TR4/4A TR4a live axle - Height adjustment

[richie]

After much digging around, I have made the conclusion that there are effectively three ways most people adjust the rear ride-height on live axle TR4's/TR4a's: Custom shackles, spacers installed between leaf spring and axle and lastly, having the leaf springs modified by a specialized shop.

After much digging, I haven't found any references to any compatible spacers or custom shackles and was wondering if there are any racers or restorer's here which have gone down this road and might be able to share some wisdom on the "better" way to do this!

The goal of my height adjustment is to level the wheel gap front & back. I will be replacing the front suspension with SPAX & moss euro/rimmerbros "uprated" front springs and would like to then match the rear to the front.

Thanks!

 

[tdskip]

Guys - any ideas for Riche?

 

[PeterK]

Here's a race car with big lowering blocks :
https://home.myfairpoint.net/kentech0822/triumph/spring_blocks.jpg

I made these https://home.myfairpoint.net/kentech0822/triumph/blocks.jpg blocks 1" thick to lower my 4A but it is not on the road yet. Mine fit with replacement u-bolts from Moss; no extensions were needed.

(note the rollbar attachment point to the frame)

At the front I have TSIs 20% stiffer 1" lower springs without using the aluminum spacers. Might haveto do some tweaking after it's all said and done.

 

[richie]

PeterK: Thanks! Any way to make some more of those blocks?!

As for your front springs, are those TSI springs uprated as well? Any shots of the ride height?

Thanks again,

 

[PeterK]

Photos would be of no use since the body is off and drivetrain is out.

I can make the blocks for you, PM me. Those in the photo are 1" thick.

and yes the springs from TSI are 1" drop 20% uprated.
https://www.tsimportedautomotive.com/tr3_tr4a.html

 

[Willie_P]

Go to Speedway Motors and get their alloy lowering blocks. Really nice and really well priced. They are slightly wider than the stock leaf springs BUT with a drill press, I was able to make semi-spherical grooves to accommodate the longer and WIDER u bolts I used (which I got from a local trucking supply shop). they are truck shackles and a heck of a lot nicer and better quality than the Moss stuff.

Speedway has many different thicknesses. I went with 1&1/2" blocks. Also, the Speedway blocks have the centering holes on them that match the studs in the center of the TR springs (I needed to widen them just a hair to fit the TR stud) and also the are MALE studded on the reverse side to match the female receiver on the bottom of the axle tube.

wp

 

[Willie_P]

Can someone else comment here; after looking at the photo of the "race car with big lowering blocks" as provided by PeterK - it appears that there are severely arched springs in use there which require the use of the lowering blocks to locate the axle.

...as opposed to what us more "pedestrian" drivers are looking to do - go for stance mainly and just use lowering blocks to get that stance, but with stock springs.

it could also just be the camera angle that makes those springs look so very arched. -w

 

[TR3driver]

Can someone else comment here; after looking at the photo of the "race car with big lowering blocks" as provided by PeterK - it appears that there are severely arched springs in use there which require the use of the lowering blocks to locate the axle.

They are arched a lot more than the earlier springs, that was a production change during the TR4 run. Moss catalog gives CT23383, but I thought it was later than that. The "lowering" blocks are visible just above the spring leaves, looks like there are two of them each about 1/2" thick. But the block above that appears to be the original spacer block, which was some 4" or 5" tall and incorporated an attachment point for the shock link.

Live axle 4As used a similar setup, but the springs were a slightly different length and spring rate as I recall.

The factory made spacer blocks from spring leaves, just stack them up on the center bolt. You'll need a longer bolt though, if you try to go more than 2 thicknesses (about 1/4"). Or it shouldn't be too hard to find spacer blocks at your local hot rod/off road shop, but I'm guessing they would be too wide and need to be cut down for the bolts to pass.

The main point is that the axle needs to be positively located to the spring, not just rely on friction. The original, early setup had the head of the center bolt protruding into a hole on the spring pad welded to the axle. If you add spacers, they need to either fit over the center bolt and protrude into the spring pad; or use a longer center bolt that still protrudes into the pad. PeterK's approach of using a SHCS looks good, but only if the blocks are thick enough to hold it. And I would want to be certain that the head of the SHCS didn't bottom against the axle tube if using them on an early setup. Might need to grind it down a bit if it does.

PS, Don't forget that the suspension has a fairly limited range. Lowering by 1" is probably about the limit without having the axle hit the straps all the time. Another way to get the car "down in the weeds" is to use smaller diameter tires, but of course that introduces other issues like speedometer accuracy. My current plan is to install 3.45 gears (from a PI TR6) which should just about compensate for my shorter tires.

IIRC, this shot was with 195/50-15 on the front, and 205/60 on the rear: