Thread: Pinion Angle

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Originally Posted by 39 Chevy

I have had trouble with vibration for a while now an could'n find the problem. I took my car to a older gentleman who kinda dose his owne thing tends to his business. I talked to him about my trouble he said I'll find the problem so I left it.In a few day he called me back said your ready to go. Now my trans angle is down an the rearend is angled down to but not on the same angle it's smooth as silk and no vibration. That's right the opposite of what I have been reading so can someone please explaine

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Ok, here's the deal. The guy had a problem, the problem is now fixed.......

No Jerry, wasn't directed at you at all.... Just get tired of having the same "facts" off the internet repeated over and over again like they came out of some sacred textbook. A lot of folks would also tell me that my front end geometry is set up wrong, the body mods I do are wrong, and a whole host of other things. Been doing the cruizin' and go fast stuff for a bunch of years on bunches of different cars. I do lots of things that other's say won't work or isn't "correct" and I just keep going fast anyways!!!!!

As I said before, the only absolute in building a Hot Rod or a Race Car is that there are no absolutes! Question everything, keep trying new things until you land on the combinations that work for you. Anyway, time to get back out to the garage and do some work. Splitting my time between the '57 and the Cutlass.

Jerry, I do need to chat with you about some LS stuff, gonna be around this weekend at all?????

Yeah We need to see some of your 57 stuff been way to long

I was in a spicer driveline class years ago and the instructors kept drilling in our heads that the up and down of the pinion isn't as nearly as important as making sure you have some operating angle on the u-joint. If you have no operating angle on the u-joint, it can cause premature wear and failure. No more than 3* on a light truck, or 7* on a heavy truck. They showed us many scenarios where pinions were up and trans's were down. On some trucks the pinion is down and trans is down. Just depends what length, and heights you have to work with. That class has helped me a lot over the years. Most of the trucks I build is a no brainer because they're so tall. Trans is automatically down and the pinion has to go up. On the low trucks I've done, they were more race type so we went down and down and haven't seen any ill effect from it. One of which is a 800hp standard cab short bed cummins street/drag truck. It went from tossing 1410 u-joints after 3 launches to driving and beating on it for years with the same spicer u-joint I put in it 5 years ago. I was surprised to hear that as those dudes let that truck eat.

Many times on these forums I have recommended mounting a video camera underneath the car with good lighting, then making a pass. You can see real quick what's goin' on under there. You could even mount a pointer on the pinion retainer that would register on a flat plate or board under there and tell you exactly the angles that are in play.

Different types of rear suspension will require different set-ups in the first place. The pinion on a leaf spring car will climb the ring gear more aggressively than on a triangulated 4-link system, for instance.

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Good points Tech.

Originally Posted by techinspector1

Many times on these forums I have recommended mounting a video camera underneath the car with good lighting, then making a pass. You can see real quick what's goin' on under there. You could even mount a pointer on the pinion retainer that would register on a flat plate or board under there and tell you exactly the angles that are in play.

Different types of rear suspension will require different set-ups in the first place. The pinion on a leaf spring car will climb the ring gear more aggressively than on a triangulated 4-link system, for instance.

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Before the days of the small little remote camera's my pal Rodney ran a little Fairmont that I built for him. Had a removal panel (dzus fasteners) for a floor around the rear end housing. Used a home made camera mount and focused the camera on the control arms....Truly amazing how things move around back there during a pass!!!! Now everyone has a Go Pro camera mounted on the roll bar facing through the windshield, and as you state Richard, they're missing the real show!!! My friend Schultzie (runs a wingless sprinter with his son) has a go pro and has mounted it many, many places on the car to watch suspension movement, shock travel, and a host of other things....very educational!

I'll have to look thru the stuff in my storage to see if I can find the sensors, etc that were used on the Indy cars in late 80s/90s---suspension/shock travel, rotation devices, accelerameters, pressure, temp, etc


do they still put the rubber o ring indicators on the shocks? tell tale needles on tacks??? probably use a phone APP these days

I've been trying to copy photos from my gallery (page 5, photos 624 and 626) to this thread in order to show explain how I deal with drive line angles. In these particlarpics, however, it is a irs altho what I want to do does do some basic install strategy and process.











In the photo at the left you can see the fixture that I use on cars similar to the 30s hot rodsto locate the crank nose centerline at the level of the top edge of the frame rails(this is for blocks/cranks similar to chev or non FE type fords or 383-hemi mopars with skirted blocks) Center pic shows crossmember with transmission mount bolt holes to locate trans tailshaft c/l in direct line toward pinion shaft c/l (yes, I do the fabrication around a direct line for crank/trans/pinion and then work offset for some u-joint angle)Pic at right shows me moughting up the brake system master and hydraboost. I will mount up all the stuff for the vehicle BEFORE I do all the tubes for the center frame structure---fuel pumps/filters/regulators/exhaust(this car got side pipes,easy)


This car got an Ford 9 inch IRS with a centered housing resulting with a sideways angle to the drive shaft amount of the pinion offset in the Ford niner (forgot exactly what the degrees result was with this length shaft but within reason)


With the IRS there is no movement of the housing so it was a piece of cake compared to a live axle type build.

[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/XGCQ99Q6/MVC-624F.JPG[/IMG]


[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/5UN7TFUG/MVC-625F.JPG[/IMG]




[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/70GAJ6B1/MVC-626F.JPG[/IMG]

Originally Posted by jerry clayton

[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/XGCQ99Q6/MVC-624F.JPG[/IMG]
[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/5UN7TFUG/MVC-625F.JPG[/IMG]
[IMG]file:///C:/Users/Gerald/AppData/Local/Microsoft/Windows/INetCache/IE/70GAJ6B1/MVC-626F.JPG[/IMG]

Those would be internal links to files on your computer, Jerry. See the "C:/Users/Gerald....."? That's your local hard drive, and you can only see those files sitting at your keyboard. Image files have to be saved out on some public server that can be accessed by anyone in the world to work.

Originally Posted by jerry clayton

I've been trying to copy photos from my gallery (page 5, photos 624 and 626) to this thread in order to show explain how I deal with drive line angles. In these particlarpics, however, it is a irs altho what I want to do does do some basic install strategy and process.











In the photo at the left you can see the fixture that I use on cars similar to the 30s hot rodsto locate the crank nose centerline at the level of the top edge of the frame rails(this is for blocks/cranks similar to chev or non FE type fords or 383-hemi mopars with skirted blocks) Center pic shows crossmember with transmission mount bolt holes to locate trans tailshaft c/l in direct line toward pinion shaft c/l (yes, I do the fabrication around a direct line for crank/trans/pinion and then work offset for some u-joint angle)Pic at right shows me moughting up the brake system master and hydraboost. I will mount up all the stuff for the vehicle BEFORE I do all the tubes for the center frame structure---fuel pumps/filters/regulators/exhaust(this car got side pipes,easy)


This car got an Ford 9 inch IRS with a centered housing resulting with a sideways angle to the drive shaft amount of the pinion offset in the Ford niner (forgot exactly what the degrees result was with this length shaft but within reason)


With the IRS there is no movement of the housing so it was a piece of cake compared to a live axle type build.

Here are your 624, 625 and 626. Two are thumbnails, so they won't get any bigger.

MVC-625F_2_.JPG

MVC-624F.JPG

MVC-626F_1_.JPG

Thanks Roger---remember doing this to these photos back in Jun 13 for Navy's thread??????????

Originally Posted by jerry clayton

Thanks Roger---remember doing this to these photos back in Jun 13 for Navy's thread??????????

1940 Ford Pickup

Slightly off the subject, but related. I had a vibration that was driving me crazy on a first gen Camaro. I installed shims at the rear axle and had up/down angles within a 1/4 degree and still got a vibration at 70+ mph highway cruising. Finally figured out that with the overdrive transmission and low geared rearend that the "balanced" driveshaft was turning a lot faster and wasn't balanced well enough. Took it to a shop that could do a high speed balance and the problem was solved.

Back in 1970 I installed a complete Lincoln 460 with C6 tranny in my then new 70 ford f 250 which had 360/C6 but being a truck it had a SHORT tailshaft housing and 2 piece driveshaft---I had a properly timed and balanced intermediate shaft make and I installed it---the only difference was that it was a few inches shorter than the originanal truck shaft but that difference in the angle of a shorter leg made a hell of a vibration/shutter just as the truck started to move and then it would be smooth as long as I was moving---chasing down basic varibles---I ended shimming up the cross member holding the bearing at the midpoint by 1/4 inch per side and the shutter was gone-----


the drive shaft lengths are a big item when your doing angles and with shorter shafts these angles come into play much more than with longer ones---of course with the longer shadfts the critical mass vibration becomes an issue that has to be dealt with by tubing od and wall thickness---------