Canam

I have a C4 road racing car that I purchased last year. I run a 355CI motor (Silverado truck block) coupled to a T10 4 speed trans and a Dana 44 with 3.07 gears. I've been evaluating the car all this year racing and although I love the T10 its gotta go. I'm short gearing on our long track which has a 4008 foot back straight and I'm on the rev limiter way before that. I don't want to go to a 2.73 diff. My motor doesn't build power over 5800rpm (335/375 at the wheels) and I can add power but I think a trans swap is a better way to go for this car for next year.

So, I can go with a 5 speed Tremic which is pretty expensive or a ZF 6 speed which can take the horsepower and torque no problem and then change the rear end gearing. This will also change my ability to use engine braking in corners which I dearly miss from my other cars and is causing me to lose time. I've been racing for 22 years.

My question is, what parts do I need to place a Tremic or a ZF in the car? My car has an SFI steel bell housing, uses a ram clutch with a centreforce pressure plate,a Howe steel flywheel, Howe TO hydraulic bearing and fabbed torque arm mount. I'm basically looking for a parts list. What can stay in the swap and what needs to be bought. Thanks for any help on this. I want to do it once and do it right. Maybe a Tremic is the best way to go if it will bolt right up?

Pat.

ScaryFast

I would expect that the Tremic will be the quicker solution for your block. There are a lot of kits out there for the ZF6, but I've not seen one for that block - unless it's the same as the L98 for mounting. I know most SBC's were close, so maybe it works.

The ZF6 is a great trans, but it is a boat anchor. If you like to keep the car light than it's not the way to go. In addition, nobody will work on them, so if you aren't experienced at transmission rebuilds you're looking at a lot of cash or a used trans.

My vote is Tremic, but they have their share of problems, too...

TJM

From the technical point of view, You can see 140MPH with the 3.07 in fourth . The 4 spd does not give up much until you look at OD.

2.73 would be like 163MPH , but with a engine that has breathing issues. I don't think you'll see it?

Kubs

The Tremic will most likely use the same or similar bellhousing/clutch setup that you currently have. Not to mention, transmissions like Tremic/TKO 600 comes with a much better geared 5th gear for road racing. I dont know how your 355 compares to an L98 long tube intake, but those dont breathe at high RPM either. I used to buzz the crap out of my L98 because if I used 5th the car fell flat on its face. I have a ZF6 and 3.33:1 gears.

bosco022

There are some used Nascar Jerico's and T101A's that have overdrive fourth gear. These would bolt in place of the T10.

If you could find one with something like 1.9 1.45 1.18 .9 it would likely work for you.

You would not have a pit out gear, but you would be able to use first gear in the slower corners on track.

Canam

4 speeds not an option. You need a 7400rpm motor to use that where I go. My engines a mild build and has huge torque but does not make power over 5800rpm, hence the extra gear I need. Tremics are great and you can even get a .68 5th gear, but if I can use a ZF I will. Much cheaper and I'm not making enough HP to cause it any grief really.
This is just a matter of money for me. If I don't have to spend 2400.00 on a Tremic I won't. If I can get a ZF in there a lot cheaper I will but I need to know if its going to bolt up. A stock gear set for an LTI (345) is probably going in the back.

Canam

I still have about 200 pounds I can take out of the car so the heavier ZF I'm fine with. If it blows up someone always has another one for 900 bucks or so. Thanks for bwing the closest to answering my question though. I'm thinking the ZF won't bolt up to the current bellhousing but I bet a Tremic would. I'd rather know before I buy though.

Kubs

The ZF has a 0.75:1 5th gear which is lower than the 0.68:1 you mention. That is more of an overdrive gear. The TKO 600 has an optional 0.82:1 5th gear which would be optimal for road race use. If I wasn't limited by class rules I eould be looking into a TKO.

Canam

Your right Kubs, I shouldn't have said that without rechecking first. I think there are 4 different ratios, the best being the .82 which is perfect for road racing as you said. I can't seem to get one for under about 2400 dollars though. Still, if it will bolt up to what I have thats not bad I guess.

TJM

A lot of money for a TKO? There is a Sticky on the C4 Tech Page that tells you everything you need to know about that swap.

We did the ZF swap out in the '84 POS. Find a donor or part out car.

Our complete set up was $1,500.00 Bell housing, nut s bolts slave cylinder, incl.

The '84 had a Dana 36 so another $1,000 for a 3:45 DANA 44, C-beam ect. Couple $100 to check them out [ finest kind no problems]

Sold the Dual Mass and bought an al. flywheel. $50.00 cost.

Runs quite well. C Beam becomes a non-issue.. even in an '84 chassis the later C-beam fit in well.

We run 3:45 gears and things do get buzzy on the back straights...

Air resistance is a limiting factor, too. Review your aerodynamics. Makes a big Diff. on C4.

mrc24x

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