TR4/4A Lowering front of TR4

[TRMark]

Recently someone made a post concerning shortening the distance pieces on an early car and its ratio to lowering the car. If I remember correctly, shaving the distance piece 5/8" lowered the car 1". Is that correct? I used search and could not find the post. Or is old LBC odor getting to my soon to be Buick brain.

 

[TRMark]

Found it. Not on the Forum, Tuning Triumphs by David Vizard.

 

[Alan_Myers]

Hi Mark,

I think you are pretty close to the right number... 5/8" lowering at the coil spring should lower the car about 1". (At the rear, 1" spacer will give 1" lowering, due to the leaf spring setup.)

Besides trimming the spacers, there are a number of ways to lower the front of our cars.

For example, swapping to the competition or heavy duty coil springs will lower the front of the car about 1" too. The ground clearance at the front on my TR4 is presently 5" (as compared to 6" with stock springs, per factory manual specs), with the only change so far being the springs. The HD springs are fitted along with the original alu spacers, too, and are actually easier to install because just a little compression is needed to fit them in place. I've got a set of spacers that have been shortened to about .75" thick, but I think that might be too much for use on the street, would lower the car to around 3.5" to 3.75" ground clearance!

TRF is now selling several different thicknesses of aluminum coil spring spacers that might be useful. (See https://www.zeni.net/trf/TR6-250GC/70.php?s_wt=1024&s_ht=768 ) They list them to raise the ride height, but of course they would lower the car if used as a substitute for tall stock alu spacers on our cars. Stock spacers are 1.25" thick. TRF's are 1", .75" and .5" thick. I'm thinking I'll try 1" thick spacers, either from TRF or by machining down another spare set I've got. (Note: TRF also offers similar spacers for the coils at the rear of IRS cars.)

In his book "Improving TR2-4A", Roger Williams mentions several times that the lower a-arms of the front suspension can be pretty easily inverted to lower the front of the car, too. The difference is about .66", so should also translate into about 1" ride height reduction. *However*, one thing Williams doesn't mention is that inverting the a-arms will also lower the bump stop .66", and that will effectively translate into a lot of increased upward travel for the front suspension. Unless something else is done - installing a taller bump stop or moving the bump bracket on the shock tower - I'd be concerned about over-extension of the front suspension/steering joints, bump steer or possible tire clearance issues. I'd also worry about using the shorter HD springs with this setup, since they would have little or no compression with inverted a-arms and just might jump off their seats over a hard bump.

With the current setup, I don't appear to have tire clearance issues. That's with 195/60x15" Goodyear Eagle HPs on KN Minator wheels (5.5J). The overall tire diameter is about 24", or roughly .5" to 1" smaller than original equipment tires. These tires are considerably wider than original and the tire/wheel combo puts them just barely inside the lip of the fender at the top of the wheel arch (no wheel spacers are installed).

The rear suspension of my car will be spaced also, eventually. Some custom made shims will be needed: 1.25" thick is a likely starting point. This is with heavy duty/competition leaf springs fitted and will require special U-bolts for mounting, as well. I'm pretty sure rear spacers would be different with stock rate leaf springs. When I bought the car way back in 1977, it had 1.5" spacers. But IMHO that lowered the rear way too much with stock leaf springs, so I switched to .25" spacers.

I should note that the HD/competition coil and leaf springs are pretty rigid! I'm sure they'll make for a fairly coarse ride once my car is back on the road. At the front, pushing down on the fender hard gives almost no noticible bounce (there is also a 3/4" sway bar installed on the front). At the rear, the HD leaf springs give a little, but not much!

Hope this info is helpful.
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[TRMark]

Thanks for the reply, Alan. The link to TRF was helpful. I have heard of the lower A arm trick but was not to interested, even less after your discussion of the bump problems that might result. At the rear, I installed the later type leaf springs with spacer, the old ones had sagged quite alot in the last 30 years, that and the wife and I aren't as skinny as we used to be. I will post up some stuff about leaf springs later. I am running Kumho ECSTA 195-65-15 on 5 1/2 inch TR6 rims. I love them, close to original diameter. Remember the skid plate posting about a year ago. I am still thinking of installing one, could smash the road kill before going under the rest of the car. /ubbthreads/images/graemlins/grin.gif

 

[trfourtune]

alan,
are those 450 lb springs up front you have? are they the same rate left to right or are they different to account for driver only weight inbalance in the car? let us know what the ride is like when you get it on the road.
rob

 

[Alan_Myers]

[ QUOTE ]
alan,
are those 450 lb springs up front you have? are they the same rate left to right or are they different to account for driver only weight inbalance in the car? let us know what the ride is like when you get it on the road.
rob

[/ QUOTE ]

Hi Rob,

I don't have any means of measuring the spring rate to be certain, but when I bought them I think they were rated at 380 lb. That's as compared to the original, stock springs at about 310 lb.

No, I don't have different rate springs installed up front. I figure I'll just always be sure to have a cute co-pilot along to balance the load... and I'm relocating the battery behind the passenger seat to compensate for the fact that she'll weigh significantly less than me. /ubbthreads/images/graemlins/cool.gif

Seriously, I suspect if I ever get to that level of chassis tuning I'll probably be converting to a more easily adjustable coil-over setup anyway.

The current coil springs are the competition/heavy duty grade, measuring just over 9" out of the car. That's compared to the stock springs that measure just under 10". In case I didn't mention it earlier, both type springs are fitted *with* the alu spacers. (The later 11" stock rate springs, post CT30000 approx., are fitted *without* the alu spacers. Those are just a very slightly higher rate than the shorter springs, I believe. Maybe a couple lbs. There are comparable "long" heavy duty replacement springs available for use without the spacers now, but there weren't back in the day.)

I might do some differential shimming side-to-side at the rear leaf springs, once I check the car out on chassis scales (lots of other work to be done first, though).

I found it a bit interesting though, that the car was sitting low in the front and high in the rear when it was "unladen". I thoiught I was looking at quite a bit of rear shimming to get it balanced. But, once I tossed the spare tire and a box of parts in the trunk, the car is sitting close to equally level front-to-rear. Plus, I have an old Group 24 battery sitting behind the pass. seat and a few things stored on the parcel shelf right now, but have removed the old "street" roll bar.

My point though is that it really didn't take much weight redistribution to significantly change the car's stance, even with competition/HD springs at all four corners. I imagine with a full tank of gas it would sit quite close to level, front-to-rear. So, I may have to rethink the shimming at the rear and any additional lowering at the front. That really shows me the importance of what the factory manual tells you to do, to be sure the suspension is "normally laden" before finally setting up the suspension, even to the point of adding weight to the driver's seat.

Before I lower any more at the front, I want to temporarily remove the springs, reinstall the tires and wheels and check out the limit of upward travel at the fenders and around suspension components, to double check that I don't have *any* clearance issues with the wide tires.

Oh yeah, when I get it back on the road, you can bet you'll hear all about it... after a 20 year hiatus! (I've never been one to name my cars, like some folks do. But am thinking in this case that "Rip Van Winkle"... "Rip", "Rippie" or "Ripper" for short, I suppose... might just be approptiate.)

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