260Alpine
Silver Level Sponsor
This stainless coupling comes in 9/16"-18:
https://www.mcmaster.com/rod-couplings/18-8-stainless-steel-coupling-nuts-8/
https://www.mcmaster.com/rod-couplings/18-8-stainless-steel-coupling-nuts-8/
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DuraPine II
- Thread starter Bill Blue
- Start date
I have one of those. I need couplings that are 9/16" - 18 left hand thread on one end and right hand on the other. I can make them as well as the matching rod threaded 9/16"- 18 on one end and right hand on the other.
Barry - positioned as it was for the photos, the rack needs to go up over an inch for the top mounted rod end or down 1/2" for the bottom mounted rod end. How sensitive is this parameter? Say it was off parallel 1/4".
Bill
Barry
Diamond Level Sponsor
Bill,
If you're only off parallel by 1/4", you should stop what you are doing and go buy a lottery ticket! From long distance, it seems like going up would reduce the depth of the notches which should be a good thing. If you do go up, make sure everything still clears at full up / down suspension travel and full left / right steering.
No lottery tickets today. I am too high by 1/2" or too low by over an inch. To go lower is going to make the cutouts much larger and rack mounts very interesting. Interesting to point of cutting the cross member for them. Especially 1/2" lower. That's why I'm fudging with the 1/4". No way I can go up 1". So I will go down or leave it pretty much as is.
Bill
What might they be? I was thinking about elongating the mounting holes in the steering arms and rotating the arm.
Bill
Barry
Diamond Level Sponsor
Bill,
That would be a simple, effective and inexpensive approach.
Another approach is to use spherical bearing rod ends (aka, Heim or Rose joints) instead of tapered pin tie-rod ends. There are a gillion bump steer adjustment kits for heim rod ends. Note that 9/16" shanks are hard to find.
I remember seeing tapered pin tie-rod ends with changeable pins (different lengths), but I can't find the information.
260Alpine
Silver Level Sponsor
Bill, just elongate one hole. It'll pivot on the other one. Probably not the one with the spacer. I'd wait until the engine was in and the suspension loaded before I fine tune for bump steer. I agree with Barry on the higher mount. Notch to the mounting bolt for boot clearance. Get the rack as far back as you can. Pieces of channel for rack mounts.
Jim, my attitude is "why do it wrong, when you know it can be better". Besides, it is easier to do now than later.
How to do it. Here are my calculations, put out for any correction needed, either thought process or arithmetic.
The holes in the arms are laid out: 2.764" mounting holes, center to center.
Tie rod hole to first mounting hole, 4.75".
Dividing distance to tie rod hole divided by mounting hole separation, 4.75/2.764 =1.72:1
Distance to elevate divided by ratio .5/1.72 = .290" distance to elongate most distant hole. The sticky part is the hole wall thickness is .250" If I elongate each hole .145" the overall effect would be the same, leaving .100" sidewall.
Okay guys, stop me, or at least correct me before it is too late.
Bill
MikeH
Diamond Level Sponsor
In the pictures posted by Aladin Sane, the Rack mount points look like part of a muffler clamp.
260Alpine
Silver Level Sponsor
Bill, Hopefully you are on the low side when compete and you can shim the rack mounts up. If on the high side you will have to cut the mounts down. The 74 and down chrome bumper MGB rack had a quicker ratio of 2.5 to 1. The 75 and up rubber bumper MGB rack had 3.5 to 1 which makes for easier steering in parking situations. They are pretty good and were used in original Cobra's and Cobra replicas. Reasonably priced new too. How long is the stub for the Ujoint? The diameter is a little under 3/4". You can shim for a 3/4" DD Ujoint. There is a 17mm Jeep DD to 3/4" DD that is a better fit. Use a wooden dowel to figure length of 3/4" DD shaft. I don't know if the end of the Alpine steering column has usable 48 splines like the MGB or can be made DD? Speedway Motors, Unisteer and Flaming River has the shafts and Ujoints. One of them has a vibration reducer Ujoint.
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Barry
Diamond Level Sponsor
Bill,
I agree with moving both mounting holes, but I calculate a slightly smaller amount of offset.
My thought process is that:
If both mounting holes are equally offset, the steering arm will pivot around an imaginary point halfway between the mounting holes. The distance between the imaginary point and the tie-rod mounting hole is 2.764" / 2 = 1.382" + 4.75" = 6.132".
If the tie-rod mount is moved up / down by 0.5" while the steering arm pivots around the imaginary point halfway between the mounting holes, the mounting holes will both move by 1.382" / 6.132" = 0.225 x 0.5" = 0.113" hole offset.
To confirm the calculated hole offset, I made a full-scale sketch which showed offsets of slightly less than 1/8".
If the tie-rod mount is moved up / down by 0.5" while the steering arm pivots around the imaginary point halfway between the mounting holes, the mounting holes will both move by 1.382" / 6.132" = 0.225 x 0.5" = 0.113" hole offset.
To confirm the calculated hole offset, I made a full-scale sketch which showed offsets of slightly less than 1/8".
0.113" is not a lot less than 0.145", but ...
HTH
If on the high side you will have to cut the mounts down Looks like I'm going to have to weld the mounts onto the cross member. In order to cut them down I'll probably have to drop the cross member. No fun in that.
I have no idea which unit this is. It is 2 3/4 turns lock to lock and has a 3" input shaft and right hand threads on the tie rods. The previous owner had the rack hooked up to a Toyota steering wheel. I intend to use as much of the existing hardware as possible. Vibration reducer joint. Is that what is commonly known as a rag joint? The PO had to support the U-joint at the stub input with a bearing. Would a vibration reducer eliminate the need?
Bill
I have no idea which unit this is. It is 2 3/4 turns lock to lock and has a 3" input shaft and right hand threads on the tie rods. The previous owner had the rack hooked up to a Toyota steering wheel. I intend to use as much of the existing hardware as possible. Vibration reducer joint. Is that what is commonly known as a rag joint? The PO had to support the U-joint at the stub input with a bearing. Would a vibration reducer eliminate the need?
Bill
260Alpine
Silver Level Sponsor
Bill, your rack looks identical to Aladin's and my MGB rack. Maybe Toyota copied it? Maybe custom tierods? The MGB is about the same width as the Sunbeam but the bent tie rods may require the adapters? I showed a picture earlier with no adapters and the MGB tie rods are long.
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Barry, thanks a big bunch for not only valaditing but correcting my thought plan. Your response is exactly the reason for my post. I look at it this way, .113" is 1/32" less than .145". A measurable improvement. I think I will do .100" offset, leaving .150" sidewall. How much do you suppose that compromises the strength of the arm? Should I be even more conservative? Maybe install a strap from mounting hole to mounting hole?
Bill
No Toyota rack. The PO attached a Toyota steering wheel to the shaft that goes to the MG rack.
Bill
Toyanvil
Gold Level Sponsor
Shouldn't your U joints be in phase?