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6100, TTspec, Baja Truck only thread

Jerry Zaiden

Well-Known Member
From our research the big advantage would be the ratio options to help offset the 40" tire. We currently do not run an underdrive in our truck because we ran outta money and time towards completion of the truck haha. I did notice we were lacking in some places around the track power wise buuut we have a few other issues to sort out with tuning before we blame our shortcomings on the lack of an underdrive.
What a 5.43 didnt cut it with a 40 ;) We could have told you that. haha For referance GHA racing runs a 5.83 with a 39" and loves it. Also doesn't feel the need for an unerdrive. Hits over 120mph. Try a 5.83.
 

MTPyle

Well-Known Member
I think 5.83 is the best overall ratio for Spec truck. Our final ratio with underdrive and 4.11:1 is around 5.8

120mph in a spec truck is crazy fast. During the Mint 400 this year there was a tail wind on Jean dry lake bed so we and everyone saw big top speed numbers we got 119mph and a few others got 120-121mph that i know of. But with no wind or average runs with and against the win will be different. I don't know of any spec truck running 120mph in race trim without a tail wind and or getting thrown out of a plane.

We spent a fair amount of time with the numbers to see if we can improve but if we went lower gear we would get out of our TQ range and if we went higher we could not pull it. We top out at 114mph corrected for wind in race trim. Hopefully with our intake upgrade we will get another 1.5-2mph on top speed.


Mike
 

michael.gonzalez

Well-Known Member
I've been thinking of 5.37 with no underdrive just for the fact that the 5.37 pinion has an 8 tooth pinion rather than the 6 tooth pinion of a 5.83.
Stronger gear with the drawback of 5.37/5.83 = 92% of the gear reduction the 5.83 would give us.

We have always been a "To finish first, you must first finish" team but things may change as we transition into the competition of the 6100 class. Are lower gearsets in the TH400 allowed for all racing bodies or are stock ratios required for some? We could possibly gain some gear reduction in the trans for 1st and 2nd but SOL for 3rd (D).
 

MTPyle

Well-Known Member
Michael,

I think 5.37 would be way too high gear with 39-40" tires. 5.37 would be way too high for 37" tires.

You cant really change the gear ratio of 3rd gear in the trans, you can but its really expensive.

If I had to do it all again I would just buy 5.83 and plan on buying a gear set every 1500 race miles. I would not go over 1500 and might change them at 1000 miles.


Josh, Haha we actually did a lot of aero work on our truck. We moved the radiator out of the back of the cab and played with vents on the hood to release air pressure. That helped a lot and I think our truck is pretty clean. Our only issue now is with our suspension set up we lane back a lot when going fast and create more drag. But not sure we can do anything about that. If We could duck out of the air stream to pick up more speed we would. You should see me tuck behind a steering wheel of an indoor Cart. LOL Like an elephant hiding behind a pole. Hehe

Mike
 

michael.gonzalez

Well-Known Member
I can't argue against your experience so I will give the recommendation to run $1500 5.83 gear sets with no underdrive with plans to replace every ~1000 miles or so.

Is isentropic polishing a gimmick? I'm seeing it as an option but don't want to spend the extra dough if it isn't too beneficial.
I might give that Cryo-Heat guy a call and see how much strength he can squeeze out of it.
 

MTPyle

Well-Known Member
I am in no way an expert, just a guy thats learning. haha

We bought gear sets from Gear Works in Vegas. We got their top leave R&P and had them set them up. We never had a problem with a 3rd member and ran one set over 1500 race miles. So I would trust them.

I do have a brand new 5.67 Gear works set, a set with 500 miles and a set with 1000 miles on them. If you wanted to try 5.67 I can hook you up. But if you are running 40" tires I would go 5.83. Our 5.67 was perfect with 37" General tires for our LS3. If you run 5.83 I would raise your rev limiter on the LS3 to 6700. We did a lot of testing and 6700 was where we ended up. But we worked on rev limiter tune to make it smooth and not violent. Our LT1 is a little lower on red line.

Not sure of your tire you are using but you need to take that in consideration. The BFG slip more than the Toyo. Fortin told me BFG is 500 rpm more than Toyo. So that changes things. We calculated our slip with our older gear set to figure out our target for what we wanted. So gearing is not super simple. You need to look at Engine power curve, RPM limit, tire size, tire slip, tire growth, etc..

Mike
 

MTPyle

Well-Known Member
Vdrive

Great looking truck, thanks for sharing. I wish we would have gone with paint and not wrap.

What kind of truck is that?

Mike
 

Ikaika

Active Member
I am in no way an expert, just a guy thats learning. haha

We bought gear sets from Gear Works in Vegas. We got their top leave R&P and had them set them up. We never had a problem with a 3rd member and ran one set over 1500 race miles. So I would trust them.

I do have a brand new 5.67 Gear works set, a set with 500 miles and a set with 1000 miles on them. If you wanted to try 5.67 I can hook you up. But if you are running 40" tires I would go 5.83. Our 5.67 was perfect with 37" General tires for our LS3. If you run 5.83 I would raise your rev limiter on the LS3 to 6700. We did a lot of testing and 6700 was where we ended up. But we worked on rev limiter tune to make it smooth and not violent. Our LT1 is a little lower on red line.

Not sure of your tire you are using but you need to take that in consideration. The BFG slip more than the Toyo. Fortin told me BFG is 500 rpm more than Toyo. So that changes things. We calculated our slip with our older gear set to figure out our target for what we wanted. So gearing is not super simple. You need to look at Engine power curve, RPM limit, tire size, tire slip, tire growth, etc..

Mike
Hey Mike,.......if those 5.67 gearsets are still available I'd be interested in all ( 3 ) three sets as we are planning to test with 37" tires sometime next year.
 

43mod

Well-Known Member
I heard a tale about a shock co owner making some lock down solenoid valves for front rebound tubes to hold front end down on high speed stuff. My buddy found them upstairs in a heap. Must not have been the ticket 20 years ago.
 

MTPyle

Well-Known Member
Exhaust is a difficult thing to do with the way the rules are. You have to be behind the cockpit and not down. So either out the side behind the cab or go up like shown here. I think the way VDrives truck is is the best. Only concern with that design is heat to the shocks. But its safer and more quiet than out the side. Ours is out the side and its really loud in cockpit.

here are the BITD rules on exhaust

SCR-28 EXHAUST
Forestry approved spark arrestors or approved mufflers are required on all vehicles. Exhaust system design and installation must be done in such a manner as to extend a minimum of 1 foot past the rear of the driver’s compartment, be directed rearward out of the body and away from the driver and co-driver, fuel cells and tires. The exhaust must be placed in such a manner as to minimize the production of dust. Exhaust Pipes must extend at least to the rear of the driver’s compartment

Mike
 

Charlietuna

Well-Known Member
Exhaust is a difficult thing to do with the way the rules are. You have to be behind the cockpit and not down. So either out the side behind the cab or go up like shown here. I think the way VDrives truck is is the best. Only concern with that design is heat to the shocks. But its safer and more quiet than out the side. Ours is out the side and its really loud in cockpit.

here are the BITD rules on exhaust

SCR-28 EXHAUST
Forestry approved spark arrestors or approved mufflers are required on all vehicles. Exhaust system design and installation must be done in such a manner as to extend a minimum of 1 foot past the rear of the driver’s compartment, be directed rearward out of the body and away from the driver and co-driver, fuel cells and tires. The exhaust must be placed in such a manner as to minimize the production of dust. Exhaust Pipes must extend at least to the rear of the driver’s compartment

Mike
Thank you...I was sure there was a particular reason for it.
 

Jerry Zaiden

Well-Known Member
I've been thinking of 5.37 with no underdrive just for the fact that the 5.37 pinion has an 8 tooth pinion rather than the 6 tooth pinion of a 5.83.
Stronger gear with the drawback of 5.37/5.83 = 92% of the gear reduction the 5.83 would give us.

We have always been a "To finish first, you must first finish" team but things may change as we transition into the competition of the 6100 class. Are lower gearsets in the TH400 allowed for all racing bodies or are stock ratios required for some? We could possibly gain some gear reduction in the trans for 1st and 2nd but SOL for 3rd (D).
I can tell you 100% that 5.37 ratio will not work. An example is Vegas to Reno I started first and ran a 5.43 with stock transmission gearing. I could go about 55-58mph in the sand wash in second gear. I would shift to third and the truck would fall on its face. Take the advice and run a 5.83. We would run at a strong pace and NEVER failed that gear. We would run it at Parker, Mint, then SIlverstate then check it in the trash. We had Gearworks in Las Vegas set them up and never had an issue. Take this advice as you wish.
 

Michael Cohen

Well-Known Member
I can't argue against your experience so I will give the recommendation to run $1500 5.83 gear sets with no underdrive with plans to replace every ~1000 miles or so.

Is isentropic polishing a gimmick? I'm seeing it as an option but don't want to spend the extra dough if it isn't too beneficial.
I might give that Cryo-Heat guy a call and see how much strength he can squeeze out of it.
REM /

Iso surface finishing is a very big deal and very worthwhile. When NASCAR Cup cars started using them 20+ years ago, surface treatment on the R&P and wheel bearings were worth 4/10 of a second @ Talladega. Smoother surface, less resistance, cooler running, not to mention the parts look good enough to be jewelry when finished! :)

I would put cryo treatment a distant second to the above. Can be useful but it really depends on who is doing the treatment (as applies for heat treatments too), their experience, and equipment. There are a number of excellent providers all over the country. Do some research and good luck with the racing.

By the way, you are quite an accomplished young man per your profile. Great to see young sharp minds pushing our sport along! Congrats, your father should be proud!
 

Vdrive

Active Member
The exhaust comes out above the bedside, you can see it in the pic with the body on. Mostly because that is where I had room for the muffler to fit behind the extra cab body panel. Its just Too loud without muffler for me, I found I had to lift to hear the codriver talk and thats not going to work!

And it blows race gas exhaust into bitches faces.
 
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