Late X19 rear strut for the 128 front compatability

Karfrik

Albert
Been told I can fit late model rear struts in the front of my 75 128.If doable, what mods do I need to perform?.....
1)can I fit the 128 top base mount into this late struts and then just mount them?
2)or do I have to keep the late X19 mounts and then redrill the strut tower base to accept the later mounts stud spacing?
3)or cant it be done?.....

Thanks in advance.....
 
Problem is, only the early rear X struts have the phenolic washer etc that makes it suitable for steering!
So you need to change out the whole upper spring perch assembly.
 
Problem is, only the early rear X struts have the phenolic washer etc that makes it suitable for steering!
So you need to change out the whole upper spring perch assembly.

So would the 128 upper spring perch assembly fit a late x strut?

And what would be the feel without the phenolic washer?..harder steering?

Thanks Ulix!!
 
Yes, IIRC it does.

Steel would be turning on rubber.
You would be grinding away your top mounts in no time.
 
Yes, IIRC it does.

Steel would be turning on rubber.
You would be grinding away your top mounts in no time.

I need to get me a diagram to visualize the parts differences involved here.Specially the phenolic washer part........:confused:
 
Yes, IIRC it does.

Steel would be turning on rubber.
You would be grinding away your top mounts in no time.

So you are saying I can switch my 128 front upper perch assembly into a late x19 rear strut and it will work?
 
I can investigate over the holidays

I've got new rear struts to install on my '86 X when I am back in CA over the holidays. I can take some measurements and compare with the measurements I already have for the early X struts. I would think the later struts would work provided the thread diameter and shoulder height are the same. I always swap the 128 top mount parts over to the early X struts when I do the swaps so the phenolic (or better yet, Plaia pivots) are included so steering is not an issue.
 
I've got new rear struts to install on my '86 X when I am back in CA over the holidays. I can take some measurements and compare with the measurements I already have for the early X struts. I would think the later struts would work provided the thread diameter and shoulder height are the same. I always swap the 128 top mount parts over to the early X struts when I do the swaps so the phenolic (or better yet, Plaia pivots) are included so steering is not an issue.

I thought about swapping the 128 top over also as it makes sense,to me that's the only issue.I have couple friends that have had Yugos and they say they have done it even using the stock late X shock rubber mount by either redrilling the shock tower top to accept the late X mount 3 stud one.Or by just cutting one of the rubber base studs as the Yugo only uses/has 2 stud holes on the top.
Im in no hurry Courtney,so if you can take measurements during the holidays please remember to do so.Im concern about the strut piston diameter on top thou.Thanks!!
 
128 sedan bump stop assembly (top spring perch) will give insufficient travel before bottoming out if used on an x19 rear strut.... it's too long.

X19 rear strut isn't the best choice at all... a FWD strut relies on quite stiff extension damping to prevent the front rising under acceleration... I would doubt that x19 inserts (same front and rear) are designed for a stiff extension setting...

It will lower the car sure... but so will lower coils from a 128 coupe...here in Oz coupe spring is 7 winds (from memory) and thicker wire than a sedan spring (nine winds) so drops the front by around 2 inches and stiffens it up nicely... coupe bump stop fits straight on and gives sufficient suspension travel before the bump stop bottoms out.... and the damper rates on bump/rebound suit the FWD setup.

Late X19 rear spring perch/bump stop doesn't have a provision for the phenolic bush and the alloy dome has been integrated into the steel bump stop... it's not designed for rotation, so not suitable for the front end of a car.

Late struts are made differently at the top of the strut shaft...not having the thinner shaft diameter and steps required for the phenolic bush and the alloy dome...

128 alloy dome and steel cup are different to the x19 alloy dome and steel cup... the X alloy dome has a larger hole thru the middle, easy enough to drill out a 128 one...the top cup also has a larger hole in the x19 application... but hole is flat sided to grip the flats on the shaft (thicker shaft on x19) and the cup is hardened steel and doesn't drill or file out very well. Phenolic bush is the same for 128 and x19.

If you need a pic to visualise it, any 128 parts book will show what you want, all except the very first 128's (like the first few thousand units made) all use the same strut/mount/phenolic bush/dome etc

SteveC
 
Thanks a lot Steve for your imput on this matter.As weather and health permits im gonna put both the stock 128 fr strut alongside a late x rear strut and check on differences ,plus use Courtneys measurements as references.
 
Rear X Strut Dims

I measured up a late X strut today (new KYB) and put it in CAD to compare to the early Koni I had previously measured. Since I'm not at my shop I was limited to the caveman tools I left in CA (small metric scale and a 10' tape) but I think I got pretty close...

The tops of the shaft are definitely different. The late one would require machining to fit the early pivot components, or the pivot components would require machining. I don't have any 128 pivot hardware to measure at the moment but I'll knock that out when I'm back in NC next week.

The measurements can be found here:

Early%20vs%20Late%20X19%20Strut%20Top%20Dims.JPG



Steve, how prevalent is coupe stuff on your side of the globe? It's pretty tough to find in the US so X1/9 parts are about the best we can do. And now only late X struts are available, except custom solutions like Matt's. New rear X struts are definitely better than worn out 128 front struts ;) It would be interesting to see some damping curves for both. There are facilities local to me (NASCAR country) but I'm afraid to ask what they'd charge...

I should have both coupe and X19 bits at my shop to compare. I might have thrown out all my stock 128 sedan front struts since everything I own is lowered with X1/9 rears. I believe the 128 strut had more tube protruding above the spring perch so it was questionable whether a shorter spring and bump stop would work without the strut rod bottoming inside the tube. Thoughts?
 
Thanks Courtney,let me finally know when you get back to NC,and no rush.
Do you think the other alternative would be to mount the late X rear strut with late X front top mounts with bearings/bushings?...but then the 128 front strut upper mounting area will need to be redrilled to accept the late X upper top mount.Just food for your thoughts as you are the engineer here!!!......:grin:
 
Coupe and sedan front struts are the same, so fitting the lower coupe 7 wind springs and the matching shorter bumpstop is the factory solution... definitely doesn't bottom out the strut rod internally when the bumpstop hits bottom.

If you want early pre 1979 x19 rears I have a huge bunch of genuine Way assuto rears available... like about 60 struts NOS. :eek:mg:

Yeah a shock dyno of the different items would be nice ... you would need a bunch of NOS struts to test though to compare, on the same shock dyno, same day, same operator... and realistically when is that ever going to happen.

I think you will find what I'm saying is correct, generally FWD cars have stiffer rebound/extension damping to counteract the front end lift... which is why on a 128 with tired struts the first symptom is the front end lifting madly... not the struts weeping or the car bouncing.

Nice CAD btw... though the measurements I have put the lower mount holes in the same positions (with OEM way assuto struts - so the KYB's might be a little different)

Albert,

the strut shaft dimensions for ALL x19 fronts is like the early rear strut, the late rear struts different dimensions will preclude the use of the early front or rear bump stop/bush assembly... so you cant do it unless you have the strut shaft machined down....late rear bump stop assemblies (which will fit the late strut shaft dimensions) won't allow any pivoting motion, so are unsuitable for the steering end.

Machining the late x19 rear strut shafts is certainly possible and doable. You could modify your existing 128 bump stop assemblies by shortening them, that's quite easy as well, drill out three spot welds that hold the collar which the rubber bump fits into, then shorten the tube, and re attach the collar. Use the 128 front top mounts and leave the body alone, 128 mounts are a lot cheaper and easier to find than x19 ones.

SteveC
 
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sl coupe front springs

Hi guys I have followed Steve's advice about lowering my 74 sedan. I got a set of 7 coil SL coupe springs and recond shocks (As Steve mentions they are the same as Sedan) The new springs lowered the front of the car 45mm and the standard bump stops are fine even when hitting unseen speed bumps at way to high a velocity. I modified the strut bottoms to take 12mm camber bolts and am running about -.8 degrees on the front.
I lowered the back by having the original spring compressed and reset 40mm lowerand am running -2degrees rear with 0 toe in.
I am running 175/70 tyres on original rims. The handling is superb compared to the original set up and corners hard and flat without any compromise in comfort
 
Hi guys I have followed Steve's advice about lowering my 74 sedan. I got a set of 7 coil SL coupe springs and recond shocks (As Steve mentions they are the same as Sedan) The new springs lowered the front of the car 45mm and the standard bump stops are fine even when hitting unseen speed bumps at way to high a velocity. I modified the strut bottoms to take 12mm camber bolts and am running about -.8 degrees on the front.
I lowered the back by having the original spring compressed and reset 40mm lowerand am running -2degrees rear with 0 toe in.
I am running 175/70 tyres on original rims. The handling is superb compared to the original set up and corners hard and flat without any compromise in comfort

I think we then need AUS versions SL front springs....not same as US 128 i guess.Thanks
 
Sl coupe front springs

Actually I think all coupe springs are the same regardless of country. I am based in New Zealand not Aussie. We got the Euro spec cars ie better Cams and higher compression the Aussie cars are speced differently from ours.All I did was look for 7 coil springs rather than the 9 coils that I originally had in the sedan. The first I knew of the springs was off a posting on this forum so the springs are available in the U.S.

sorry I only have the pic from the posting I hope the author doesn't mind me reposting it


If your car has the longer USA spec sedan springs then I would say the 7 coil springs would lower it a lot more than my car that was running the shorter euro spec sedan springs
 
Actually I think all coupe springs are the same regardless of country. I am based in New Zealand not Aussie. We got the Euro spec cars ie better Cams and higher compression the Aussie cars are speced differently from ours.All I did was look for 7 coil springs rather than the 9 coils that I originally had in the sedan. The first I knew of the springs was off a posting on this forum so the springs are available in the U.S.

sorry I only have the pic from the posting I hope the author doesn't mind me reposting it


If your car has the longer USA spec sedan springs then I would say the 7 coil springs would lower it a lot more than my car that was running the shorter euro spec sedan springs

So we got 10 coils in USA!!!....OMG,....why?:sigh:....
that's a great picture!! and im saving it for future references.Now let see whos got 128SL 7 coil springs laying around.Thanks much!!!
 
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