The Rear Suspension

[pacotaco]

I just got a email back from TRF (A Runyon). I inquired about the set that is in their catalog #RFK777/E and asked about the lb rating front and rear. He stated that that set was discontinued the new number was HP132 with a rating of 390lb front and 470lb on back. He also said they would lower the car about one inch. This is way too heavy for me. He did not respond to the ratings on buying SAH606 and SAH1081/E or if they were the same as what came in the matched set. I'll have to call them to see what is available if anything in the 350lb rear range and whatever the appropriate matching rating would be for the front. I guess I am looking for stock TR250/TR6 shocks?

 

[tdskip]

Shocks or springs? I think you are looking for stock both based on this thread.

 

[sail]

Richard,
Wow! You and Tom weren't kidding about how high those made it stand. You mentioned you thought they had the issue worked out now? Is that the feedback you got from TRF?
Scott

Scott, yes I spoke with Albert last year on this. They had gone thru the TR5 and I think have it figured out. How they could have sold the 4WD springs less than 4 years ago beats me with all the TR6 stuff they do. Now they list the HP 132 as lower by 1" just as the supplier GoodParts does. They state a 3/4" spacer will get back the inch. That is true for me in front. My rear seems about where it was w/o spacers, maybe just a tad lower.

I just got a email back from TRF (A Runyon). I inquired about the set that is in their catalog #RFK777/E and asked about the lb rating front and rear. He stated that that set was discontinued the new number was HP132 with a rating of 390lb front and 470lb on back. He also said they would lower the car about one inch. This is way too heavy for me. He did not respond to the ratings on buying SAH606 and SAH1081/E or if they were the same as what came in the matched set. I'll have to call them to see what is available if anything in the 350lb rear range and whatever the appropriate matching rating would be for the front. I guess I am looking for stock TR250/TR6 shocks?

If you mean shocks I have stock. If you mean springs:
As noted above I have the TRF HP 132 which are GoodParts. From their site above:
"Front spring rate is 390 lb/in. I measure stock to be approximately 305 lb/in.

Rear spring rate 470 lb/in or 600 lb/in. I measure stock to be approximately 350 lb/in."

So if you are looking for 350# that is what GoodParts found stock to be. Or if you need new fillings they also list a 600# set.

 

[pacotaco]

Yes I meant coil springs not shocks. So as I understand it if I want to upgrade my handling without sacrificing my ride I should buy standard TR6 springs front and rear which would be about 354lb rear and 312lb front. Will this keep my height normal or will it raise it?

 

[pacotaco]

One other thing keep in mind, my car is a TR4A IRS not a TR6 so the stock TR6 coils would be an upgrade. Right?

 

[JerryVV]

Also keep in mind if you lower the front or the rear you'll need to adjust at a minimum the camber front and rear as lowering will affect alignment.

 

[pacotaco]

Don't want to lower the car. I want to enhance the suspension as much as I can without (I repeat without) significantly affecting ride quality. My wife will be riding with me alot so I have to keep the ride comfortable. Can anybody answer my post 4th back?

 

[Foura]

My 4A is now running stock springs at the front with Koni shocks and Supapro poly bushings. I originally had new springs at the back which came from a supplier in Queensland. They were very comfortable but the car sat a bit high at the back. The guy who did my bodywork gave me a pair of springs which were far too short so I bought a pair of 470lb springs from Goodparts. These have the car sitting level and the ride is a little firmer but still comfortable. I did have to put a 1/2 inch spacer under the RH rear spring to get the car level from side to side.
I am running poly bushes at the back too and a telescopic conversion with Monroe shocks which was on the car when it came from the US. This bolts inside the wheel well but then is affixed via brackets back to the original shock mount. I disagree with Neil Revington about this form of mounting as it gives a much longer shock travel allowing a softer shock with good control compared with mounting the shock inside the spring. The car has a better ride than my 95 Holden V8 with sports suspension and my wife never complains!

I will try and have a look at the springs again tonight and give you an idea of the free length which might be of help.

 

[JerryVV]

I have original springs on the front of my 4A and the TR6 springs on the rear. Ride height is normal. I can send a photo if you provide an e-mail address. I don't know how to post one here and really don't need to learn how. Ride is OK but you cannot expect a soft ride in a 4A. If I were to change anything I'd put original soft rear springs back and improve the handling with stiff anti sway bars.

Does that help to answer your questions 4 or 5 back?

 

[pacotaco]

Jerry - my email is b3ammons@epbfi.com if you wish to send a picture. Yes you and Foura answered my question but as usual with these forums I got two different answers. Foura is running very stiff (470lb) springs at the rear and says ride is good. JerryVV you say you would go back to original (280lb). I know this isn't a Rolls and don't expect that kind of ride, what I am trying to find someone with driving experience of a car with TR6 springs front and rear and hear if it hurt the ride much. I have a set of new Moss 470lb rear springs which I think would be way to harsh? The springs came with the car and were never installed. Foura is running 470lb on back and stock on the front - that sounds like it you be a mismatch and affect handling in a bad way.

 

[Foura]

I measured my springs last night. The springs that I originally put in the car were 11.5 inches long (free length) and the car sat too high. I believe that they were TR6 springs which would have had a rate of 320lb/in. The ride was good. The next set were TT4216 which have a rate of 420 lb/in and were way too low. I now have the Goodparts 470 lb/in springs. The ride is a little firmer but the car sits level with the height to the middle of the wheel well at 28" front and rear.

We have to remember that the spring is mounted in front of the axle so the effective spring rate at the wheel is about 2/3 of the actual spring rate. Also, I recall that the TR6 was heavier than the 4A which is possibly why the TR6 springs made mine too high and why the Goodparts springs make it look standard rather than lowered. As for handling, the TR club President commented on how well my car kept up with his 911 on one of our runs!

There is a lot of spring info on the UK TR register.
www.tr-register.co.uk/forums/index.php?showtopic=29428

I would go for poly bushes throughout (including the diff), a telescopic conversion, stock front springs and at least 350lb springs in the back. Good luck!

 

[Foura]

I posted my previous before I read your post.

Another issue to consider is bottoming. When the suspension bottoms out, all of the impact is taken by the notoriously weak stub axles. I wonder how many of the failures were caused by continual bottoming due to the soft 280 lb/in springs? That was an issue even with the TT4216 springs which were too short. On our less than perfect roads here in Oz, I would rather have a firmer ride and little or no bottoming.

That raises another issue. The SECOND thing I would do in restoring a TR (after buying a brand new wiring loom!) is replace the rear driveshafts with modified ones. I have used some which came from Germany and use modified Audi parts with CV joints. This hugely improves both safety and handling. The last thing you want is to have all your hard restoration work wrecked by a wheel coming off.

 

[pacotaco]

As I am building this car I have urethane diff mounts and urethane trailing arm bushings. I have not ordered yet but will probably get the adjustable trailing arm brackets. Was considering a tube shock conversion but seem to be reading about too many case of mount cracking. The coil springs I have new that came with the car are from Moss (670-148) and according to a earlier response are rated at 420lbs and I just measured them they are 10-10 1/8" high. My old stocks measure 9 - 9 1/8" so I assume that if I were to use the new ones my ride height would increase 1"?

 

[Foura]

According to a copy of the Moss catalogue https://obswww.unige.ch/~wildif/cars/docs/sellers/TRI-12.pdf

on page 100, the 670-148 is rated at 390 lbs which may be just what you need. The length of your old springs seems very short. Were you able to measure the car at all before restoration? Sounds like they have sagged severely! Moss quotes 11.5" for standard springs on their current website (which no longer lists 670-148). They may well raise the car compared with how it used to be but the general consensus seems to be around a measurement of 28" to the top of the wheel well with 185-15 tyres is normal for standard suspension. Check the photo I sent you off list.

 

[pacotaco]

OK maybe I accidently measured the old front springs. The other pair of springs I took of measure 11". RJS in a earlier response says Moss 670-148 (discontinued) has a rate of 420LB and the info Foura has shows 390Lbs. I would be inclined to try them at 390lbs since I already have them going above that starts to sound pretty harsh to me but not having driven with springs this stiff I don't really know 420lb may be great for all I know. I have to keep the ride decent for my wife and I just to want to make the ride unpleasant. The Moss 670-148 says on the tag that they are HD so I would assume that at a 25% increased rate they would be around 420lbs as RJS says. I guess I need to call Moss again - when I called them about these springs before and asked for information on what I had they were not helpful and almost unfriendly.

 

[pacotaco]

Ok Foura I just printed out that info and I appreciate you providing that link. That is exactly the info I wanted but have been unable to find myself. I wonder why Moss would not help me? I assumed that that part number must have been old because the guy who bought it would have bought it in the 80's I believe. Anyways based on this new info and a 390lb rate I believe I will use them and see how they are. The catalog link says they these will maintain proper height so that is great. Thanks for all the help on this guys.

 

[TR3driver]

I guess I need to call Moss again - when I called them about these springs before and asked for information on what I had they were not helpful and almost unfriendly.

Keep in mind that Moss almost certainly did not design the springs themselves. At best, they have them made to a print from the TriumphTune days; at worst they buy from someone else and just repeat the specifications they are given. They also don't keep a suspension engineer on staff to discuss the finer points with you, nor a QA department to examine every part that comes in to be sure it meets specification.

Not bashing Moss, just telling it like it is with all of the 'Big 3' and most of the smaller vendors. Possible exceptions would be people like Richard Goode (Goodparts) or Ted Schumacher (TSi) that have some first-hand knowledge of what works on the track. (Others as well, like Neil Revington and Daryl Uprichard in the UK.)

Suspension design always involves compromises. The factory springs were actually a pretty good compromise between handling and ride quality; stiffer springs are going to degrade ride quality particularly on rough roads (and may not improve handling very much unless combined with other changes).

That is my opinion of course ... you can't expect to get the same answers from everyone when you start asking for opinions. But I would put it together stock first, to at least get a baseline using your butt & driving style; and then evaluate what aspects of performance you would like to improve. My Stags are somewhat different of course (heavier), but stiffer rear springs would hurt, not help. Next step for them would be a heavier anti-roll bar in the front, as they have a definite tendency to lift the inside rear wheel.

You can't really tell it in this shot, but the left rear was just barely touching the ground and the least bit more throttle would spin it. With stiffer springs at the same speed, it would have been in the air.