School me on CVs.

bobsson

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So I was looking into a truggy chassis and had some questions.

I'm thinking of taking the LS3 used for 6100, running that through a T400 and to an IRS 9 inch center.

Will a 35 spline 934 cv set up work with this horsepower level and approximately 22 inches of travel? I'm not sure on the width of the rear. I might use it to race some sports man classes and pre run races so it will need to survive abuse.

Thanks.
 

isdtbower

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Just a reply: Probably borderline with 35 spline. 33/40 spline probably better for the IRS. You could start that way and then buy axles and stars if there is a problem. The 35 will absorb more hits, but I would opt for 33 spline to start and minimize the half shaft diameter for those hits. 9"' might be too small depending on what you are planning with the truggy. Ultra4 are running 35 spline 935 and 30 series in the IFS for turning. No one is having 35 spline issues but is IFS. A 9" , 40 spline is minimal in the Ultra 4 rear straight axles. It is probably used more for the high pinion and acceptance of 10" gears.
 

bobsson

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Just a reply: Probably borderline with 35 spline. 33/40 spline probably better for the IRS. You could start that way and then buy axles and stars if there is a problem. The 35 will absorb more hits, but I would opt for 33 spline to start and minimize the half shaft diameter for those hits. 9"' might be too small depending on what you are planning with the truggy. Ultra4 are running 35 spline 935 and 30 series in the IFS for turning. No one is having 35 spline issues but is IFS. A 9" , 40 spline is minimal in the Ultra 4 rear straight axles. It is probably used more for the high pinion and acceptance of 10" gears.
If I'm understanding what you're saying, use 33 on flanges of the 9" and 40 spline on the wheel end? I'd be concerned with 450+ HP going through a 33 spline set up breaking CVs at in opportune times and leaving me stranded which is why I was thinking of going straight to 35 spline. I'd rather be over built instead of under built.

Thanks for taking the time to respond, I've never run anything with CVs before so I'm complete new to them.
 

isdtbower

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I really goofed! I knew it within a few minutes but was away from the computer. 35 spline is the biggest you can get in a 934/935/934.5 CV So there is part of your answer. To go bigger like probably many of the newer Class1 buggies, you have to go to the bigger 30 series CV. They can take the 1 3/4" 33 or 40 spline axles. The 935-35 spline axle is about 1 1/2". That was the confusion over the smaller 934-33spline at around 1 1/4".

A few years ago when HP was around 450 most class 1 was probably using the 935-35spline CV's. Today Class 1 (IRS) and Ultra4 (IFS) with 700hp+ motors they are running the larger series 30 CV's with 33 or 40 spline axles.

I would also note that the stub axles for a 935 size CV can be built with 33/40 splines if the drive flanges/lockers/spool/etc. can take the size. This is very common as those are short and can break before the longer half shafts.

Actually I am in the same boat as you are building a IFS/IRS 4x4 KOH style rig. I have a 500hp SBC and anticipate that I will be about 4k lbs, with 40" tires. The IFS center is a 9" and the IRS center is a Quick change. I will also use 35 spline half shafts in 935 CV's except for the IFS outer which will be the larger 30 series with the "small" 35 spline shaft for 39' turning. Unfortunately the 935 size was set a few years ago before the 33/40 was popular. I am now going to rely on the torsion absorption of the haft shafts, the torsion bar in the QC, torsion bars for drive shafts and a torque converter to absorb the shock loads from rock crawling and jumping with 4wd.

I know I will have to drive with the CV's constantly on my mind. Everyone is tooled up for the 33/40 spline CV's and axles now. You can't care much about protecting your drivetrain in KOH racing and the larger stuff is working pretty well. If something breaks it was a huge hit, the front overturned, or the limit strap broke. 10" rocks are nuisance rocks. Consider where the sportsman class is going. It is a real budget decision to go the bigger route, But along with flattening the whole wallet you get less maintenance, worry, etc.

FYI: The QC was chosen because they can handle high HP, and can be built at 7" Flange to Flange distance instead of the 12.5-14.5" F-F 9".

Since you are running desert, I would guess someone in Class 1 could give you some more relevant info. 35 spline is an easy decision. Going larger yet another. ($$$)
 

bobsson

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I really goofed! I knew it within a few minutes but was away from the computer. 35 spline is the biggest you can get in a 934/935/934.5 CV So there is part of your answer. To go bigger like probably many of the newer Class1 buggies, you have to go to the bigger 30 series CV. They can take the 1 3/4" 33 or 40 spline axles. The 935-35 spline axle is about 1 1/2". That was the confusion over the smaller 934-33spline at around 1 1/4".

A few years ago when HP was around 450 most class 1 was probably using the 935-35spline CV's. Today Class 1 (IRS) and Ultra4 (IFS) with 700hp+ motors they are running the larger series 30 CV's with 33 or 40 spline axles.

I would also note that the stub axles for a 935 size CV can be built with 33/40 splines if the drive flanges/lockers/spool/etc. can take the size. This is very common as those are short and can break before the longer half shafts.

Actually I am in the same boat as you are building a IFS/IRS 4x4 KOH style rig. I have a 500hp SBC and anticipate that I will be about 4k lbs, with 40" tires. The IFS center is a 9" and the IRS center is a Quick change. I will also use 35 spline half shafts in 935 CV's except for the IFS outer which will be the larger 30 series with the "small" 35 spline shaft for 39' turning. Unfortunately the 935 size was set a few years ago before the 33/40 was popular. I am now going to rely on the torsion absorption of the haft shafts, the torsion bar in the QC, torsion bars for drive shafts and a torque converter to absorb the shock loads from rock crawling and jumping with 4wd.

I know I will have to drive with the CV's constantly on my mind. Everyone is tooled up for the 33/40 spline CV's and axles now. You can't care much about protecting your drivetrain in KOH racing and the larger stuff is working pretty well. If something breaks it was a huge hit, the front overturned, or the limit strap broke. 10" rocks are nuisance rocks. Consider where the sportsman class is going. It is a real budget decision to go the bigger route, But along with flattening the whole wallet you get less maintenance, worry, etc.

FYI: The QC was chosen because they can handle high HP, and can be built at 7" Flange to Flange distance instead of the 12.5-14.5" F-F 9".

Since you are running desert, I would guess someone in Class 1 could give you some more relevant info. 35 spline is an easy decision. Going larger yet another. ($$$)
I was looking into QC rears and really liked the idea of them being narrower to reduce CV angles, but everything I saw said they wouldn't stand up to desert abuse. Which one are you going with if you don't mind me asking?
 

isdtbower

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I got mine from B&J Engineering , now in Kingman, AZ. They might not be tooled up anymore??? Fortin has a QC and a regular center also. A call to them would give you some numbers and whether running 935 is adequate. Jeff Fields at Transaxle Engineering would be another to check. Figure in the $6k range.??
 
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