Body height FHC vs DHC

[nick]

I finally decided to answer this question definitively. Why are the body heights different between the FHC and DHC? My premise has been that the two body styles differed only so far as the roof. And that to get a drop head they just chopped of the roof and faired it in. So to prove this premise I swapped the springs between the two cars. And to my amazement the body heights did not change. The FHC remained about 3/4" higher than the DHC. Actually I wasn't amazed. During the swap over I started to suspect that rear body frames, where the springs are seated, are at different heights relative to the top of the rear fender. So with the same springs the FHC will always sit about 3/4" to 1" heigher.

Now if I could only figure out why the front springs on the FHC seem so much stiffer than on the DHC I'll be in business. Some people may say I have too much time on my hands.



[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC

[Hasbeen]

Nick I remember reading somewhere, many years ago, that at some stage they changed the ride height of the US cars, raising them by about an inch.

I have had a similar experience to you on rear ride height, but all with FHCs. My present car sat about 1.3 inches, at the rear bumper, higher than the other 2 I had at the time. Even after having the free height of the springs set as low as they could be, without falling out, the car still sat a bit higher. I can't remember the heights, or the wheel arch measurements, but it was noticeable, even after the springs were shortened.

I'd check the front springs for wire diameter, a PO may have fitted stiff fronts. It is often impossible to understand what some POs were thinking.

It could easily be your shocks too. With the adjustable on the 8 the fronts can be set from almost not working at all, to so hard you think the next pothole will rip the fenders off the thing. Who knows what some PO may have fitted?

Hasbeen

[Workshop Help]

You boys out there really do need to step & fetch a factory parts manual. It makes for some very interesting reading.

The TR7 front springs were changed over the years has evidenced by different parts numbers. For cars prior to VIN ACW7001, the front spring part # is TKC 1329 for air conditioned cars and TKC 1328 for non A/C cars. From VIN ACW 7001 to ACG 25001, ACW 300001, the part # is TKC 3455 for A/C cars and TKC 3454 for non A/C cars.

The rear springs on the TR7 used part # TKC 2404 up to VIN ACW7001. After VIN 7001 they used part # TKC 3300.

This all translates to the early cars prior to VIN ACW7001 had higher springs front and rear by about an inch. For the 1977 model year, the springs were lowered about an inch. However, by using the 185/70-13 tires which are a bit taller, some of that inch was lifted to maintain U.S. regulations for bumper and headlight height.

Time marched on. Over the years, it is normal for the effects of gravity, spring tension, and flexing for springs to settle a bit. Then there is that disgustingly bad habit of human beings to want to improve on perfection, so new springs that are shorter, or taller, or stiffer, or softer are installed. Then there is the possibility of A/C springs sold as non A/C springs. Or, maybe the new springs were inferior and sagged after two weeks on the car. All these factors can alter the ride height and ride quality of the car.

Is there a part # on the factory springs? Not that I have noticed. The same with dabs of paint seen on other cars springs, I've never seen any.

So, where does this leave us? It's giving me a confusing headache.

Mildred Hargis

[FI Spyder]

My original springs had red paint dabbed on them (even had the original "chalk" marks on the lower link) as evidenced in the pictures below. According to "The Untold Story" when first introduced the car sat very high to get the suspension travel they wanted plus you could see right through the rear wheel wells to the other side. The Automotive journalists thought this looked very strange so they welded in some sheet metal on the inner rear wheel wells and lowered the suspension about an inch. Not sure when this happened but fairly early on.







- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[nick]

Mildred dear, while appreciate all the research you did on the various production models you must have missed the details of my previous post. Perhaps your glasses were soiled from a day of working in the machine shed. Let me reiterate. I measured the cars' heights and swapped springs from one car to the other. Then I remeasured the cars with the same calibrated steel tape. The conclusion was that the heights had not changed on either car. The FHC is a 1976 and the DHC is a 1979. There has to be a difference in body construction or the DHC is heavier by more than 150lbs in the rear. That's pure science.

Hasbeen, I have changed the front inserts in both cars and they are the same brand, KYBs. The FHC came with AC therefore it has a spring that has 5.5 working coils and 2.4mm taller as opposed to non AC which has 5.25 working coils. That is not a lot of difference. Both cars are at the same height in the front but the FHC will knock parts off when rolling over a rough road. Both cars have good tires and running about the same pressure. Both cars have new front bushes and ball joints.

Spyder, I have three sets of rear springs. 76 FHC has red and white paint. 79 DHC has red and white paint and 80 DHC no paint. All of them measure to the same free height and all of them hold the cars at the same height. Of course I can't say if all of these springs came as original with each car.

[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC

[Workshop Help]

Yes, fogged over bifocals do blur one's vision. Here's a couple of questions, do both cars have the same tire height? So, the coupe came with A/C, how about the convertible?

I'd say that anyone who engages in a rear spring swapping party deserves a whole lot more appreciation from their spouse than the usual amount.

Mildred Hargis

[nick]

[quote]<i>Originally posted by Mildred</i>

Yes, fogged over bifocals do blur one's vision. Here's a couple of questions, do both cars have the same tire height? So, the coupe came with A/C, how about the convertible?

I'd say that anyone who engages in a rear spring swapping party deserves a whole lot more appreciation from their spouse than the usual amount.

Mildred Hargis
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Essentially yes. The DHC is on 195/60-14 and the FHC is on 185/70-13. The below tire size calculator says they are both 23.2 in diameter. The DHC has no AC. The FHC came with AC but is removed at the moment.

I rather doubt that the DHC weighs so much more that it would drop the rear by 3/4". I also checked to see if the quarter panels are the same by measuring from the top fender crease to the bottom of the panel behind the rear wheel. Identical. Any way I slice it it comes out that the spring pad on the rear frame has to be a shorter distance to the ground on the FHC.

http://www.miata.net/garage/tirecalc.html

[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC