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Triumph TR6 - Rear suspension improvements...
|If I have an option of adding tube shocks or lever shocks to the trailing arms & coils, what's best? The car is being restored and thus it may ride fine with the coils only. I have not driven it yet and have no previous experience with TR6s. Advice appreciated.|
|I have heard the BEST improvement is a rear sway bar....period.|
Be careful on the style of tube shocks. There are some on the market that have not had the best of reviews.
You will definitely need shocks of some sort.
Springs alone will provide you with "entertaining" handling and ride qualities bordering on the abyssmal.
The function of the damper (shock absorber) is moderate the action of the spring at whatever rate is desireable for the intended application.
To do this it will need to be matched to the spring and this point is where some people manage to have it all fall apart.
Lever shocks are fine and work well BUT they do require maintenance and many meachnics these days heve never heard of them let alone seen one.
Tube shocks also work well and require virtually zero maintenance hence the popularity of them in todays cars.
Usually they are the least expensive option too.
Gas tube shocks (not to be confused with the above items) are the third way. They are also zero maintenance and will provde consistent performance regardless of the use. They don't fade in other words.
Matching them to the springs requires the builder to know the mechanical spring rate and the rate of the gas spring in the damper. Many people over look this bit and gas shocks have a reputation for riding like a truck as a result.
Find a decent Triumph or even (cough , gasp )an MG club and join up. They will be able to provide helpful suggestion for your location as to who knws their stuff and who will just walk out to the back room take an item off the shelf they have had for ages and tell you it is a "puropose designed kit" and up the price into the deal.
Post further if you want more information and I hope this is some help.
Cheers , Pete.
|Ken, here's my .02 worth as I struggled with the decision on tube shock conversion for my '73. After months of investigation, my "opinion" is that the tube shock conversion increases the "moment" or the torsional stress on the shock mounting frame location. This is the same section of the frame that supports half of the differential and we all have heard differential mopunt failures. Obviously, the frame was never designed for this added stress. 33 years and 163K miles on my TR6 must result in some metal fatigue. Rather than risk a structural failure, I decided to install the HD remanufactured lever shocks from Apple Hydraulics (not a promo) and have been well pleased. Yes, this is on the conservative side. Good luck.|
|Thanks for the lever shock input Bob. Say, my wife and I will be RVing to MS this fall and will be staying near Tupelo for a while which I think is about two hours (maybe more) away from Hoover (Birmingham)AL. Do you think I could pop over for a 1/2 hour and see / sit your seat conversion? If you want to discuss offline my email is firstname.lastname@example.org. Ken|
|Ken, we would be happy to have a visit. Maybe you will be in the area and get to come to one of our LBC club meetings or events. Another great time to visit will be Oct 13-15 for the Historic Sportscar Racing (HSR) event at Barber Motorsports. This local world class track is also the home for the Porsche Driving Experience. www.barbermotorsports.com|
We look forward to meeting you and the wife. Please E-mail me with your schedule. Bob
|There are some things out there that should be considered. This is one of those areas where you need to decide where you want to go with this car before you commit. There is a price for performance and the more performance you want, the higher price in terms of comfort you will have to pay. |
First, not so much a stated performance improver, but very much a defacto one are the adjustable trailing arm brackets from Richard Good. These things make settng the rear camber and within the bounds of the bracket design the ride height also, so much easier. Proper alignment is one key to extract handling from these cars and having adjustable brackets will put an end to that 1, 2, or 3 notch bracket and notches up or notches down bracket swapping business that you would go through otherwise to get proper camber settings at the rear. Sorry, nothing out there that I know of to make toe adjustments at the rear other than the stock add/delete shim routine. A couple of words though about these brackets. The bolts supplied with the brackets to mount them to the frame are a bit on the short side so either get longer ones or use the ones you have, then my own personal preference is to toss the Grade 8 SAE bolts Richard supplies for the trailing arm pivot and replace with AN7-40A bolts (7/16" bolt, 3+7/16" grip length, undrilled shank). The SAE bolts put the threads in shear loading against the bracket and well, the engineer in me says that is a bad thing on two counts. First, the thread minor diameter serves as a stress riser, also the threads can wear away at the surface of the part they are passing through. You can get the AN hardware from your local aviation supply, some local fastener companies, Aircraft Spruce, Coast Fabrication, etc. It is not a matter of using aircraft vs. standard hardware, it is one of being able to select grip lengths appropriate to the application. This is the type of bracket they should have fitted to these cars in the first place and probably the only suspension modification mentioned that has no comfort price. I recommend this to any TR6 owner, you and your alignment people will be glad you did when alignment time rolls around.
A rear anti-roll bar should defintely be considered. The old Kastner style (such as the one from Addco) is pretty much a bolt on deal. The down side is that it will reduce your rear ground clearance slightly and you should also consider going to a slightly larger front bar to go with it. There is also a high mount rear bar available, but it is used in conjunction with the tube shock conversion that runs through the springs with the welding and such. As long as you dont go to stiffer springs, anti-roll bars will have little impact on the comfort level.
On the rear shocks/dampers, I am not a fan of the bolt on tube shock conversions. They reduce the size envelope available for tire choices and you are hanging your load path out in the breeze. There is one tube shock conversion that I would recommend, but to go there you will need some decent fabrication skills and equipment. You have to weld in frame gussets and reaction plates, modify the trailing arms, etc so you can run the shocks through the springs like nature intended. If you are interested, post back and I will e-mail additional information. Otherwise, stick with the lever units, the ones from Apple mentioned above are pretty nice.
Springs, well they are kind of like sauces, you can hide a multitude of sins with stiff springs to a point. The usual suspects (Roadster, Moss, etc) have stiffer springs, so does Richard Good. Try not to go too crazy here though as you don't want to run over a dime and know if it is heads or tails.
Finally, the easiest thing you can do to enhance handling on these cars and it is not a suspension modification. Fit the car with some decent tires. The tires we get now are orders of magnitude better than the stuff that was available when these cars were made. You can improve both handling and comfort with tires. Go to the archives and you find a plethora of threads on tires.
|Thanks Steve. Hopefully your contribution will help many others in addition to this newbie. Once I'm in my new toy next spring and can appreciate the ride as built by the restorer I'll go from there.|
After all these threads, postings, and help from us, you better buy one soon and post some pics of her. No problem, we can teach you how to post some pics.
|Getting very close to closing a deal Rick but won't have her until spring. It's still a work in progress. In the meantime I'm living the dream through all you wonderful people, your pictures, and getting more pumped with each thread. I have received confirmation from Al Watt re my TTC membership... another ministep to playing with all you big kids. Ken.|
Welcome! My two cents worth on rear suspension...I used the bpnorthwest HD road springs with Apple Hydraulic HD lever shocks (OE shocks rebuilt to HD). The ride is slightly firmer than stock but is very comfortable and doesn't bottom out easily. The ride height stays the same as stock. You won't believe the fun of owning a "6"!
Sway bar is a good investement, and a good brand:
|J. G. Catford|
|I've had two brands of tube shock conversion on my TR6. |
The first was the conversion designed for the KYB Gas shocks from
The KYB's had poor rebound damping - didn't like them at all. I was running stock springs at the time.
The second kit I tried is designed for Koni's which are adjustable, and just an excellent shock. The kit is available from:
I'm running Richard Good lowering springs, adjustable trailing arm brackets, poly bushings throughout and no rear swaybar. Handling is excellent.
My understanding is there are thousands of miles on these conversion kits in the TR6 market with no reported failures of any kind. I think the forces placed on the frame by the tube shock mounting bracket are mitigated simply becasue the shock piston is able to move freely.
|After the long and hard road to being, well, on the road, my wife pointed out that I have a lot of camber on the rear wheels when driving. She may not have said "camber" so much as "tyres sticking in a lot", but her point was well made, and I think she now realises that she effectively said "why don't you spend a load more money on the car?" |
Anyway, I already picked up some new springs and being a long time sufferer from shipwright's disease, I have also decided to put some new trailing arm bushes in, and I am interested in the Good Parts adjustable brackets. Really I just like the idea of being able to set the camber, toe and such with relative ease. Is this total overkill? Is there any chance that I can set these myself, or do I need to find a shop to do the alignment?
I was planning to keep the lever shocks, but just drain and refill them with new oil. Is there anything else I can do to them, other than a) have them rebuilt and b) scrap them in favour of tube shocks? Also, is it worth using longer bolts to hold the lever shocks to the chassis and put a nyloc on the other side? It feels like there should be room, but if Triumph didn't feel it necessary...
While I have the trailing arms out, what else should I look at doing? If the rubber boots on the driveshafts are intact is it worth replacing them?
Well, sorry for the long post, and thanks in advance for any advice. With any luck I might actually have some time to work on the car in a month or two...
When I removed my trailing arms and trailing arm brackets, I noticed the bolts holding the brackets to the frame had rusted to a 1/4 of thier original diameter.
Also, don't make too much out of the shock conversion it is cheap and simple; installation takes all of 20 minutes. Unless your goal is to keep the car stock, then just do it - you'll get better performance with modern equipment.
|First the trailing arm brackets, I personally don't think it is overkill. You must keep in mind that they make the camber adjustment easier and while that has some impact on toe, the toe adjustment is still by shim. It's adjusting the rear camber that is a "fun" task in these cars, the rear toe is not that bad. See my earlier post from 30 September 02:32:59 for additional information on Richard Good's trailing arm brackets.|
You can do the alignment yourself, but it is a bit tedious. Go check local libraries and bookstores for stuff on chassis and suspension set up for procedures. You may consider getting a good initial one from a shop that you trust and then recheck and tweak periodically using the stuff from the afore mentioned books.
As for the longer bolt and then backing it up with a nut, I think it is a good idea and have done that in the past. Having had the unfortunate experience many, many years ago of a bolt working its way loose and killing a shock, maybe a little "belts and braces" approach is not such a bad thing to me. Just remember to size the grip length of the bolts such that you do not have threads under the lug area of the lever dampers or if you go to one of the bolt on tube conversion under the flange of the mount bracket.
I prefer the lever dampers over most of the tube conversions, others don't. Go do some research on the board and other spots on the web. You should find a good bit of stuff out there on the topic.
I wouldn't fiddle with the boots on the axles unless they show signs of cracking. As for the large bells over the inner u-joint, I just leave those off as they just seem to get in the way, the important one is the little bellows over the sliding joint between the inner and half shaft sections.
|Alistair, a little something you might want to do while|
the trailing arm is off is clean all the corrosion
off of the seat where the springs rubber seat goes.
After I got down to bare aluminum I coated the seat with spray sealer and a thin layer of grease.
Poly bushes are the way to go.
This thread was discussed between 28/09/2006 and 09/10/2006
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