Helping a sprite turn into a 3 month DD

[saabmp3]

Hello all,

About a year ago I bought a great condition (or so I think) 68 Sprite Mark IV out in WA. I had a chance to drive it around on sunny days for the summer but then was forced to put her in storage while I came back to NY for the winter. While I had the sprite in WA, I also had my primary car (lovely Saab 9-3 hatchback) to do the bulk of my transportation.

Now, coming up in a couple months I'm going to have to go back to WA to work for roughly 3 months. My Saab is going to stay on the east coast (too long of a drive for only 3 months) and my Sprite is going to have to become my primary form of transportation. I'm looking at perhaps a 5 to 10 mile commute to work with the occasional grocery trip. Nothing will be over 25 miles and I plan on putting on less than 2000 miles over the entire summer.

Now, for the current condition of my beauty. The engine seems to run fine, I've noticed a small oil leak (when I was putting her away for storage) dripping onto the floor, but I won't know how much until I get back there. Of note, the oil leak was after a roughly 40-50 mile drive to the storage location. While I was taking this drive, I found that the tranny tunnel cover was getting pretty hot, I'd say basically hot enough where you wouldn't want to keep your hand on it. The top speed that I can push her is around 50mph, and that's going at 4500 RPM on the tach (which I'm inclined to think is right, just based on engine noise and the likes). The roof has a hole in it (right next to the window on the drivers side rear), but the support braces for the roof are in excellent condition. The spedo does not work. I think these are all the problems (off the top of my head).

What I want to do is turn this vehicle into a daily drive for the three months while I'm going to be in WA over next summer. The weather there is nearly perfect during the summer months, so I'm not anticipating that it'll have to go through the rain for more than 10 days total. The advantage to making this my DD is that I can spend the money I would have spent on a beater car fixing the sprite up (something that I want to do anyways).

Now on to where I'm hoping for some input. The biggest problem with the Sprite is the fact that it tops out around 50 MPH, which just isn't fast enough for (safe) occasional highway driving. I'd like to drop out the tranny and replace it with something with an overdrive in the least. If I can smooth out the gear box, that would be great as well. I'm also hoping that when I replace the tranny, I'll fix the spedo at the same time. What kind of equipment do I need to look for in this kind of job. There's a shop in the Tacoma area which specializes in british cars, so I'd like to have some good information before I go talk to them about this (I'm not going to attempt a tranny replacement on my own). I don't want to lose the vintage appeal of the car, but I think it's best in this case to go for something newer (maybe from a junk yard). What kind of trannys will fit into the Sprite and what kind of money am I looking at to put one in? Will I have to replace the clutch with a different type at the same time? The previous owner of this car put a new clutch in under 5000 miles ago.

What other improvements do I need to make this into a more reliable DD? I'm going to replace the Lucas electronics at some point, but as they're working now, I don't want to mess up a good thing. Is the suspension safe to drive on the highway at 65-70? Are there any other safety improvements that I should make (which can be done in minimal time).

After the importance of safety, are there any other reliability improvements that I can make so I don't get stuck riding a bike to work 5 days a week?

Hopefully that gives enough to start. I tried searching the boards, but couldn't come up with what I'm looking to do.

Thanks,

Ben

 

[ChrisS]

Take a look at https://www.britishcarforum.com/ubbthread...;gonew=1#UNREAD There are essentailly two kits out there, the Rivergate and the Morriservice. Morriservice is in Oregon so that may be better for you. They both use a Datsun 5 speed with OD. I've emailed Paul at Morriservice and got a good feeling about his setup. He uses the datsun pressure plate and modifies the flywheel, rivergate uses the datsun clutch disk, but the original pressure plate. He can explain his reasoning. I don't have the same vintage car as you so I can't comment on the suspension, but I put 4000 miles on my '73 last year with no issue.

 

[msoylemez]

Yes, ChrisS is right--the Datsun 210 will work for you with some mods (adaptor plate). Also, just saw on ebay today a guy who has an extra Datsun 210 tran--$250-500 is about right for a decent one. Plan on another $500 for the adaptor and install.

https://cgi.ebay.com/ebaymotors/1967-Aust...029376369QQrdZ1

 

[saabmp3]

Wow, thanks for the quick replies on the kits. There was one more question that I wanted to throw in there that I didn't. Is there any market for my old tranny? I wouldn't have any need for it after the conversion obviously and I'm assuming that most people still use it for their current vehicles?

Ben

 

[Trevor Jessie]

I think a '68 should have a 3.9 rearend and a 1275 engine. If the front suspension/tires/brakes/steering are in good order then it would be fine for 65 mph blasts on the Highway without a 5 speed (My '70 midget did well). However, I did change to a 5-speed and it is much nicer. But I would put time and money on making sure the suspension/tires/brakes/steering are in good order first.
Just my 2 cents.

 

[Trevor Jessie]

Not a huge market for those transmissions. We've seen a few on ebay converted to bar stools, and they brought more money than used ones.

 

[SilentUnicorn]

[ QUOTE ]
Not a huge market for those transmissions. We've seen a few on ebay converted to bar stools, and they brought more money than used ones.

[/ QUOTE ]


really /ubbthreads/images/graemlins/ooo.gif........hmmmm

mark

 

[Bugeye58]

I've got essentially the same setup in a '74, 3.9 rear gear, and a stock tranny, and I can run all day long at 75 MPH. Or better. Even if it has the 4.22, you should be able to run much faster than 50. I run a '65 1098 with a 4.22, and never had any problem keeping up with traffic on I-80 around San Francisco. That car has seen the plus side of 90 more than once.
Jeff

 

[spritenut]

Your Sprite should go 65-75 in stock form with no problem.
If it maxs out at 50 mph, you may have the wrong diff in it.
Like a Morris truck diff in the 500 range. It may be worth big bucks to some racers or autocrossers.
As for the used tranny, if you go with Paul at Morriservice, he may buy your old tranny from you. He is the Spridget/Morris tranny guru and a nice guy too.
Give him an email Paul Asgeirsson <pasgeirsson@worldnet.att.net>

 

[saabmp3]

So, it looks like I might have a problem with my rear end if it's revving so high just to get to 50 mph? As I'm totally unable to access the car at the moment, I can either assume that my tach is totally off (and my ears are a little wack as well), or that I do have a replaced diff. When you say big bucks, what are we talking about there, just out of curiosity.

On a note, the first thing I thought when I started driving the car was that it accelerated incredibly fast. It also was repainted from orange to candy red, I'm assuming to cover up rock dings from racing. I wouldn't dream of approaching 80 with it, even with an inaccurate tach, the engine would shoot a piston out of the bonnet.

Although I can't find prices on the Morris kit, the Rivergate one seems to cost 895 for the deluxe EZ kit and 595 for the standard kit. I don't mind reusing my driveshaft, but if I have to purchase a new clutch and weld the gearshift lever (totally out of my tool range), then I think the deluxe kit is what I'll need. Then I'm figuring around 400 for a new tranny. If I have to replace the rear diff, what am I looking at there to get the stock one back?

On the rear diff note, does anyone have any experience with a modded rear diff? Should I start thinking about other "race" modifications that have been done over the life of the car?

What kind of tools will I need to do this work? I'm going out there with absolutely no tools at all. Every I need to do this work I'm going to have to borrow (aka wrenches) or buy (like an engine hoist). I'd consider myself a shade tree mechanic, so pulling the engine sounds like the edge of the work I'd be willing to do out there.

Summarizing, 895 for the kit, 400 for the tranny, ?? for a new diff (I want to count that in the cost at the moment and if I need to buy a new one, I'm going to sell the old one) - ?? selling the diff + tools/install labor = what? If I start approaching the 2k mark here, this isn't financially worth it for 3 months of service (as it's only a 2 seater). Can anyone whose done this comment on total price (I'm talking everything here)?

I have to admit, I wasn't expecting the speed of responses that I've received so far, I want to thank all of you for this help!

Ben

 

[jlaird]

Something screweeeee here. Bugeye should do 72 MPH down hill with a following wind. Sixty, sixtyfive is fine all day.

It is not the transmission, rear end maybe, but never heard of one that would only let you go 50.

Think I would check spedo and tach first. Spedo easy have some one follow you.

Rear ends easy, no big deal, wonder if it is locked as well if it was a race car? Do the rear wheels/tires scuff and scrape when you go around corners? otherwise, jack one side and see if you can turn the wheel.

 

[ChrisS]

Attached is a table with the three stock Spridget differential rations and different tire sizes, all at 4500 RPM, showing what 4th gear speed should be. In order to be doing 50mph at 4500 rpm with stock tires the rear differential ratio would need to be 5.9:1. This seems very high to me, even for a race gear. I would suspect that either the tachometer or speedometer or both are off.

Chris

 

[vping]

Put the tranny in the belly of the plane. Someone in Farmingdale NY might have a use for it. I wonder who? /ubbthreads/images/graemlins/devilgrin.gif

 

[Matthew E. Herd]

If you don't have the right rear end gear for your year (most likely 3.90), it's easy to check. Unbolt the driveshaft from the differential (there's a flange with 4 bolts). Then spin the flange on the differential (with one wheel in the air. Then count the number of times you spin the differential flange and the number of times the wheel rotates. If only one wheel is in the air (and the other fixed by being on the ground with the car blocked so it cannot roll -- a critical safety item), it should rotate as follows:

Differential Flange Rotations * 2 = Gear Ratio * Wheel Rotations

(I think I've got that right). At any rate, just changing the rear gear to a 3.9 or 3.73 would greatly reduce highway revs. Do you know if the car has been 'raced'? Generally it's easy to tell by a large diameter exhaust and other non-stock components (another owner could probably tell inside of a minute). It's reasonably unlikely that it was indeed raced, as it would generally require a full roll cage, etc. More likely your previous owner (or one awhile back) simply preferred acceleration over top speed, so he changed the rear end to something very high. Getting the car working by getting functional instruments, replacing the top, and changing the rear (a fairly easy job) will probably set you back plenty without bothering with the 5 speed swap (not necessary for occasional highway). Jeff (Bugeye58) drives these beasts on the highway all the time, so I don't think there's much to worry about. Yes I know, it may get a little hair-raising if you're used to overdrive, but you will get used to it in time. /ubbthreads/images/graemlins/smile.gif

BTW, how much highway do you really plan on driving? 20 miles in my 3.9 geared autocross car (which is very loud and not very comfortable to ride in due to the stiff suspension) at 65 mph isn't unbearable. 55 miles and below is pleasant (esp. on country roads, as opposed to divided highways).

 

[GB1]

Just a quick little item, it maybe as simple as low transmission oil, noise\heat and a bad tach.

I agree with the others, that would have to be one heck of a rear end ratio.

 

[saabmp3]

[ QUOTE ]
Think I would check spedo and tach first. Spedo easy have some one follow you.

[/ QUOTE ]

Well, to start, my speedometer doesn't work at all, but I know for sure the 50mph mark from a following car. This was at a supposed 4500 RPM on my tach. Now, on to the tach, at idle I'm running around 900 RPM (which I figured was a little high buy normal). I have no proof that it's right, but I am positive that it's close (think within 1000 RPM).

[ QUOTE ]
Attached is a table with the three stock Spridget differential rations and different tire sizes, all at 4500 RPM, showing what 4th gear speed should be. In order to be doing 50mph at 4500 rpm with stock tires the rear differential ratio would need to be 5.9:1. This seems very high to me, even for a race gear. I would suspect that either the tachometer or speedometer or both are off.

[/ QUOTE ]

Well, I did something smart for once. Before putting her up for storage, I wrote down the tires and took a picture of them. I'm running Firestone 155/80R13's.

[ QUOTE ]
Do you know if the car has been 'raced'?

[/ QUOTE ]
No, I don't, it was just a suspicion when I bought it.
[ QUOTE ]
Generally it's easy to tell by a large diameter exhaust and other non-stock components (another owner could probably tell inside of a minute). It's reasonably unlikely that it was indeed raced, as it would generally require a full roll cage, etc.

[/ QUOTE ]
The exhaust is stock (chrome cover, about 1.5inch diameter pipe), and it doesn't have a roll cage.... I guess that's a blow to the racing theory, which I wasn't a fan of in the first place anyways.

However, as far as I remember, when adjusting the rear drums, I noted that the rear wheels were locked. I was very surprised about this at the time.

The 5 speed conversion idea is a means to the end, not the end result in of itself. If I can survive on the highway without it, then that much the better. As long as I can a) count on it to start (haha), b) keep up with traffic on I5 c) feel somewhat safe in it, then it's a success for me.

Ben

 

[Trevor Jessie]

Has anyone mentioned a slipping clutch?

 

[Matthew E. Herd]

No. A slipping clutch hasn't been suggested as of yet.

Since (like I originally suspected) you admit that you're only seeking a means to an end, I believe it's probably more cost effective (and faster) to avoid a 5 speed conversion, and the end result should be adequate (if not precisely comfortable when cruising at 65+). I'd suggest the following steps:

-Confirm rear-end ratio by the manual spin and see method.
-Measure Road speed at an engine RPM
-Check that the tach. RPM is correct
-Calculate road speed based on the measured gear ratio per 1000 RPM (in top gear -- 1:1 ratio), compare to measured road speed.

If these two numbers don't match up, you have a transmission slipping problem. A good mechanic may be able shorten this process, but I'm trying to give you a methodical checklist to go through to make sure your transmission/rear end is functioning properly and figure out what gear ratio you have.

 

[jlaird]

Ho ho. It is a locked rear end.

Guys, would that make things a bit hot? I know it puts a lot of strain on axels and such. As it is a locked rear end I would suspect that it is a very quick ratio as well. Just the thing for parking lot raceing I would expect.

 

[Matthew E. Herd]

What makes you think it's a welded rear? Nothing thus far has supported that theory, as far as I can tell. Even so, it wouldn't change highway RPMs if it were.

As far as the racing bit, I sincerely doubt that it was raced if it's running 155 anything tires! I happen to know that the smallest DOT legal street tire that one can buy in a 13" wheel (there may be smaller for Mini 10" wheels) is a 175/60R13 from Hoosier, Yokohama, and Kumho. If someone had a different set of wheels with race tires, it could have been autocrossed without any changes to the car. Remember, however, that people DO modify their cars (and don't race them)!

Lets approach this problem as one of two possibilities:
1) a mechanical (or instrumentation) fault
2) a VERY high final drive ratio

Lets not cloud the issue with idle speculation. Even if it was raced, it has no real bearing on the issue that the car seems to scream at less than highway speeds.