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5 or 6 speed C3



Tired of reving the engine to bits on the highway.....
Planning to do a transmission transplant this winter, but need some info from somebody who already gone thru this.

Would like to use the Richmond 5 or preferably the 6 speed. My concern is not to have to cut or modify my crossmember to much
(so I can restore to original some day) and that the new shifter ends up in the original hole in my console.
Anybody out there with some input on whats involved to make this work ?

Question two : Who sells better drive / halveshafts (considering a
"upgrade" while I am changing the gears) ?


/ Henjo
Henjo, I can't help you with your questions about the actual swap, but I too was thinking of switching to a Richmond six-speed.

After talking to several people in person, and some more people on the internet, I found that a lot were disappointed in the Richmond unit for the street. Among the list of complaints were comments about difficulty shifting, popping out of gear, etc..

Now some of those problems may have been ajustment related and may not be problems after all, but I'd do my research before committing. ;)
Chris, How is your project coming?
Glad you asked.

Just dropped the block off for some unpleasant repairs this week. We are going to weld a stud on the oil filter side of the trans to block mount. This is where the edge of this block had been cracked. It should work fine. At least it saves me from having to replace the block.

Picked up a replacement passenger door today. Mine was way too rusty to save.

I decided to fully mount and fit both doors before going to the race shop for the roll bars/saftey harness mount. That should come soon. I will work on that this whole weekend.

Here comes the scary part. I am putting the part number list back together and putting the finishing touches for the engine list.

Edlebrock is going to love me.

This is what is killing me. I have an awesome 355 small block that I built for my V8 Fiero. I put about 3k miles on the engine and then yanked it in favor of a mild motor to sell the car with.

This engine is a 1990 full roller with Edelbrock alum heads, Crane .500 lift hydraulic roller cam, 1.5 roller rockers, hardend push rods, fully balanced, 9.6:1 compression, and a dozen other nice little goodies. With the Weiand intake it was good for 430 hsp.

This thing is just sitting in the shop waiting for a good home. I would like to sell, but never know when I might have a use for it. Anyway, the wife and I had a long talk this morning about the plus and minus of putting that in the car to get it up and running and build the big block on the back burner. I actually think she is hoping the small block will find its way into her 90.

Believe it or not, she says--build the big block. Why have crackers when you can have cake!

If I ran my small block (at least for now), I could have this whole car on the road in about 4 months.

The decision is killing me.

Decisions, decisions.
Another alternative

I think all us guys who voted yes in the "modify or not" pole go through the same decision making schema.
I too looked at the 5-speed conversions, Richmond ROD 6 speed.
I decided to go instead for an electric overdrive from GearVendors.
I did so not for price reasons, it ain't cheap, but for performance and dependability reasons. It provides a 22% reduction in rpm, you can use it in any gear or not, you don't need to use the clutch to engage it, just hit the button.
It can handle up to 1600 (!!!!!) horsepower. Doesn't require the any structural modifications except a shortened drive shaft and dimpling your floorboard a little.
Turn your M-21 or M-22 4 speed into a 7 speed (not recommended for first gear).
Although it is sitting in my garage I have scheduled this as a winter project along with the Vintage Air system in anticipation of next year's Hot Rod Power Tour.
Thanks to all

Thanks all for the input. After reading a whole bunch of net traffic on the overdrive subject, I am leaning most towards the 5 speed ROD swap. This appears to have the least impact on my car (originality and all that...) and also more people seems to have had problems with the 6 speed then the 5 speed. So the 5 speed and a 2.73 in the rear will give me a relaxing 2300 rpm (approx) at 70, and still provide a resonable launch.
Will however check out the GearVendors overdrive - but the "dimpling of floorboard" could be a showstopper !

/ Henjo
Hanlon Motorsports

Henjo and others,

I know it's been a while since this thread has been looked at, but in my search for information about the subject I figured I'd see how your project turned out and post another suggestion.

Have any of ya'll heard of Hanlon Motorsports . A friend of mine has an old firebird, not sure what year, that he put one of these transmissions in. It's a 5-speed Ford transmission (if we can look past that part, haha) that is fit for GM spline. He said that it has dropped his RPM from 3100 at 65 mph to 1100. Now, I'd have to see this to believe it, but there's no harm in doing a little research. The upgrade is $1800 and bolted right in for him. I emailed Hanlon to see what they could do for me specifically. I'll post what they say.

Just another thought.

The GV overdrive is installed and running. Very cool. You can use the clutch for regular driving or hit the button on the specially designed Hurst t-handle and lay down some rubber.
Passing at highway speed is cool too. Just hit the button to downshift at 80mph from 4th overdrive to 4th and launch.
GV Overdrive.

Can you send pics and a little info about your overdrive unit? For example: part number you used...approx. cost of unit and expenses incurred during installation. How many hours it took to install. I'm very interested. I don't think that the gasoline prices are going to go down anytime soon. ($1.67 and climbing) 93 octane :(

Thanks, Sarge

I think what you are referring to is the Tremec 5 spd. This thing is great! I have done some research so I will let you guys know what I have found.

The tranny costs about $1900 and is made for Ford and GM to.
The gear ratios are as follows
3.27 1.98 1.34 1.00 .68 Reverse 3.00
This thing can handle 525 ftlbs! With a 4.11 in the back you can do some damage on the street with a well built strong engine and have durability.

In terms of bang for buck this is the best that I have found, at least other than flat out racing. If thats the case then you can get the super T-10 to handle 1000ftlbs for $4k. I have considered buying the tremec but don't know how well it will bolt up to a C-3.I will eventually be putting in a stroker and need something that can handle the torque. That tranny was my answer. I wouldnt doubt there would have to be modifications to the tunnel and crossmember but how much i don't know.

check this site out


hope this helps

Thanks for the extra info

I appreciate you posting the info. I emailed the Hanlon Motorsports to find out the difficulty of bolting onto a C3. I'll post what they tell me.
sscam69 said:

I think what you are referring to is the Tremec 5 spd. This thing is great! I have done some research so I will let you guys know what I have found.


The T-5 is a piece of junk. No way I would use it for nothing!:nono
When you want to put in reverse its always hard and will make noise unless if you put it in 5th before going to R, moreover when downshifting hard from 3rd to 2nd, it will always make that freaky noise, even if you hit the cluch long before shifting, more, it doesn't like to be speed shifted from 2nd to 3rd, on high speed, it simply wont engage. Now the T-56 is better in all of these aspects, but it only has a problem (in F-Bodies) when downshifting to 2nd from any other gear it's hard not to put it in 4th instead of the 2nd (may be shifter problem??) and the ZF-6 is the best trans I've ever seen in US cars. No problems at all, good shifting and engaging at all speeds, very smoth operation too.


Thanks for the info on your experience. I looked around on information in the ZF-6. From what I found in the couple readings I did was that this transmission would fit '93 Vettes and up. Do you know if it'll bolt up to a C3 or if the modifications are minor enough that it would be worth using?
Well.... I have a ZF-6 in my 82 but it came like that when I bought the car, and I don't see any major interferences in the frame or cross member (which looks like it was relocated!) The shifter is not the same also, and more thant this I still have to discover :)But the ZF-6 came in corvettes from 89 to 96 so you can find it in these years.

Whats the ZF-6?

Well that sucks, about the T-5. Did you own a stang? Was that a problem your particular tranny have or were those common problems?

Well the T-56 can handle 425ftlbs. I am eventually going big, I am talking about 600ftlbs or so. So what I wanted to do is just make the long term investment with the Tremec TKO and have that be the least of my worries as I build up the engine, at least for a while. The T-56 costs about $3k (don't want a used one). In that case I would just go with the super T-10 beefed up to handle 1000ftlbs for $4k. Bang for buck and longevity you know what I mean.:confused

If you look at the website address I posted they sell a yoke for 63-82 vettes.

sscam69 said:

Whats the ZF-6?

Well that sucks, about the T-5. Did you own a stang? Was that a problem your particular tranny have or were those common problems?

Well the T-56 can handle 425ftlbs. I am eventually going big, I am talking about 600ftlbs or so. So what I wanted to do is just make the long term investment with the Tremec TKO and have that be the least of my worries as I build up the engine, at least for a while. The T-56 costs about $3k (don't want a used one). In that case I would just go with the super T-10 beefed up to handle 1000ftlbs for $4k. Bang for buck and longevity you know what I mean.:confused

Well ZF is the 6 speed trans that came in the C4 from 89 to 96. It's German as is the best all around trans that I know, it comes in cars like: BMW's Mercs, Jags...Chevy is now puting them in the pickup series with those vortec 8100. Oh, and ZF has now the new ZF 6 speed automatic!:_rock
The torque rating I don't know but the ZF from a C4 was built to handle around 400 ft/lbs(??) but the new one in the pickups is rated for 650 ft/lbs so it should be enough!
The T56 was used in the F-boby and the viper so it's reasonable!!! About the T10, Hmmmmm 4 speed!!! 1000 ft/lbs sounds very good but 4-speed... It all depends what you want to do to your car! If you wanna drag race it, its a good trans, but if your road racing or just cruising :nono you'll need more gearing.

I'm doing auto-to-manual swap as part of my body off job. I got the tranny from G-Force Transmissions with Long shifter for 1450$

The tranny is Richmonds 5-speed road race version, which means tougher stuff inside.

Now I'm changing the rear end ratio to 2,70ish.
I'm surprised no one mentioned the Big Block From Hell series, by Hib Halverson. They put a Richmond 6-speed in his '71 BB Vette. I have that issue and in it was another article on transmission swaps by Vinnie Kung. Here are a few excerpts:

If you feel that a 6-speed is unnecessary, Richmond also offers a 5-speed setup that may be more to your liking. According to Terry Meehan at Sport Center in Hoboken, NJ, can be installed with little difficulty. Tony elaborated on an installation in a 1981 Corvette, but informed us that just about any Vette with a 4-speed can be easily updated to this overdrive unit with little difficulty.

The Richmond 5-speed practically slides right in, as it uses the same bellhousing bolt pattern at the original 4-speed, and the original shifter from the 4-speed can be reused as well. As long as you get the proper input shaft dimensions, there is no need for any gearbox or bellhousing modifications. However, there are two points that need to be addressed: The driveshaft yoke going into the gearbox needs to be the larger unit as used in the 6-speed, and the rear crossmember requires a small flange welded to it to accomodate the 5-speed's rear mount.

Many of you have written to Vette to learn more about the feasability of installing a fourth-generation Camaro or Firebird T56 6-speed gearbox in your Corvette. Although the OEM T56 has many outstanding feature, including an internal rail shift mechanism, small size and relatively light weight, this gearbox may seem an easy sawp, but in truth, it's quite difficult to make it's installation a bolt-in affair.

Despite the fact that it will bolt onto the back of any small- or big-block V8 engine, production units for General Motors applications utilize a pull-style clutch, as employed on all 1993-98 Camaros and Firebirds. Because of this, the T56 bellhousing must be used. If you look at how the geometry of thearm works,you can see how it changes the motion of the slave cylinder to activate a pull-style clutch. The slave cylinder must be checked for actual bolt-on compatibility; if not, a T56 slave cylinder is needed. Since the T56 has the slave cylider mounted on the driver's side, C4 Corvettes don't pose a serious threat ti its' installation, because a flexible hose is easier to move than a fixed linkage. On 1982 and older Corvettes, getting the Z-bar linkage to work would either require a major redesign of the linkage system or a conversion to a hydraulic system. There are other teething problems to be taken care of, amking the expense of the T-56 conversion questionable.

When we called Borg-Warner to see if it offers a T-56 conversion package for Corvette owners, they told us that, unfortunately, no such conversion currently exists. (1998) A knowledgable technican from one of their distributors in the Northeast was versed in the sawp, and she explained that aside from a major clutch re-engineering, many additional modifications would be required to make the T56 work.

The article goes on about how a custom driveshaft needs to be custom fabricated for a Shark, because the length of the T56 is shorter than the Doug Nash/Richmond box. Also cited were mounting concerns for C4 Corvettes, with the strength of a torque arm created and bolted in to handle high torque.

The T56 shifter is placed slightly more toward the center, whereas the 4+3 had a side-mounted shifter assembly. This is where the design of the internal rail design of the T56 becomes immdeiate, as it is different than the external rod mechanism that the Doug Nash uses. GM always placed it's center-mounted shifter gearboxes, such as the T5, in third-generation Camaros and Firebirds on a 15-degree angle.They tilted it so the shifter wqould be closer to the driver. Therefore, one would think the T56 has to sit on an angle to have the shifter sticking out and over. If the handle is not modified correctly, shifter-to-console interfernence is guaranteed. But then, custom bellhousing modifications would be invloved because the bellhousing is integral with the case. Cutting and weldind the aluminum piece will only make more work for yourself. Besides, making sure that the input shaft is still centered to the block's bolt pattern is impoosible to do unless you have a proper fixture. Not to mention that it probably won't hold together.

If you don't mind cutting up your Corvette's floorpan, you could simply bolt up the unit without any modifications to the bellhousing. Two advantages to bolting it on the way it was designed are proper shifter location and a handle that does not have to be modified.

It would be completely up to you whether or not the Borg-Warner T56 would be appriopiate. The extensive labor that is required may not offset the final result, when you simple could go with a bolt-in kit that is commercially available.

Whew, my fingers are tired!


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