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TR5/TR250 Very stiff rear end

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tinman58

tinman58

Jedi Knight
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I have gotten the 250 up and running. With only about 100 miles on the car, The rear springs are very stiff. When you hit a bump it real rattles your teeth. I checked my order from Moss and I did order the suplex spring set. 675-046 Rear, 661-651 Front. I also have the Monroe shock kit installed (the bolt thru the body and frame setup). The car sits high even with a full tank of fuel. The front springs seam ok. But I have never really driven 250 for any length of time. I am almost ready to remove them and take them tot a suspension shop and see what they recommend. Any ideas?
 
See how the car sits without the tube shocks on the rear.
Maybe they are extending the suspension....they shouldn't be there anyway. The suspension was designed for articulated lever arm shocks.
 
I removed the tube shocks. They were fully extended I did a half a&$ measurement and with the weight of the car on the springs, about 9 1/2 inches.
 
I tried some "uprated" springs on my TR250, I don't remember the exact part number or source, but they made the car sit way too high in the back, I swapped back to the originals before I even tried to drive it and they work fine, rear sway bar keeps things in check when I turn, and the stock springs give a nice ride and good ride height.
 
I think that I will go to the stock set up. Should I also change the front springs?
 
I would think you would probably want the front and rear springs matched, but I don't know if it is absolutely necessary, you certainly wouldn't want uprated stiff springs on one end, and softer stock springs on the other.
 
My bro is a bit of a self trained suspension guru. His thoughts are never change spring rate at*just one end of the car, that changes the "roll-couple" dramatically and can*create problems like snap-oversteer or plowing understeer.** Recognize too*that any upgrade to spring rate is necessarily going to require a stiffer*shock to control that spring rate.* Also realize that a Triumph was never a*model of chassis stiffness.* That chassis and body are pretty flexible by*modern standards.* Much stiffer springs, shocks etc. could bring out issues*with body flexibility.* There's a reason (beyond safety) that racing*Triumphs often had significant roll cages installed...it was to stiffen up*the flexi-flyer body.

Having said all that, I realize the spring rate you chose (350lbs) is considered stock for the TR6 and a fairly normal upgrade for the TR250. So, I'm not exactly sure why it's feeling so stiff. What was you original goal in going to new springs? Were the stock ones deficient in some way?

Bob
 
Bob
the car sat for 30 + years. I wanted a nice smooth ride, remember the 250 is my Wife's car. From what I read I thought that the "suplex" springs would be a nice extra. I have removed the springs and rechecked everything. I even removed the Monroe shock, and still very little flex. I think that I will order all new springs for stock. I think that the back of a 250 is supposed to be even or lower than the front end. Is it almost 2" higher in the rear. Thanks Bob&Glemon
 
Uprated springs even if they are the same uncompressed height as stock springs will not compress as much from the weight of the body
Stiffer springs need to be shorter and usually with just the thin packing, certainly not a spacer, though.
 
Put the originals back on and see how you like it. They probably weren't bad to start with. Then sell the new springs on E Bay. A friend of mine just the did the same thing on his 250.

Marv
 
Marvin Gruber said:
Put the originals back on and see how you like it. They probably weren't bad to start with. Then sell the new springs on E Bay. A friend of mine just the did the same thing on his 250.

Marv
Click to expand...
Yes, that is exactly what I did with mine, put the old back on and listed the uprated on Ebay, have been perfectly happy with the original springs for about 3 years now.
 
Oh how I wish I could reach back into the recycle bin and yank them back out. They are long gone........ Just ordered some from BPNW. I should get them on Monday.
 
Nobody mentioned the trailing arm brackets in all of this, at least I don't think they were mentioned. Buy a set of Good Parts brackets so that the alignment of the IRS can be achieved. Improperly installed brackets can have an effect on the rear ride height. As Marv said go back to the original springs, it's very unlikley they are bad.
JVV
 
I have removed the springs and shocks, the trailing arm moves freely up and down. No binding at all. I just pit 160 lbs of salt in the trunk, it lowered the rear 1/2 " and still feels very stiff..
 
i will let you know on Monday evening if the new springs from BPNW work. Thanks Marv!
 
Dan,

I'll be interested if they work - and part number too. I still have stock springs in my TR4A and was strongly considering the standard "upgrade" to TR6 springs. In fact, I had pretty much decided on the Suplex spring you chose. Only now, after this post, I am not so sure any more.

My ride height and feel with stock suspension is just fine. I do get the rear end squat under acceleration - which I just tell myself is part of the character of the TR4A. My only complaint is that if I am in a long sweeping curve (35+ mph) and hit a bump, the entire car hops towards the outside of the curve. Does anyone know if this would be solved by new shocks or by uprated springs?

Bob
 
For 20 years or more I ran with TR6 rear and original TR4A front springs in my 66 4A. 4A replacements were not available. Never an issue. However there are some "up-rated" rear springs on the market which result in the rear ride height being too high and a stiff ride. I suspect that's what you installed. Get rid of those as fast as the scrap man will take them.

Recently I replaced all four corners with GOODPARTS 1" lower springs which also have an increased spring rate. Frankly I cannot tell any difference in the ride. These cars never did ride all that softly. Doing this resulted in some small challenging alignment issues that were solved by using the GOODPART rear TA brackets and custom modified front upper A Arms. My point in all of this is if you are going to deviate from stock you will need to address some unique alignment issues as well.

For your desired results I'd suggest finding an original set of 250 springs or using TR6 springs (they may well be the same) and as I mentioned earlier installing the GOODPART TA brackets to give you the best shot at getting the rear alignment spec's correct.
 
RJS, that hop may well be caused by the half shaft sticking on the splines and suddenly releasing causing the car to hop to the outside of the curve. The bump releases the stuck spline. Common issue with our IRS cars.
 
Well, funny enough, I have the axle shafts out now. Last weekend I cleaned the splines and installed two new u-joints. This afternoon I hope to install the other two new u-joints, lube-up the splines (I picked up some Lucas Red N Tacky #2 grease) and get it all back together. Reason I am doing all this is to track down a clunk when I pull away in 1st gear.

Last time I lubed the splines was 4,500 miles ago when I had the differential rebuilt. I used a heavily fortified moly grease at the time (which I read may have a habit to dry out). The reason I had the diff rebuilt was...to remove a clunk in the rear end. The clunk was gone but, perhaps it was the rebuilt diff, the greased splines or both, which removed the clunk.

Anyway, sometime mid-season last year the clunk returned. I doubt it is the diff again after only 4,500 miles. Soooo, I suspect axle shaft splines are dry and need to be re-lubed combined with slightly worn splines and slightly worn u-joints. Heck, if all it takes to remove the clunk is to re-lube the axles every year or two then that's easy. And an added bonus if it remedies the "hop" I experience in a sweeping curve!

Thanks

Bob
 
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