55.2-59 GM 10 Bolt Not Centered

[SARBlade]

Hi All,

Just putting my welder series triangulated 4 link in my 56 Chev and noticed that with the axle centered, the pinion is 5/8" right of center. The drive shaft is not centered. I thought I messed things up, but measured the TH350 and its offset to the passenger side. So I guess this is normal eh? I ran into this when I was about to install the upper bars to a cross member I made and the bars met in the middle of the member, but looking down, the axle could come up and hit the right upper bar! Any thoughts on this?

A few pictures


You can see the two center marks, one is driveshaft/pinion, the other between frame bars



Here you can see the 2x3 cross member has the driveshaft cutout, now the upper bar mounts fall in the wrong place. I'll just have to change the mounting angle now. They are currently at 29º. I guess I'll go to 27º

[dsraven]

no pics attached but this is what I would do.
first check if the frame is straight fore to aft. I usually mark each cross member at it's centre point from side to side. a piece of masking tape and a pencil works good. then run a string or laser down the middle from front to rear to see if all the marks line up or use a plumb bob and mark the floor under each spot, as ong as the truck is up on frame stands so it can't move
next check the engine and trans to see if they are parallel to the frame and if they are in the centre of the rails. check from the front pulley and the trans output shaft areas as reference points for a front and rear of that particular unit as a whole. you can use a plumb bob and mark the floor under each spot and also under each frame rail front to rear, then connect the dots with a chalk line or tape or whatever. then do your dimension checks to see if the engine and trans line (from the front to the rear) is parallel to the frame lines and if it is offset. some manufacturers offset the engne/trans to the passenger's side
next drop a plumb bob a mark from the end of each axle center at the wheel end where the wheel mounting surface is and mark the floor. when done do a dimension check from each of those over to your trans output mark. if the driveline is centered these should be the same. this makes sure the axle is square with the trans. you could do another one of these checks using the mark dropped from the front of the engine just as a double check. if the axle is square with the rest of th driveline it won't make a difference if the pinion is offset to one side because the u joint angle at the rear is cancelled out by the u joit angle at the front, as long as the rest of the drivelne angles are also equal but opposite like the offset angles are. the problem comes from when the rear axle isn't square with the engine and trans so the rear u joint angle isn't the same (but opposite) as the front u joint angle.
next check to see if the axle flanges are the same dimension from each frame rail (at ride height because, depending on your suspension type, that dimension can change as the suspension goes up and down. a 4 link using a panhard bar is known for this especialy if using a short panhard bar).
a few pics would help. if you look at the TCI 4 link you will notice they use a cross link bar from the front of one 4 link bar mount on one side and it crosses over to the rear on the other side. this keeps the axle square all the time and it doesn't allow change laterally. the cross bar does possibly get in the way of a driveshaft depending on the set up.
I used a 4 link made from welders series parts and made a drag link that was level, at ride height, and stretched from one frame rail over to the far side of the axle on the other side. so as long as possible. that ensured the least amount of lateral movement without using a watts link or a different style of cross link

[dsraven]

I guess one way to know if the axle is set up to have an offset pinion would be to remove the brake drum or disc on both sides, clamp a length of angle iron onto those flanges to act as a straight edge that will extend the plane of the wheel mounting surface. do that on both sides and lay the angle iron on some jack stands so they will be at the same height as the pinion. then simply use a tape measure from the angle iron to the pinion on each side and compare the results. thats what I do and it works. thats how i come up with a real axle track width dimension on different donor axles at a wrecker or whatever.
really, if the pinion is offset and the engine and trans are also offset by roughly the same amount and the engine/trans are parallel to the frame, and the rear axle is perpendicular to the frame, then it should work out fine. but, if the pinion is offset and the engine trans are not then that is not a big deal as long as the axle is perpendicular to the engine and trans centreline. u joints can work that way. the frame is just what holds all the parts together.

[mr48chev]

That "OMH my driveshaft isn't in a stright and square line from the trans to the rear end" nonsense is just that, NONSENSE. Every Ford ever built with a 9 inch that didn't have an ugly from the back off center pumpkin had a driveshaft that angled off to the passenger side a bit. Almost every other rear end around does. Still guys mess their britches and have a panic attack when the driveshat doesn't run perfectly square from trans to rear end.

Yes you can fix that if it is a real issue with you if you shorten one side and move the pinion over but why? The driveshaft doesn't care, the U joints rollers like having a bit more room to roll on every turn of the driveshaft rather than being pounded in one spot all the time.

Actually as long as you have the wheel mount surface where the wheels are evenly spaced from the frame on each side life is good.

As far as the bars on the 4 link hitting something, if it is a Universal kit you may have to make some slight adjustments to have it fit and work right.

[SARBlade]

Thanks Draven, did the pics not show in thread? I put three in the post. Anyway, the tranny is offset as the engine is as well because of the steering box. Took me sometime to measure all that as truck still has cab and front clip on it. There is an issue with the front Camaro clip as well, but the truck wheelbase is the same for and aft both sides, and rear end is aligned and centred in the rear. After spot welding everything in, my axle was only 1/8” out and pinion angle off by .5°. I can correct these easily enough with the 4 link adjustments.

[SARBlade]

Thanks Mr.Chevy, I went with what you’re saying. I think I was surprised as I had not measured where to pinion was in between frame members, so when I fabricated the cross member for the upper mounts, I discovered the pinion offset by 3/4” to the passenger side. A lot of scratching my head then occurred and of course re-measuring everything yet again. Then crawling under cab, I measured tranny nose and yep, it was offset, so I’m ok with the offset now. Just a day of WTF did I do? Just gotta go in and weld everything up. I think I’ll check travel of diff first by jacking it up and down to see 4 link work it’s magic.

[bowt1ed]

I noticed the same passenger side offset in my 2nd Gen Camaro subframe back to 10 bolt. Still not sure why, I but did read it was intentional.
Cheers, Jim

[59chev]

I am running a second gen 10 bolt in my truck with a camaro clip. I mounted my engine in the stock camaro motor mounts and found that the engine is offset to the passenger side by the same amount as the rear end offset. In researching it I found that Chevy did this intentionally, though I'm not sure why. Perhaps It may have been to give more room for the Steering box and shaft?

[cameo]

I did the same thing, Nova clip and 10 bolt, my own 4-link, made the 4-link crossmember all nice on the bench, installed it, and the relief I put in centered on the crossmember didnt line up with where the drive shaft would be. cut, reweld.
Ive heard its for weight distribution, more foot room for peddles, room for steering... I think some engineer messed up, and it was too late to make the required changes.

[dsraven]

-room for steering box
-room for drivers compartment, cluster package, etc
-weight offset to help load a passenger rear wheel as it's always the one that breaks loose
-room for the extra pedal for the stick shift group
-room for brake booster etc under the hood
- dunno. musta been an answer somewhere other than being different.

[mr48chev]

A lot of engines are offset to the passenger side a bit. Most rear wheel drive 60 or so and later Mopars are.

Thing is as I said in post 4 it really doesn't make a rippy doo dah if the drive shaft angles off to one side just a bit but too many guys really get their undies in a big uncomfortable knot if it does. It only matters to people who cannot deal with the driveshaft being perfectly square and centered between the frame rails. You see that with guys who put nine inch Ford rears under their hot rods on the Hamb and other hot rod groups all the time. Panic time because "OMG the driveshaft doesn't go perfectly straight back what do I do now?. The answer is nothing, it will work perfectly that way.

[dsraven]

u joints don't know or care if they are matchy matchy to anything else but their running mate at the other end of the shaft they run on. so, long story short, as long as the other end of the shaft is at the equal but opposite angles that they are running at they cancel each other out. thats why I mentioned to use a plumb bob, mark the floor under the critical points mentioned, and then adjust things until the axle is perpendicular to the engine and trans. if that is done correctly then the offset angles will cancel each other out and then as the axle goes up and down it will be a matter of adjusting the down slope of the engine and trans and/or the pinion angle of the axle so those angles match as close as possible at ride height. this can be a little tricky depending on the suspension type as some suspension types allow some flex under hard loads which will change the pinion angle slightly. leaf springs can have what is known as spring wrap, control arms can have different upper lengths compared to lower lengths so as the axle moves up and down the pinion angle changes. but, if youre set up correct at ride height then vibration and noise from an unmatched u joint set will be at a minimum.
there are youtube videos showing how it all works, spring wrap, uneven length links etc. take a few moments to apprentice under the you tube school of knowledge. lol.

[SARBlade]

Thanks for all the input, no pun intended lol, I burned the suspension in and will deal with the offset when I put the LS in. It just surprised me I guess and thought how did I miss that. Anyone know a good place to buy rear coilover? I’ve looked at QA1, Aldan, Ridetech, a few others I can’t remember. I think the QA1 brand were the most reasonable and were priced a bit better, however, how to buy and get shipped to Canada?

[mr48chev]

Boy Howdy, you are way out past the end of the known world sign.

It really isn't viable to just do the Jump in the car and run down to Seattle for the day to go to a shop that stocks them thing as guys who live just above the border might. Your area is better known to boaters headed north or south who stop at Comox for fuel and provisions than to car and truck folk.

To me you are looking at two things, Price of course but just as important and maybe more important serious tech support that you can contact and get good answers.

I've never had a need to check into coil overs (yet) but the feedback for Alden is that their tech people are good to work with you. QA-1 seem to be gaining popularity though.

You have probably already played with it but Alden's website does let you figure out pretty close to what you need https://aldanamerican.com/

This shows the posibility of at least one and maybe two QA1 dealer (s) in the Vancouver area https://www.qa1.net/find-a-dealer

I'd contact all of the brands that you have in mind and ask if they do have a vendor in Canada and preferrably BC. That probably does't save any money on your end but usually saves some hassles all around and may save some shipping costs if that vendor gets regular shipments.

No need to explain the hassles of getting stuff to Canada to a Canadian.

[SARBlade]

Thanks Mr.48, I did use the Aldan site, so pretty much have it down to what I'm after for a shock. I sent the guys in Vancouver who handle QA1 a request on pricing and they have not got back to me. And your right about where I am in the world lol. Perhaps I should just gas up the Searay and sail her down to the Seattle area and do a major purchase! For now, a couple of 1x1 steel tubes are my shocks for ride height.

[MARTINSR]

Originally Posted by mr48chev

That "OMH my driveshaft isn't in a stright and square line from the trans to the rear end" nonsense is just that, NONSENSE. Every Ford ever built with a 9 inch that didn't have an ugly from the back off center pumpkin had a driveshaft that angled off to the passenger side a bit. Almost every other rear end around does. Still guys mess their britches and have a panic attack when the driveshat doesn't run perfectly square from trans to rear end.

Yes you can fix that if it is a real issue with you if you shorten one side and move the pinion over but why? The driveshaft doesn't care, the U joints rollers like having a bit more room to roll on every turn of the driveshaft rather than being pounded in one spot all the time.

Actually as long as you have the wheel mount surface where the wheels are evenly spaced from the frame on each side life is good.

As far as the bars on the 4 link hitting something, if it is a Universal kit you may have to make some slight adjustments to have it fit and work right.

YES and in fact if it's perfect the U joints will FAIL because the bearings are spinning!


Brian