I check to make sure it's for a car and not for a truck?
"truck" bellhousings have a bore in the rear face (called a 'snap diameter') of 5.125". The traditional car bellhousing has a bore of 4.685". The front retainer casting (the casting on the front of the trans that would incorporate your throwout bearing tube), has a flange that has to match the bore. There are spacer/adapter rings; but since youre buying a bellhousing, stick to the 4.685" standard dimension.
 

·
Registered
Joined
·
443 Posts
In the ad you posted it says that its for a Muncie 4 speed as well as some others. The Muncie has the same size bearing retainer as the Tremec.

Is there a reason why you want an explosion proof housing rather than a stock cast housing? They are safer if you expect to rev really high, but stock housings can be had used for about $100.

They sometimes interfere with the floorboard due to their size. The one below has all the "little things" that add up already included.

 

·
Registered
Joined
·
131 Posts
Discussion Starter · #17 ·
In the ad you posted it says that its for a Muncie 4 speed as well as some others. The Muncie has the same size bearing retainer as the Tremec.

Is there a reason why you want an explosion proof housing rather than a stock cast housing? They are safer if you expect to rev really high, but stock housings can be had used for about $100.

They sometimes interfere with the floorboard due to their size. The one below has all the "little things" that add up already included.

No sir. No reason other than the bellhousing I asked about comes with the kit I want to buy. Will a 168 flywheel fit into the bellhousing you suggested? Mine is GM# 3789733 (168 teeth) and specs say it's 11 inches in diameter. Shouldn't the bellhousing be slightly bigger than 11 then?
 

·
Registered
Joined
·
5,225 Posts
Just me, but thats a throwout bearing without a name and a pretty cheap fork. I like the bellhousing (but prefer the blowproof, even in a street car). The bellhousings have casting core shift occasionally, but so did the original 621's. If you really want a turn-key kit; Russ at 4speedconversions does a great job of sourcing high quality parts. As do the guys at AutoPartsObsolete.com
Theres nothing wrong with the eBay kit, its a personal preference for things like Aetna throwout bearings and NOS forks (or at least $50 reproduction from a known seller). I know not everyone feels the same way, and thats ok.
 

·
Registered
Joined
·
5,225 Posts
No sir. No reason other than the bellhousing I asked about comes with the kit I want to buy. Will a 168 flywheel fit into the bellhousing you suggested? Mine is GM# 3789733 (168 teeth) and specs say it's 11 inches in diameter. Shouldn't the bellhousing be slightly bigger than 11 then?
Its not your fault. People cross the 168-tooth flywheel and the 11 inch clutch disc and shorthand it as "an 11" flywheel". A 168-T flywheel is about 14", and the clutch and pressureplate are 11". Regardless of which way you go, the 621 style bellhousing or the Lakewood scattershield will work. But I for sure wouldnt trust anything but a namebrand throwout (Aetna for an OEM, or the McLeod adjustable mechanical). Im off for the weekend, if you have a question you NEED clarification on, PM me because I don't check the forums on the weekends routinely.

Nathan
 

·
Registered
Joined
·
443 Posts
Like Autogear says, different people prefer different things. I don't have anything against the explosion proof housing, I just prefer the aluminum or cast iron housings because they are usually lighter to work with and usually more compact than the formed housings. The formed housing has a flat plate that goes on the back of the engine that makes it more difficult to work on the clutch stuff and sometimes the explosion housings don't clear the tunnel as well. I have a formed housing for my Magnum to Cadillac conversion because its the only one thats available as far as I know. Nothing "wrong" with them. You are trying to do things the right way and learning things as you do. One thing you should learn is that there will always be differing viewpoints on even the simplest stuff. Often there is more than one acceptable way to do something. In any case there are a blue million Chevy engines that have had manual transmissions over the years, and the vast majority had no problems .....at least till they abused the clutches and transmissions for a while. I live near a clutch rebuilding shop. Everyone around here uses them. They can sell someone a "name" clutch, or they can build custom race clutches, and just regular clutches. They are a lot cheaper and thats where I always go. Never had a problem with anything I got from them. They also regrind the flywheels when I buy a clutch, which is handy. I'm just saying that I don't buy high dollar name brand clutches and I have always been happy with what I bought. Is every clutch rebuilder that good....probably not. On the other hand, they make clutches for everything from forklifts to huge trucks, and they grew from nothing to over a million a year gross. They do well because they treat people well and make good clutches for reasonable prices. So its not always necessary to buy a "name".
 
1 - 20 of 22 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top