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rear spring adjusters

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
As promised here is how I do rear adjustable spring perches. Start by grinding down the center raised lip on the stock spring perch because that is right where the new 2.5" spring is going to sit. Then take a piece of 1.5" ID steel pipe, and cut off a 2" piece. In my case it was from a length of 1.5" black steel gas pipe, but in the past I have used 1.75" roll cage tubing. The inner bore of the sleeve is usually right around 2.02" so it fits snuggly over a 2" strut tube. Weld the 2" piece of tube in the center of the spring perch. This is now the locater for the threaded sleeve. Don't make a huge slaggy bead when you weld it, or it will foul the sleeve from sliding all the way on. Paint everything up and slide on the sleeve. It may fall off, but don't worry. Once the spring is in there, the sleeve won't go anywhere. Pack in between the pipe and the sleeve so it won't rattle around. I have a bunch of rubber O rings that come with some of the sleeve kits I roll up in there, but you could use wraps of duct tape. Once the rear end is fitted, you should cut down the sleeves to a minimum. You want some adjustability to get ride height correct, but you don't want the threaded perch sitting 3 inches away from the frame rail either. Keep as much suspension travel as possible. You will need to weld a 1 to 1.5"" piece of the same pipe to the perch on the control arm as well to locate the spring there. That one gets welded at an angle because the spring sits on an angle.

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TeamEvil Avatar
TeamEvil Thomas C
Kingston, MA, USA   USA
Seen this done and works beautifully. Might go another step further with it and drill through the top of the threaded sleeve and collar for a through pin or even safety wire to keep everything up there over time.

Duct tape is unquestionably the Fourth Gift of the Magi, but still . . . .

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
The threaded collar has three tapped holes in it just in case you want to thread in three set screws. Not sure if they all do, but nothing is stopping someone from drilling and tapping holes if they are not there. Install the three set screws and tighten them down on the steel tube just as you would the three screws in the christmas tree stand around the trunk of the tree.

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Sydney.Wedgehead Sydney Wedgehead
Sydney, NSW, Australia   AUS
Hi Todd,

Thanks for posting this.

Out of curiosity, have you experimented with using rose joints in the wedge suspension?

Cheers,
Owen

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Yes. Great for freeing up suspension travel on the race car, but not ideal noise wise for a street car. You can get bushed rod ends that are essentially an adjustable rod end with a hard rubber or replaceable urethane bushing in the end. Thats probably the way I'm going in the rear with the LS3 car. Plan is to make up aluminum rods with bushed ends for the uppers, and then fab up steel tubes with bushed ends on the bottom. The adjustability will enable me to square up the new rear end after I get done welding in all of the new attachment points.

darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Todd,

Do you have a picture of the mount on the trailing arm?

What spring rates and lengths do you recommend?

Thanks,
Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
No pictures of the stock arms since its been a while since I did a set. Basically its just a 1.5" long piece of the same 1.5" ID black iron pipe welded onto the existing spring perch. Just got a set of lower control arms that I plan on using on the LS3 car. One end is threaded. The other end gets cut to length and the end gets welded in. Both sides get urethane bushings with a 9/16" bolt. Bushed ends get grease fittings. Now that I have them, I can cut to length and weld them up. Then mount a spring perch and a piece of fat steel on the bottom to mount the roll bar to. These are inspired by ones I've seen for Mustangs. I wanted bushed ends instead of standard metal rod ends, which would have been cheaper but noisier.

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darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Todd,

Thanks, do you use 10" springs in the rear? What rate for a "sporty driver"? You recommend 200 lb for the front in that case.

Regarding the angle, would you just put the trailing arm where it would sit under load, and angle the pipe so that it pointed to the top mount?

Thanks,
Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
The first time I tried this, I put the adjuster on the arm. Didn't work out so well, because the seat changes its angle as the arm moves up and down. The top perch never moves, so ultimately thats where i ended up installing the threaded collar. #200 in the rear is soft just as it is in the front. Anywhere between 225 and 275 seems to be where most people end up. My personal favorite for the street is 300 front and rear, but thats harsh. Car handles like its on rails, and you can toss the car around and slide it in and out of turns with confidence. Even my hard core buddies think 300 is too much in the rear for a street car. Final choice on spring rates is personal choice. With 200 being soft, and 300 being too harsh, there's not a lot of room to play with. Total length depends entirely on spring rate, whether you run helper springs, and what you run for perches. Some math will be involved. What I can tell you is each rear wheel will carry about 550 pounds and each front will carry about 650 in an empty TR8 before you start messing with springs and ride heights. So if you run a #275 spring in the rear, the installed height will be 2" lower than the free height of the spring. You have to measure the installed spring length of what you have in there now with the ride height you want to achieve. Then you can work backwards from there taking into account the height of the adjustable perch. The other way of doing it is to run a true coilover shock and mount that shock spring combo where the shock mounts. This will change spring rates drastically and I have no experience with them mounted like that. The boys in Australia do it this way. As far as angling the pipe on the control arm goes, yes, no somewhere in between is the answer. The pigtail accounts for that angle change. Beveling the welded end of the pipe so that it points slightly forward is a good thing, but the existing perch doesn't angle at all. On the control arms I'm building now, that perch will angle forward slightly so the spring makes squarer contact.

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