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TR6 Rear springs
- Thread starter davjac889
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Tybalt
Jedi Warrior
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Excessive negative camber at the rear is for lack of a better term, a “feature” on these cars. The factory tried to address this by changing the trailing arm bracket configuration and altering the fitment during the production run. They even went so far as to offer a rear spring spacer under a BL/BMC type part number in the “HAC” series of parts. This issue has been addressed over the years by others as well. For a good while the best was a table of the three brackets and the bracket orientation (notches up/down) to alter the camber angle. Moss at one time used to print it in their catalog. It is still available at the Buckeye Triumphs Technical page and a description of the “how to” procedure toward the bottom of this linked page:
https://buckeyetriumphs.org/technical/Suspension/AdjRS/AdjRS.htm
I have done this to adjust camber and it does work. Unfortunately, there is some degree of trial and error involved to get where you want to be and it is a bit of a workout as a result. The other thing as stated in the article, bushings should be checked and at this point there is a reasonably good chance that the bushings are a bit long in the tooth and could stand replacement. Springs, I’ll get to in a minute.
An alternative to playing the bracket mix and match game to adjust camber are the adjustable trailing arm brackets from Good Parts:
https://www.goodparts.com/shop/index.php?categoryID=13
From what I understand, these were originally developed by Group 44 for the TR250 and later TR6 cars they raced. Having done the “three bracket mix and match” and fitted some of these adjustable brackets to a TR250 and a TR6, these make life much easier. While the brackets themselves are very well made, I don’t care for the hardware that comes with them. The pivot bolts for the trailing arm are your basic SAE spec bolt and due to that spec configuration have a longer threaded area and shorter grip for a given length bolt than an AN/MS/NAS type bolt. This means that some of the threads are loaded in shear and I was always taught that threads in shear was a bad thing. I replaced them with AN7-41 bolts to eliminate having threads in shear. The other was that the bolts for mounting the brackets to the frame are too short when you have to add any shims to adjust rear toe. Minor quibbles, they should not stop you from considering these brackets.
Springs, all of the usual suspects (TRF, Moss, VB, etc) were offering stock and uprated springs with some unknown higher spring rate. Richard Good offers springs that are stiffer than stock with known spring rates, but they are shorter. If you want to maintain a stock ride height, you will need to run some of the spacers. On the TR250 that got the adjustable trailing arm brackets, we also fitted it with some of his 390 lb/in front springs, the 470 lb/in rear springs, the polyurethane spring packings, 1/2” spacers, Spax adjustable dampers up front, Apple Hydraulics heavy duty lever dampers at the back along with a set of ADDCO anti-roll bars front and rear that we had just sitting around in the shop after being removed from another car. The ride was noticeably stiffer than stock but not too bad since the damping rates were set to work with the spring rate. The car had a good balance with significantly less body roll due to both the higher spring rates and the anti-roll bars that had been fitted. Whether you want stiffer springs is purely a function of how much of a “hard ass” you happen to be, but in any event springs should be on your list when you start trying to address the rear camber issue on these cars. The only bit of caution that I would offer is that if you do elect to go stiffer at the rear, then you should stiffen up the front as well so you don’t throw off the roll couple distribution between the two ends.
https://buckeyetriumphs.org/technical/Suspension/AdjRS/AdjRS.htm
I have done this to adjust camber and it does work. Unfortunately, there is some degree of trial and error involved to get where you want to be and it is a bit of a workout as a result. The other thing as stated in the article, bushings should be checked and at this point there is a reasonably good chance that the bushings are a bit long in the tooth and could stand replacement. Springs, I’ll get to in a minute.
An alternative to playing the bracket mix and match game to adjust camber are the adjustable trailing arm brackets from Good Parts:
https://www.goodparts.com/shop/index.php?categoryID=13
From what I understand, these were originally developed by Group 44 for the TR250 and later TR6 cars they raced. Having done the “three bracket mix and match” and fitted some of these adjustable brackets to a TR250 and a TR6, these make life much easier. While the brackets themselves are very well made, I don’t care for the hardware that comes with them. The pivot bolts for the trailing arm are your basic SAE spec bolt and due to that spec configuration have a longer threaded area and shorter grip for a given length bolt than an AN/MS/NAS type bolt. This means that some of the threads are loaded in shear and I was always taught that threads in shear was a bad thing. I replaced them with AN7-41 bolts to eliminate having threads in shear. The other was that the bolts for mounting the brackets to the frame are too short when you have to add any shims to adjust rear toe. Minor quibbles, they should not stop you from considering these brackets.
Springs, all of the usual suspects (TRF, Moss, VB, etc) were offering stock and uprated springs with some unknown higher spring rate. Richard Good offers springs that are stiffer than stock with known spring rates, but they are shorter. If you want to maintain a stock ride height, you will need to run some of the spacers. On the TR250 that got the adjustable trailing arm brackets, we also fitted it with some of his 390 lb/in front springs, the 470 lb/in rear springs, the polyurethane spring packings, 1/2” spacers, Spax adjustable dampers up front, Apple Hydraulics heavy duty lever dampers at the back along with a set of ADDCO anti-roll bars front and rear that we had just sitting around in the shop after being removed from another car. The ride was noticeably stiffer than stock but not too bad since the damping rates were set to work with the spring rate. The car had a good balance with significantly less body roll due to both the higher spring rates and the anti-roll bars that had been fitted. Whether you want stiffer springs is purely a function of how much of a “hard ass” you happen to be, but in any event springs should be on your list when you start trying to address the rear camber issue on these cars. The only bit of caution that I would offer is that if you do elect to go stiffer at the rear, then you should stiffen up the front as well so you don’t throw off the roll couple distribution between the two ends.
sail
Darth Vader
Offline
My 4A had a soft and saggy rear end. I also put on Goodpart springs, 470 rear and 390 front. The front needs a spacer, the rear on my car currently does not have a spacer but does have a tad of negative camber. It rides and handles great on the road, in town cracks in the streets are more annoying than before.
It was a difficult process, the first set of springs TRF sent was way too high, they exchanged them for the Goodpart springs and I got to change them all again and now I get to add spacers which I was reluctant to do after my first experience.
In hindsight I would put in a new set of stock rear springs and call it good.
It was a difficult process, the first set of springs TRF sent was way too high, they exchanged them for the Goodpart springs and I got to change them all again and now I get to add spacers which I was reluctant to do after my first experience.
In hindsight I would put in a new set of stock rear springs and call it good.
Tybalt
Jedi Warrior
Offline
It entails relieving the spring load on the trailing arm and removing the trailing arm pivot bolts along with removing and installing the bracket in the orientation that you need. Depending on how the suspension was assembled, you may need to pull the bracket before you can pull the pivot bolt (in other words, you may need to pull the trailing arm with the bracket attached).
This is why the adjustable trailing arm brackets make life so much easier. You can just loosen the trailing arm pivot bolt and move the bearing block up or down to adjust camber and to a limited degree the ride height as well, then tighten the trailing arm pivot bolt at each bracket.